Merge updated item and helper work into mob groundwork

Co-Authored-By: Codex GPT-6.1 Terra <[email protected]>

.github/trusted-reviewers.txt

@@ -13,4 +13,3 @@
 87152661 rdbtCVS         # added by Ludovic, 2026-10-27
 84875247 Online5277      # added by Ludovic, 2026-10-27 (his top three by merged pull requests)
 86072227 levzzz5154      # added by Ludovic, 2026-10-28 (Horizon Team; author of horizon-mixins)
-169198624 itarqos5        # added by Ludovic, 2026-11-08 (Discord Literal; Horizon Team)

.github/workflows/runner-watch.yml

@@ -0,0 +1,34 @@
+name: runner watch
+# Every 30 minutes: one issue when jobs wait over 2 hours for a self-hosted runner nobody runs (the maintainer's
+# machines are off), closed again once nothing waits (tools/ci/runner_watch.py, docs/operations.md). It runs on
+# GitHub's runners, never ours: it must work when every self-hosted runner is gone.
+#   gh workflow run "runner watch" -f dry_run=true
+on:
+  schedule:
+    - cron: '11,41 * * * *'
+  workflow_dispatch:
+    inputs:
+      dry_run:
+        description: Only print what it would do with the issue
+        type: boolean
+        default: false
+permissions:
+  actions: read
+  contents: read
+  issues: write
+concurrency:
+  group: runner-watch
+  cancel-in-progress: false
+
+jobs:
+  watch:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          persist-credentials: false
+      - name: Jobs waiting for a self-hosted runner
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: python3 tools/ci/runner_watch.py ${{ inputs.dry_run && '--dry-run' || '' }}

AGENTS.md

@@ -20,6 +20,13 @@ Feature → files → harness for the most-changed areas: [docs/architecture.md]
   is the GitHub account the PR is opened from (`gh api user --jq .login`). Issues say "Filed by", reviews
   "Review by". Every comment starts with `🤖 Agent:`. Write only as the person you work for: the lines on
   this page that name Ludovic are for his own agents (account `ludovic111`), never for anyone else's.
+- **Review only when asked, and decide.** Review a pull request only when its author or a maintainer asks.
+  Asked by a maintainer to review open pull requests in general, take them one at a time, oldest first, skipping
+  drafts, your person's own and those they already reviewed. Check that the change does what it says (bugs, edge
+  cases), what it could break, whether tests cover it, and whether its scope and description hold up. Report only
+  what you can point to with a `file:line`, each point marked Blocker (fix before merge), Important, Nit,
+  Suggestion, Question or Praise. Submit a decision, never a plain comment: `gh pr review --approve` when nothing
+  blocks, `--request-changes` when something does.
 - **Attribution.** Commits end with a `Co-Authored-By:` line for the agent that wrote them, and PR bodies
   with that agent's own "Generated with" line. Example, Ludovic's agents (Claude Code on `ludovic111`):
   first line `> 🤖 Opened by Ludovic's AI agent (Claude), not by Ludovic himself.`, commits

CONTRIBUTING.md

@@ -198,3 +198,5 @@ new pushes, we add it again.
 
 [Discord](https://discord.gg/playhorizon) for questions and ideas, [issues](https://github.com/horizon-rust/horizon/issues)
 for bugs. To take something on, `/claim` its issue ([above](#claim-before-you-start)).
+
+How Horizon is run, and how people join the Team or lead a group: [GOVERNANCE.md](GOVERNANCE.md).

Cargo.lock

@@ -706,6 +706,25 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "622f3fc73690be383c7214310406f28a90e6edeadc3cea882f9d71e495b9711a"
+dependencies = [
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc74980687109a3b14c72fd458107bf0baa1da1a1a805e178d15501ba9b86d9d"
+dependencies = [
+ "crossbeam-utils",
+]
+
 [[package]]
 name = "crossbeam-queue"
 version = "0.3.14"
@@ -926,6 +945,12 @@ version = "1.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "92773504d58c093f6de2459af4af33faa518c13451eb8f2b5698ed3d36e7c813"
 
+[[package]]
+name = "either"
+version = "1.19.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0e9c71c2167ca323c882b99918929403426e2373ea17242ff5653e0d5e1058be"
+
 [[package]]
 name = "embedded-io"
 version = "0.4.0"
@@ -1449,6 +1474,7 @@ dependencies = [
  "horizon-core",
  "horizon-cosmetics",
  "horizon-dualsense",
+ "horizon-friends",
  "horizon-hdr",
  "horizon-hooks",
  "horizon-items",
@@ -1553,6 +1579,7 @@ dependencies = [
  "open",
  "png",
  "pollster",
+ "rayon",
  "rustix 1.1.5",
  "serde",
  "serde_json",
@@ -1649,6 +1676,15 @@ dependencies = [
  "ureq",
 ]
 
+[[package]]
+name = "horizon-discord"
+version = "0.1.0"
+dependencies = [
+ "horizon-platform",
+ "log",
+ "serde_json",
+]
+
 [[package]]
 name = "horizon-dualsense"
 version = "0.1.0"
@@ -1792,14 +1828,25 @@ dependencies = [
 name = "horizon-official"
 version = "0.1.0"
 dependencies = [
+ "horizon-discord",
  "horizon-friends",
  "horizon-game",
  "horizon-heartbeat",
+ "horizon-official-servers",
  "horizon-platform",
  "log",
  "winresource",
 ]
 
+[[package]]
+name = "horizon-official-servers"
+version = "0.1.0"
+dependencies = [
+ "horizon-addresses",
+ "horizon-platform",
+ "log",
+]
+
 [[package]]
 name = "horizon-optifine"
 version = "0.1.0"
@@ -3643,6 +3690,26 @@ dependencies = [
  "objc2-quartz-core 0.3.2",
 ]
 
+[[package]]
+name = "rayon"
+version = "1.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fb39b166781f92d482534ef4b4b1b2568f42613b53e5b6c160e24cfbfa30926d"
+dependencies = [
+ "either",
+ "rayon-core",
+]
+
+[[package]]
+name = "rayon-core"
+version = "1.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "22e18b0f0062d30d4230b2e85ff77fdfe4326feb054b9783a3460d8435c8ab91"
+dependencies = [
+ "crossbeam-deque",
+ "crossbeam-utils",
+]
+
 [[package]]
 name = "rc2"
 version = "0.8.1"

Cargo.toml

@@ -34,6 +34,8 @@ members = [
     "crates/horizon-game",
     "crates/horizon-official",
     "crates/horizon-heartbeat",
+    "crates/horizon-discord",
+    "crates/horizon-official-servers",
     "crates/horizon-bench",
     "crates/horizon-friends",
     "crates/horizon-relay",

GOVERNANCE.md

@@ -0,0 +1,583 @@
+# Horizon governance
+
+> Adopted 2026-11-09 by the founder as his last decision as head of the project. It takes effect when he
+> announces that he is stepping down. From then on only the council changes it, by a 2/3 poll (section 15).
+>
+> Amended 2026-11-10 by the founder (three kinds of action, elections by tier, who may do what, and council poll P41:
+> the mods decide moderation matters). The council can overturn this amendment by poll.
+
+Horizon has no boss. A **council of equals** decides by polls. **Theme groups** do the work in their areas, each
+with a **lead**. The **Horizon Team** reviews and merges code. **Moderators** keep the Discord server and the
+official server safe. Every role of trust is earned with work the project can measure, and it ends when that work
+stops.
+
+## Contents
+
+1. [Principles](#1-principles)
+2. [The levels at a glance](#2-the-levels-at-a-glance)
+3. [Each level in detail](#3-each-level-in-detail)
+4. [The council and its polls](#4-the-council-and-its-polls)
+5. [The selection filter](#5-the-selection-filter)
+6. [Theme groups](#6-theme-groups)
+7. [Moderation and appeals](#7-moderation-and-appeals)
+8. [Conflicts and hard cases](#8-conflicts-and-hard-cases)
+9. [The age rule (18+)](#9-the-age-rule-18)
+10. [The agents](#10-the-agents)
+11. [Accounts and the handover path](#11-accounts-and-the-handover-path)
+12. [Money](#12-money)
+13. [Transparency](#13-transparency)
+14. [Rules that are never voted on](#14-rules-that-are-never-voted-on)
+15. [Changing this document](#15-changing-this-document)
+
+## 1. Principles
+
+- **Equals.** Every council member has one vote. Nobody, the founder included, stands above the others.
+- **The founder.** Ludovic keeps the title of **Founder**: his role stays at the top of the member list and he is
+  credited as Horizon's founder everywhere. The title is symbolic. It carries no extra vote or power: on the council
+  he counts exactly like every other member.
+- **Evidence, not popularity.** You get a role by doing the work first. Kira measures that work: merged pull
+  requests, reviews, triage, support answers and days active. A vote then confirms it.
+- **Small, clear powers.** Each role can do a short, written list of things. Anything else goes to the council.
+- **Roles are on loan.** Every role has a 30-day probation and an inactivity rule. Stepping down for inactivity is
+  not a sanction, and you can come back.
+- **Public by default.** Polls, results and rules are public. Only matters about a person stay private, and even then
+  the result is published.
+- **18+ for roles of trust** (section 9).
+- **Mojang's and Microsoft's rules come first.** They are never put to a vote (section 14).
+
+## 2. The levels at a glance
+
+From the most open level to the most trusted. A person can hold several levels at once: a group lead can also be on
+the Horizon Team, for example.
+
+| Level | What it can do | How you get in | How you leave | 18+ |
+| --- | --- | --- | --- | --- |
+| **Member** | Play, chat, report bugs, suggest ideas, open issues and pull requests, pick group roles | Join the Discord server or the GitHub repo | Leave, or get banned | No |
+| **Contributor** (⛏️ Iron, 🥇 Gold, 💎 Diamond, 🟪 Netherite ranks) | Write in #contributors; `/claim` issues; vote in their group's elections (if active in that group) | One merged pull request in a public horizon-rust repo, linked with `/link-github` and `/verify-github`. Ranks come from merged pull requests: 10, 40, 100 and 200 | Contributor status and ranks stay | No |
+| **Group member** | Read and write in the group's channel; get the group's pings; vote in the group's elections and votes when active | Pick the group's role in Channels & Roles, or with `/groups` | Remove the role | No |
+| **🤝 Support** | Answer and close posts in #horizon-support | Given by any moderator (a free action, section 2.1) | Resign, 30 days inactive, or removed by a moderator, the Chief of Mods or the council | No |
+| **🛡️ Moderator** | Time out, delete messages, manage threads, quarantine. No bans | Elected by the mods (section 5.3); council veto within 24 h | Resign, 30 days inactive, suspended by the Chief of Mods, recalled by the mods, removed by a council poll (simple majority) | **Yes** |
+| **🛡️ Chief of Mods** | A moderator's powers, plus bans; leads the mods; suspends a mod at once pending the council | Elected by the mods, from the mods with at least 30 days (section 5.3); council veto within 24 h | Resign, 30 days inactive, recalled by the mods, council poll (simple majority) | **Yes** |
+| **🧭 Group lead** | Decides inside the group's topic (section 6); manages the group's channel; triage on the group's GitHub issues | Elected by the group's active members and the Team (section 5.3); council veto within 24 h; 30 days probation | Resign, 30 days inactive (automatic), recalled by the same electorate, council poll (simple majority); confirmed again every 6 months | **Yes** |
+| **🌌 Horizon Team** | Review and merge pull requests (GitHub `horizon-team`, write access); `/nightly` and triage commands (trusted reviewers); #horizon-team | Elected by the Team, 2/3 (section 5.3); council veto within 24 h; 30 days probation | Resign, 60 days without a merge or review (automatic), recalled by the Team (2/3), council poll (2/3, without the person) | **Yes** |
+| **🏛️ Council** | Decides everything else by poll (section 4); bans; emergency actions by any 2 members | Nominated by a council member, the filter, a 24 h public discussion, then a council poll (2/3); 30 days probation | Resign, inactivity (section 5.5), council poll (2/3, without the person) | **Yes** |
+
+**The account holder** isn't a level. The founder (Ludovic) still holds the project's accounts (GitHub organisation
+owner, Discord server owner, the Microsoft app approved by Mojang, the domains, Railway, money). He carries out the
+council's decisions on them and hands them over step by step (section 11). As a council member he has one vote,
+like everyone else.
+
+### 2.1 Three kinds of action
+
+Most things need no vote at all. A vote is for power over other people, and for decisions that bind a whole body.
+
+| Kind | What | How |
+| --- | --- | --- |
+| **Free** | Everyday actions inside your own role (the list below, and anything of the same weight) | Just do it. Kira logs the ones she sees in #staff-log. The tier above can reverse it; if people disagree, the tier above votes. A pattern of abuse is a recall |
+| **Body vote** | Giving or taking a role that carries power (an election), or a decision that belongs to one body: the mods, the Team, a group | `/elect` or `/vote body:` in Kira (section 5.3). Any council member can call a veto within 24 hours |
+| **Council poll** | Rules, money, accounts and ownership, the council's own members, vetoes, anything that spans several bodies | `/poll` (section 4) |
+
+Free actions, for example:
+
+- a lead gives or removes their group's helper role (🧩 Horizon Modding Team), through Kira;
+- a moderator gives or removes 🤝 Support, through Kira;
+- a moderator times out, deletes, quarantines, or changes a channel's slowmode or topic; the Chief of Mods bans and
+  unbans;
+- the Team merges and labels;
+- a server operator restarts the official server, or prunes backups and chunks by the written rule;
+- a lead pins, renames or creates threads in their group's channels;
+- Kira's automatic actions.
+
+**The 24-hour rule.** Every vote lasts 24 hours at most, and closes earlier once its result can't change. Only council
+polls on this document, the licence, money and the GitHub organisation's ownership last 48 hours. A veto is called
+within 24 hours of a result.
+
+### 2.2 Who may do what
+
+What each post decides, and what it holds on Discord, on the official server and on GitHub. Anything not listed is a
+council matter.
+
+| Post | Decides | Discord | Official server | GitHub |
+| --- | --- | --- | --- | --- |
+| **Member** | — | Chat, threads, picks group roles | Play | Issues, pull requests, `/claim` |
+| **Group helper** (🧩 Horizon Modding Team) | — | Writes in the group's team channel | — | — |
+| **🤝 Support** | Closes support posts | Manages threads in #horizon-support | — | — |
+| **🛡️ Moderator** | Moderation matters, by the mods' vote (section 7) | Time out, delete messages, manage threads and nicknames, audit log, voice mute and move; quarantine through Kira; the staff channels | In-game op if also elected operator | — |
+| **🛡️ Chief of Mods** | A moderator's, plus bans and unbans; suspends a mod at once; breaks ties in the mods' votes | Plus Ban | As a moderator | — |
+| **Server operator** | In-game moderation by the server rules | — | Op (the server's ops list); no panel, no `server.toml` | — |
+| **🧭 Server & SMP lead** | The server's settings, by the written rules (backup first, warning in game) | As every lead | A panel sub-user once a council accounts poll gives one | As every lead |
+| **🧭 Group lead** | The group's free actions; gives and removes its helper role | In the group's channels: delete messages, manage and pin threads, ping the group; the helper role through Kira | — | Triage on the group's labels through Kira (no repository role) |
+| **🌌 Horizon Team** | Merges; elects Team members | #horizon-team and the staff channels. The role still carries timeout and delete; whether it keeps them is a mod matter | — | `horizon-team`: write on horizon, horizon-mods, horizon-mixins, horizon-native-mod-template and horizon-server; also kira and horizon-site if P37 passes |
+| **🔧 Server Manager** | — | Manage Channels and Manage Roles (the server's layout); given by council poll | — | — |
+| **🏛️ Council** | Council polls, vetoes, emergencies (any 2) | A moderator's permissions plus Ban, mention @everyone and pin; #council | Panel sub-users for two members if P38 passes | The `council` team: code-owner reviews and the release tools' owner powers if P35 passes, security managers if P36 passes; a second organisation owner if P28 passes |
+| **Account holder** (the founder) | Carries out decisions on his accounts (section 11) | Server owner | The panel's owner account | Organisation owner |
+
+Kira applies a passed election everywhere she can: Discord roles herself, GitHub team membership when the council has
+given her a token for it. Whatever she can't do (a panel sub-user, the ops list, a GitHub team without a token) she
+posts as a list of clicks for a named person.
+
+## 3. Each level in detail
+
+### Member
+
+Anyone in the Discord server or on GitHub. Members follow the server rules and Horizon's
+[contributing guide](CONTRIBUTING.md). They can propose anything: an idea in #horizon-ideas, a bug in #horizon-bugs,
+an issue or a pull request on GitHub, or a request for a council poll (any council member can pick it up).
+
+### Contributor
+
+- **Discord:** the 🛠️ Contributor role writes in #contributors and in the threads of #polls-and-decisions. A rank
+  role (⛏️ Iron at 10 merged pull requests, 🥇 Gold at 40, 💎 Diamond at 100, 🟪 Netherite at 200, counted over every
+  public horizon-rust repo) shows how much has been merged. Ranks only go up.
+- **GitHub:** no repository role. Anyone can `/claim` and `/unclaim` their own issues.
+- **Alone:** their own work.
+
+### Group member
+
+Each theme group (section 6) has a role that anyone can pick and drop. It opens the group's channel and receives the
+group's pings. Picking a role grants no power. A group member counts as **active in the group** when Kira has seen at
+least one counted action in the group's area (section 5.1) in the last 60 days. Active group members vote in the
+group's elections and decisions (section 5.3).
+
+### 🤝 Support
+
+Unchanged: Support members help players in #horizon-support. They answer every post there and mark posts solved.
+The role carries no permission, so it has no age rule. A moderator gives it, and takes it back, through Kira.
+
+### 🛡️ Moderators and the Chief of Mods
+
+- **Discord:** time out members, delete messages, manage threads and nicknames, read the audit log, quarantine
+  through Kira, and see the staff channels. **Moderators don't ban.** Bans are done by council members and the Chief of
+  Mods. Kira's automatic actions (the honeypot, clear scams, illegal images) stay as they are.
+- **Official server:** server operators (ops) are moderators in game. They need the 18+ rule and are confirmed the
+  same way (section 6, Server and SMP).
+- **Alone:** a timeout, a deleted message, a quarantine, with a reason in the mod case.
+- **The Chief of Mods** is the first contact for moderation questions. They organise the mods, can ban, and can take a
+  moderator's role away at once when there is a problem. The council confirms or reverses that within 72 hours.
+
+### 🧭 Group leads
+
+Section 6 says what a lead decides alone and what goes to the council.
+
+- **Discord:** in their group's channel only, delete messages, manage and pin threads, and ping the group role. The
+  🧭 lead role carries no server-wide permission.
+- **GitHub:** triage on the issues and pull requests that carry their group's label (`/label`, `/unlabel`, `/close`,
+  `/reopen`, `/unclaim`), from a list of group leads that grants no repository role. Leads merge only if they are on
+  the Horizon Team too.
+
+### 🌌 Horizon Team
+
+The Horizon Team **merges pull requests**. Its rules are in [the release flow](docs/release-flow.md): read the whole
+diff, never merge your own pull request, and use `needs-proof` for anything risky.
+
+- **GitHub:** member of the `horizon-team` team (write access to the Horizon repos), on the trusted reviewers list
+  (`/nightly` and triage commands).
+- **Discord:** the 🌌 Horizon Team role, #horizon-team, and writing in #contributors and the read-only channels.
+  Moderation permissions belong to the moderators and the council: a Team member moderates only if they also hold
+  one of those roles.
+- **During the 30-day probation:** they merge only ordinary pull requests. They don't merge `needs-proof` pull
+  requests, don't approve files that CODEOWNERS guards, and don't use `/nightly`.
+
+### 🏛️ Council
+
+- **Discord:** the 🏛️ Council role: the moderators' permissions plus ban and mention @everyone; #council (private);
+  starting polls in #polls-and-decisions.
+- **GitHub:** the `council` team. Over time it takes over the founder's CODEOWNERS review and his owner powers in the
+  release tools (section 11).
+- **Alone (any one member):** start a poll; pick up a member's request for a poll; do anything their other roles
+  allow.
+- **Any two members together:** an emergency action (section 4.6).
+- **Everything else** is decided by poll.
+
+## 4. The council and its polls
+
+### 4.1 Founding council
+
+kacpherek, levzzz5154, rdbtCVS, Online5277, dezer-x and Ludovic: six members, one vote each. The founding members
+don't go through the filter or a probation. They do make the 18+ declaration (section 9). The council has at most
+**9** members. It adds a seat only when a 2/3 poll says it needs one.
+
+### 4.2 How a poll works
+
+| Rule | Value |
+| --- | --- |
+| Who starts one | Any council member, with `/poll` (Kira). Anyone else asks a council member to start it |
+| Where | #polls-and-decisions, in public. Polls about a person (removal, appeals, the age rule) run in #council, and only their result is public |
+| How long | 24 hours; 48 hours for this document, the licence, money and the GitHub organisation's ownership. It closes early only if every council member has voted |
+| Ballot | Yes, No or Abstain. You can change it until the poll closes |
+| Quorum | At least half of the council votes (Abstain counts). With 6 members, 3 votes |
+| Simple majority | More Yes than No |
+| Two-thirds | Yes is at least 2/3 of the Yes and No votes, **and at least 3 Yes votes** |
+| Tie | Nothing changes |
+| No quorum | Nothing changes. Kira reminds the members who haven't voted 12 hours and 2 hours before the end |
+| About yourself | You don't vote, and you don't count in the council's size for that poll |
+| Asking again | A poll that failed can't be asked again for 7 days, unless two members agree that new facts justify it |
+
+### 4.3 Which threshold applies
+
+| Simple majority | Two-thirds |
+| --- | --- |
+| Day-to-day project decisions: direction, priorities, settling disputes between groups, a public statement | Adding council members |
+| Vetoing a body's vote or election (section 5.3) | Removing a council member or a Team member (without the person concerned) |
+| Removing a group lead, a moderator, the Chief of Mods or Support (their bodies can also recall them) | Rules: this document, the server rules, the contributing policy, the licence |
+| Ending a probation early | Money (section 12) |
+| Confirming an emergency action | Account handover steps (section 11) |
+| Deciding for a body that has fewer than 3 voters | Waiving part of the selection filter (section 5.4) |
+| Bringing back someone who stepped down for inactivity, within 6 months | Changing the council's size |
+
+**When in doubt, two-thirds.** Any council member can say a poll needs 2/3, and Kira then counts it at 2/3.
+
+### 4.4 Discussion
+
+Polls that add someone to the council start with a **24-hour public discussion**. Other polls, and elections, are
+discussed in their own thread while they run. A member who wants more time votes No and says
+why. A failed poll can come back after 7 days.
+
+### 4.5 Conflicts of interest
+
+A member doesn't vote on a poll about themselves: their own role, their own removal, an appeal of their own
+moderation action, or money paid to them. They say so in the poll's thread and Kira leaves them out of the count.
+
+### 4.6 Emergencies
+
+For **security** (a leaked secret, a malicious pull request or mod, a hijacked account), **Mojang or Microsoft** (a
+request from them, a risk to the approved sign-in) or **legal** matters (a takedown, the law), **any two council
+members act at once**. They may:
+
+- pause releases and the Nightly;
+- take a mod down from the registry;
+- remove someone's roles or access for now;
+- lock or hide channels and content;
+- ask the account holder to rotate a secret or a key.
+
+They record it with `/emergency` in Kira, and both of them confirm it there. Kira opens a council poll at once
+(simple majority) to confirm it. If the poll doesn't pass, the action is undone where it can be. An emergency never
+adds members, changes rules or spends money.
+
+### 4.7 Removing a council member
+
+A 2/3 poll of the other members, in #council. The person concerned doesn't vote and doesn't count in the quorum.
+Only the result is published, never the reasons. Other ways to leave: resigning, inactivity (section 5.5), or a
+false age declaration (section 9).
+
+### 4.8 When the council drops below a quorum
+
+- **Fewer than 5 members:** Kira opens nominations for the council at once. The council fills seats within 30 days.
+- **Fewer than 3 members, or fewer than 3 who voted in the last 30 days:** an **interim council** forms. It counts the
+  remaining council members, the Horizon Team and the group leads past probation. Its only task is adding council
+  members, by its own 2/3 poll with a quorum of half. Any two of its members can take emergency actions. All other
+  decisions wait. The Team keeps merging and the leads keep leading.
+- **Nobody left:** the Team and the group leads form the interim council in the same way.
+
+## 5. The selection filter
+
+Nobody becomes a lead, a Team member or a council member just because they are well liked or talk a lot. Kira
+measures the work, and only people above a floor can be nominated. Their body then elects them (section 5.3).
+
+### 5.1 What Kira measures
+
+| Signal | What counts | Source |
+| --- | --- | --- |
+| **Merged pull requests** | Pull requests merged in a public horizon-rust repo. For Modding, also in the mod API's fork (arismoko/horizon). Counted overall, and per group by label or by files touched | GitHub search, as the ranks are counted today |
+| **Reviews** | Others' pull requests you reviewed: approved, asked for changes, or left a review with comments. One per pull request | GitHub search `reviewed-by:` and Kira's GitHub webhook |
+| **Triage** | Triage commands run (`/label`, `/close`, duplicates), issues labelled or closed, bug posts routed on Discord | The triage workflow's comments and Kira's webhook |
+| **Support answers** | #horizon-support posts you answered that ended solved | Kira's support feature |
+| **Active days** | Distinct days with any of the above, or with messages in #contributors or a group's channel. Chat elsewhere doesn't count | Kira |
+| **Tenure** | Days since your first counted contribution (since you joined the server, for moderators) | GitHub, Discord |
+| **Clean record** | No timeout, quarantine or ban in the last 90 days | Kira's mod cases |
+| **Verified GitHub** | `/verify-github` done | Kira |
+| **18+ declaration** | Made (section 9) | Kira |
+
+Kira turns these into an **evidence card**: the person's numbers, overall and in the group's area, for the last 60
+days and in total. Anyone can see their own card with `/evidence`. A nomination shows the card publicly.
+
+### 5.2 The floors
+
+A nomination is refused below these floors.
+
+| Role | Floor |
+| --- | --- |
+| **Group lead** | Verified GitHub; tenure of 30 days or more; **in the group's area: 8 or more merged pull requests, or 20 or more reviews** (Translations: 5 or more merged translation pull requests; Server and SMP: 8 pull requests, or 30 days as an official server operator with activity); 15 or more active days in the last 60; clean record; 18+ |
+| **Moderator** | In the server for 30 days or more; Kira level 10 or more; 15 or more active days in the last 60; clean record; 18+ |
+| **Chief of Mods** | Moderator for 30 days or more, past probation; 18+ |
+| **Horizon Team** | 🥇 Gold rank (40 merged pull requests); 20 or more reviews of others' pull requests; tenure of 30 days or more; 20 or more active days in the last 60; clean record; verified GitHub; 18+ |
+| **Council** | Horizon Team member, group lead or Chief of Mods for 60 days or more, past probation; 20 or more active days in the last 60; clean record; 18+ |
+
+The numbers are checked again once a year (section 15). They should stay reachable for people who really work on
+Horizon and out of reach for people who don't.
+
+### 5.3 Elections
+
+The body that works with a person elects them. Kira runs it: `/elect post: member: [group:]`, and `action: remove`
+for a recall.
+
+| Post | Who votes | Passes with | Who can start it |
+| --- | --- | --- | --- |
+| **🛡️ Moderator** | The mods (🛡️ Mod and 🛡️ Chief of Mods) | Simple majority; the Chief of Mods breaks a tie | Any mod, a council member |
+| **🛡️ Chief of Mods** | The mods; candidates are mods for 30 days or more | Simple majority | Any mod, a council member |
+| **Server operator** | The mods and the 🧭 Server lead | Simple majority | The Server lead, the Chief of Mods, a council member |
+| **🧭 Group lead** (a co-lead once the group has 8 active members) | The group's active members, and the Team | Simple majority | The current lead, a Team member, a council member |
+| **🌌 Horizon Team** | The Team | Two thirds, and at least 3 Yes | A Team member, a council member |
+| **🏛️ Council** | The council, by poll after a 24-hour discussion (section 4) | Two thirds, and at least 3 Yes | A council member |
+| 🤝 Support, a group's helper role | Nobody: a free action (section 2.1) | — | A moderator; the group's lead |
+
+An **active group member** has held the group's role for 14 days or more (Kira counts from when she first saw it)
+and has at least one merged pull request or review with the group's label in the last 60 days.
+
+1. **Start.** Kira checks the floor (5.2) and the 18+ declaration. If the candidate falls short, the person starting
+   gets a private "not now", and the candidate a private message saying what is missing. Nothing is posted and no
+   reason is ever shown to anyone else. Kira checks what she can measure (verified GitHub, merged pull requests and
+   reviews, overall and by the group's label, rank, days in the server, Kira level, clean record, the declaration);
+   the voters judge the rest.
+2. **Vote, 24 hours,** in the body's channel, discussed in the vote's thread. Yes, No or Abstain, changeable while it
+   runs. Kira shows how many voted, never who. It closes early once the result can't change.
+3. **Result,** applied at once. Kira gives or takes the Discord role and, with a token, the GitHub team; she lists the
+   rest as clicks for a named person. Only the result is published, never the ballots.
+4. **Veto, 24 hours.** Any council member can call it with the button under the result. A council poll (simple
+   majority, without the people involved) decides; if it passes, Kira undoes the result.
+5. **Probation, 30 days,** for leads and Team members. It ends by itself unless someone who can vote starts a recall.
+
+The council can always remove someone by its own poll. **Body votes** work the same way for a body's own decisions:
+`/vote body:mods`, `body:team` or `body:group`, simple majority, 24 hours, the same veto.
+
+#### Hard cases
+
+| Case | What happens |
+| --- | --- |
+| Fewer than 3 can vote | The council decides by poll |
+| Quorum | A third of the electorate, and at least 3 ballots (Abstain counts). Without it, nothing changes |
+| Tie | Fails, and nothing changes. In the mods' votes, the Chief of Mods' ballot breaks it |
+| The candidate | Doesn't vote on themselves, and can decline (the election ends). The person who started it votes normally |
+| Conflicts | Whoever the vote is about, or who gave or received the moderation action in question, doesn't vote |
+| Several candidates for one seat | Nominations within the first 12 hours join one approval ballot. The seat goes to the most approvals if that is at least half of the voters; otherwise a 24-hour run-off between the top two |
+| A seat that is held | Changes only by a recall or by the 6-month confirmation |
+| The council is already voting on it | No election starts for the same person and post |
+| Cooldown | A failed or vetoed election can't be started again for the same person and post for 30 days. At most 3 elections run at once in a body |
+| Vacancy | When a lead or the Chief of Mods leaves, Kira opens the seat's election herself: 24 hours of nominations, then the vote with everyone nominated. Nobody nominated: the seat stays open, and the tier above acts meanwhile. Kira never picks a candidate |
+| Abuse of a free action | The tier above reverses it; a disagreement goes to its vote. A pattern is a recall |
+| Emergency | Section 4.6. The Chief of Mods can still suspend a mod at once |
+| Kira is down | The body may run the same vote as a Discord poll in its channel for 24 hours; Kira records the result when she is back |
+
+#### Reminders, not nominations
+
+Once a month in a group's channel, Kira says how to propose someone, only when the group has no lead or someone in it
+meets a post's floor. When a seat opens, she posts once in the electorate's channel. Once a month in #council, she
+lists privately the people who meet a floor. These are suggestions: only people start elections.
+
+### 5.4 Exceptions
+
+Some valuable people don't show up in the numbers, such as a designer for the website. The council can **waive the
+tenure or the area floors** by a 2/3 poll that says why. The age rule and the clean record are never waived.
+
+### 5.5 Inactivity
+
+Kira checks every day. It warns the person in a DM and in #council, then posts the step-down in
+#polls-and-decisions with neutral wording ("stepped down: inactive"), and removes the Discord role. The account
+holder or an org owner removes GitHub access when the Team role ends.
+
+| Role | What counts as activity | Warning | Steps down |
+| --- | --- | --- | --- |
+| Group lead | A counted action in the group's area, or messages in the group's channel | Day 21 | Day 30 |
+| Horizon Team | A merge or a review | Day 45 | Day 60 |
+| Moderator, Chief of Mods | A moderation action, or messages in the staff channels | Day 21 | Day 30 |
+| Support | An answer in #horizon-support | Day 21 | Day 30 |
+| Council | A vote in a poll. At 30 days with no vote, while at least 2 polls were held | Day 23 | Day 30, or 45 days with no counted activity at all |
+
+- **Away.** Anyone can announce an absence with `/away` for up to 45 days, once every 6 months. Away days don't
+  count. A lead names someone from the group to cover for them.
+- **Coming back.** Within 6 months: a simple-majority poll, with no new probation. After 6 months: the normal path.
+
+### 5.6 Terms
+
+- **Group leads** are confirmed every 6 months by an election in their group. If someone else in the group passes the
+  floor and is nominated within its first 12 hours, both go on the same ballot.
+- **Council and Team** have no fixed term. They stay as long as they are active and keep the council's trust. Removal
+  is always possible (section 4.7).
+
+## 6. Theme groups
+
+### 6.1 The groups
+
+| Group | Covers | GitHub | Discord |
+| --- | --- | --- | --- |
+| **Modding** | The mod API, native and content mods, mixins, the mod registry, `cargo horizon-mod` | The mod API lives in Ari's fork **arismoko/horizon**. Its owner runs that repo by their own rules; the council governs only what is Horizon's: horizon-rust/horizon-mods, horizon-mixins, horizon-native-mod-template, the registry. Label `mods` | The 🧩 MODDING category (#modding, #horizon-modding-team); roles 🧩 Modder (picked) and 🧩 Horizon Modding Team (the lead gives it) |
+| **Shaders and rendering** | The renderer, shaders, shader packs, OptiFine and Polytone pack formats | Label `rendering`; `crates/horizon-client-render` (gfx), `*.wgsl`, `horizon-shaders`, `horizon-shader-api`, `horizon-optifine`, `horizon-polytone` | #shaders-rendering |
+| **Performance** | Frame rate, memory, server tick, benchmarks | Label `perf`; `horizon-bench`, the benchmark tools | #performance |
+| **Launcher** | The launcher: installs, updates, instances, its pages | Label `launcher`; `launcher/` | #launcher |
+| **Server and SMP** | Dedicated server, hosting, the anticheat, multiplayer, and the official SMP | Labels `server`, `multiplayer`; `horizon-server*`, `horizon-anticheat`, `lan/`, `dedicated*`; horizon-rust/horizon-server | #server-smp (plus #join-server, #server-chat) |
+| **Translations** | The game's and the launcher's languages | Label `roadmap:languages`; `launcher/lang/`, `crates/horizon-client/assets/horizon/lang/` | #translations and the 🌍 language channels |
+| **Website** | playhorizon.dev | horizon-rust/horizon-site; label `website`. The site's design stays as it is unless the council decides otherwise | #website |
+| **Vanilla accuracy** | Parity with vanilla 26.3: harnesses, oracles, the port ledger | Labels `parity`, `parity-regression`, `full-parity`; `tools/test_*_parity.py`, the Java oracles | #vanilla-accuracy |
+| **UI** | The game's menus, HUD, settings, controller navigation, the design system | Labels `ui`, `accessibility`; `title/`, `settings_shell.rs`, `hud*`, `ui.rs`, `docs/design-system.md`, `horizon-theme`. The launcher's look is shared with Launcher | #ui |
+
+A pull request can belong to two groups. Both leads can comment, and the Team merges as usual. If the leads disagree,
+the council decides.
+
+### 6.2 Leads per group
+
+- **One lead per group.** A group with 8 or more active members may also have **one co-lead**, chosen the same way.
+- A person leads **at most two groups**. Council members may lead a group, though a lead from outside the council is
+  preferred: it spreads the work.
+
+### 6.3 What a lead decides alone
+
+Inside their group's topic, and within this document, the contributing guide, the vanilla-first rule, the layers and
+the design system:
+
+- the group's priorities and the order of its roadmap items;
+- which issues are `good first issue`, and triage of the group's issues;
+- technical and design direction inside the area, when vanilla behaviour and the default look don't change;
+- accepting or declining an idea or a proposal in the area. Any two active group members or one council member can
+  take that decision to the council;
+- giving and removing the group's helper role, through Kira (a free action);
+- how the group organises itself (threads, meetings, the channel's rules on top of the server's);
+- asking the Team for reviews, adding `needs-proof`, and starting elections in the group.
+
+### 6.4 What goes to the council
+
+- the rules, money, accounts and secrets;
+- who is on the council, the Team or the mods;
+- anything that changes vanilla behaviour or turns a Horizon-only feature on by default;
+- breaking a public promise: the mod API, server compatibility, save and file formats;
+- disputes between groups;
+- anything involving Mojang, Microsoft or the law;
+- speaking for the whole project outside the group's topic.
+
+### 6.5 A group without a lead
+
+The work goes on. The Team reviews and merges, and Kira still routes the group's issues and questions to its
+channel. Until a lead is chosen, any council member may take a lead's decision for that group and says so in the
+channel. Kira posts once that the seat is open and how to start its election (section 5.3). **No lead is better than a lead who doesn't do the work:**
+nobody is appointed just to fill the seat.
+
+## 7. Moderation and appeals
+
+- **The mods decide moderation matters** (council poll P41, imposed by the founder on 2026-11-10): who joins or
+  leaves the mod team, the mods' permissions and the staff channels, bans and unbans, and channel settings for
+  moderation. Everyday actions are free (section 2.1). Anything bigger is a mods' vote (`/vote body:mods`, simple
+  majority, 24 hours), and the Chief of Mods breaks ties. **The council keeps a veto:** within 24 hours of a mods'
+  decision, any council member can call a council poll, and a simple majority overturns it.
+- **The server rules** are in #rules. Moderators enforce them, the Chief of Mods leads the mods, and the council can
+  change the rules (2/3).
+- **Every action has a mod case**: who acted, what they did, and why. Kira keeps the cases.
+- **First appeal:** within 14 days, through #appeal (for a quarantine) or mod mail. A moderator who wasn't involved,
+  or the Chief of Mods, answers within 72 hours.
+- **Second appeal:** for bans, timeouts over 24 hours and quarantines, a mods' vote in #mod-chat. Mods who were
+  involved don't vote, and the council's veto applies. The answer is final for 90 days.
+- **Not appealable here:** actions that Discord's rules or the law require. Those are reported where the law says.
+- **Removing a moderator:** the Chief of Mods can suspend a moderator at once, and the mods decide within 72 hours by
+  a recall vote. The mods recall the Chief of Mods the same way. The council can also remove either by poll.
+- **Council members keep the ban permission** for emergencies and when no moderator is around. They log the ban like
+  any other, and the mods can reverse it by vote.
+- **Staff are moderated like everyone.** When a council member is involved, the council decides without them.
+
+## 8. Conflicts and hard cases
+
+| Case | What happens |
+| --- | --- |
+| Two groups disagree | The leads talk first. If they still disagree, the council decides (simple majority) |
+| A lead's decision is contested | Any two active group members or one council member can bring it to the council |
+| A Team member merges against the rules | Any council member can revert the merge. The council can remove the member (2/3) |
+| A council member breaks the rules | The council decides without them. Removal takes 2/3 (section 4.7) |
+| Someone holds a role and is under 18 | Section 9 |
+| The council can't reach quorum | Section 4.8 |
+| The founder and the council disagree about one of his own accounts | Until a step of section 11 hands it over, the account stays his. He carries out the council's decisions on project matters, or he says publicly that he won't |
+
+## 9. The age rule (18+)
+
+**Who must be 18 or older:** members of the council and the Horizon Team, trusted reviewers, group leads and
+co-leads, the Chief of Mods and the moderators, official server operators, and anyone with admin rights anywhere in
+the project: Discord (Administrator, Manage Roles, Manage Channels, ban), GitHub (write, admin, organisation),
+server panels, Railway, or Kira's admin side. The same goes for anyone who holds a project secret.
+
+**Who doesn't have to be:** members, contributors (with any rank), group members and 🤝 Support. Contributors under
+18 are welcome and valued. They just can't hold the roles above.
+
+**How it's checked, without collecting ID:**
+
+- **A declaration.** Before taking such a role, and once at the start for everyone who holds one, the person presses
+  a button in Kira: "I confirm that I am 18 or older. I understand that a false declaration removes all my roles of
+  trust." Kira keeps only the Discord account, the date and the wording's version. It never stores a birth date, an
+  ID, a photo, or any outside age-checking service's result.
+- **No declaration, no role.** At the start, current role holders have 7 days to make it. Until they do, their role is
+  paused.
+- **When there's doubt** (the person says they are younger, or there is a credible private report), one council
+  member asks the person privately. If the doubt remains, any council member pauses the role, and the council decides
+  within 72 hours in #council.
+- **A false declaration** removes every role of trust at once, and the person can't hold one for 12 months.
+- **Privacy.** Age is never discussed in public. A role that ends for this reason ends with the same neutral line as
+  any other step-down.
+
+## 10. The agents
+
+Horizon uses AI agents: the founder's orchestrator, which runs coding agents, and Kira, the Discord bot.
+
+- **They obey council decisions only:** a passed poll recorded by Kira, a recorded emergency action of two council
+  members, and the standing rules in this document and the project's docs.
+- **The only exception is the founder's own things:** his spending, his machines (they run CI and the vanilla tests),
+  his personal accounts and his time. On those, his word decides. This list should get shorter over time (section 11).
+- **Role work isn't a decision.** A lead asking Kira to route issues, or a Team member asking an agent to prove a pull
+  request, is that person using their role. The agents help, within the role's powers.
+- **They check the source.** An agent acts on a decision only when it finds it in Kira's decisions log
+  (section 13). A message saying "the council decided", or a screenshot, is not enough.
+- **They post as agents.** Everything an agent posts says it comes from an agent, and states decisions as the
+  project's.
+
+## 11. Accounts and the handover path
+
+Today the founder holds every account. The aim is for him to hold fewer, in an order that never leaves the project
+unable to act, and never puts an account that is tied to a person into anyone else's hands.
+
+| Account | Today | Can it be shared? | Plan |
+| --- | --- | --- | --- |
+| **GitHub organisation** (horizon-rust) | One owner (the founder) | Yes: an organisation can have several owners | **Step 1:** a second owner from the council, chosen by a 2/3 poll in the council's first week, with two-factor authentication on. **Step 2:** a `council` team; CODEOWNERS reviews and the release tools' owner powers (`paused`, `/nightly remove`) move from the founder to that team |
+| **Discord server** | Owned by the founder | Partly: a server has exactly one owner; powers can be given through roles | **Step 1:** the 🏛️ Council role gets moderation and ban permissions; Kira applies the outcomes of passed polls, so nobody needs Manage Roles; two-factor authentication becomes required for moderation. Ownership itself stays with the founder until a legal entity exists |
+| **Kira** (bot application, Railway service) | The founder's Discord developer account and Railway | The bot: yes (a Discord developer team). Railway: adding members may need a paid plan | **Step 1:** a Discord developer team with two council members. Railway members once the council decides on money |
+| **Official server** (hosting panel) | The founder's account | Yes: panel sub-users | **Step 1:** sub-users for the Server and SMP lead and for one council member |
+| **Domains** (playhorizon.dev and the others) | The founder's registrar account | Not without moving it | Auto-renewal on, registered for several years ahead. They move only to a legal entity, if one is created |
+| **The Microsoft app approved by Mojang** (sign-in) | The founder's Azure app registration; Mojang approved it after his application | **No.** The approval was given on his application. Moving the app or adding owners would change who Mojang deals with, and we have found no documented way to transfer an approval | **Never moves** without Mojang's written agreement. The only change considered: a legal entity, if one is created, and only if Mojang agrees |
+| **Signing** (Apple developer certificate, release signing keys) | The founder's | The Apple certificate is in his legal name: no | The Apple certificate never moves. Release keys stay in GitHub's protected environments, and the council team approves their use from step 2 |
+| **Money** (sponsorship, donations) | Personal accounts of the founder | Through a fiscal host | Section 12 |
+| **The founder's machines, AI accounts and password vault** | His | No | His own things: they never move. The project should depend on them less over time |
+
+**Order:** first the safety nets that remove a single point of failure (a second organisation owner, the bot's
+developer team, panel sub-users). Then the day-to-day powers (CODEOWNERS and release tools to the council team). Last,
+whatever needs a legal entity: domains, money, and with Mojang's agreement the sign-in app. Each step is a 2/3 poll,
+and the founder carries it out.
+
+## 12. Money
+
+*Placeholder: the options (Open Collective and others) are being researched.*
+
+- The council approves every expense by a **2/3 poll**.
+- **Every income and every expense is public.**
+- Nobody votes on money paid to themselves.
+
+## 13. Transparency
+
+- **#polls-and-decisions:** every poll and every result, posted by Kira, and the 24-hour discussions of nominations.
+  For polls that aren't about a person, each member's vote is shown once the poll closes. The results of elections
+  and body votes are posted there too; for elections, only the result.
+- **#staff-log:** the free actions Kira sees (roles given or taken, bans, unbans), so the tier above can check them.
+- **The decisions log:** Kira keeps an append-only record of every poll, emergency action, appointment and
+  step-down, with its date and result. It is public and machine-readable, so the agents can check a decision there.
+- **This document** lives in horizon-rust/horizon as `GOVERNANCE.md`. A short summary is pinned in #rules and in
+  #polls-and-decisions.
+- **Who holds which role:** the people page of playhorizon.dev's hub shows the council, the Team, the group leads,
+  the Chief of Mods, the moderators and Support.
+- **#council** is private for discussion and for polls about people. Everything the council decides is published.
+
+## 14. Rules that are never voted on
+
+These are Horizon's conditions for existing, not choices. No poll can change them:
+
+- Playing needs a **Microsoft account that owns Minecraft: Java Edition**. There is no play without one.
+- **No Mojang files** in Horizon's repos or downloads. Players' own copies stay on their own machines.
+- **No gambling**, in any form, including with in-game currency.
+- **Mojang's and Microsoft's terms and Usage Guidelines** apply to everything Horizon does.
+- **The law**, and the terms of service of Discord and GitHub.
+
+## 15. Changing this document
+
+A 2/3 council poll, then a pull request that a Team member merges. The council reviews the floors' numbers
+(section 5.2) once a year, or sooner if they turn out wrong.

README.md

@@ -135,6 +135,8 @@ python3 tools/pr_ready.py
 
 It runs rustfmt, clippy, the touched crates' tests, the Python tests, the public-tree check and the vanilla harnesses your change affects. Never commit game files, decompiled source or prepared resources.
 
+How Horizon is run (the council, theme groups and their leads, the Horizon Team, moderation): [GOVERNANCE.md](GOVERNANCE.md).
+
 ## Project status
 
 **Player-visible gaps: 0 open** of the 833 the [port ledger](tools/port_ledger.py) found, reading every vanilla 26.3 method against Horizon's code: vanilla behaviour a player would notice that Horizon doesn't have yet. By area: Animals [0](https://github.com/horizon-rust/horizon/issues/3512); Monsters and bosses [0](https://github.com/horizon-rust/horizon/issues/3513); Entities, projectiles, vehicles and decorations [0](https://github.com/horizon-rust/horizon/issues/3514); Items, enchantments and inventories [0](https://github.com/horizon-rust/horizon/issues/3515); Blocks, redstone and fluids [0](https://github.com/horizon-rust/horizon/issues/3516); World, world generation and saves [0](https://github.com/horizon-rust/horizon/issues/3517); Screens, HUD and client packets [0](https://github.com/horizon-rust/horizon/issues/3518); Entity and block rendering, models [0](https://github.com/horizon-rust/horizon/issues/3519); Server and players on the server [0](https://github.com/horizon-rust/horizon/issues/3520); Mob AI, villagers and raids [0](https://github.com/horizon-rust/horizon/issues/3521). This number goes down as gaps close (`tools/parity_gaps.py`); the table below says what the harnesses compare.

THIRD_PARTY_NOTICES.md

@@ -358,3 +358,29 @@ state of Starling's `crates/horizon-client-render/src/touch.rs` at the same comm
 
 `crates/horizon-client-render/src/android_runtime.rs` and `android_runtime/tests/` are adapted from the
 input part of Starling's `crates/horizon-client-render/src/android_runtime.rs` at the same commit.
+
+## PCG3D hash
+
+`hash3` in `crates/horizon-client-render/src/hdr.wgsl`, the noise HDR10 output's dither is made from, is the
+`pcg3d` hash of Mark Jarzynski and Marc Olano ("Hash Functions for GPU Rendering", Journal of Computer Graphics
+Techniques 9(3), 2020), from <https://github.com/markjarzynski/PCG3D>. Copyright 2020 Mark Jarzynski & Marc Olano,
+licensed under MIT:
+
+```
+Copyright 2020 Mark Jarzynski & Marc Olano
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+associated documentation files (the "Software"), to deal in the Software without restriction,
+including without limitation the rights to use, copy, modify, merge, publish, distribute,
+sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial
+portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
+OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+```

crates/horizon-addresses/src/lib.rs

@@ -15,6 +15,10 @@ pub const OFFICIAL_SERVER: &str = "play.playhorizon.dev";
 /// `official_server_previous` in `launcher/links.json`).
 pub const OFFICIAL_SERVER_PREVIOUS: &[&str] = &["horizon.bunchy7s.dev"];
 
+/// Afri-Network, a partner server the game added once below the official server (#9299) until
+/// the partnership ended: kept so the game can take back out the entry it added.
+pub const WITHDRAWN_PARTNER_SERVER: &str = "afri-network.co.za";
+
 /// [`OFFICIAL_SERVER`] with the port its SRV record gives, for askers that don't look SRV up
 /// (the telemetry server's status checks).
 pub const OFFICIAL_SERVER_STATUS: &str = "play.playhorizon.dev:24454";

crates/horizon-bots/src/main.rs

@@ -70,6 +70,8 @@ horizon-bots: load-test bots for a Minecraft Java Edition 26.3 server (offline m
                          other one 30 000 characters long), flood-book (100 pages of 1024 characters
                          into a writable book), flood-sign (four 384-character lines on the block
                          below), flood-recipe (recipe book placements)
+  --ack-mode MODE        chunk batch feedback: vanilla (default) or 64 (fixed chunks per tick);
+                         one ACK per completed batch; use explore for a controlled pacing test
   --flood N              packets a tick for the flood behaviours; default 100
   --attack NAME          attack the player NAME twice a second, from wherever the bot is (a reach test),
                          swinging after each attack as vanilla's client does. NAME,NAME...: each of them
@@ -171,6 +173,8 @@ struct Options {
     /// --crits: fight bots alternate jumped critical hits and sweeps at a sword's cooldown.
     crits: bool,
     flood: usize,
+    /// None uses vanilla estimation; --ack-mode 64 requests a fixed rate.
+    ack_rate: Option<f32>,
     no_read: bool,
     no_loaded: bool,
     height: f64,
@@ -209,6 +213,7 @@ fn options() -> Result<Options, String> {
         no_swing: false,
         crits: false,
         flood: 100,
+        ack_rate: None,
         no_read: false,
         no_loaded: false,
         height: 24.0,
@@ -266,6 +271,13 @@ fn options() -> Result<Options, String> {
                 o.explore_speed = value.parse().map_err(|_| number("blocks a second"))?;
             }
             "--pvp" => o.pvp = value.parse().map_err(|_| number("true or false"))?,
+            "--ack-mode" => {
+                o.ack_rate = match value.as_str() {
+                    "vanilla" => None,
+                    "64" => Some(64.0),
+                    _ => return Err(format!("--ack-mode {value}: use vanilla or 64")),
+                };
+            }
             "--flood" => o.flood = value.parse().map_err(|_| number("packets a tick"))?,
             "--attack" => o.attack = Some(value),
             "--attack-after" => o.attack_after = value.parse().map_err(|_| number("seconds"))?,
@@ -950,6 +962,7 @@ fn read(
     writer: Arc<Mutex<ConnWriter>>,
     bot: Arc<Bot>,
     track: bool,
+    ack_rate: Option<f32>,
     mut capture: Option<Capture>,
 ) {
     use ids::play::clientbound as cb;
@@ -1035,7 +1048,8 @@ fn read(
                 batch.finished(r.varint().unwrap_or(0));
                 send(
                     play::Serverbound::ChunkBatchReceived(play::ChunkBatchReceived {
-                        chunks_per_tick: batch.desired_chunks_per_tick(),
+                        chunks_per_tick: ack_rate
+                            .unwrap_or_else(|| batch.desired_chunks_per_tick()),
                     })
                     .encode(),
                 )
@@ -1139,7 +1153,8 @@ fn run_bot(
         let capture = (index == 0)
             .then(|| o.capture.as_deref().and_then(Capture::create))
             .flatten();
-        thread::spawn(move || read(reader, writer, bot, track, capture));
+        let ack_rate = o.ack_rate;
+        thread::spawn(move || read(reader, writer, bot, track, ack_rate, capture));
     }
     use ids::play::serverbound as sb;
     // Wait for the spawn position.
@@ -1519,6 +1534,7 @@ fn main() {
         "behaviour": o.behaviour,
         "seed": o.seed,
         "explore_speed": o.explore_speed,
+        "ack_mode": o.ack_rate.map_or("vanilla", |_| "64"),
         "pvp": o.pvp,
         "view_distance": o.view_distance,
         "seconds": o.seconds,
@@ -1584,6 +1600,83 @@ mod tests {
         AddEntity, Clientbound, MoveEntity, MoveEntityPos, RemoveEntities, SetEntityData, VecDelta,
     };
 
+    /// Exercise the production reader over framed connections. Pings are barriers
+    /// so extra ACKs are observable without sleeps or timing guesses.
+    fn check_chunk_acks(ack_rate: Option<f32>) {
+        use horizon_protocol::connection::Pipe;
+        let (client, server) = Pipe::pair();
+        let (reader, writer) = Connection::local(client).split();
+        let mut server = Connection::local(server);
+        server
+            .reader
+            .set_read_timeout(Some(Duration::from_secs(2)))
+            .unwrap();
+        let bot = Arc::new(Bot::default());
+        bot.online.store(true, Ordering::SeqCst);
+        let handle = thread::spawn(move || {
+            read(
+                reader,
+                Arc::new(Mutex::new(writer)),
+                bot,
+                false,
+                ack_rate,
+                None,
+            )
+        });
+        for (nonce, size) in [0, 1, 5].into_iter().enumerate() {
+            server
+                .send(&raw(ids::play::clientbound::CHUNK_BATCH_START, |_| {}))
+                .unwrap();
+            server
+                .send(&raw(ids::play::clientbound::PING, |w| w.i32(nonce as i32)))
+                .unwrap();
+            let (id, body) = server.recv().unwrap();
+            assert_eq!(
+                id,
+                ids::play::serverbound::PONG,
+                "batch start must not send an ACK"
+            );
+            assert_eq!(Reader::new(&body).i32().unwrap(), nonce as i32);
+            server
+                .send(&raw(ids::play::clientbound::CHUNK_BATCH_FINISHED, |w| {
+                    w.varint(size)
+                }))
+                .unwrap();
+            server
+                .send(&raw(ids::play::clientbound::PING, |w| w.i32(nonce as i32)))
+                .unwrap();
+            let (id, body) = server.recv().unwrap();
+            assert_eq!(id, ids::play::serverbound::CHUNK_BATCH_RECEIVED);
+            let rate = Reader::new(&body).f32().unwrap();
+            if let Some(fixed) = ack_rate {
+                assert_eq!(rate, fixed);
+            } else if size == 0 {
+                assert_eq!(rate, 3.5, "vanilla initial rate must remain the default");
+            } else {
+                assert!(rate.is_finite() && rate > 0.0);
+            }
+            let (id, body) = server.recv().unwrap();
+            assert_eq!(
+                id,
+                ids::play::serverbound::PONG,
+                "exactly one ACK per finished batch"
+            );
+            assert_eq!(Reader::new(&body).i32().unwrap(), nonce as i32);
+        }
+        server.writer.shutdown();
+        handle.join().unwrap();
+    }
+
+    #[test]
+    fn fixed_64_ack_is_sent_once_per_finished_batch() {
+        check_chunk_acks(Some(64.0));
+    }
+
+    #[test]
+    fn vanilla_acks_remain_once_per_finished_batch() {
+        check_chunk_acks(None);
+    }
+
     fn feed(entities: &mut Entities, packet: &Clientbound) {
         let bytes = packet.encode();
         let mut r = Reader::new(&bytes);

crates/horizon-client-core/src/component.rs

@@ -514,6 +514,34 @@ pub fn name_text(tag: &Tag) -> Text {
 #[cfg(test)]
 mod tests {
     use super::*;
+
+    #[test]
+    fn nested_fallback_references_stay_bounded() {
+        // 300 references to the argument, nested three deep: 27 million copies of "A" from a
+        // 4 KB component, which ran a client out of memory.
+        let bomb = |depth: usize, text: &str| {
+            let pattern = "%1$s".repeat(300);
+            let mut v = serde_json::json!({ "text": text });
+            for _ in 0..depth {
+                v = serde_json::json!({"translate": "x.unknown", "fallback": pattern, "with": [v]});
+            }
+            v
+        };
+        let started = std::time::Instant::now();
+        let text = to_text(&bomb(3, "A"), &mut |s| Text::literal(s));
+        assert!(text.spans.len() < 1 << 15, "{} spans", text.spans.len());
+        // One long argument referenced many times multiplies bytes, not spans.
+        let long = "B".repeat(64 << 10);
+        let text = to_text(&bomb(1, &long), &mut |s| Text::literal(s));
+        let bytes: usize = text.spans.iter().map(|s| s.text.len()).sum();
+        assert!(bytes <= 4 << 20, "{bytes} bytes");
+        assert!(started.elapsed() < std::time::Duration::from_secs(5));
+        // A real fallback still formats.
+        let ok = serde_json::json!({
+            "translate": "x.unknown", "fallback": "%1$s and %1$s", "with": [{"text": "A"}]
+        });
+        assert_eq!(to_text(&ok, &mut |s| Text::literal(s)).plain(), "A and A");
+    }
     use crate::lang::{self, Language, ResourceSource};
 
     struct Mem(std::collections::HashMap<String, Vec<u8>>);

crates/horizon-client-core/src/scoreboard.rs

@@ -529,10 +529,13 @@ impl Team {
             None => t,
         }
     }
-    /// `PlayerTeam.getFormattedDisplayName`.
+    /// `PlayerTeam.getFormattedDisplayName`: the display name in the team's
+    /// `displayNameStyle`, which its constructor makes the team's name on hover
+    /// (`ShowText`) and as insertion.
     pub fn formatted_display_name(&self) -> Text {
         let inner = hover_name(comp_text(&self.display_name), &self.name).with_style(&Style {
             click: None,
+            insertion: Some(self.name.clone()),
             ..Style::default()
         });
         self.apply_color(bracketed(inner))
@@ -1411,6 +1414,21 @@ fn finish(node: &mut serde_json::Map<String, Value>, extra: Vec<Comp>) -> Comp {
 #[cfg(test)]
 mod tests {
     use super::*;
+    /// #14279: `PlayerTeam`'s `displayNameStyle` puts the team's name on hover
+    /// and as insertion; `getFormattedDisplayName` brackets the name in it.
+    #[test]
+    fn a_teams_formatted_name_inserts_the_team_name() {
+        let team = Team::new("reds");
+        let c = team.formatted_display_name().component();
+        assert_eq!(c["translate"], "chat.square_brackets");
+        let inner = &c["with"][0];
+        assert_eq!(inner["text"], "reds");
+        assert_eq!(inner["insertion"], "reds");
+        assert_eq!(inner["hover_event"]["action"], "show_text");
+        // `{"text":"reds"}` or its short form `"reds"`: the same component.
+        let value = &inner["hover_event"]["value"];
+        assert!(value == "reds" || value["text"] == "reds", "{value}");
+    }
 
     fn board() -> Scoreboard {
         let mut sb = Scoreboard::default();

crates/horizon-client-core/src/text.rs

@@ -282,17 +282,20 @@ impl Text {
     pub fn push(&mut self, other: impl Into<Text>) {
         let other = other.into();
         let sibling = other.component();
-        let mut root = if self.spans.is_empty() && self.source.is_none() {
-            json!({ "text": "" })
-        } else {
-            let c = self.component();
-            if STYLE_KEYS.iter().any(|k| c.get(*k).is_some()) {
-                json!({ "text": "", "extra": [c] })
-            } else {
-                c
-            }
+        // The tree is appended to in place: cloning all of it on every append made a component
+        // with N siblings (a server's chat or MOTD "extra") cost N^2.
+        let root = match self.source.take() {
+            None if self.spans.is_empty() => std::sync::Arc::new(json!({ "text": "" })),
+            None => std::sync::Arc::new(self.component()),
+            Some(c) => c,
         };
-        if let Value::Object(o) = &mut root {
+        let mut root = if STYLE_KEYS.iter().any(|k| root.get(*k).is_some()) {
+            let c = std::sync::Arc::try_unwrap(root).unwrap_or_else(|c| (*c).clone());
+            std::sync::Arc::new(json!({ "text": "", "extra": [c] }))
+        } else {
+            root
+        };
+        if let Value::Object(o) = std::sync::Arc::make_mut(&mut root) {
             match o.get_mut("extra") {
                 Some(Value::Array(a)) => a.push(sibling),
                 _ => {
@@ -300,7 +303,7 @@ impl Text {
                 }
             }
         }
-        self.source = Some(root.into());
+        self.source = Some(root);
         self.spans.extend(other.spans);
     }
     /// Apply `style` underneath every span (MutableComponent.withStyle on a parent).
@@ -671,11 +674,22 @@ pub fn legacy_format(style: &Style, code: char, reset: &Style) -> Style {
     s
 }
 
+/// The most spans one translation expands to. Vanilla's `TranslatableContents.decompose` keeps
+/// references to its arguments, so its cost stays linear in the input; copying them here makes
+/// nested `%1$s` templates multiply (`k` references nested `D` deep: `k^D` copies), and a server's
+/// `fallback` template is any text it likes.
+const MAX_TRANSLATION_SPANS: usize = 1 << 15;
+/// The most text one translation expands to: one long argument referenced many times multiplies
+/// bytes, not spans.
+const MAX_TRANSLATION_BYTES: usize = 1 << 22;
+
 /// TranslatableContents.decomposeTemplate: `%s` takes the next argument,
 /// `%n$s` a numbered one and `%%` is a percent sign. Malformed templates are
-/// shown verbatim.
+/// shown verbatim, and so is one that would expand past [`MAX_TRANSLATION_SPANS`] or
+/// [`MAX_TRANSLATION_BYTES`].
 pub fn format_translation(template: &str, args: &[Text]) -> Text {
     let mut out = Text::default();
+    let mut bytes = 0usize;
     let mut literal = String::new();
     let mut next = 0usize;
     let chars: Vec<char> = template.chars().collect();
@@ -725,6 +739,14 @@ pub fn format_translation(template: &str, args: &[Text]) -> Text {
                 let Some(arg) = args.get(index) else {
                     return Text::literal(template);
                 };
+                bytes = bytes
+                    .saturating_add(literal.len())
+                    .saturating_add(arg.spans.iter().map(|s| s.text.len()).sum());
+                if out.spans.len().saturating_add(arg.spans.len()) >= MAX_TRANSLATION_SPANS
+                    || bytes > MAX_TRANSLATION_BYTES
+                {
+                    return Text::literal(template);
+                }
                 if !literal.is_empty() {
                     out.spans.push(Span {
                         text: std::mem::take(&mut literal),
@@ -750,6 +772,42 @@ pub fn format_translation(template: &str, args: &[Text]) -> Text {
 mod tests {
     use super::*;
     #[test]
+    fn appending_builds_the_same_tree_in_linear_time() {
+        // A styled text is wrapped once, so its style doesn't reach what follows; a plain one
+        // takes the siblings itself; a copy taken before an append keeps its own tree.
+        let mut styled = Text::literal("a").with_style(&Style {
+            bold: Some(true),
+            ..Style::default()
+        });
+        styled.push(Text::literal("b"));
+        let before = styled.clone();
+        styled.push(Text::literal("c"));
+        assert_eq!(
+            styled.component(),
+            json!({"text": "", "extra": [{"text": "a", "bold": true}, {"text": "b"}, {"text": "c"}]})
+        );
+        assert_eq!(
+            before.component(),
+            json!({"text": "", "extra": [{"text": "a", "bold": true}, {"text": "b"}]})
+        );
+        let mut plain = Text::default();
+        plain.push(Text::literal("x"));
+        plain.push(Text::literal("y"));
+        assert_eq!(
+            plain.component(),
+            json!({"text": "", "extra": [{"text": "x"}, {"text": "y"}]})
+        );
+        // 20 000 siblings, as a server's chat may carry: 76 s before, as each append cloned the
+        // whole tree.
+        let started = std::time::Instant::now();
+        let mut long = Text::default();
+        for _ in 0..20_000 {
+            long.push(Text::literal("a"));
+        }
+        assert_eq!(long.spans.len(), 20_000);
+        assert!(started.elapsed() < std::time::Duration::from_secs(5));
+    }
+    #[test]
     fn click_events_serialize_and_inherit_as_one_style_field() {
         for (event, json) in [
             (

crates/horizon-client-input/Cargo.toml

@@ -9,11 +9,13 @@ description = "The client's input layer: key bindings and their names, mouse, co
 [dependencies]
 horizon-client-core = { path = "../horizon-client-core" }
 winit = "0.30.13"
-# The window icon.
-horizon-theme = { path = "../horizon-theme" }
 png = "0.18"
 arboard = { version = "3.6.1", default-features = false, features = ["wayland-data-control"] }
 
+[dev-dependencies]
+# The window icon test decodes Horizon's icon.
+horizon-theme = { path = "../horizon-theme" }
+
 [features]
 controllers = []
 

crates/horizon-client-input/src/actions.rs

@@ -98,6 +98,7 @@ actions! {
     Emote, "key.emote", Some(KeyCode::KeyB);
     HotbarPrevious, "pad.hotbarPrevious", None;
     HotbarNext, "pad.hotbarNext", None;
+    Radial, "pad.radial", None;
 }
 
 impl Action {

crates/horizon-client-input/src/gamepad.rs

@@ -253,6 +253,17 @@ impl Activity {
 /// Horizon's pad-only actions (no vanilla key mapping).
 pub const HOTBAR_PREVIOUS: &str = "pad.hotbarPrevious";
 pub const HOTBAR_NEXT: &str = "pad.hotbarNext";
+/// Held, opens the radial menu (`radial.rs`).
+pub const RADIAL: &str = "pad.radial";
+
+mod radial_file;
+pub use radial_file::{RadialMode, RadialStick, opener_refused};
+
+/// The `bindLayout` the settings file is written in. 1: the defaults of the binds list as they
+/// are; 2: the radial menu's opener resolved against the player's own buttons.
+const BIND_LAYOUT: u32 = 2;
+/// The layout from which the file, not the default, says where the opener is.
+const OPENER_LAYOUT: u32 = 2;
 
 /// Bindable actions and their default buttons: vanilla key mappings (the
 /// game acts as their default key) and Horizon's pad-only actions. Start is
@@ -271,6 +282,7 @@ pub const ACTIONS: &[(&str, Option<Button>)] = &[
     ("key.togglePerspective", Some(Button::Select)),
     ("key.pickItem", Some(Button::DPadLeft)),
     ("key.chat", Some(Button::DPadUp)),
+    (RADIAL, Some(Button::DPadRight)),
     ("key.advancements", None),
     ("key.playerlist", None),
     ("key.command", None),
@@ -303,11 +315,14 @@ pub enum Route {
     HotbarStep {
         next: bool,
     },
+    Radial,
     /// Held, or flipped when the pad's toggle sneak is on.
     Sneak,
     Screenshot,
     SmoothCamera,
     Fullscreen,
+    /// F3's debug screen, shown or hidden as F3 alone does.
+    DebugOverlay,
     /// Does nothing by itself: what reads it asks whether the button is held
     /// (`Minecraft.handleKeybinds`' toolbar keys, held with a hotbar key).
     Held,
@@ -320,10 +335,12 @@ pub fn route(action: &str) -> Option<Route> {
     match action {
         HOTBAR_PREVIOUS => Some(Route::HotbarStep { next: false }),
         HOTBAR_NEXT => Some(Route::HotbarStep { next: true }),
+        RADIAL => Some(Route::Radial),
         "key.sneak" => Some(Route::Sneak),
         "key.screenshot" => Some(Route::Screenshot),
         "key.smoothCamera" => Some(Route::SmoothCamera),
         "key.fullscreen" => Some(Route::Fullscreen),
+        "key.debug.overlay" => Some(Route::DebugOverlay),
         "key.saveToolbarActivator" | "key.loadToolbarActivator" => Some(Route::Held),
         _ => {
             let default = crate::keybinds::KeyBinds::default_of(action);
@@ -334,12 +351,16 @@ pub fn route(action: &str) -> Option<Route> {
     }
 }
 
+/// The radial menu's opener, as the binds list and the gameplay guide name it.
+pub const RADIAL_CAPTION: &str = "horizon.pad.action.radial";
+
 /// An action's name in the binds list: vanilla's translation key, or
 /// Horizon's own English for the pad-only actions.
 pub fn action_caption(action: &str) -> &str {
     match action {
         HOTBAR_PREVIOUS => "Hotbar: Previous Slot",
         HOTBAR_NEXT => "Hotbar: Next Slot",
+        RADIAL => RADIAL_CAPTION,
         other => other,
     }
 }
@@ -654,6 +675,21 @@ pub struct PadSettings {
     pub repeat_interval: f32,
     /// Action name -> button, `None` for unbound; missing means the default.
     bindings: BTreeMap<&'static str, Option<Button>>,
+    /// The radial menu's pages.
+    pub radial: crate::radial::Pages,
+    /// Whether the radial menu's opener is held or pressed once.
+    pub radial_mode: RadialMode,
+    /// The stick that selects in it.
+    pub radial_stick: RadialStick,
+    /// Lines this game doesn't read (a newer Horizon's settings, an action it doesn't have, a
+    /// button it doesn't know), kept as they were so a save here loses nothing.
+    extra: Vec<(String, String)>,
+    /// The newest `bindLayout` the file has been written in: this game's, or a newer Horizon's,
+    /// kept so that one doesn't resolve its file again as older than it is.
+    bind_layout: u32,
+    /// The opener last used with each stick (`RadialStick::ALL` order), so stepping the Selects
+    /// With row and back gives each stick's own opener again.
+    openers: radial_file::StickOpeners,
 }
 impl Default for PadSettings {
     fn default() -> Self {
@@ -680,6 +716,12 @@ impl Default for PadSettings {
             repeat_delay: 0.35,
             repeat_interval: 0.09,
             bindings: BTreeMap::new(),
+            radial: Default::default(),
+            radial_mode: RadialMode::Hold,
+            radial_stick: RadialStick::Right,
+            extra: Vec::new(),
+            bind_layout: BIND_LAYOUT,
+            openers: radial_file::StickOpeners::default(),
         }
     }
 }
@@ -706,6 +748,7 @@ impl PadSettings {
     }
     pub fn parse(text: &str) -> Self {
         let mut s = Self::default();
+        let mut saved_opener = None;
         for line in text.lines() {
             let Some((key, value)) = line.split_once(':') else {
                 continue;
@@ -754,22 +797,85 @@ impl PadSettings {
                 "scrollSpeed" => s.scroll_speed = bounded(s.scroll_speed, 1.0, 36.0),
                 "repeatDelay" => s.repeat_delay = bounded(s.repeat_delay, 0.1, 1.0),
                 "repeatInterval" => s.repeat_interval = bounded(s.repeat_interval, 0.03, 0.3),
+                "radialMode" => s.radial_mode = RadialMode::parse(value),
+                "radialStick" => s.radial_stick = RadialStick::parse(value),
+                // Read after the loop, from the whole text.
+                "bindLayout" => {}
+                // The radial menu's pages (`radial::Pages::parse`).
+                other if other.starts_with("radial_") || other == crate::radial::LAYOUT_KEY => {}
                 other => {
-                    if let Some(action) = other.strip_prefix("bind_") {
-                        let button = if value == "none" {
-                            Some(None)
-                        } else {
-                            Button::parse(value).map(Some)
-                        };
-                        if let Some(button) = button {
-                            s.bind(action, button);
-                        }
+                    let known = other
+                        .strip_prefix("bind_")
+                        .filter(|action| ACTIONS.iter().any(|a| a.0 == *action));
+                    let button = if value == "none" {
+                        Some(None)
+                    } else {
+                        Button::parse(value).map(Some)
+                    };
+                    match (known, button) {
+                        // The opener once the selecting stick is known.
+                        (Some(RADIAL), Some(button)) => saved_opener = Some(button),
+                        (Some(action), Some(button)) => s.bind(action, button),
+                        _ => s.extra.push((other.to_owned(), value.to_owned())),
                     }
                 }
             }
         }
-        // A file from before these defaults: its player's buttons stay where they were.
-        if !text.is_empty() && !text.lines().any(|line| line.starts_with("bindLayout:")) {
+        // An opener on a button it can't be with this stick reads as never saved.
+        let refused_opener = match saved_opener {
+            Some(Some(b)) if opener_refused(s.radial_stick, b) => true,
+            Some(button) => {
+                s.bind(RADIAL, button);
+                false
+            }
+            None => false,
+        };
+        if let Some(pages) = crate::radial::Pages::parse(
+            text.lines()
+                .filter_map(|line| line.split_once(':'))
+                .map(|(key, value)| (key.trim(), value.trim())),
+        ) {
+            s.radial = pages;
+        }
+        let lines = || text.lines().map(str::trim);
+        let saved = |action: &str| {
+            let prefix = format!("bind_{action}:");
+            lines().any(|line| line.starts_with(&prefix))
+        };
+        // The layout the file was written in; none in a file from before these defaults.
+        let layout = lines()
+            .find_map(|line| line.strip_prefix("bindLayout:"))
+            .map(|value| value.trim().parse::<u32>().unwrap_or(0));
+        s.bind_layout = layout.map_or(BIND_LAYOUT, |layout| layout.max(BIND_LAYOUT));
+        // Once, for a file from before the radial menu's opener, or one with the opener on a
+        // button it can no longer be: a button the player bound by hand stays theirs, and the
+        // opener's default doesn't take it. From then on the file says where the opener is, and
+        // a conflict made since stays shown in the binds list.
+        let before_opener = layout.is_none_or(|layout| layout < OPENER_LAYOUT);
+        if !text.is_empty() && (refused_opener || (before_opener && !saved(RADIAL))) {
+            let default_opener = ACTIONS
+                .iter()
+                .find(|(action, _)| *action == RADIAL)
+                .and_then(|(_, button)| *button);
+            let taken = s.bindings.iter().any(|(action, button)| {
+                *action != RADIAL && button.is_some() && *button == default_opener
+            });
+            if taken {
+                s.bindings.insert(RADIAL, None);
+            }
+        }
+        // The default too can be under the selecting thumb (D-pad Right, the left stick
+        // selecting): no button opens the menu until the player picks one.
+        if s.binding(RADIAL)
+            .is_some_and(|b| opener_refused(s.radial_stick, b))
+        {
+            s.bindings.insert(RADIAL, None);
+        }
+        // A file from before these defaults: its player's buttons stay where they were, and
+        // nothing they saved shares a button with the radial menu's opener. They can bind one
+        // in the binds list.
+        if !text.is_empty() && layout.is_none() {
+            s.bindings.entry(RADIAL).or_insert(None);
             for (action, button) in [
                 ("key.drop", Button::East),
                 ("key.togglePerspective", Button::DPadUp),
@@ -778,10 +884,7 @@ impl PadSettings {
                 ("key.advancements", Button::DPadDown),
             ] {
                 // A button saved by hand stays, even one that's now this action's default.
-                if !text
-                    .lines()
-                    .any(|line| line.starts_with(&format!("bind_{action}:")))
-                {
+                if !saved(action) {
                     s.bindings.entry(action).or_insert(Some(button));
                 }
             }
@@ -822,7 +925,25 @@ impl PadSettings {
             "playInBackground:{}\n",
             bool_text(self.play_in_background)
         ));
-        text.push_str("bindLayout:1\n");
+        text.push_str(&format!(
+            "radialMode:{}\nradialStick:{}\n",
+            self.radial_mode.name(),
+            self.radial_stick.name()
+        ));
+        text.push_str(&format!("bindLayout:{}\n", self.bind_layout));
+        for (key, value) in &self.extra {
+            // A button this game didn't know, for an action the player has bound here since.
+            let rebound = key
+                .strip_prefix("bind_")
+                .is_some_and(|action| self.bindings.contains_key(action));
+            if !rebound {
+                text.push_str(&format!("{key}:{value}\n"));
+            }
+        }
+        // The default pages aren't written: they can improve for a player who never changed them.
+        if self.radial != crate::radial::Pages::default() {
+            text.push_str(&self.radial.serialize());
+        }
         text
     }
     pub fn default_of(action: &str) -> Option<Button> {
@@ -835,11 +956,15 @@ impl PadSettings {
             None => Self::default_of(action),
         }
     }
-    /// Bind an action (`None` unbinds); unknown actions are ignored.
+    /// Put `action` on `button`, or unbind it. An unknown action, or a button it can't take
+    /// (`can_bind`), changes nothing.
     pub fn bind(&mut self, action: &str, button: Option<Button>) {
         let Some((name, default)) = ACTIONS.iter().find(|a| a.0 == action) else {
             return;
         };
+        if button.is_some_and(|b| !self.can_bind(action, b)) {
+            return;
+        }
         if button == *default {
             self.bindings.remove(name);
         } else {
@@ -1440,6 +1565,24 @@ pub enum Rumble {
         radius: f32,
     },
     Totem,
+    /// The radial menu's stick reached a slot that would run: a tick.
+    RadialSlot,
+    /// The radial menu's page turned: a shorter tick.
+    RadialPage,
+    /// The page turn went round an end: a second tick after the first.
+    RadialWrap,
+    /// A release ran nothing after something had been selected: a soft buzz.
+    RadialNothing,
+}
+impl From<crate::input_source::Feedback> for Rumble {
+    fn from(event: crate::input_source::Feedback) -> Self {
+        use crate::input_source::Feedback;
+        match event {
+            Feedback::BlockBroken => Rumble::BlockBroken,
+            Feedback::Explosion { distance, radius } => Rumble::Explosion { distance, radius },
+            Feedback::Totem => Rumble::Totem,
+        }
+    }
 }
 /// A vibration: the heavy (low-frequency) and light motors, 0..1, and how
 /// long it lasts.
@@ -1449,6 +1592,7 @@ pub struct Pulse {
     pub weak: f32,
     pub millis: u32,
 }
+use crate::radial::{RADIAL_NOTHING, RADIAL_PAGE_TICK, RADIAL_TICK};
 impl Rumble {
     pub fn name(self) -> &'static str {
         match self {
@@ -1456,6 +1600,10 @@ impl Rumble {
             Rumble::BlockBroken => "block",
             Rumble::Explosion { .. } => "explosion",
             Rumble::Totem => "totem",
+            Rumble::RadialSlot => "radial",
+            Rumble::RadialPage => "radial_page",
+            Rumble::RadialWrap => "radial_wrap",
+            Rumble::RadialNothing => "radial_nothing",
         }
     }
     /// The pulse, or `None` when it is too faint to feel.
@@ -1482,6 +1630,9 @@ impl Rumble {
                     millis: 350,
                 })
             }
+            Rumble::RadialSlot => Some(RADIAL_TICK),
+            Rumble::RadialPage | Rumble::RadialWrap => Some(RADIAL_PAGE_TICK),
+            Rumble::RadialNothing => Some(RADIAL_NOTHING),
             Rumble::Totem => Some(Pulse {
                 strong: 0.7,
                 weak: 0.7,
@@ -1503,6 +1654,10 @@ impl Rumble {
         };
         match self {
             Rumble::BlockBroken => vec![Pulse { millis: 35, ..p }],
+            Rumble::RadialSlot
+            | Rumble::RadialPage
+            | Rumble::RadialWrap
+            | Rumble::RadialNothing => vec![p],
             Rumble::Hurt(_) => {
                 let tail = p.millis.saturating_sub(50) / 2;
                 vec![step(1.0, 50), step(0.55, tail), step(0.25, tail)]
@@ -1863,7 +2018,55 @@ bind_key.hotbar.2:north
         let odd = PadSettings::parse(
             "lookSensitivity:NaN\nbind_key.nope:south\nbind_key.jump:x9\nbindLayout:1\n",
         );
-        assert_eq!(odd, PadSettings::default());
+        assert_eq!(
+            odd.look_sensitivity,
+            PadSettings::default().look_sensitivity
+        );
+        assert_eq!(odd.binding("key.jump"), Some(Button::South));
+        assert_eq!(odd.actions_of(Button::South), ["key.jump"]);
+    }
+
+    #[test]
+    fn lines_this_game_doesnt_read_survive_a_save() {
+        // A newer Horizon's setting, an action this game doesn't have, a button it doesn't know.
+        let text =
+            "bindLayout:2\nhapticStrength:0.4\nbind_horizon:dash:south\nbind_key.jump:paddle1\n";
+        let s = PadSettings::parse(text);
+        assert_eq!(
+            s.binding("key.jump"),
+            Some(Button::South),
+            "the default meanwhile"
+        );
+        let saved = s.serialize();
+        for line in [
+            "hapticStrength:0.4\n",
+            "bind_horizon:dash:south\n",
+            "bind_key.jump:paddle1\n",
+        ] {
+            assert!(saved.contains(line), "{line} lost from\n{saved}");
+        }
+        assert_eq!(PadSettings::parse(&saved), s);
+        // Bound here since, the action's own line is the one written.
+        let mut s = s;
+        s.bind("key.jump", Some(Button::West));
+        let saved = s.serialize();
+        assert!(!saved.contains("paddle1"), "{saved}");
+        assert_eq!(
+            PadSettings::parse(&saved).binding("key.jump"),
+            Some(Button::West)
+        );
+    }
+
+    #[test]
+    fn a_newer_bind_layout_is_kept() {
+        let newer = BIND_LAYOUT + 1;
+        let s = PadSettings::parse(&format!("bindLayout:{newer}\nvibration:false\n"));
+        assert!(s.serialize().contains(&format!("bindLayout:{newer}\n")));
+        let s = PadSettings::parse("bindLayout:1\nvibration:false\n");
+        assert!(
+            s.serialize()
+                .contains(&format!("bindLayout:{BIND_LAYOUT}\n"))
+        );
     }
 
     #[test]

crates/horizon-client-input/src/gamepad/radial_file.rs

@@ -0,0 +1,354 @@
+//! The radial menu's settings in the controller file (`horizon-controller.txt`): how its opener
+//! holds it open, the stick that selects, which buttons the opener may be with that stick, and the
+//! opener each stick had this session. `PadSettings::parse` and `serialize` read and write their
+//! lines (`radialMode`, `radialStick`, `bind_pad.radial`).
+use super::{Button, PadSettings, RADIAL};
+
+/// The buttons under the right thumb, which steers the right stick.
+const RIGHT_THUMB: [Button; 4] = [
+    Button::South,
+    Button::West,
+    Button::North,
+    Button::RightStick,
+];
+/// The buttons under the left thumb, which steers the left stick.
+const LEFT_THUMB: [Button; 5] = [
+    Button::DPadUp,
+    Button::DPadDown,
+    Button::DPadLeft,
+    Button::DPadRight,
+    Button::LeftStick,
+];
+
+/// Whether the radial menu's opener can't be `button` while `stick` selects. One rule: the opener
+/// is never under a thumb that selects (holding it and steering are two jobs for one thumb), nor
+/// B, which cancels the open menu. So with the right stick the face buttons and R3 go, with the
+/// left the D-pad and L3, with either both; a bumper, a trigger and View are always free, and
+/// with a bumper for the opener the other bumper turns the pages.
+pub fn opener_refused(stick: RadialStick, button: Button) -> bool {
+    button == Button::East
+        || (stick != RadialStick::Left && RIGHT_THUMB.contains(&button))
+        || (stick != RadialStick::Right && LEFT_THUMB.contains(&button))
+}
+
+/// How the radial menu's opener holds it open.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
+pub enum RadialMode {
+    /// Held: letting go runs what is selected.
+    #[default]
+    Hold,
+    /// A press opens it; A or the opener again runs what is selected, B closes it.
+    Toggle,
+}
+impl RadialMode {
+    pub const ALL: [Self; 2] = [Self::Hold, Self::Toggle];
+    pub fn name(self) -> &'static str {
+        match self {
+            Self::Hold => "hold",
+            Self::Toggle => "toggle",
+        }
+    }
+    pub fn parse(value: &str) -> Self {
+        Self::ALL
+            .into_iter()
+            .find(|mode| mode.name() == value)
+            .unwrap_or_default()
+    }
+}
+
+/// The stick that selects in the radial menu.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Default)]
+pub enum RadialStick {
+    #[default]
+    Right,
+    Left,
+    /// The last stick to lean past the select tilt.
+    Either,
+}
+impl RadialStick {
+    pub const ALL: [Self; 3] = [Self::Right, Self::Left, Self::Either];
+    pub fn name(self) -> &'static str {
+        match self {
+            Self::Right => "right",
+            Self::Left => "left",
+            Self::Either => "either",
+        }
+    }
+    pub fn parse(value: &str) -> Self {
+        Self::ALL
+            .into_iter()
+            .find(|stick| stick.name() == value)
+            .unwrap_or_default()
+    }
+}
+
+/// The opener each stick had, for this session: what the player stepped through, not a setting,
+/// so it is neither saved nor compared.
+#[derive(Clone, Copy, Debug, Default)]
+pub(super) struct StickOpeners([Option<Button>; 3]);
+impl PartialEq for StickOpeners {
+    fn eq(&self, _: &Self) -> bool {
+        true
+    }
+}
+impl StickOpeners {
+    fn slot(&mut self, stick: RadialStick) -> &mut Option<Button> {
+        let at = RadialStick::ALL
+            .iter()
+            .position(|s| *s == stick)
+            .unwrap_or(0);
+        &mut self.0[at]
+    }
+}
+
+impl PadSettings {
+    /// Whether `button` can be bound to `action`: anything but the radial menu's opener under
+    /// a thumb that selects, or on B (`opener_refused`).
+    pub fn can_bind(&self, action: &str, button: Button) -> bool {
+        action != RADIAL || !opener_refused(self.radial_stick, button)
+    }
+    /// The stick the radial menu selects with. An opener under the thumb that now selects is
+    /// unbound, and its row in the radial page says so. An unbound opener then takes the one this
+    /// stick had before in this session, or else its default where nothing else has it (D-pad
+    /// Right, back on the right stick).
+    pub fn set_radial_stick(&mut self, stick: RadialStick) {
+        let was = self.radial_stick;
+        *self.openers.slot(was) = self.binding(RADIAL);
+        self.radial_stick = stick;
+        if self
+            .binding(RADIAL)
+            .is_some_and(|b| opener_refused(stick, b))
+        {
+            self.bindings.insert(RADIAL, None);
+        }
+        if self.binding(RADIAL).is_some() {
+            return;
+        }
+        // The player's own, shared or not: they put it there.
+        if let Some(own) = self
+            .openers
+            .slot(stick)
+            .filter(|b| !opener_refused(stick, *b))
+        {
+            self.bind(RADIAL, Some(own));
+            return;
+        }
+        let default = Self::default_of(RADIAL);
+        let free =
+            default.is_some_and(|d| !opener_refused(stick, d) && self.actions_of(d).is_empty());
+        if free {
+            self.bindings.remove(RADIAL);
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::super::Rumble;
+    use super::*;
+
+    #[test]
+    fn a_new_player_holds_d_pad_right_for_the_radial_menu() {
+        for s in [PadSettings::default(), PadSettings::parse("")] {
+            assert_eq!(s.binding(RADIAL), Some(Button::DPadRight));
+            assert!(!s.conflicts(RADIAL));
+        }
+        let s = PadSettings::parse(&PadSettings::default().serialize());
+        assert_eq!(s, PadSettings::default());
+    }
+
+    #[test]
+    fn a_button_bound_by_hand_stays_with_it_over_the_openers_default() {
+        let s = PadSettings::parse("bindLayout:1\nbind_key.playerlist:right\n");
+        assert_eq!(s.binding("key.playerlist"), Some(Button::DPadRight));
+        assert_eq!(s.binding(RADIAL), None);
+        assert!(!s.conflicts("key.playerlist"));
+        assert_eq!(PadSettings::parse(&s.serialize()), s);
+    }
+
+    #[test]
+    fn a_saved_opener_stays_where_it_was_saved() {
+        let s =
+            PadSettings::parse("bindLayout:1\nbind_pad.radial:right\nbind_key.playerlist:right\n");
+        assert_eq!(s.binding(RADIAL), Some(Button::DPadRight));
+    }
+
+    #[test]
+    fn a_conflict_made_since_the_migration_stays_after_a_restart() {
+        // Bound in the binds list onto the opener's button: both stay, and the list marks it.
+        let mut s = PadSettings::default();
+        s.bind("key.playerlist", Some(Button::DPadRight));
+        let text = s.serialize();
+        assert!(text.contains("bindLayout:2"));
+        let read = PadSettings::parse(&text);
+        assert_eq!(read.binding(RADIAL), Some(Button::DPadRight));
+        assert!(read.conflicts(RADIAL));
+        assert_eq!(read, s);
+        // The same, hand-written with spaces around the lines.
+        let read = PadSettings::parse("  bindLayout:2\n  bind_key.playerlist:right\n");
+        assert_eq!(read.binding(RADIAL), Some(Button::DPadRight));
+    }
+
+    #[test]
+    fn a_layout_one_file_resolves_the_opener_once() {
+        let s = PadSettings::parse("bind_key.chat:up\n bindLayout:1\nbind_key.playerlist:right\n");
+        assert_eq!(s.binding(RADIAL), None, "the player's own button wins");
+        assert_eq!(s.binding("key.playerlist"), Some(Button::DPadRight));
+        assert_eq!(s.binding("key.chat"), Some(Button::DPadUp));
+        let text = s.serialize();
+        assert!(text.contains("bindLayout:2\n") && text.contains("bind_pad.radial:none\n"));
+        assert_eq!(PadSettings::parse(&text), s);
+        // Without a conflict the opener keeps its default.
+        let s = PadSettings::parse("bindLayout:1\nvibration:false\n");
+        assert_eq!(s.binding(RADIAL), Some(Button::DPadRight));
+        // A line with leading spaces is still a saved opener.
+        let s =
+            PadSettings::parse("bindLayout:1\n bind_pad.radial:right\nbind_key.playerlist:right\n");
+        assert_eq!(s.binding(RADIAL), Some(Button::DPadRight));
+    }
+
+    #[test]
+    fn the_opener_never_goes_under_the_selecting_thumb_nor_on_b() {
+        use Button as B;
+        let face = [B::South, B::West, B::North, B::RightStick];
+        let dpad = [
+            B::DPadUp,
+            B::DPadDown,
+            B::DPadLeft,
+            B::DPadRight,
+            B::LeftStick,
+        ];
+        for stick in RadialStick::ALL {
+            let mut s = PadSettings::default();
+            s.set_radial_stick(stick);
+            for button in Button::ALL {
+                let refused = button == B::East
+                    || (stick != RadialStick::Left && face.contains(&button))
+                    || (stick != RadialStick::Right && dpad.contains(&button));
+                assert_eq!(!s.can_bind(RADIAL, button), refused, "{stick:?} {button:?}");
+                // Other actions still take any of them.
+                assert!(s.can_bind("key.chat", button));
+            }
+            // A bumper is always free, and stays one through the file.
+            s.bind(RADIAL, Some(B::LeftBumper));
+            assert_eq!(s.binding(RADIAL), Some(B::LeftBumper), "{stick:?}");
+            assert_eq!(PadSettings::parse(&s.serialize()), s, "{stick:?}");
+        }
+        // A file with a refused opener reads as never saved: the default, unless taken.
+        for button in [B::South, B::East, B::West, B::North, B::RightStick] {
+            let text = format!("bindLayout:2\nbind_pad.radial:{}\n", button.name());
+            let read = PadSettings::parse(&text);
+            assert_eq!(read.binding(RADIAL), Some(B::DPadRight), "{button:?}");
+            let taken = format!("{text}bind_key.playerlist:right\n");
+            assert_eq!(
+                PadSettings::parse(&taken).binding(RADIAL),
+                None,
+                "{button:?}"
+            );
+        }
+        // Read with the stick it was saved for, wherever the stick's line is.
+        let left = PadSettings::parse("bind_pad.radial:north\nbindLayout:2\nradialStick:left\n");
+        assert_eq!(left.binding(RADIAL), Some(B::North));
+    }
+
+    #[test]
+    fn a_stick_that_takes_the_openers_thumb_unbinds_it_and_the_right_gives_it_back() {
+        let mut s = PadSettings::default();
+        s.set_radial_stick(RadialStick::Left);
+        assert_eq!(
+            s.binding(RADIAL),
+            None,
+            "D-pad Right is under the left thumb"
+        );
+        assert_eq!(PadSettings::parse(&s.serialize()).binding(RADIAL), None);
+        s.set_radial_stick(RadialStick::Right);
+        assert_eq!(s.binding(RADIAL), Some(Button::DPadRight));
+        // An opener the player picked that both sticks allow stays.
+        s.bind(RADIAL, Some(Button::RightBumper));
+        s.set_radial_stick(RadialStick::Either);
+        assert_eq!(s.binding(RADIAL), Some(Button::RightBumper));
+    }
+
+    #[test]
+    fn stepping_the_stick_and_back_gives_each_stick_its_own_opener() {
+        // Left with Y, back to the right stick: Y is under the right thumb, D-pad Right opens.
+        let mut s = PadSettings::default();
+        s.set_radial_stick(RadialStick::Left);
+        s.bind(RADIAL, Some(Button::North));
+        s.set_radial_stick(RadialStick::Right);
+        assert_eq!(s.binding(RADIAL), Some(Button::DPadRight));
+        // And Left again has its Y back, shared with Inventory as the player left it.
+        s.set_radial_stick(RadialStick::Left);
+        assert_eq!(s.binding(RADIAL), Some(Button::North));
+        // Right with D-pad Left: the left stick refuses it, and the right gets it back.
+        let mut s = PadSettings::default();
+        s.bind(RADIAL, Some(Button::DPadLeft));
+        s.set_radial_stick(RadialStick::Left);
+        assert_eq!(s.binding(RADIAL), None);
+        s.set_radial_stick(RadialStick::Either);
+        assert_eq!(s.binding(RADIAL), None);
+        s.set_radial_stick(RadialStick::Right);
+        assert_eq!(s.binding(RADIAL), Some(Button::DPadLeft));
+    }
+
+    #[test]
+    fn a_file_from_before_the_radial_menu_binds_no_opener() {
+        let s = PadSettings::parse("vibration:false\nbind_key.chat:up\n");
+        assert_eq!(s.binding(RADIAL), None);
+        assert_eq!(PadSettings::parse(&s.serialize()), s);
+    }
+
+    #[test]
+    fn the_radial_menus_ticks_are_felt_and_tell_apart() {
+        let tick = Rumble::RadialSlot.pulse().unwrap();
+        assert!((40..=50).contains(&tick.millis), "{tick:?}");
+        assert!((0.25..=0.35).contains(&tick.weak), "{tick:?}");
+        let page = Rumble::RadialPage.pulse().unwrap();
+        assert!(page.millis < tick.millis, "a page turn is the shorter tick");
+        assert_eq!(Rumble::RadialWrap.pulse(), Some(page));
+        let nothing = Rumble::RadialNothing.pulse().unwrap();
+        assert!(
+            nothing.strong > 0.0 && nothing.millis > tick.millis,
+            "{nothing:?}"
+        );
+        assert!(
+            nothing.strong.max(nothing.weak) < 0.3,
+            "a soft buzz: {nothing:?}"
+        );
+    }
+
+    #[test]
+    fn the_radial_menus_mode_and_stick_survive_the_settings_file() {
+        let s = PadSettings::default();
+        assert_eq!(
+            (s.radial_mode, s.radial_stick),
+            (RadialMode::Hold, RadialStick::Right)
+        );
+        for mode in RadialMode::ALL {
+            for stick in RadialStick::ALL {
+                let mut s = PadSettings {
+                    radial_mode: mode,
+                    ..PadSettings::default()
+                };
+                s.set_radial_stick(stick);
+                assert_eq!(PadSettings::parse(&s.serialize()), s);
+            }
+        }
+        let read = PadSettings::parse("radialMode:sideways\nradialStick:up\n");
+        assert_eq!(
+            (read.radial_mode, read.radial_stick),
+            (RadialMode::Hold, RadialStick::Right)
+        );
+    }
+
+    #[test]
+    fn radial_pages_survive_the_settings_file() {
+        let mut s = PadSettings::default();
+        let pages = "radial_0_label:Mine\nradial_0_slots:key.chat,,,,,,,\n";
+        s.radial =
+            crate::radial::Pages::parse(pages.lines().filter_map(|l| l.split_once(':'))).unwrap();
+        let read = PadSettings::parse(&s.serialize());
+        assert_eq!(read.radial, s.radial);
+        assert_ne!(read.radial, crate::radial::Pages::default());
+    }
+}

crates/horizon-client-input/src/gameplay_guide.rs

@@ -141,8 +141,13 @@ impl Guide {
     pub fn at_detail(self, detail: GuideDetail) -> Self {
         match detail {
             GuideDetail::Full => self,
+            // Nothing else in play names the radial menu.
             GuideDetail::Basic => Guide {
-                left: Vec::new(),
+                left: self
+                    .left
+                    .into_iter()
+                    .filter(|row| row.caption == crate::gamepad::RADIAL_CAPTION)
+                    .collect(),
                 right: self.right,
             },
             GuideDetail::Off => Guide {
@@ -178,6 +183,8 @@ pub fn resolve(facts: &Facts, settings: &PadSettings) -> Guide {
                 "key.swapOffhand",
                 (player && any_item).then_some("horizon.controller.guide.swap"),
             ),
+            // Nothing else in play says the menu is there; it opens for a spectator too.
+            row(crate::gamepad::RADIAL, Some(crate::gamepad::RADIAL_CAPTION)),
         ]
         .into_iter()
         .flatten()
@@ -566,6 +573,7 @@ mod tests {
                 (Button::North, "key.inventory"),
                 (Button::DPadDown, "horizon.controller.guide.drop"),
                 (Button::West, "horizon.controller.guide.swap"),
+                (Button::DPadRight, crate::gamepad::RADIAL_CAPTION),
             ]
         );
     }
@@ -736,12 +744,12 @@ mod tests {
                 gliding: true,
                 ..Facts::default()
             }),
-            ["key.inventory"]
+            ["key.inventory", crate::gamepad::RADIAL_CAPTION]
         );
     }
 
     #[test]
-    fn a_spectator_only_flies_opens_spectates_and_has_its_menu() {
+    fn a_spectator_only_flies_opens_spectates_and_has_its_menus() {
         let facts = Facts {
             spectator: true,
             flying: true,
@@ -765,7 +773,8 @@ mod tests {
             captions(&guide.left),
             [
                 "horizon.controller.guide.fly_up",
-                "horizon.controller.guide.fly_down"
+                "horizon.controller.guide.fly_down",
+                crate::gamepad::RADIAL_CAPTION
             ]
         );
     }

crates/horizon-client-input/src/input_source.rs

@@ -0,0 +1,15 @@
+//! The engine's side of the input source (docs/layers.md, "Controllers, splitscreen, replays and
+//! UI pages"): what gameplay tells a device beyond the keyboard and mouse. Gameplay names these
+//! types, never a controller's; the controller code answers.
+
+/// Something that happened to the player that a device may let them feel (a controller's
+/// vibration). The device decides how, or whether.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub enum Feedback {
+    /// The player broke a block.
+    BlockBroken,
+    /// An explosion this far away (blocks) with this power.
+    Explosion { distance: f64, radius: f32 },
+    /// A totem of undying saved the player.
+    Totem,
+}

crates/horizon-client-input/src/lib.rs

@@ -9,11 +9,13 @@ pub mod gamepad;
 pub mod gameplay_guide;
 pub mod held;
 pub mod input;
+pub mod input_source;
 pub mod interaction_input;
 pub mod key_names;
 pub mod keybinds;
 pub mod keymapping;
 pub mod modifiers;
 pub mod mouse;
+pub mod radial;
 pub mod snap;
 pub mod window;

crates/horizon-client-input/src/window.rs

@@ -638,10 +638,30 @@ pub fn fullscreen_request(
     }
 }
 
-/// Horizon's icon for the window's title bar and the task bar (X11 and Windows; Wayland takes
-/// it from the `horizon.desktop` entry, macOS from the app bundle). `None` if it can't be read.
+/// The PNG the windows show as their icon, given once at startup by the layer that brands the
+/// game (the engine has none of its own).
+static ICON_PNG: std::sync::OnceLock<&'static [u8]> = std::sync::OnceLock::new();
+
+/// Give the windows their icon, a PNG: call it before the first window opens. A second call
+/// keeps the first icon.
+pub fn set_icon_png(png: &'static [u8]) {
+    let _ = ICON_PNG.set(png);
+}
+
+/// The icon given to [`set_icon_png`], if any.
+pub fn icon_png() -> Option<&'static [u8]> {
+    ICON_PNG.get().copied()
+}
+
+/// The icon for the window's title bar and the task bar (X11 and Windows; Wayland takes it from
+/// the `.desktop` entry, macOS from the app bundle). `None` with no icon given, or one that
+/// can't be read.
 pub fn icon() -> Option<winit::window::Icon> {
-    let mut decoder = png::Decoder::new(std::io::Cursor::new(horizon_theme::ICON_PNG));
+    decode_icon(icon_png()?)
+}
+
+fn decode_icon(png: &[u8]) -> Option<winit::window::Icon> {
+    let mut decoder = png::Decoder::new(std::io::Cursor::new(png));
     decoder.ignore_checksums(true);
     decoder.set_transformations(png::Transformations::EXPAND | png::Transformations::STRIP_16);
     let mut reader = decoder.read_info().ok()?;
@@ -654,14 +674,15 @@ pub fn icon() -> Option<winit::window::Icon> {
     winit::window::Icon::from_rgba(bytes, info.width, info.height).ok()
 }
 
-/// Apply Horizon's icon to every window. Windows has a separate taskbar icon slot from the small
-/// window icon; requiring the decoded icon there prevents a generic taskbar icon from appearing.
-pub fn with_horizon_icon(
-    attributes: winit::window::WindowAttributes,
-) -> winit::window::WindowAttributes {
+/// Apply the icon given to [`set_icon_png`] to a window. Windows has a separate taskbar icon slot
+/// from the small window icon; requiring a given icon to decode there prevents a generic taskbar
+/// icon from appearing.
+pub fn with_icon(attributes: winit::window::WindowAttributes) -> winit::window::WindowAttributes {
+    #[cfg(not(target_os = "windows"))]
     let icon = icon();
     #[cfg(target_os = "windows")]
-    let icon = Some(icon.expect("Horizon's icon must be available on Windows"));
+    let icon =
+        icon_png().map(|png| decode_icon(png).expect("the window icon must decode on Windows"));
 
     let attributes = attributes.with_window_icon(icon.clone());
     #[cfg(target_os = "windows")]
@@ -739,7 +760,8 @@ mod tests {
     }
     #[test]
     fn the_window_icon_decodes() {
-        assert!(icon().is_some());
+        assert!(decode_icon(horizon_theme::ICON_PNG).is_some());
+        assert!(decode_icon(b"not a png").is_none());
     }
 
     #[test]

crates/horizon-client-lib/Cargo.toml

@@ -27,6 +27,9 @@ horizon-mcp = { path = "../horizon-mcp" }
 # The server thread ahead of the workers (MinecraftServer.spin's Thread.setPriority).
 horizon-optifine = { path = "../horizon-optifine" }
 horizon-threads = { path = "../horizon-threads" }
+# One pool of helper threads for the server tick's parallel phases (`parallel.rs`): threads made
+# once, not for every phase of every tick.
+rayon = "1.10"
 horizon-hdr = { path = "../horizon-hdr" }
 horizon-world = { path = "../horizon-world" }
 horizon-protocol = { path = "../horizon-protocol" }
@@ -70,7 +73,6 @@ flate2 = { version = "1.1.10", default-features = false, features = ["zlib-rs",
 mio = { version = "1.2.4", features = ["os-poll", "net"] }
 # Shared chunk frames are found by one keyed 128-bit hash of their body (lan/conn.rs SharedFrames).
 xxhash-rust = { version = "0.8.19", features = ["xxh3"] }
-horizon-theme = { path = "../horizon-theme" }
 # Opt-in data collection: the game keeps, the launcher sends (docs/telemetry.md).
 horizon-telemetry = { path = "../horizon-telemetry", default-features = false }
 horizon-bench = { path = "../horizon-bench" }
@@ -109,17 +111,12 @@ objc2-foundation = { version = "0.3", default-features = false, features = ["std
 wgpu = { version = "30.0.1", default-features = false, features = ["gles"] }
 
 [features]
-default = ["audio", "controllers", "horizon-extras"]
+default = ["audio", "controllers"]
 # Sound output. Without it (and `controllers`) the program links neither libasound nor libudev on
 # Linux: the server build (`--no-default-features`, released as horizon-engine; docs/server.md).
 audio = ["horizon-client-render/audio"]
 # Controllers: gilrs, and the DualSense's own output. Without it only `horizon-ctl pad`'s virtual pad.
 controllers = ["dep:gilrs", "horizon-client-input/controllers"]
-# Horizon's own parts (docs/forking.md, docs/layers.md): the features below, and the official
-# server in the list (`official_servers`).
-horizon-extras = ["discord"]
-# "Playing Horizon" on the player's Discord profile (`discord_presence`).
-discord = []
 # Records the call sites of mob random draws (`mob_ai_probe` traces).
 rng-trace = ["horizon-core/rng-trace"]
 # Compatibility with earlier experiment commands: main already uses mimalloc.
@@ -131,6 +128,8 @@ windows-segment-heap = []
 workspace = true
 
 [dev-dependencies]
+# ui_theme's unit tests draw text in the design system's fonts.
+horizon-theme = { path = "../horizon-theme" }
 horizon-client-render = { path = "../horizon-client-render", features = ["test-support"] }
 horizon-items = { path = "../horizon-items", features = ["test-support"] }
 # Every WGSL shader translated as wgpu's DirectX 12 backend does (gfx.rs tests).

crates/horizon-client-render/Cargo.toml

@@ -29,7 +29,6 @@ horizon-protocol = { path = "../horizon-protocol" }
 horizon-shader-api = { path = "../horizon-shader-api" }
 horizon-shaders = { path = "../horizon-shaders" }
 horizon-system = { path = "../horizon-system" }
-horizon-theme = { path = "../horizon-theme" }
 horizon-threads = { path = "../horizon-threads" }
 horizon-world = { path = "../horizon-world" }
 ab_glyph = "0.2.32"
@@ -85,5 +84,7 @@ horizon-extras = []
 workspace = true
 
 [dev-dependencies]
+# Tests: a TrueType font to load, and the design system the menus' motion curves match.
+horizon-theme = { path = "../horizon-theme" }
 horizon-items = { path = "../horizon-items", features = ["test-support"] }
 naga = { version = "30.0.1", features = ["wgsl-in", "hlsl-out", "glsl-out", "msl-out", "spv-out"] }

crates/horizon-client-render/examples/audio_bench.rs

@@ -0,0 +1,158 @@
+//! Audio occlusion, attenuation and mixing benchmark.
+//! Run with: `cargo run --profile fast -p horizon-client-render --example audio_bench`
+use horizon_client_render::{
+    audio::Audio,
+    sound_engine::{MobSound, SoundInstance, Sounds, TickContext},
+};
+use std::{path::Path, time::Instant};
+
+fn main() {
+    println!("=== Horizon Audio Attenuation & Mixing Benchmark ===");
+
+    let mut audio = Audio::silent(Path::new("/nonexistent"));
+    audio.engine.loaded = true;
+    audio.backend_live_for_bench();
+    audio.record_heard = false;
+
+    // Register a sound event with attenuation distance 16
+    audio.engine.registry.add_file(
+        "minecraft",
+        br#"{"bench.loop":{"attenuation_distance":16,"sounds":[{"name":"bench/loop","stream":false}]}}"#,
+        &|_, _| true,
+    );
+    // Insert 1 second of audio into cache (48000 mono samples)
+    let samples: Vec<f32> = (0..48_000)
+        .map(|i| ((i as f32) * 440.0 * 2.0 * std::f32::consts::PI / 48000.0).sin() * 0.5)
+        .collect();
+    audio.insert_cached_sound("minecraft:bench/loop", samples, 48_000, 1);
+
+    // 1. Benchmark set_listener (called every client render frame)
+    let listener_iterations = 200_000;
+    let start = Instant::now();
+    for i in 0..listener_iterations {
+        let angle = (i as f32) * 0.01;
+        audio.set_listener(
+            [
+                100.0 + (angle.cos() as f64) * 5.0,
+                64.0,
+                200.0 + (angle.sin() as f64) * 5.0,
+            ],
+            angle,
+            0.0,
+        );
+    }
+    let listener_elapsed = start.elapsed();
+    println!(
+        "1. set_listener moving (render frame): {:?} for {} calls ({:.2} ns/call)",
+        listener_elapsed,
+        listener_iterations,
+        (listener_elapsed.as_nanos() as f64) / (listener_iterations as f64)
+    );
+
+    // 1b. Benchmark set_listener stationary (lock elimination early-out)
+    let stationary_iterations = 200_000;
+    let start = Instant::now();
+    for _ in 0..stationary_iterations {
+        audio.set_listener([100.0, 64.0, 200.0], 0.0, 0.0);
+    }
+    let stationary_elapsed = start.elapsed();
+    println!(
+        "1b. set_listener stationary (lock early-out): {:?} for {} calls ({:.2} ns/call)",
+        stationary_elapsed,
+        stationary_iterations,
+        (stationary_elapsed.as_nanos() as f64) / (stationary_iterations as f64)
+    );
+
+    // 2. Play 128 sounds in the world at various distances from listener at [100.0, 64.0, 200.0]
+    // 64 sounds within attenuation distance (<16 blocks)
+    // 64 sounds outside attenuation distance (>16 blocks)
+    for i in 0..128 {
+        let dist = if i < 64 {
+            (i as f64) * 0.24 // 0 to 15.1 blocks (audible)
+        } else {
+            17.0 + ((i - 64) as f64) * 1.5 // 17 to 111.5 blocks (out of attenuation range)
+        };
+        let pos = [100.0 + dist, 64.0, 200.0];
+        let instance = SoundInstance::new(
+            "minecraft:bench.loop",
+            crate_sound_source(i),
+            1.0,
+            1.0,
+            horizon_core::random::LegacyRandom::new(i as i64),
+            true, // looping
+            0,
+            horizon_client_render::sound_engine::Attenuation::Linear,
+            pos,
+            false,
+        );
+        audio.play_instance(instance, false);
+    }
+
+    // 3. Benchmark mix_buffer (5000 buffers of 1024 stereo frames @ 48kHz = ~106 seconds of audio mixing)
+    let mut buffer = vec![0.0f32; 1024 * 2];
+    let mix_iterations = 5_000;
+    let start = Instant::now();
+    for _ in 0..mix_iterations {
+        audio.mix_buffer(&mut buffer, 2, 48_000);
+    }
+    let mix_elapsed = start.elapsed();
+    println!(
+        "2. mix_buffer (128 active channels, 1024 stereo frames): {:?} for {} buffers ({:.2} µs/buffer)",
+        mix_elapsed,
+        mix_iterations,
+        (mix_elapsed.as_micros() as f64) / (mix_iterations as f64)
+    );
+
+    // 4. Benchmark SoundEngine::tick with ticking mob sounds
+    let mut mobs = Vec::new();
+    for i in 0..64 {
+        mobs.push(MobSound {
+            id: 2000 + i,
+            position: [100.0 + (i as f64) * 0.5, 64.0, 200.0 + (i as f64) * 0.5],
+            speed: 0.25,
+            baby: false,
+            angry: i % 2 == 0,
+            silent: false,
+            attack_scale: 0.5,
+            sniffer_digging: false,
+        });
+    }
+
+    let tick_ctx = TickContext {
+        player_underwater: false,
+        player_removed: false,
+        vehicle: None,
+        carts: Vec::new(),
+        mobs: mobs.clone(),
+        frozen: false,
+        player_position: [100.0, 64.0, 200.0],
+        player_speed_sqr: 0.1,
+        player_fall_flying: false,
+        ridden: None,
+        camera_position: [100.0, 64.0, 200.0],
+    };
+
+    let tick_iterations = 10_000;
+    let start = Instant::now();
+    for _ in 0..tick_iterations {
+        audio.tick(false, &tick_ctx);
+    }
+    let tick_elapsed = start.elapsed();
+    println!(
+        "3. SoundEngine::tick (64 channels + ticking): {:?} for {} ticks ({:.2} µs/tick)",
+        tick_elapsed,
+        tick_iterations,
+        (tick_elapsed.as_micros() as f64) / (tick_iterations as f64)
+    );
+}
+
+fn crate_sound_source(i: u32) -> usize {
+    match i % 6 {
+        0 => 0, // master
+        1 => 1, // music
+        2 => 2, // records
+        3 => 3, // weather
+        4 => 4, // blocks
+        _ => 5, // hostile
+    }
+}

crates/horizon-client-render/examples/scene_replay.rs

@@ -386,6 +386,7 @@ fn replay(window: Arc<Window>) -> Result<(), Box<dyn std::error::Error>> {
                 path: path.clone(),
                 size: None,
                 scaled: false,
+                background: false,
             });
             for _ in 0..32 {
                 draw(&mut renderer)?;

crates/horizon-client-render/examples/standard_pack_gpu_entities.rs

@@ -207,6 +207,7 @@ fn fixture(window: Arc<Window>) -> Result<(), Box<dyn std::error::Error>> {
         path: out.join("cpu.png"),
         size: None,
         scaled: false,
+        background: false,
     });
     renderer.render(&frame)?;
     let expected = read(&out.join("cpu.png"));
@@ -251,6 +252,7 @@ fn fixture(window: Arc<Window>) -> Result<(), Box<dyn std::error::Error>> {
         path: out.join("gpu.png"),
         size: None,
         scaled: false,
+        background: false,
     });
     renderer.render(&frame)?;
     assert_eq!(

crates/horizon-client-render/examples/world_warp_check.rs

@@ -167,6 +167,7 @@ fn fixture(window: Arc<Window>) -> Result<(), Box<dyn std::error::Error>> {
             path: path.clone(),
             size: None,
             scaled: false,
+            background: false,
         });
         // twice: the first frame of a new warp builds it
         renderer.render(&frame).unwrap();
@@ -336,6 +337,7 @@ fn bench(renderer: &mut Renderer, out: &Path) -> Result<(), Box<dyn std::error::
             path: out.join("bench.png"),
             size: None,
             scaled: false,
+            background: false,
         });
         renderer.render(&frame).unwrap();
         renderer.render(&frame).unwrap();

crates/horizon-client-render/src/assets.rs

@@ -6,7 +6,12 @@ use horizon_world::{
     worldgen::{tags::TagDefinitions, terrain::TerrainBlockStates},
 };
 use serde_json::Value;
-use std::{collections::BTreeSet, io, path::Path, sync::Arc};
+use std::{
+    collections::BTreeSet,
+    io,
+    path::Path,
+    sync::{Arc, Mutex},
+};
 
 pub const MATERIALS: [&str; 6] = ["bedrock", "dirt", "stone", "sand", "oak_planks", "bricks"];
 #[derive(Clone, Copy)]
@@ -182,6 +187,23 @@ static GENERATION: std::sync::atomic::AtomicU64 = std::sync::atomic::AtomicU64::
 fn invalid(message: &str) -> io::Error {
     io::Error::new(io::ErrorKind::InvalidData, message)
 }
+/// Every block registry [`Assets::load`] has handed out, one per distinct
+/// content. Callers keep `&'static` references, so a registry is never freed;
+/// loading equal data again (tests load the same root once per fixture)
+/// returns the one already leaked instead of leaking another (about 11 MB for
+/// vanilla).
+static REGISTRIES: Mutex<Vec<&'static BlockRegistry>> = Mutex::new(Vec::new());
+
+/// `registry` leaked, or the equal one leaked before it.
+fn intern_registry(registry: BlockRegistry) -> &'static BlockRegistry {
+    let mut leaked = REGISTRIES.lock().unwrap_or_else(|e| e.into_inner());
+    if let Some(&same) = leaked.iter().find(|&&known| *known == registry) {
+        return same;
+    }
+    let registry: &'static BlockRegistry = Box::leak(Box::new(registry));
+    leaked.push(registry);
+    registry
+}
 impl Assets {
     pub fn load(root: &Path) -> Result<Self> {
         let manifest: Value = horizon_world::json_file::read(&root.join("horizon-resources.json"))?;
@@ -256,7 +278,7 @@ impl Assets {
         // Chunks hold every state of this registry: content mods can take it
         // past vanilla's 16-bit global palette.
         crate::chunk::set_block_states(registry.len());
-        let registry: &'static BlockRegistry = Box::leak(Box::new(registry));
+        let registry = intern_registry(registry);
         Ok(Self {
             registry,
             properties,
@@ -320,6 +342,16 @@ impl RenderAssets {
             }
             None => crate::model_library::ParsedModels::default(),
         };
+        // Connected-texture rules find their faces by sprite layer: what they match by name keeps a
+        // layer of its own, decided before the models insert their textures.
+        let ctm_rules = if draws {
+            horizon_optifine::ctm::load(root)
+        } else {
+            Vec::new()
+        };
+        sprites.keep_apart(crate::connected::ConnectedTextures::matched_sprites(
+            &ctm_rules,
+        ));
         let mut models = if draws {
             let _step = crate::spans::startup::step("core.models_bake");
             crate::models::prepare_with_models(root, registry, &mut sprites, &parsed)?
@@ -359,6 +391,7 @@ impl RenderAssets {
             let mut found = Vec::new();
             crate::connected::ConnectedTextures::load(
                 root,
+                ctm_rules,
                 registry,
                 &mut sprites,
                 |state, face| {
@@ -496,6 +529,29 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn equal_registries_are_leaked_once() {
+        use horizon_world::registry::BlockRegistry;
+        let registry = |extra: &str| {
+            let facts = format!(
+                r#"{{"defaults":{{"minecraft:air":0,"fixture:{extra}":1}},"states":[
+                    ["air",true,false,"","minecraft:air"],
+                    ["{extra}",false,false,"","fixture:{extra}"]
+                ]}}"#
+            );
+            BlockRegistry::from_facts_json(facts.as_bytes()).unwrap()
+        };
+        let first = super::intern_registry(registry("interned_once"));
+        let again = super::intern_registry(registry("interned_once"));
+        let other = super::intern_registry(registry("interned_other"));
+        assert!(std::ptr::eq(first, again), "equal content leaked twice");
+        assert!(!std::ptr::eq(first, other), "different content shared");
+        assert_eq!(
+            other.default_state("fixture:interned_other"),
+            Some(horizon_world::registry::BlockStateId(1))
+        );
+    }
+
     #[test]
     fn sprite_pixels_come_back_the_same_once_packed() {
         // Two layers of 16x16 RGBA with some structure, as sprites have.

crates/horizon-client-render/src/audio.rs

@@ -478,6 +478,7 @@ pub struct Audio {
     pub record_heard: bool,
     pub listener: [f64; 3],
     pub listener_yaw: f32,
+    pub listener_pitch: f32,
     pub master: f32,
     /// Seeds of positional plays (the client level random's `nextLong`).
     random: LegacyRandom,
@@ -722,6 +723,29 @@ impl Backend for MixerBackend {
     fn set_unmuffled(&mut self, channel: ChannelId, unmuffled: bool) {
         self.with(channel, |c| c.unmuffled = unmuffled);
     }
+    fn update_channel(&mut self, channel: ChannelId, volume: f32, pitch: f32, position: [f64; 3]) {
+        if let Ok(mut m) = self.mixer.lock()
+            && let Some(c) = m.channels.get_mut(&channel)
+        {
+            c.gain = volume;
+            c.pitch = pitch;
+            c.at = [position[0] as f32, position[1] as f32, position[2] as f32];
+        }
+    }
+    fn filter_stopped(&mut self, live: &[(u64, ChannelId)], stopped: &mut Vec<u64>) {
+        if let Ok(m) = self.mixer.lock() {
+            for &(h, c) in live {
+                if m.channels
+                    .get(&c)
+                    .is_none_or(|ch| ch.state == State::Stopped)
+                {
+                    stopped.push(h);
+                }
+            }
+        } else {
+            stopped.extend(live.iter().map(|&(h, _)| h));
+        }
+    }
     /// `getCompleteBuffer` (cached, else decoded on the decoder thread) or
     /// `getStream` (decoded on a thread of its own), then attach and
     /// `alSourcePlay`. A sound that cannot load leaves its source initial,
@@ -822,18 +846,24 @@ impl Backend for MixerBackend {
 /// pinned client's) rendered through `ALC_SOFT_loopback` within 1e-5.
 fn stereo_gains(right: f32, up: f32, forward: f32) -> [f32; 2] {
     let length = (right * right + up * up + forward * forward).sqrt();
+    stereo_gains_with_length(right, up, forward, length)
+}
+#[inline]
+fn stereo_gains_with_length(right: f32, up: f32, forward: f32, length: f32) -> [f32; 2] {
     if length <= f32::EPSILON {
-        return stereo_gains(0.0, 0.0, 1.0);
+        return stereo_gains_with_length(0.0, 0.0, 1.0, 1.0);
     }
-    let elevation = (up / length).clamp(-1.0, 1.0).asin();
+    let u = (up / length).clamp(-1.0, 1.0);
+    let cos_elev = (1.0 - u * u).max(0.0).sqrt();
     let mut azimuth = right.atan2(forward);
     if azimuth.abs() < std::f32::consts::FRAC_PI_2 {
         azimuth = (azimuth.abs() * 1.5)
             .min(std::f32::consts::FRAC_PI_2)
             .copysign(azimuth);
     }
-    let side = azimuth.sin() * elevation.cos();
-    let front = azimuth.cos() * elevation.cos() * 0.095_660_8;
+    let (sin_az, cos_az) = azimuth.sin_cos();
+    let side = sin_az * cos_elev;
+    let front = cos_az * cos_elev * 0.095_660_8;
     [0.5 - 0.5 * side + front, 0.5 + 0.5 * side + front]
 }
 /// The gain OpenAL applies for distance (`AL_LINEAR_DISTANCE` with reference
@@ -853,16 +883,10 @@ fn mix(mixer: &mut Mixer, data: &mut [f32], channels: usize, rate: u32) {
     // and OpenAL's right = forward x up.
     let basis = |yaw: f32, pitch: f32| {
         let (yaw, pitch) = (f64::from(yaw.to_radians()), f64::from(pitch.to_radians()));
-        let forward = [
-            -yaw.sin() * pitch.cos(),
-            -pitch.sin(),
-            yaw.cos() * pitch.cos(),
-        ];
-        let up = [
-            -yaw.sin() * pitch.sin(),
-            pitch.cos(),
-            yaw.cos() * pitch.sin(),
-        ];
+        let (yaw_sin, yaw_cos) = yaw.sin_cos();
+        let (pitch_sin, pitch_cos) = pitch.sin_cos();
+        let forward = [-yaw_sin * pitch_cos, -pitch_sin, yaw_cos * pitch_cos];
+        let up = [-yaw_sin * pitch_sin, pitch_cos, yaw_cos * pitch_sin];
         let right = [
             forward[1] * up[2] - forward[2] * up[1],
             forward[2] * up[0] - forward[0] * up[2],
@@ -896,7 +920,7 @@ fn mix(mixer: &mut Mixer, data: &mut [f32], channels: usize, rate: u32) {
     // Gains and pans per source for this buffer.
     let mut voices = std::mem::take(&mut mixer.voices);
     voices.clear();
-    for (id, c) in &mixer.channels {
+    for (id, c) in &mut mixer.channels {
         let Some((_, source_rate, source_channels)) = &c.samples else {
             continue;
         };
@@ -907,6 +931,7 @@ fn mix(mixer: &mut Mixer, data: &mut [f32], channels: usize, rate: u32) {
         if c.state != State::Playing {
             continue;
         }
+
         let at = [f64::from(c.at[0]), f64::from(c.at[1]), f64::from(c.at[2])];
         let away = |listener: [f64; 3]| {
             [
@@ -915,45 +940,56 @@ fn mix(mixer: &mut Mixer, data: &mut [f32], channels: usize, rate: u32) {
                 at[2] - listener[2],
             ]
         };
-        let length = |d: [f64; 3]| d[0] * d[0] + d[1] * d[1] + d[2] * d[2];
-        // The nearest camera hears it (one camera but in splitscreen).
-        let camera = mixer
-            .cameras
-            .iter()
-            .filter(|camera| c.relative || camera.2 == c.world)
-            .min_by(|a, b| length(away(a.0)).total_cmp(&length(away(b.0))))
-            .map(|camera| (camera.0, camera.1));
-        // Unheard sources still advance: returning to a world must not resume stale sounds.
+        let length_sq = |d: [f64; 3]| d[0] * d[0] + d[1] * d[1] + d[2] * d[2];
+        let camera = if !shared {
+            let cam = &mixer.cameras[0];
+            if c.relative || cam.2 == c.world {
+                Some((cam.0, cam.1))
+            } else {
+                None
+            }
+        } else {
+            mixer
+                .cameras
+                .iter()
+                .filter(|camera| c.relative || camera.2 == c.world)
+                .min_by(|a, b| length_sq(away(a.0)).total_cmp(&length_sq(away(b.0))))
+                .map(|camera| (camera.0, camera.1))
+        };
         let (listener, (forward, up, right)) = camera.unwrap_or(([0.0; 3], basis(0.0, 0.0)));
         let d = if c.relative { at } else { away(listener) };
-        let distance = (d[0] * d[0] + d[1] * d[1] + d[2] * d[2]).sqrt() as f32;
-        let gain = if camera.is_some() {
-            c.gain.clamp(0.0, 1.0)
-                * if direct {
-                    1.0
-                } else {
-                    distance_gain(c.linear, distance)
+        let d_sqr = length_sq(d);
+
+        let (gain, [left, right]) = if camera.is_none() {
+            (0.0, [0.0, 0.0])
+        } else if direct {
+            let gain = c.gain.clamp(0.0, 1.0);
+            (gain, [gain, gain])
+        } else {
+            let mut zero = false;
+            if let Some(max) = c.linear {
+                let max_d = max as f64;
+                if max <= 0.0 || (!c.relative && d_sqr >= max_d * max_d) {
+                    zero = true;
                 }
-        } else {
-            0.0
-        };
-        let [left, right] = if direct {
-            [gain, gain]
-        } else {
-            // Relative sources are already in OpenAL's listener space (-Z ahead).
-            let [mut left, mut right] = if c.relative {
-                stereo_gains(d[0] as f32, d[1] as f32, -d[2] as f32)
-            } else {
-                stereo_gains(dot(d, right), dot(d, up), dot(d, forward))
-            };
-            if shared {
-                // Several players on the speakers: half the stereo width, as left and right are
-                // nobody's in particular.
-                let middle = (left + right) / 2.0;
-                left = middle + (left - middle) / 2.0;
-                right = middle + (right - middle) / 2.0;
             }
-            [left * gain, right * gain]
+            if zero {
+                (0.0, [0.0, 0.0])
+            } else {
+                let distance = d_sqr.sqrt() as f32;
+                let gain = c.gain.clamp(0.0, 1.0) * distance_gain(c.linear, distance);
+                let [mut left, mut right] = if c.relative {
+                    stereo_gains_with_length(d[0] as f32, d[1] as f32, -d[2] as f32, distance)
+                } else {
+                    stereo_gains_with_length(dot(d, right), dot(d, up), dot(d, forward), distance)
+                };
+                if shared {
+                    let middle = (left + right) * 0.5;
+                    left = middle + (left - middle) * 0.5;
+                    right = middle + (right - middle) * 0.5;
+                }
+                (gain, [left * gain, right * gain])
+            }
         };
         let step = f64::from(*source_rate) / f64::from(rate) * f64::from(c.pitch.max(0.0));
         voices.push((*id, [left, right, gain], step));
@@ -974,6 +1010,40 @@ fn mix(mixer: &mut Mixer, data: &mut [f32], channels: usize, rate: u32) {
         };
         let source_channels = source_channels as usize;
         let frames = samples.len() / source_channels;
+        let inaudible = if channels >= 2 {
+            left == 0.0 && right == 0.0
+        } else {
+            gain == 0.0
+        };
+        if inaudible {
+            let buffer_frames = data.len() / channels;
+            // As the loop below: a sound of one frame or none stops, looping or not.
+            if !c.looping || frames <= 1 {
+                // `frames` may be 0: no `frames - 1` in usize. A step of 0 never
+                // reaches the end, as in the loop below.
+                let needed = frames as f64 - 1.0 - c.position;
+                if needed <= 0.0 {
+                    c.state = State::Stopped;
+                } else if step > 0.0 {
+                    let steps_to_stop = needed / step;
+                    if (buffer_frames as f64) >= steps_to_stop {
+                        c.state = State::Stopped;
+                    } else {
+                        c.position += step * (buffer_frames as f64);
+                    }
+                }
+            } else {
+                for _ in 0..buffer_frames {
+                    let i = c.position as usize;
+                    if i + 1 >= frames {
+                        c.position = 0.0;
+                    }
+                    c.position += step;
+                }
+            }
+            continue;
+        }
+
         let out: &mut [f32] = if muffling && !c.unmuffled {
             &mut bus
         } else {
@@ -992,8 +1062,8 @@ fn mix(mixer: &mut Mixer, data: &mut [f32], channels: usize, rate: u32) {
             }
             let t = (c.position - i as f64) as f32;
             if source_channels > 1 {
-                let l = samples[i * 2] * (1.0 - t) + samples[(i + 1) * 2] * t;
-                let r = samples[i * 2 + 1] * (1.0 - t) + samples[(i + 1) * 2 + 1] * t;
+                let l = samples[i * 2] + (samples[(i + 1) * 2] - samples[i * 2]) * t;
+                let r = samples[i * 2 + 1] + (samples[(i + 1) * 2 + 1] - samples[i * 2 + 1]) * t;
                 if channels >= 2 {
                     frame[0] += l * left;
                     frame[1] += r * right;
@@ -1001,7 +1071,7 @@ fn mix(mixer: &mut Mixer, data: &mut [f32], channels: usize, rate: u32) {
                     frame[0] += (l + r) * 0.5 * gain;
                 }
             } else {
-                let s = samples[i] * (1.0 - t) + samples[i + 1] * t;
+                let s = samples[i] + (samples[i + 1] - samples[i]) * t;
                 if channels >= 2 {
                     frame[0] += s * left;
                     frame[1] += s * right;
@@ -1412,6 +1482,7 @@ impl Audio {
             record_heard: false,
             listener: [0.0; 3],
             listener_yaw: 0.0,
+            listener_pitch: 0.0,
             master: 1.0,
             random: crate::random_source::create(),
             source_override: None,
@@ -1535,8 +1606,12 @@ impl Audio {
     /// `SoundManager.updateSource`: the camera position and rotation
     /// (`Listener.setTransform` takes its forward and up vectors).
     pub fn set_listener(&mut self, position: [f64; 3], yaw: f32, pitch: f32) {
+        if self.listener == position && self.listener_yaw == yaw && self.listener_pitch == pitch {
+            return;
+        }
         self.listener = position;
         self.listener_yaw = yaw;
+        self.listener_pitch = pitch;
         if let Ok(mut m) = self.backend.mixer.lock() {
             if self.backend.owner == 0 {
                 m.listener = position;
@@ -1576,6 +1651,7 @@ impl Audio {
             record_heard: false,
             listener: [0.0; 3],
             listener_yaw: 0.0,
+            listener_pitch: 0.0,
             master: self.master,
             random: crate::random_source::create(),
             source_override: None,
@@ -2109,6 +2185,25 @@ impl Audio {
             })
             .collect()
     }
+    /// Mixes one buffer of audio into `data` (channels: 1 or 2, rate in Hz).
+    pub fn mix_buffer(&mut self, data: &mut [f32], channels: usize, rate: u32) {
+        if let Ok(mut m) = self.backend.mixer.lock() {
+            mix(&mut m, data, channels, rate);
+        }
+    }
+    #[doc(hidden)]
+    pub fn insert_cached_sound(&mut self, key: &str, samples: Vec<f32>, rate: u32, channels: u16) {
+        if let Ok(mut c) = self.backend.cache.lock() {
+            c.insert(
+                key.to_owned(),
+                Some((std::sync::Arc::new(samples), rate, channels)),
+            );
+        }
+    }
+    #[doc(hidden)]
+    pub fn backend_live_for_bench(&mut self) {
+        self.backend.live = true;
+    }
 }
 impl Sounds for Audio {
     fn engine(&mut self) -> &mut SoundEngine {
@@ -2613,6 +2708,25 @@ mod tests {
         assert_eq!(data, [0.0; 4], "returning must not resume the old one-shot");
     }
 
+    /// A sound of one frame or none, heard or not, looping or not, stops at its first
+    /// buffer as the mixing loop stops it: none stays playing (and holds its channel).
+    #[test]
+    fn sounds_too_short_to_mix_stop_even_unheard() {
+        for (samples, looping) in [(vec![], false), (vec![1.0], false), (vec![1.0], true)] {
+            let mut mixer = Mixer::default();
+            let mut source = channel(samples.clone(), None, [0.0; 3], looping);
+            source.gain = 0.0;
+            mixer.channels.insert(1, source);
+            let mut data = [0.0; 4];
+            mix(&mut mixer, &mut data, 2, 48_000);
+            assert_eq!(
+                mixer.channels[&1].state,
+                State::Stopped,
+                "{samples:?} {looping}"
+            );
+        }
+    }
+
     #[test]
     fn variants_of_one_sound_are_the_same_sound() {
         assert_eq!(

crates/horizon-client-render/src/biome.rs

@@ -7,7 +7,7 @@ use serde_json::Value;
 use std::{
     collections::{BTreeMap, HashMap},
     path::Path,
-    sync::Arc,
+    sync::{Arc, OnceLock},
 };
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -398,7 +398,37 @@ impl Biomes {
     pub fn contains(&self, name: &str) -> bool {
         self.index.contains_key(name)
     }
+    /// The biome at `id`, clamped to the last entry when `id` is past the
+    /// table (a stale column from an older registry keeps its id).
+    ///
+    /// When the table is empty (a resource pack with no biome files), returns
+    /// a shared default plains biome instead of panicking on `list.len() - 1`.
     pub fn get(&self, id: u16) -> &BiomeInfo {
+        if self.list.is_empty() {
+            static DEFAULT: OnceLock<BiomeInfo> = OnceLock::new();
+            return DEFAULT.get_or_init(|| BiomeInfo {
+                spawns: HashMap::new(),
+                spawn_costs: HashMap::new(),
+                creature_probability: 0.0,
+                increased_fire_burnout: false,
+                name: "minecraft:plains".to_owned(),
+                temperature: 0.8,
+                frozen: false,
+                downfall: 0.4,
+                precipitation: false,
+                grass: 0x7f_c0_55,
+                modifier: GrassModifier::None,
+                foliage: 0x6a_ab_37,
+                dry_foliage: 0x79_75_54,
+                water: 0x3f_76_e4,
+                sky: None,
+                fog: None,
+                water_fog: 0x3f_76_e4,
+                ambient_particles: Vec::new(),
+                features: Vec::new(),
+                attributes: Default::default(),
+            });
+        }
         &self.list[usize::from(id).min(self.list.len() - 1)]
     }
     /// The name of biome `id`, plains (as for an unknown name) when the id is
@@ -795,4 +825,34 @@ mod blend_tests {
         }
         assert!(at(-2.0) > 0.0 && at(-2.0) < 0.5);
     }
+
+    /// An empty biome table (a resource pack with no biome files) must not
+    /// panic on `get`: before the fix, `list.len() - 1` underflowed.
+    #[test]
+    fn get_on_empty_biome_table_returns_default_instead_of_panicking() {
+        use std::sync::Arc;
+
+        let empty = Biomes {
+            builtin: Arc::new(Vec::new()),
+            index: HashMap::new(),
+            list: Vec::new(),
+            info_noise: SimplexNoise::with_skipped_offsets(&mut LegacyRandom::new(2345), true),
+            colormaps: Arc::new(Colormaps {
+                grass: Vec::new(),
+                foliage: Vec::new(),
+                dry: Vec::new(),
+            }),
+            packs: BTreeMap::new(),
+        };
+        // Any id returns the shared default plains biome, no panic.
+        let b = empty.get(0);
+        assert_eq!(b.name, "minecraft:plains");
+        let b = empty.get(65535);
+        assert_eq!(b.name, "minecraft:plains");
+        // Colours and temperature come from the default.
+        assert_eq!(b.temperature, 0.8);
+        assert_eq!(b.grass, 0x7f_c0_55);
+        assert_eq!(b.foliage, 0x6a_ab_37);
+        assert_eq!(b.water, 0x3f_76_e4);
+    }
 }

crates/horizon-client-render/src/brewing.rs

@@ -84,6 +84,71 @@ pub fn contents_effects(stack: &ItemStack) -> Vec<(&'static str, i32, i32)> {
         )
         .collect()
 }
+/// `PotionContents.getAllEffects`, retaining each custom instance's flags.
+pub fn contents_instances(stack: &ItemStack) -> Vec<crate::effects::EffectInstance> {
+    use horizon_client_core::nbt_value::{number, text};
+    use horizon_world::nbt::Tag;
+    let mut effects: Vec<_> = stack
+        .potion()
+        .and_then(potion)
+        .map_or(&[][..], |p| p.effects)
+        .iter()
+        .map(|(id, duration, amp)| crate::effects::EffectInstance::new(id, *duration, *amp))
+        .collect();
+    if let Some((_, Tag::List(custom))) = stack
+        .data()
+        .and_then(|d| d.potion_extra.iter().find(|(k, _)| k == "custom_effects"))
+    {
+        for e in custom {
+            let Some(def) = text(e.get("id")).and_then(|id| effect(&id)) else {
+                continue;
+            };
+            let mut instance = crate::effects::EffectInstance::new(
+                def.id,
+                number(e.get("duration")).unwrap_or(0) as i32,
+                number(e.get("amplifier")).unwrap_or(0).clamp(0, 255) as i32,
+            );
+            instance.ambient = number(e.get("ambient")).unwrap_or(0) != 0;
+            instance.visible = number(e.get("show_particles")) != Some(0);
+            effects.push(instance);
+        }
+    }
+    effects
+}
+/// `PotionContents.getColor`: an explicit colour wins; otherwise mix only
+/// visible base and custom effects, with their amplifier weights.
+pub fn contents_color(stack: &ItemStack) -> u32 {
+    use horizon_client_core::nbt_value::number;
+    if let Some(color) = stack
+        .data()
+        .and_then(|d| d.potion_extra.iter().find(|(k, _)| k == "custom_color"))
+        .and_then(|(_, v)| number(Some(v)))
+    {
+        return color as u32;
+    }
+    0xFF00_0000
+        | horizon_client_core::potions::effects_color(
+            contents_instances(stack)
+                .iter()
+                .filter(|e| e.visible)
+                .map(|e| (e.id, e.amplifier)),
+        )
+}
+/// `PotionContents.equals(EMPTY)`: colour and custom name also make contents
+/// nonempty, even when there is no registered potion or custom effect.
+pub fn contents_empty(stack: &ItemStack) -> bool {
+    use horizon_world::nbt::Tag;
+    stack.potion().is_none()
+        && stack.data().is_none_or(|d| {
+            d.potion_extra
+                .iter()
+                .all(|(key, value)| match key.as_str() {
+                    "custom_effects" => matches!(value, Tag::List(list) if list.is_empty()),
+                    "custom_color" | "custom_name" => false,
+                    _ => true,
+                })
+        })
+}
 /// Roman amplifier suffix (`potion.potency.N`) and duration lines of a potion.
 pub fn tooltip(
     potion: Option<&str>,
@@ -706,4 +771,39 @@ mod tests {
         let lines = effect_lines([("minecraft:resistance", 15, 0)], 1.0, &translate);
         assert_eq!(lines[0].0, "resistance");
     }
+    #[test]
+    fn custom_contents_color_and_empty_semantics() {
+        use horizon_world::nbt::Tag;
+        let mut stack = ItemStack::new("minecraft:tipped_arrow", 1);
+        assert!(contents_empty(&stack));
+        stack
+            .data_mut()
+            .potion_extra
+            .push(("custom_effects".into(), Tag::List(Vec::new())));
+        assert!(contents_empty(&stack));
+        stack.data_mut().potion_extra = vec![(
+            "custom_effects".into(),
+            Tag::List(vec![
+                Tag::compound([
+                    ("id", Tag::String("minecraft:glowing".into())),
+                    ("amplifier", Tag::Int(1)),
+                ]),
+                Tag::compound([
+                    ("id", Tag::String("minecraft:poison".into())),
+                    ("show_particles", Tag::Byte(0)),
+                ]),
+            ]),
+        )];
+        assert!(!contents_empty(&stack));
+        // Glowing's colour; hidden poison contributes no weight.
+        assert_eq!(contents_color(&stack), 0xFF94_A061);
+        stack
+            .data_mut()
+            .potion_extra
+            .push(("custom_color".into(), Tag::Int(123456)));
+        assert_eq!(contents_color(&stack), 123456);
+        stack.data_mut().potion_extra = vec![("custom_name".into(), Tag::String("test".into()))];
+        assert!(!contents_empty(&stack));
+        assert_eq!(contents_color(&stack), 0xFF38_5DC6);
+    }
 }

crates/horizon-client-render/src/chat.rs

@@ -1974,7 +1974,11 @@ impl ChatScreen {
             return false;
         }
         let max = l.list.len().saturating_sub(self.layout.line_limit) as i32;
-        l.offset = ((l.offset as f64 - amount.clamp(-1.0, 1.0)) as i32).clamp(0, max) as usize;
+        // Round instead of truncating: touchpad/PixelDelta produces fractional
+        // amounts and truncation drops movement in one direction (#14338).
+        l.offset = (l.offset as f64 - amount.clamp(-1.0, 1.0))
+            .round()
+            .clamp(0.0, max as f64) as usize;
         true
     }
     /// `CommandSuggestions.formatText`: argument colours over the input. The
@@ -2086,6 +2090,11 @@ impl ChatScreen {
     ) {
         let limit = l.list.len().min(self.layout.line_limit);
         let [rx, ry, rw, rh] = l.rect;
+        // SuggestionsList.extractRenderState: the whole list asks for the
+        // pointing hand while the pointer is inside its rectangle.
+        if mouse.0 >= rx && mouse.0 < rx + rw && mouse.1 >= ry && mouse.1 < ry + rh {
+            crate::widgets::request_cursor(crate::widgets::Cursor::PointingHand);
+        }
         let has_prev = l.offset > 0;
         let has_next = l.list.len() > l.offset + limit;
         let moved = l.last_mouse != mouse;

crates/horizon-client-render/src/chat_tests.rs

@@ -1066,3 +1066,32 @@ fn a_server_filter_mask_hides_or_masks_the_message() {
             .all(|s| s.style.color.is_none())
     );
 }
+
+/// `SuggestionsList.extractRenderState`: the list's rectangle asks for the
+/// pointing hand; outside it the cursor stays the arrow.
+#[test]
+fn the_suggestion_list_asks_for_the_pointing_hand() {
+    let font = font();
+    let m = Measure(&font);
+    let registries = Registries::default();
+    let c = Commands {
+        dispatcher: crate::command::vanilla::game_dispatcher(),
+        registries: &registries,
+    };
+    let mut screen = ChatScreen::new(&m, &c, "", false, 0, 640, 360, full());
+    screen.type_text(&m, &c, "/");
+    let rect = screen
+        .suggestions
+        .as_ref()
+        .expect("the root commands are a suggestion list")
+        .rect;
+    let _ = crate::widgets::take_cursor();
+    screen.draw(&m, (rect[0] + 2, rect[1] + 2), 0, 0);
+    assert_eq!(
+        crate::widgets::take_cursor(),
+        crate::widgets::Cursor::PointingHand
+    );
+    let _ = crate::widgets::take_cursor();
+    screen.draw(&m, (rect[0] - 1, rect[1] + 2), 0, 0);
+    assert_eq!(crate::widgets::take_cursor(), crate::widgets::Cursor::Arrow);
+}

crates/horizon-client-render/src/chunk/block_entity.rs

@@ -539,6 +539,7 @@ pub struct Data {
     pub current: Option<Info>,
     pub travel: i32,
     pub selector: Selector,
+    pub reload_particle: bool,
 }
 /// Which sculk block entity this is.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]

crates/horizon-client-render/src/connected.rs

@@ -124,15 +124,25 @@ fn sprite_name(resource: &str) -> String {
 }
 
 impl ConnectedTextures {
-    /// The rules under `root`, with their tiles inserted into `sprites` (before it finishes).
-    /// `face_layer` answers a block state's sprite on a side, for rules that connect by tile.
+    /// The sprites `rules` match by name (`matchTiles`, `connectTiles`), for
+    /// [`Sprites::keep_apart`]: before the models insert theirs.
+    pub fn matched_sprites(rules: &[Rule]) -> Vec<String> {
+        (rules.iter())
+            .flat_map(|r| r.match_tiles.iter().chain(&r.connect_tiles))
+            .map(|t| sprite_name(t))
+            .collect()
+    }
+
+    /// `rules` (`ctm::load` under `root`), with their tiles inserted into `sprites` (before it
+    /// finishes). `face_layer` answers a block state's sprite on a side, for rules that connect
+    /// by tile.
     pub fn load(
         root: &Path,
+        mut rules: Vec<Rule>,
         registry: &BlockRegistry,
         sprites: &mut Sprites,
         mut face_layer: impl FnMut(BlockStateId, Face) -> Option<u32>,
     ) -> Self {
-        let mut rules = ctm::load(root);
         // Rules with a custom name load no tiles: section meshes see no block entity.
         rules.retain(|r| r.name.is_none());
         // Rule indices are `u16`.
@@ -1270,6 +1280,41 @@ mod tests {
         assert!(!ctm.stacked_pane_hides(3, 3, post));
     }
 
+    #[test]
+    fn rules_name_the_sprites_they_match() {
+        // `matchTiles` among the textures and beside the file (a chain onto another rule's
+        // tile), and `connectTiles`: each as the sprite name the textures and tiles are inserted
+        // under.
+        let dir = "assets/minecraft/optifine/ctm/pack/crops";
+        let rule = |file: &str, text: &str| {
+            Rule::parse(
+                &format!("{dir}/{file}"),
+                &horizon_optifine::properties::Properties::parse(text),
+            )
+            .unwrap()
+            .unwrap()
+        };
+        let rules = [
+            rule(
+                "1.properties",
+                "matchTiles=./19.png\nmethod=random\ntiles=5-6",
+            ),
+            rule(
+                "2.properties",
+                "matchTiles=textures/block/extra/placeholder.png\nmethod=overlay\n\
+                 connectTiles=textures/block/stone.png\ntiles=0-16",
+            ),
+        ];
+        assert_eq!(
+            ConnectedTextures::matched_sprites(&rules),
+            [
+                format!("{dir}/19.png"),
+                "minecraft:block/extra/placeholder".to_owned(),
+                "minecraft:block/stone".to_owned(),
+            ]
+        );
+    }
+
     #[test]
     fn sprite_names() {
         assert_eq!(

crates/horizon-client-render/src/controller_ui.rs

@@ -57,6 +57,8 @@ pub enum Item {
     /// Wait for a button to bind to this action.
     Bind(&'static str),
     ResetBinds,
+    /// Opens the radial menu's pages (`radial_editor`).
+    Radial,
     Info(Info),
 }
 
@@ -106,6 +108,15 @@ fn choice_description(opt: Opt, pad: &PadSettings) -> Option<&'static str> {
             }
             gamepad::Lightbar::Off => "A DualSense keeps its own light.",
         },
+        Opt::PadRadialMode => match pad.radial_mode {
+            gamepad::RadialMode::Hold => "horizon.options.radial_mode.hold.about",
+            gamepad::RadialMode::Toggle => "horizon.options.radial_mode.toggle.about",
+        },
+        Opt::PadRadialStick => match pad.radial_stick {
+            gamepad::RadialStick::Right => "horizon.options.radial_stick.right.about",
+            gamepad::RadialStick::Left => "horizon.options.radial_stick.left.about",
+            gamepad::RadialStick::Either => "horizon.options.radial_stick.either.about",
+        },
         _ => return None,
     })
 }
@@ -123,6 +134,11 @@ fn info(info: Info, text: &'static str) -> Setting {
     }
 }
 
+/// The radial menu's group, on General (how it opens and selects) and Bindings (its pages).
+const RADIAL_GROUP: &str = "Radial Menu";
+/// The row that opens the radial menu's pages.
+const RADIAL_PAGES: &str = "horizon.pages.open.controller_radial";
+
 /// Shown on a binding's row until it is focused, and in the search.
 const BIND_TEXT: &str = "Press this row, then the button that should do it.";
 
@@ -201,6 +217,13 @@ pub fn rows() -> Vec<(Page, Vec<(&'static str, Vec<Setting>)>)> {
                         ),
                     ],
                 ),
+                (
+                    RADIAL_GROUP,
+                    vec![
+                        option(Opt::PadRadialMode, "horizon.options.radial_mode.about"),
+                        option(Opt::PadRadialStick, "horizon.options.radial_stick.about"),
+                    ],
+                ),
                 (
                     "Menus",
                     vec![
@@ -231,6 +254,13 @@ pub fn rows() -> Vec<(Page, Vec<(&'static str, Vec<Setting>)>)> {
         (
             Page::Bindings,
             vec![
+                (
+                    RADIAL_GROUP,
+                    vec![Setting {
+                        item: Item::Radial,
+                        text: "Named pages of eight actions, held open with a button.",
+                    }],
+                ),
                 ("Actions", binds),
                 (
                     "Reset",
@@ -437,6 +467,7 @@ fn row(setting: Setting, s: &Settings, context: &Context) -> Row<Item> {
             Row::new(item, name, value).about(about)
         }
         Item::ResetBinds => Row::new(item, lang::get(RESET_ALL), Value::Press).about(about),
+        Item::Radial => Row::new(item, lang::get(RADIAL_PAGES), Value::Press).about(about),
         Item::Info(which) => {
             let (name, value) = context.read(which);
             Row::new(item, lang::get(name), Value::Read(value)).about(about)
@@ -496,6 +527,7 @@ impl Screen for ControllerScreen {
                 s.controller.reset_bindings();
                 vec![Output::Event(Event::Changed)]
             }
+            Item::Radial => vec![Output::Push(crate::options_ui::Page::ControllerRadial)],
             Item::Bind(_) | Item::Info(_) => Vec::new(),
         }
     }
@@ -533,15 +565,21 @@ impl Screen for ControllerScreen {
     fn undoes(&self) -> bool {
         true
     }
-    /// This player's controller settings, bindings included, as the screen found them.
+    /// This player's controller settings, bindings included, as the screen found them. The
+    /// radial menu's pages stay as they are: their own screen has its own Undo.
     fn undo(&mut self, s: &mut Settings, before: &Settings) -> Vec<Output> {
+        let radial = std::mem::take(&mut s.controller.radial);
         s.controller = before.controller.clone();
+        s.controller.radial = radial;
         Vec::new()
     }
     /// Undo is there exactly while the controller settings differ from what the screen opened
-    /// with: a binding the game made while the row waited counts, a value stepped back doesn't.
+    /// with: a binding the game made while the row waited counts, a value stepped back doesn't,
+    /// and nor do the radial menu's pages, which this Undo keeps.
     fn differs(&self, s: &Settings, before: &Settings) -> Option<bool> {
-        Some(s.controller != before.controller)
+        let mut now = s.controller.clone();
+        now.radial = before.controller.radial.clone();
+        Some(now != before.controller)
     }
 }
 
@@ -793,6 +831,48 @@ mod tests {
         assert_eq!(arts(&batch, row), 0);
     }
 
+    /// The radial menu's pages have their own screen and Undo: editing them shows no Undo here,
+    /// and another change's Undo keeps them as edited.
+    #[test]
+    fn radial_pages_edited_on_their_own_screen_leave_undo_alone() {
+        let mut s = Settings::default();
+        let mut ui = ui(Page::General);
+        draw(&mut ui, &s, None);
+        s.controller.radial.remove(1);
+        draw(&mut ui, &s, None);
+        assert!(
+            !ui.changed(),
+            "Undo here keeps the pages: it has nothing to do"
+        );
+        s.controller.invert_y = !s.controller.invert_y;
+        draw(&mut ui, &s, None);
+        assert!(ui.changed());
+        let reached = (0..100).any(|_| {
+            key(&mut ui, &mut s, K::Tab);
+            ui.focused() == Some(Target::Undo)
+        });
+        assert!(reached);
+        key(&mut ui, &mut s, K::Enter);
+        assert_eq!(s.controller.radial.len(), 1);
+        assert_eq!(s.controller.invert_y, PadSettings::default().invert_y);
+    }
+
+    /// The Bindings page's radial row opens the radial menu's pages.
+    #[test]
+    fn the_radial_row_opens_the_radial_pages() {
+        let mut s = Settings::default();
+        let mut ui = ui(Page::Bindings);
+        let at = ui.point_at(&s, SIZE, Item::Radial);
+        let outputs = ui.click(&mut s, at, SIZE, false, false, false);
+        assert_eq!(
+            outputs,
+            [
+                CLICK,
+                Output::Push(crate::options_ui::Page::ControllerRadial)
+            ]
+        );
+    }
+
     #[test]
     fn the_search_finds_rows_across_pages_and_drops_empty_pages() {
         let s = Settings::default();
@@ -816,8 +896,8 @@ mod tests {
         let mut s = Settings::default();
         s.controller.bind(JUMP, Some(Button::North));
         let mut ui = ui(Page::Bindings);
-        // Search, the three pages, then the first action.
-        for _ in 0..Page::ALL.len() + 2 {
+        // Search, the three pages, the radial menu's row, then the first action.
+        for _ in 0..Page::ALL.len() + 3 {
             key(&mut ui, &mut s, K::Tab);
         }
         assert_eq!(ui.focused(), Some(Target::Row(Item::Bind(JUMP))));
@@ -939,6 +1019,8 @@ mod tests {
             (Opt::PadNintendoButtons, 2),
             (Opt::PadKeyboard, 3),
             (Opt::PadLightbar, 3),
+            (Opt::PadRadialMode, 2),
+            (Opt::PadRadialStick, 3),
         ] {
             let setting = option(opt, "the fixed sentence");
             let mut seen = Vec::new();
@@ -972,6 +1054,8 @@ mod tests {
                 Opt::PadNintendoButtons,
                 Opt::PadKeyboard,
                 Opt::PadLightbar,
+                Opt::PadRadialMode,
+                Opt::PadRadialStick,
             ] {
                 for _ in 0..4 {
                     lang::get(choice_description(opt, &settings.controller).unwrap());
@@ -990,6 +1074,7 @@ mod tests {
             }
             ControllerScreen::default().side();
             lang::get(TITLE);
+            lang::get(RADIAL_PAGES);
             for text in [
                 "Press the button for this. %s cancels.",
                 "This button also does: %s",

crates/horizon-client-render/src/datapack.rs

@@ -1,6 +1,7 @@
 //! Data packs (`<world>/datapacks`: folders and zips with `pack.mcmeta`) and
 //! the parts of them commands use: `.mcfunction` functions (with macros and
 //! line continuation), function tags and predicates.
+mod slot_sources;
 use crate::zip::Zip;
 use horizon_world::{
     nbt::Tag,
@@ -663,6 +664,8 @@ pub struct DataStore {
     pub item_modifiers: BTreeMap<String, serde_json::Value>,
     /// `slot_source` definitions, evaluated against a command's live accessor.
     pub slot_sources: BTreeMap<String, serde_json::Value>,
+    /// Slot-source tags belong to the same loaded snapshot as their definitions.
+    pub slot_source_tags: BTreeMap<String, Vec<(String, bool)>>,
     /// The content tables' raw files from the packs after the built-in one:
     /// `recipe/`, `recipe_filter/`, `loot_table/`, `advancement/`, `dialog/`, `damage_type/`, `data_maps/`, `enchantment/` and `tags/…/` files, by
     /// `<kind-dir>/<ns>:<path>`, each id's files in pack order. The tables
@@ -759,6 +762,16 @@ impl DataStore {
                     && let Ok(v) = serde_json::from_slice(&bytes)
                 {
                     s.item_modifiers.insert(id, v);
+                } else if let Some(id) = resource_id(&f, "tags/slot_source", ".json")
+                    && let Some(bytes) = pack.read(&f)
+                    && let Ok(v) = serde_json::from_slice::<serde_json::Value>(&bytes)
+                {
+                    let entries = tag_entries(&v);
+                    let slot = s.slot_source_tags.entry(id).or_default();
+                    if v["replace"].as_bool() == Some(true) {
+                        slot.clear();
+                    }
+                    slot.extend(entries);
                 } else if let Some(id) = resource_id(&f, "slot_source", ".json")
                     && let Some(bytes) = pack.read(&f)
                     && let Ok(v) = serde_json::from_slice(&bytes)

crates/horizon-client-render/src/datapack/slot_sources.rs

@@ -0,0 +1,86 @@
+//! Slot-source holder-set tags share DataStore's pack ordering and snapshot.
+use super::DataStore;
+use std::collections::BTreeSet;
+impl DataStore {
+    /// TagLoader's required-member validation and first-seen membership order.
+    pub fn slot_source_tag(&self, id: &str) -> Result<Vec<String>, String> {
+        fn visit(
+            store: &DataStore,
+            id: &str,
+            active: &mut BTreeSet<String>,
+        ) -> Result<Vec<String>, String> {
+            if !active.insert(id.to_owned()) {
+                return Err(format!("Recursive slot-source tag #{id}"));
+            }
+            let result = (|| {
+                let entries = store
+                    .slot_source_tags
+                    .get(id)
+                    .ok_or_else(|| format!("Unknown slot-source tag #{id}"))?;
+                let mut out = Vec::new();
+                for (entry, required) in entries {
+                    let values = if let Some(tag) = entry.strip_prefix('#') {
+                        visit(store, tag, active)
+                    } else if store.slot_sources.contains_key(entry) {
+                        Ok(vec![entry.clone()])
+                    } else {
+                        Err(format!("Unknown slot source {entry}"))
+                    };
+                    match values {
+                        Ok(values) => {
+                            for value in values {
+                                if !out.contains(&value) {
+                                    out.push(value);
+                                }
+                            }
+                        }
+                        Err(error) if *required => return Err(error),
+                        Err(_) => {}
+                    }
+                }
+                Ok(out)
+            })();
+            active.remove(id);
+            result
+        }
+        visit(self, id, &mut BTreeSet::new())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn holder_set_tags_keep_order_required_members_and_snapshot_authority() {
+        let mut store = DataStore::default();
+        for name in ["t:a", "t:b"] {
+            store.slot_sources.insert(
+                name.into(),
+                serde_json::json!({"type":"slot_range","slots":"container.0"}),
+            );
+        }
+        store.slot_source_tags.insert(
+            "t:child".into(),
+            vec![("t:b".into(), true), ("t:a".into(), true)],
+        );
+        store.slot_source_tags.insert(
+            "t:all".into(),
+            vec![
+                ("t:a".into(), true),
+                ("#t:child".into(), true),
+                ("t:absent".into(), false),
+            ],
+        );
+        assert_eq!(store.slot_source_tag("t:all").unwrap(), ["t:a", "t:b"]);
+        store
+            .slot_source_tags
+            .get_mut("t:all")
+            .unwrap()
+            .push(("t:absent".into(), true));
+        assert!(store.slot_source_tag("t:all").is_err());
+        store
+            .slot_source_tags
+            .insert("t:cycle".into(), vec![("#t:cycle".into(), true)]);
+        assert!(store.slot_source_tag("t:cycle").is_err());
+    }
+}

crates/horizon-client-render/src/environment.rs

@@ -12,6 +12,8 @@ use std::collections::HashMap;
 use std::path::Path;
 use std::sync::{Arc, RwLock};
 
+mod noise;
+
 pub struct Environment {
     system: System,
     /// What the packs' expressions read; the frame sets it before sampling.
@@ -559,16 +561,31 @@ impl<'a> BlockHost<'a> {
     }
 }
 
-/// The simplex noise `r.noise(x, y)` reads, the same for blocks and particles.
-pub(crate) fn polytone_noise() -> &'static horizon_core::noise::SimplexNoise {
-    static NOISE: std::sync::OnceLock<horizon_core::noise::SimplexNoise> =
-        std::sync::OnceLock::new();
-    NOISE.get_or_init(|| {
-        horizon_core::noise::SimplexNoise::new(&mut horizon_core::random::LegacyRandom::new(0))
-    })
+/// The noise `r.noise(x, y)` reads, the same for blocks and particles.
+pub(crate) fn polytone_noise() -> &'static noise::PerlinSimplex {
+    noise::builtin()
 }
 
 impl horizon_polytone::expr::Host for BlockHost<'_> {
+    fn field(
+        &mut self,
+        root: horizon_polytone::expr::Root,
+        field: horizon_polytone::expr::Field,
+    ) -> Option<horizon_polytone::expr::Value> {
+        use horizon_polytone::expr::Field as F;
+        if root != horizon_polytone::expr::Root::Object {
+            return None;
+        }
+        Some(horizon_polytone::expr::Value::Num(match field {
+            F::X => f64::from(self.at[0]),
+            F::Y => f64::from(self.at[1]),
+            F::Z => f64::from(self.at[2]),
+            F::Temperature => f64::from(self.biome.temperature),
+            F::Downfall => f64::from(self.biome.downfall),
+            _ => return None,
+        }))
+    }
+
     fn root(&mut self, root: horizon_polytone::expr::Root) -> horizon_polytone::expr::Value {
         use horizon_polytone::expr::Root;
         horizon_polytone::expr::Value::Object(match root {
@@ -596,7 +613,7 @@ impl horizon_polytone::expr::Host for BlockHost<'_> {
             (V::Object(2), "noise") => {
                 let mut coords = args.iter().filter(|v| !matches!(v, V::Str(_))).map(V::num);
                 let (x, y) = (coords.next().unwrap_or(0.0), coords.next().unwrap_or(0.0));
-                num(f64::from(polytone_noise().get2(x, y)))
+                num(polytone_noise().get(x, y))
             }
             _ => Err(format!("{name} is not available to block colormaps")),
         }

crates/horizon-client-render/src/environment/noise.rs

@@ -0,0 +1,116 @@
+//! Polytone's `r.noise(x, y)`: 1.18-1.21's `PerlinSimplexNoise` over simplex noises, which 26.3 no
+//! longer has. Measured on the real mod (Polytone 26.3-6.8.6) with a pack whose grass colormap encodes
+//! the noise: the built-in noise is seed 0 with octaves `{1}`, read with the noise offsets
+//! (`getValue(x, y, true)`), and a `polytone/noises` definition with seed 0 or 1 and octaves `{0}`,
+//! `{1}` or `{0, 1}` matches this construction too.
+
+use horizon_core::noise::SimplexNoise;
+use horizon_core::random::{LegacyRandom, RandomSource};
+
+/// `PerlinSimplexNoise(random, octaves)`: one simplex noise per octave, the highest octave first.
+pub(crate) struct PerlinSimplex {
+    levels: Vec<Option<SimplexNoise>>,
+    input_factor: f64,
+    value_factor: f64,
+}
+
+impl PerlinSimplex {
+    /// The construction of `PerlinSimplexNoise(new LegacyRandomSource(seed), octaves)`: octave 0 takes
+    /// the first noise of `seed`'s random; the positive octaves come from a random seeded by that
+    /// noise's value at its own offsets, the negative ones from `seed`'s random after it.
+    pub(crate) fn new(seed: i64, octaves: &[i32]) -> Self {
+        let mut random = LegacyRandom::new(seed);
+        let lowest = octaves.iter().copied().min().unwrap_or(0);
+        let highest = octaves.iter().copied().max().unwrap_or(0);
+        let count = (highest - lowest + 1) as usize;
+        let first = SimplexNoise::new(&mut random);
+        let top = highest;
+        let wanted = |index: i32| octaves.contains(&(top - index));
+        let mut levels: Vec<Option<SimplexNoise>> = (0..count).map(|_| None).collect();
+        for index in top + 1..count as i32 {
+            if index >= 0 && wanted(index) {
+                levels[index as usize] = Some(SimplexNoise::new(&mut random));
+            } else {
+                random.consume_count(262);
+            }
+        }
+        if highest > 0 {
+            // `(long)(getValue(xo, yo, zo) * 9.223372E18F)`: the noise at its own offsets, which
+            // 26.3's get3 reads at (0, 0, 0). The float constant is 2^63.
+            let value = first.get3_f64(0.0, 0.0, 0.0) * 9.223_372e18_f32 as f64;
+            let mut upper = LegacyRandom::new(value as i64);
+            for index in (0..top).rev() {
+                if (index as usize) < count && wanted(index) {
+                    levels[index as usize] = Some(SimplexNoise::new(&mut upper));
+                } else {
+                    upper.consume_count(262);
+                }
+            }
+        }
+        if (0..count as i32).contains(&top) && octaves.contains(&0) {
+            levels[top as usize] = Some(first);
+        }
+        Self {
+            levels,
+            input_factor: 2f64.powi(highest),
+            value_factor: 1.0 / (2f64.powi(count as i32) - 1.0),
+        }
+    }
+
+    /// `getValue(x, y, true)`: each octave read with its offsets, which 26.3's simplex adds itself.
+    pub(crate) fn get(&self, x: f64, y: f64) -> f64 {
+        let (mut input, mut value, mut sum) = (self.input_factor, self.value_factor, 0.0);
+        for level in &self.levels {
+            if let Some(noise) = level {
+                sum += noise.get2_f64(x * input, y * input) * value;
+            }
+            input /= 2.0;
+            value *= 2.0;
+        }
+        sum
+    }
+}
+
+/// The built-in `r.noise(x, y)`: seed 0, octaves `{1}`.
+pub(crate) fn builtin() -> &'static PerlinSimplex {
+    static NOISE: std::sync::OnceLock<PerlinSimplex> = std::sync::OnceLock::new();
+    NOISE.get_or_init(|| PerlinSimplex::new(0, &[1]))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// `r.noise(x/8, z/8)` read on the real mod (Polytone 26.3-6.8.6): a grass colormap whose pixel
+    /// encodes the value, decoded to about 0.01 (polytone-work/rnoise in the measurement notes).
+    #[test]
+    fn the_builtin_noise_reads_what_the_mod_draws() {
+        for (x, z, mod_value) in [
+            (0, 10, -0.28373),
+            (3, 10, -0.14683),
+            (10, 0, 0.31833),
+            (24, 14, -0.55941),
+            (40, 25, -0.48358),
+            (7, 3, -0.68202),
+        ] {
+            let value = builtin().get(f64::from(x) / 8.0, f64::from(z) / 8.0);
+            assert!(
+                (value - mod_value).abs() < 0.02,
+                "({x}, {z}): {value} against {mod_value}"
+            );
+        }
+    }
+
+    /// The octaves add as `PerlinSimplexNoise`'s do: `{0, 1}` is a third of `{1}` and two thirds of
+    /// `{0}` (measured: 0.067 = 0.33 x -0.284 + 0.67 x 0.247 at (0, 10) / 8).
+    #[test]
+    fn two_octaves_weigh_a_third_and_two_thirds() {
+        let both = PerlinSimplex::new(0, &[0, 1]);
+        let (low, high) = (PerlinSimplex::new(0, &[0]), PerlinSimplex::new(0, &[1]));
+        for (x, y) in [(0.0, 1.25), (2.5, -3.0), (17.1, 4.4)] {
+            let mixed = high.get(x, y) / 3.0 + low.get(x, y) * 2.0 / 3.0;
+            assert!((both.get(x, y) - mixed).abs() < 1e-12);
+        }
+        assert!((both.get(0.0, 1.25) - 0.067).abs() < 0.02);
+    }
+}

crates/horizon-client-render/src/extras.rs

@@ -2,7 +2,7 @@
 //! settings, kept in `horizon-extras.txt` next to `options.txt` so that file
 //! stays exactly vanilla's, and the logic behind them. Every extra is off by
 //! default; see `docs/extras.md`. Horizon's own switches outside the Extras page
-//! (No AI, Agent Control, Discord Rich Presence) are kept here too.
+//! (No AI, Agent Control) are kept here too.
 use std::{collections::VecDeque, fs, path::Path};
 
 pub const FILE: &str = "horizon-extras.txt";
@@ -145,8 +145,6 @@ pub struct Extras {
     /// F3+R and F3+E start/stop a repro recording and write its bundle (off by
     /// default: a recording copies the world).
     pub repro_keys: bool,
-    /// "Playing Horizon" on the player's Discord profile (`discord_presence`; on by default).
-    pub discord_presence: bool,
     /// Another controller can join P1's world (`splitscreen`, off by default).
     pub splitscreen: bool,
     /// Two players in one window: 0 auto (side by side when wider than tall), 1 side by side,
@@ -233,7 +231,6 @@ impl Default for Extras {
             no_ai: false,
             agent_control: false,
             repro_keys: false,
-            discord_presence: true,
             splitscreen: false,
             splitscreen_two: 0,
             splitscreen_three: 0,
@@ -338,7 +335,6 @@ impl Extras {
                 horizon_core::no_ai::KEY => e.no_ai = flag(e.no_ai),
                 "agentControl" => e.agent_control = flag(e.agent_control),
                 "reproKeys" => e.repro_keys = flag(e.repro_keys),
-                "discordPresence" => e.discord_presence = flag(e.discord_presence),
                 "splitscreen" => e.splitscreen = flag(e.splitscreen),
                 "splitscreenTwo" => e.splitscreen_two = value.parse().unwrap_or(0).min(2),
                 "splitscreenThree" => e.splitscreen_three = value.parse().unwrap_or(0).min(2),
@@ -376,7 +372,7 @@ impl Extras {
     }
     pub fn serialize(&self) -> String {
         let mut text = format!(
-            "packBrowser:{}\npregen:{}\nfullbright:{}\ndynamicLights:{}\nzoom:{}\nzoomKey:{}\nzoomLevel:{}\nzoomSmooth:{}\nzoomSensitivity:{}\nlodZoomDetail:{}\nfps:{}\nfpsCorner:{}\nfpsLows:{}\nkeystrokes:{}\nkeystrokesCorner:{}\nkeystrokesCps:{}\nmovedToMods:{}\nminimap:{}\nminimapCorner:{}\nminimapSize:{}\nminimapShape:{}\nminimapZoom:{}\nminimapRotate:{}\nautoReconnect:{}\nuiSoundReserve:{}\nownNameTag:{}\nhideBlockParticles:{}\nmouseTweaks:{}\nmouseTweaksWheel:{}\nsort:{}\nsortKey:{}\nchatAnimation:{}\nchatIndicator:{}\n{}:{}\nagentControl:{}\nreproKeys:{}\ndiscordPresence:{}\nsplitscreen:{}\nsplitscreenTwo:{}\nsplitscreenThree:{}\nsplitscreenNames:{}\nwheelCyclesListSettings:{}\nmusicOff:{}\nmusicPage:{}\ncosmeticsMine:{}\n{}cosmeticsHideFx:{}\ncosmeticsSolo:{}\n{}:{}\n{}:{}\n{}:{}\n",
+            "packBrowser:{}\npregen:{}\nfullbright:{}\ndynamicLights:{}\nzoom:{}\nzoomKey:{}\nzoomLevel:{}\nzoomSmooth:{}\nzoomSensitivity:{}\nlodZoomDetail:{}\nfps:{}\nfpsCorner:{}\nfpsLows:{}\nkeystrokes:{}\nkeystrokesCorner:{}\nkeystrokesCps:{}\nmovedToMods:{}\nminimap:{}\nminimapCorner:{}\nminimapSize:{}\nminimapShape:{}\nminimapZoom:{}\nminimapRotate:{}\nautoReconnect:{}\nuiSoundReserve:{}\nownNameTag:{}\nhideBlockParticles:{}\nmouseTweaks:{}\nmouseTweaksWheel:{}\nsort:{}\nsortKey:{}\nchatAnimation:{}\nchatIndicator:{}\n{}:{}\nagentControl:{}\nreproKeys:{}\nsplitscreen:{}\nsplitscreenTwo:{}\nsplitscreenThree:{}\nsplitscreenNames:{}\nwheelCyclesListSettings:{}\nmusicOff:{}\nmusicPage:{}\ncosmeticsMine:{}\n{}cosmeticsHideFx:{}\ncosmeticsSolo:{}\n{}:{}\n{}:{}\n{}:{}\n",
             bool_text(self.pack_browser),
             bool_text(self.pregen),
             bool_text(self.fullbright),
@@ -418,7 +414,6 @@ impl Extras {
             bool_text(self.no_ai),
             bool_text(self.agent_control),
             bool_text(self.repro_keys),
-            bool_text(self.discord_presence),
             bool_text(self.splitscreen),
             self.splitscreen_two,
             self.splitscreen_three,
@@ -613,8 +608,6 @@ pub enum Item {
     /// Not on the Extras page: Horizon Settings shows No AI, its AI Agent page Agent Control.
     NoAi,
     AgentControl,
-    /// On the Horizon Settings page.
-    DiscordPresence,
     /// On the AI Agent page, next to Agent Control: the F3 recording shortcuts.
     ReproKeys,
     /// On the Splitscreen settings page.
@@ -691,7 +684,6 @@ impl Item {
             Item::NoAi => "horizon.extras.no_ai",
             Item::AgentControl => "horizon.extras.agent_control",
             Item::ReproKeys => "horizon.extras.repro_keys",
-            Item::DiscordPresence => "horizon.extras.discord_presence",
             Item::Splitscreen => "horizon.extras.splitscreen",
             Item::ChatAnimation => "horizon.extras.chat_animation",
             Item::ChatIndicator => "horizon.extras.chat_indicator",
@@ -724,7 +716,6 @@ impl Item {
             Item::NoAi => "horizon.extras.no_ai.tooltip",
             Item::AgentControl => "horizon.extras.agent_control.tooltip",
             Item::ReproKeys => "horizon.extras.repro_keys.tooltip",
-            Item::DiscordPresence => "horizon.extras.discord_presence.tooltip",
             Item::Splitscreen => "horizon.extras.splitscreen.tooltip",
             Item::ChatAnimation => "horizon.extras.chat_animation.tooltip",
             Item::ChatIndicator => "horizon.extras.chat_indicator.tooltip",
@@ -768,7 +759,6 @@ impl Item {
             Item::NoAi => "No AI",
             Item::AgentControl => "Agent Control",
             Item::ReproKeys => "Recording shortcuts",
-            Item::DiscordPresence => "Discord Rich Presence",
             Item::Splitscreen => "Splitscreen",
             Item::WheelCyclesSettings => "Scroll wheel changes settings",
             Item::PackBrowser => "Resource pack browser",
@@ -792,10 +782,9 @@ impl Item {
             ChatIndicator => ChatAnimation,
             Pvp(o) => return o.parent().map(Pvp),
             Fullbright | DynamicLights | OwnNameTag | HideBlockParticles | MouseTweaks | Sort
-            | AutoReconnect | NoAi | AgentControl | ReproKeys | DiscordPresence | Splitscreen
-            | ChatAnimation | WheelCyclesSettings | MusicPage | PackBrowser | CosmeticsMine
-            | CosmeticsOthers | CosmeticsHideFx | CosmeticsSolo | HorizonMarks | HorizonMe
-            | Pregen => {
+            | AutoReconnect | NoAi | AgentControl | ReproKeys | Splitscreen | ChatAnimation
+            | WheelCyclesSettings | MusicPage | PackBrowser | CosmeticsMine | CosmeticsOthers
+            | CosmeticsHideFx | CosmeticsSolo | HorizonMarks | HorizonMe | Pregen => {
                 return None;
             }
         })
@@ -844,9 +833,6 @@ impl Item {
             Item::NoAi => {
                 "Hides and turns off every AI feature: agent control, horizon-ctl and the MCP servers. The launcher's switch too."
             }
-            Item::DiscordPresence => {
-                "Shows Playing Horizon on your Discord profile while Discord runs: menus, single player or multiplayer, the dimension and the time played. Never a world's name or a server's address."
-            }
             Item::Splitscreen => {
                 "In a world, another controller can join as a new player: press A when it asks, then pick a profile and where to play."
             }
@@ -927,7 +913,6 @@ impl Item {
             Item::NoAi => e.no_ai,
             Item::AgentControl => e.agent_control,
             Item::ReproKeys => e.repro_keys,
-            Item::DiscordPresence => e.discord_presence,
             Item::Splitscreen => e.splitscreen,
             Item::WheelCyclesSettings => e.wheel_cycles_settings,
             Item::PackBrowser => e.pack_browser,
@@ -986,7 +971,6 @@ impl Item {
             Item::NoAi => e.no_ai = !e.no_ai,
             Item::AgentControl => e.agent_control = !e.agent_control,
             Item::ReproKeys => e.repro_keys = !e.repro_keys,
-            Item::DiscordPresence => e.discord_presence = !e.discord_presence,
             Item::Splitscreen => e.splitscreen = !e.splitscreen,
             Item::WheelCyclesSettings => e.wheel_cycles_settings = !e.wheel_cycles_settings,
             Item::PackBrowser => e.pack_browser = !e.pack_browser,
@@ -1104,7 +1088,7 @@ mod tests {
         assert!(!d.mouse_tweaks && !d.sort && !d.own_name_tag && !d.ui_sound_reserve);
         assert!(!d.hide_block_particles && !d.pregen);
         assert!(!d.music_page && d.music_off.is_empty());
-        assert!(d.discord_presence && !d.wheel_cycles_settings);
+        assert!(!d.wheel_cycles_settings);
         assert_eq!(Extras::parse(""), d);
         assert_eq!(Extras::parse(&d.serialize()), d);
         let mut e = d.clone();
@@ -1143,7 +1127,6 @@ mod tests {
         e.sort_key = "key.keyboard.r".into();
         e.chat_animation = true;
         e.chat_indicator = false;
-        e.discord_presence = false;
         assert!(!e.splitscreen);
         Item::Splitscreen.cycle(&mut e, false);
         assert_eq!(Item::Splitscreen.switch(&e), Some(true));

crates/horizon-client-render/src/fog.rs

@@ -233,6 +233,8 @@ pub struct FogInputs<'a> {
     pub night_vision: f32,
     /// The packs' `environment` fog settings (Polytone's).
     pub environment: crate::pack_palette::Environment,
+    /// The packs' fluid modifiers' fog.
+    pub fluid_fog: crate::pack_palette::FluidFogs,
 }
 
 /// `FogRenderer.setupFog` + `computeFogColor`.
@@ -397,6 +399,24 @@ pub fn setup_fog(tables: &FogTables, state: &FogState, input: &FogInputs) -> Fog
             }
         }
     }
+    // A pack's fluid modifier over its fluid's fog, after everything else (wiki "Custom Colors").
+    let fluid = match input.fog_type {
+        FogType::Lava => input.fluid_fog.lava,
+        FogType::Water if input.blindness.is_none() && input.darkness.is_none() => {
+            input.fluid_fog.water
+        }
+        _ => None,
+    };
+    if let Some(f) = fluid {
+        if let Some(rgb) = f.color {
+            let [r, g, b] = self::rgb(rgb);
+            fog.color = [r, g, b, 1.0];
+        }
+        let end = fog.environmental_end * f.radius;
+        let start = end - (end - fog.environmental_start * f.radius) * f.fade;
+        (fog.environmental_start, fog.environmental_end) = (start, end);
+        (fog.sky_end, fog.cloud_end) = (end, end);
+    }
     let span = (rd / 10.0).clamp(4.0, 64.0);
     fog.render_distance_start = rd - span;
     fog.render_distance_end = rd;
@@ -495,6 +515,7 @@ mod tests {
             full_water_vision: false,
             night_vision: 0.0,
             environment: Default::default(),
+            fluid_fog: Default::default(),
         }
     }
     #[test]
@@ -611,6 +632,38 @@ mod tests {
         let kept = setup_fog(&tables, &state, &input).color;
         assert_eq!(&kept[..3], &[0.1, 0.2, 0.4]);
     }
+    #[test]
+    fn a_fluid_modifier_scales_and_colours_its_fog_last() {
+        let sky = Sky {
+            fog_start: 10.0,
+            fog_end: 96.0,
+            ..Sky::default()
+        };
+        let tables = FogTables {
+            water_fog_end: vec![1.0],
+        };
+        let mut input = inputs(&sky);
+        input.fog_type = FogType::Lava;
+        input.fire_resistance = true;
+        let vanilla = setup_fog(&tables, &FogState::default(), &input);
+        assert_eq!(
+            (vanilla.environmental_start, vanilla.environmental_end),
+            (0.0, 5.0)
+        );
+        input.fluid_fog.lava = Some(crate::pack_palette::FluidFog {
+            color: Some(0x00FF00),
+            radius: 2.0,
+            fade: 0.5,
+        });
+        let fog = setup_fog(&tables, &FogState::default(), &input);
+        assert_eq!(fog.color, [0.0, 1.0, 0.0, 1.0]);
+        // The end doubles; half the fade from 0 to 10 starts it at 5.
+        assert_eq!(
+            (fog.environmental_start, fog.environmental_end),
+            (5.0, 10.0)
+        );
+        assert_eq!((fog.sky_end, fog.cloud_end), (10.0, 10.0));
+    }
     fn inputs_with<'a>(
         input: &FogInputs<'a>,
         environment: crate::pack_palette::Environment,

crates/horizon-client-render/src/gfx.rs

@@ -60,6 +60,7 @@ mod entity_outline;
 mod fluid;
 #[cfg(test)]
 mod inter_stage_tests;
+mod section_fade;
 mod terrain_model;
 #[cfg(test)]
 pub(crate) mod test_gpu;
@@ -74,6 +75,10 @@ pub use entity_batch::{
     WATER_MASK_OVERLAY, WORLD_TEXT_OVERLAY, WORLD_TEXT_POLYGON_OFFSET_OVERLAY, is_native_terrain,
     mark_oit,
 };
+use section_fade::{
+    CHUNK_VISIBILITY_THRESHOLD, FadeInputs, chunk_visibility, fade_millis, section_instance,
+    section_visibility,
+};
 pub use view::{View, ViewSet};
 
 /// Window.getAppropriateLineWidth, in framebuffer pixels.
@@ -201,6 +206,7 @@ pub use hdr::{Calibration as HdrCalibration, Output as HdrOutput};
 mod hold;
 pub use hold::WorldHold;
 pub use output::{DisplayReading, EffectiveOutput, FrameConfiguration, FrameRequest};
+pub use screenshot_save::Saved as SavedScreenshot;
 pub mod block_light;
 mod custom_sky;
 mod displace;
@@ -236,6 +242,7 @@ pub mod panorama;
 mod readback;
 mod resident;
 mod reuse;
+mod screenshot_save;
 mod stars;
 mod surface_setup;
 use surface_setup::{AdapterChoice, AdapterFailure, open_adapter, pick_adapter, set_up_surface};
@@ -363,62 +370,6 @@ fn pack_terrain_camera(camera: DVec3) -> DVec3 {
     let whole = camera.floor();
     whole + ((camera - whole) * 65536.0).round() / 65536.0
 }
-/// A section's instance: its camera-relative origin and its UV step, negated
-/// past its fade code while it fades in over far terrain (`lod::instance`).
-fn section_instance(origin: [f32; 3], fade: u32, visibility: f32) -> [f32; 4] {
-    let step = 1.0 / crate::mesher::UV_STEPS;
-    [
-        origin[0],
-        origin[1],
-        origin[2],
-        if fade == 0 {
-            // The step is a power of two, so its mantissa is free: it holds the vanilla
-            // chunk fade-in's `1 - visibility` in 23 bits (terrain.wgsl's `instance_step` and
-            // `instance_visibility` read it back). A whole section is the bare step.
-            let faded = ((1.0 - visibility) * 8_388_608.0)
-                .round()
-                .clamp(0.0, 8_388_607.0) as u32;
-            f32::from_bits(step.to_bits() | faded)
-        } else {
-            -(fade as f32 + step)
-        },
-    ]
-}
-/// `SectionRenderDispatcher.RenderSection.getVisibility`: how far through its fade-in a section
-/// uploaded `elapsed_ms` ago is.
-fn chunk_visibility(elapsed_ms: u64, fade_ms: u64) -> f32 {
-    if elapsed_ms >= fade_ms {
-        1.0
-    } else {
-        elapsed_ms as f32 / fade_ms as f32
-    }
-}
-/// `Util.toMillis`: `Mth.floor(seconds * 1000.0)`.
-fn fade_millis(seconds: f32) -> u64 {
-    (f64::from(seconds) * 1000.0).floor().max(0.0) as u64
-}
-/// `chunk_visibility` at `now` of a section first uploaded at `uploaded`
-/// (`Renderer::section_uploaded`; none: one that fades in over far terrain, or
-/// whose column left), with the chunk fade-in `fade_ms`.
-fn section_visibility(uploaded: Option<&Instant>, fade_ms: u64, now: Instant) -> f32 {
-    uploaded.map_or(1.0, |&t| {
-        let elapsed = now.saturating_duration_since(t).as_millis() as u64;
-        chunk_visibility(elapsed, fade_ms)
-    })
-}
-/// What a section's fade depends on besides the section itself
-/// (`SectionGpu::drawn_faded`): the time, the chunk fade-in time, the sections'
-/// first uploads (`Renderer::section_uploaded`) and those held while far
-/// terrain comes in (`Renderer::lod_retiring`).
-#[derive(Clone, Copy)]
-struct FadeInputs<'a> {
-    now: Instant,
-    fade_ms: u64,
-    uploaded: &'a FxHashMap<SectionKey, Instant>,
-    retiring: &'a crate::fast_hash::FxHashSet<SectionKey>,
-}
-/// `LevelRenderer.CHUNK_VISIBILITY_THRESHOLD`: a section's block entities wait for it.
-const CHUNK_VISIBILITY_THRESHOLD: f32 = 0.3;
 /// A new value for `Renderer::block_entity_revision`.
 fn next_block_entity_revision() -> u64 {
     static NEXT: std::sync::atomic::AtomicU64 = std::sync::atomic::AtomicU64::new(0);
@@ -1084,6 +1035,9 @@ pub struct ScreenshotRequest {
     /// F2's: drawn at the game's resolution (Resolution Scale above 100%) times
     /// `Renderer::screenshot_quality`, not the window's.
     pub scaled: bool,
+    /// Written on a thread of its own (F2's, the world icon's): its outcome comes back a
+    /// frame or a few later in `Renderer::saved_screenshots`, not `screenshot_result`.
+    pub background: bool,
 }
 /// A solid terrain pipeline without HDR output's lighting (terrain.wgsl's `HDR_LIGHTING`),
 /// for the frames HDR is off, and with it where the display offers HDR output: the
@@ -1171,6 +1125,8 @@ pub struct Renderer {
     /// Sections upload their solid quads in the compact layout (`mesher::packed`): the solid
     /// passes read the arena themselves (`flat`) and no shader pack reads it as vertices.
     packed_quads: bool,
+    /// The compact layout is allowed (`HORIZON_PACKED_QUADS`, `set_packed_layout`).
+    packed_on: bool,
     /// The visibility buffer for flat frames' solid terrain (`visbuffer`,
     /// `HORIZON_VISBUFFER=1`).
     visbuf: Option<visbuffer::Visbuffer>,
@@ -1578,6 +1534,9 @@ pub struct Renderer {
     pub screenshot_result: Option<std::result::Result<[u32; 2], String>>,
     /// The HDR copy the last screenshot wrote beside it, if it wrote one.
     pub screenshot_hdr: Option<std::path::PathBuf>,
+    /// `background` screenshots written since the caller last took them.
+    pub saved_screenshots: Vec<SavedScreenshot>,
+    screenshot_saves: screenshot_save::Saves,
     /// Screenshot Quality (Horizon setting): a `scaled` screenshot's frame is this many
     /// times the game's resolution (1, 2, 4 or 8).
     pub screenshot_quality: u32,
@@ -4945,8 +4904,8 @@ impl Renderer {
             }
             None => (solid, solid_opaque, solid_cutout, solid_mirror),
         };
-        // The solid quads in the compact layout, while no shader pack reads the arena
-        // (`follow_packed_layout`).
+        // The solid quads in the compact layout where every pass reads it; the first world
+        // frames settle it for the picked pack (`follow_packed_layout`).
         let packed_quads = flat.is_some() && !shader_pack && packed_wanted();
         packed::pack_quads(packed_quads);
         // A native mod's world warp builds its pipelines with these layouts once it is given one.
@@ -5077,6 +5036,7 @@ impl Renderer {
             ));
         }
         let world_primitives = world_primitives::WorldPrimitives::new(&device, frame_format);
+        let screenshot_saves = screenshot_save::Saves::new(&device);
         Ok(Self {
             display: None,
             reading: display,
@@ -5113,6 +5073,7 @@ impl Renderer {
             world_warps,
             flat_on: flat.is_some(),
             packed_quads,
+            packed_on: packed_wanted(),
             cull_on: cull.is_some(),
             sides_on: true,
             gpu_culling: None,
@@ -5348,6 +5309,8 @@ impl Renderer {
             screenshot: None,
             screenshot_result: None,
             screenshot_hdr: None,
+            saved_screenshots: Vec::new(),
+            screenshot_saves,
             screenshot_quality: 1,
             screenshot_halvings: 0,
             gamma: 0.5,
@@ -6747,13 +6710,17 @@ impl Renderer {
             flat.set_translucent_page_vertices(arena.page_vertices());
         }
     }
-    /// Uploads solid quads in the compact layout (`packed_quads`) while no shader pack runs:
-    /// a pack's terrain and shadow programs, and Horizon's own packs' stages, read the
-    /// arena's vertices as `TerrainVertex`es. Leaving it drops every section and far tile
-    /// for the game to mesh again, as `follow_translucent_layout` does.
+    /// Uploads solid quads in the compact layout (`packed_quads`) unless a pack reads the
+    /// arena's vertices as `TerrainVertex`es: Horizon's own packs' stages, and a `shaders/`
+    /// pack's terrain and shadow programs outside flat draws (flat ones unpack the records,
+    /// `pack_atlas::PULL_FLAT`). Leaving it drops every section and far tile for the game to
+    /// mesh again, as `follow_translucent_layout` does.
     fn follow_packed_layout(&mut self) {
         let pack = self.pack_post.as_ref().and_then(|p| p.1.as_ref()).is_some();
-        let want = self.flat.is_some() && !pack && self.native.is_none() && packed_wanted();
+        let want = self.flat.is_some()
+            && (!pack || self.pack_terrain_flat)
+            && self.native.is_none()
+            && self.packed_on;
         if want == self.packed_quads {
             return;
         }
@@ -6764,6 +6731,10 @@ impl Renderer {
             let waiting = self.hold.take_all();
             self.place_held(waiting);
         }
+        log::info!(
+            "Horizon: compact solid terrain {}",
+            if want { "on" } else { "off" }
+        );
         self.packed_quads = want;
         packed::pack_quads(want);
         let laid_out = self.sections.values().any(|s| s.packed)
@@ -6773,6 +6744,17 @@ impl Renderer {
             self.clear_sections(self.layout);
         }
     }
+    /// Allows the compact layout of solid quads or not, for A/B checks: every section and far
+    /// tile is meshed again in the layout that follows. Replies whether sections now use it.
+    pub fn set_packed_layout(&mut self, on: bool) -> bool {
+        if on != self.packed_on {
+            self.packed_on = on;
+            self.follow_packed_layout();
+            self.sections_dropped = true;
+            self.clear_sections(self.layout);
+        }
+        self.packed_quads
+    }
     /// Whether every section and far tile was dropped since the last call, to be
     /// laid out again (`follow_translucent_layout`): the game meshes them again,
     /// as for a new renderer.
@@ -7041,8 +7023,10 @@ impl Renderer {
         }
     }
     /// This renderer's output as applied, with what its destination offers and reports.
-    pub fn output(&self) -> &output::EffectiveOutput {
-        &self.output
+    pub fn output(&self) -> output::EffectiveOutput {
+        let native = self.native.as_ref().map(|n| n.frame.api);
+        self.output
+            .with_pack(self.shader_pack_kind() == Some("iris"), native)
     }
     /// What this renderer's display last reported: a renderer made again for the window
     /// starts from it (`Renderer::new`'s `display`).
@@ -7213,7 +7197,8 @@ impl Renderer {
                     .as_ref()
                     .map_or([1, 1], |t| [t.width(), t.height()]),
                 terrain: self.pack_atlas.as_ref().map(|_| pack_post::Geometry {
-                    buffers: if flat { &buffers[..1] } else { &buffers },
+                    // Flat terrain programs pull their vertices (`pack_atlas::PULL_FLAT`).
+                    buffers: if flat { &[] } else { &buffers },
                     table: self.flat.as_ref().filter(|_| flat).map(|f| &f.draw_layout),
                     depth_write: true,
                     atlas: None,
@@ -7383,7 +7368,8 @@ impl Renderer {
                 lightmap,
                 gui_size,
                 terrain: terrain.then(|| pack_post::Geometry {
-                    buffers: if flat { &buffers[..1] } else { &buffers },
+                    // Flat terrain programs pull their vertices (`pack_atlas::PULL_FLAT`).
+                    buffers: if flat { &[] } else { &buffers },
                     table: table.as_ref(),
                     depth_write: true,
                     atlas: None,
@@ -7548,7 +7534,8 @@ impl Renderer {
                 );
                 horizon_shaders::GeometryInputs {
                     inputs,
-                    pull: pack_atlas::PULL.to_owned(),
+                    // Flat terrain inputs pull their own vertex (`PULL_FLAT`, `gl_VertexIndex` → `hz_vertex_index`).
+                    pull: String::new(),
                     index: "hz_indices[@]".to_owned(),
                 }
             });
@@ -7975,6 +7962,8 @@ impl Renderer {
         if self.device_lost() {
             return Err("the graphics device was lost".into());
         }
+        let saved = self.screenshot_saves.finished();
+        self.saved_screenshots.extend(saved);
         if let Some(request) = self.capture.take() {
             let result = self.write_capture(&request, frame);
             self.capture_result = Some(result.map_err(|e| e.to_string()));
@@ -8319,9 +8308,7 @@ impl Renderer {
         let taa = !frame.title
             && self.pack_post.as_ref().is_none_or(|p| p.1.is_none())
             && self.native.as_ref().is_none_or(|n| n.post.is_none());
-        let hdr_lighting = self.native.is_none()
-            && self.pack_post.as_ref().is_none_or(|p| p.1.is_none())
-            && std::env::var_os("HORIZON_HDR_LIGHTING").is_none_or(|v| v != "0");
+        let hdr_lighting = self.shader_pack_kind().is_none();
         if let Some(hdr) = &mut self.hdr {
             hdr.lighting = hdr_lighting && hdr.look;
         }
@@ -12044,24 +12031,18 @@ impl Renderer {
                 self.screenshot = Some(request);
             } else {
                 self.screenshot_halvings = 0;
-                self.screenshot_hdr = None;
-                if let Some(hdr_buffer) = hdr_readback {
-                    let hdr_path = hdr_screenshot_path(&request.path);
-                    match self.write_hdr_screenshot(&hdr_path, &hdr_buffer) {
-                        Ok(()) => {
-                            log::info!("Saved HDR screenshot to {}", hdr_path.display());
-                            self.screenshot_hdr = Some(hdr_path);
-                        }
-                        Err(e) => log::warn!(
-                            "Horizon renderer: HDR screenshot {}: {e}",
-                            hdr_path.display()
-                        ),
-                    }
+                let size = [self.config.width, self.config.height];
+                let hdr = hdr_readback
+                    .filter(|_| self.hdr.is_some())
+                    .map(|b| (hdr_screenshot_path(&request.path), b));
+                let shot = screenshot_save::Shot::new(&request, size, self.config.format, hdr);
+                if request.background {
+                    self.screenshot_saves.start(shot, buffer);
+                } else {
+                    let saved = screenshot_save::save_now(&self.device, shot, &buffer);
+                    self.screenshot_hdr = saved.hdr;
+                    self.screenshot_result = Some(saved.result);
                 }
-                self.screenshot_result = Some(
-                    self.write_screenshot(&request, &buffer)
-                        .map_err(|e| e.to_string()),
-                );
             }
         }
         // The frame's own waits for the submit thread (its queue writes and passes).
@@ -12664,96 +12645,22 @@ impl Renderer {
             let texture = copy.as_ref().unwrap_or(texture);
             Some((request, copy_frame(&self.device, encoder, texture, size)))
         } else {
-            self.screenshot_result = Some(Err(format!(
+            let error = format!(
                 "screenshots need a 32-bit surface format, not {:?}",
                 self.config.format
-            )));
+            );
+            if request.background {
+                self.saved_screenshots.push(screenshot_save::Saved {
+                    path: request.path,
+                    result: Err(error),
+                    hdr: None,
+                });
+            } else {
+                self.screenshot_result = Some(Err(error));
+            }
             None
         }
     }
-    /// The pixels `copy_frame` read back into `buffer`, 4 bytes each, row after row.
-    fn read_frame(&self, buffer: &wgpu::Buffer) -> Result<Vec<[u8; 4]>> {
-        let (sender, receiver) = std::sync::mpsc::channel();
-        buffer.map_async(wgpu::MapMode::Read, .., move |r| {
-            let _ = sender.send(r);
-        });
-        self.device
-            .poll(wgpu::PollType::wait_indefinitely())
-            .map_err(|e| e.to_string())?;
-        receiver
-            .recv()
-            .map_err(|e| e.to_string())?
-            .map_err(|e| e.to_string())?;
-        let (width, height, row) = (
-            self.config.width as usize,
-            self.config.height as usize,
-            padded_row(self.config.width) as usize,
-        );
-        let mut pixels = Vec::with_capacity(width * height);
-        {
-            let data = buffer.get_mapped_range(..).map_err(|e| e.to_string())?;
-            for y in 0..height {
-                pixels.extend_from_slice(data[y * row..y * row + width * 4].as_chunks::<4>().0);
-            }
-        }
-        buffer.unmap();
-        Ok(pixels)
-    }
-    fn write_screenshot(
-        &self,
-        request: &ScreenshotRequest,
-        buffer: &wgpu::Buffer,
-    ) -> Result<[u32; 2]> {
-        let bgra = matches!(
-            self.config.format.remove_srgb_suffix(),
-            wgpu::TextureFormat::Bgra8Unorm
-        );
-        let mut pixels = Vec::with_capacity((self.config.width * self.config.height * 4) as usize);
-        for px in self.read_frame(buffer)? {
-            let (r, b) = if bgra { (px[2], px[0]) } else { (px[0], px[2]) };
-            pixels.extend_from_slice(&[r, px[1], b, 255]);
-        }
-        // NativeImage.resizeSubRectTo on takeAutoScreenshot's grab: the icon
-        // is the frame's centre square averaged down to its size.
-        let (width, height, pixels) = match request.size {
-            Some(size) => (
-                size[0],
-                size[1],
-                square_downscale(&pixels, self.config.width, self.config.height, size),
-            ),
-            None => (self.config.width, self.config.height, pixels),
-        };
-        let mut encoder = png::Encoder::new(
-            std::io::BufWriter::new(std::fs::File::create(&request.path)?),
-            width,
-            height,
-        );
-        encoder.set_color(png::ColorType::Rgba);
-        encoder.set_depth(png::BitDepth::Eight);
-        encoder.write_header()?.write_image_data(&pixels)?;
-        Ok([width, height])
-    }
-    /// The HDR10 copy (`Hdr::capture`) as a 16-bit PNG tagged BT.2020 with PQ (cICP, PNG's
-    /// third edition), with the content light levels its pixels hold (cLLI), and
-    /// an ICC profile for the programs that don't read cICP (`hdr_icc`).
-    fn write_hdr_screenshot(&self, path: &std::path::Path, buffer: &wgpu::Buffer) -> Result<()> {
-        if self.hdr.is_none() {
-            return Ok(());
-        }
-        let pixels = hdr10_to_rgb16(&self.read_frame(buffer)?);
-        let mut info = png::Info::with_size(self.config.width, self.config.height);
-        info.color_type = png::ColorType::Rgb;
-        info.bit_depth = png::BitDepth::Sixteen;
-        info.icc_profile = Some(hdr_icc::profile().into());
-        let encoder =
-            png::Encoder::with_info(std::io::BufWriter::new(std::fs::File::create(path)?), info)?;
-        let mut writer = encoder.write_header()?;
-        // BT.2020 primaries, PQ, RGB, full range.
-        writer.write_chunk(png::chunk::cICP, &[9, 16, 0, 1])?;
-        writer.write_chunk(png::chunk::cLLI, &hdr_icc::content_light_levels(&pixels))?;
-        writer.write_image_data(&pixels)?;
-        Ok(())
-    }
 }
 /// `screenshots/2026-10-28_12.00.00.png` -> `screenshots/2026-10-28_12.00.00-hdr.png`.
 fn hdr_screenshot_path(path: &std::path::Path) -> PathBuf {
@@ -15373,8 +15280,8 @@ fn log_os_reported(reported: Option<crate::graphics::Reported>) {
     });
 }
 /// What the OS reports in absolute nits, HDR output's scale (Windows: DXGI's SDR white level,
-/// the brightness slider's, as Paper White, and its `MaxLuminance`, mostly the display's EDID
-/// guess, as Peak Brightness), kept within the settings' ranges. The player's values win.
+/// the brightness slider's, as Paper White, and its `MaxLuminance`, the display's or a calibration
+/// profile's, as Peak Brightness), kept within the settings' ranges. The player's values win.
 fn os_reported(info: &wgpu::DisplayHdrInfo) -> Option<crate::graphics::Reported> {
     let luminance = info.luminance?;
     let usable = |n: f32| n.is_finite() && n > 0.0;

crates/horizon-client-render/src/gfx/binding_cache.rs

@@ -0,0 +1,42 @@
+//! A bind group's validity depends on the identity of its buffers and the
+//! bound slice, not on the bytes written into those buffers.
+
+pub(super) struct BindingKey<B, const N: usize> {
+    pub first: u64,
+    pub count: u64,
+    pub buffers: [B; N],
+}
+
+impl<B: PartialEq, const N: usize> BindingKey<B, N> {
+    pub fn matches(&self, first: u64, count: u64, buffers: [&B; N]) -> bool {
+        self.first == first
+            && self.count == count
+            && self
+                .buffers
+                .iter()
+                .zip(buffers)
+                .all(|(old, new)| old == new)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn changes_to_any_resource_or_range_invalidate_the_binding() {
+        let key = BindingKey {
+            first: 16,
+            count: 8,
+            buffers: [1u64, 2, 3, 4],
+        };
+        assert!(key.matches(16, 8, [&1, &2, &3, &4]));
+        assert!(!key.matches(0, 8, [&1, &2, &3, &4]));
+        assert!(!key.matches(16, 9, [&1, &2, &3, &4]));
+        for i in 0..4 {
+            let mut resources = [1u64, 2, 3, 4];
+            resources[i] += 100;
+            assert!(!key.matches(16, 8, resources.each_ref()));
+        }
+    }
+}

crates/horizon-client-render/src/gfx/flat.rs

@@ -19,7 +19,10 @@
 //! start, and the run is drawn indirectly with the count the copy reached.
 use super::SolidPipeline;
 use super::arena::GRAIN;
-use smallvec::SmallVec;
+
+#[path = "binding_cache.rs"]
+mod binding_cache;
+use binding_cache::BindingKey;
 
 /// One section draw for `flatten.wgsl`: index count, first sorted index (or
 /// `QUADS` for a solid draw; phase 2: its entry in phase 2's draws), base
@@ -85,6 +88,11 @@ pub struct Call {
     pub count: u32,
 }
 
+struct CachedGroup<const N: usize> {
+    key: BindingKey<wgpu::Buffer, N>,
+    group: wgpu::BindGroup,
+}
+
 pub struct Flat {
     /// The solid draws in one pass (`fs_solid`), where the GPU doesn't hide pixels
     /// by tiles (`split_solid` in `Renderer::draw_frame`: elsewhere than Metal).
@@ -109,8 +117,9 @@ pub struct Flat {
     phase2_call_data: Vec<[u32; 5]>,
     /// GPU culling's phase 2 uses indirect draws; flat draws without culling do not.
     indirect_execution: bool,
-    /// The copy of phase 2's draws, and its ranges.
-    phase2_group: Option<(wgpu::BindGroup, u32)>,
+    /// Bindings reused while the range and all GPU buffers are unchanged.
+    phase2_group: Option<CachedGroup<4>>,
+    groups: Vec<CachedGroup<3>>,
     /// The layout of a page's bind group 1 (shader packs' terrain pipelines share it).
     pub(super) draw_layout: wgpu::BindGroupLayout,
     blocks_per_page: u64,
@@ -515,6 +524,7 @@ impl Flat {
             phase2_call_data: Vec::new(),
             indirect_execution,
             phase2_group: None,
+            groups: Vec::new(),
             draw_layout,
             blocks_per_page: page_vertices.div_ceil(GRAIN),
             translucent_blocks_per_page: page_vertices.div_ceil(GRAIN),
@@ -626,6 +636,8 @@ impl Flat {
     }
     pub fn clear(&mut self) {
         self.pages.clear();
+        self.groups.clear();
+        self.phase2_group = None;
         self.free_ids.clear();
         self.next_id = 0;
     }
@@ -665,7 +677,6 @@ impl Flat {
         sorted_page: impl Fn(u32) -> wgpu::Buffer,
         timing: Option<&mut super::pack_timing::PassTiming>,
     ) -> bool {
-        self.phase2_group = None;
         let phase2 = phase2.filter(|_| self.indirect_execution);
         let phase1_draws = if phase2.is_some() {
             phase1_draws
@@ -729,6 +740,9 @@ impl Flat {
         self.shadow_calls = shadow_calls;
         self.pass_calls = pass_calls;
         if total == 0 || total * 4 > device.limits().max_storage_buffer_binding_size {
+            // Do not retain bindings for a frame that cannot use flat draws.
+            self.phase2_group = None;
+            self.groups.clear();
             self.calls.clear();
             self.phase1_calls = 0;
             self.solid_calls = 0;
@@ -802,39 +816,63 @@ impl Flat {
             phase2,
             self.segments.iter().find(|(s, ..)| *s == Source::Seen),
         ) {
-            let group = device.create_bind_group(&wgpu::BindGroupDescriptor {
-                label: Some("Flatten phase 2 section draws"),
-                layout: &self.seen_layout,
-                entries: &[
-                    wgpu::BindGroupEntry {
-                        binding: 0,
-                        resource: ranges_at(first, count),
+            let buffers = [&self.ranges, &self.indices, phase2, &self.phase2_calls];
+            if !self
+                .phase2_group
+                .as_ref()
+                .is_some_and(|cached| cached.key.matches(first, count, buffers))
+            {
+                let group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+                    label: Some("Flatten phase 2 section draws"),
+                    layout: &self.seen_layout,
+                    entries: &[
+                        wgpu::BindGroupEntry {
+                            binding: 0,
+                            resource: ranges_at(first, count),
+                        },
+                        wgpu::BindGroupEntry {
+                            binding: 2,
+                            resource: self.indices.as_entire_binding(),
+                        },
+                        wgpu::BindGroupEntry {
+                            binding: 3,
+                            resource: phase2.as_entire_binding(),
+                        },
+                        wgpu::BindGroupEntry {
+                            binding: 4,
+                            resource: self.phase2_calls.as_entire_binding(),
+                        },
+                    ],
+                });
+                self.phase2_group = Some(CachedGroup {
+                    key: BindingKey {
+                        first,
+                        count,
+                        buffers: buffers.map(|b| b.clone()),
                     },
-                    wgpu::BindGroupEntry {
-                        binding: 2,
-                        resource: self.indices.as_entire_binding(),
-                    },
-                    wgpu::BindGroupEntry {
-                        binding: 3,
-                        resource: phase2.as_entire_binding(),
-                    },
-                    wgpu::BindGroupEntry {
-                        binding: 4,
-                        resource: self.phase2_calls.as_entire_binding(),
-                    },
-                ],
-            });
-            self.phase2_group = Some((group, count as u32));
+                    group,
+                });
+            }
+        } else {
+            self.phase2_group = None;
         }
-        let groups: SmallVec<[(wgpu::BindGroup, u32); 8]> = self
-            .segments
-            .iter()
-            .filter_map(|&(source, first, count)| {
-                let sorted = match source {
-                    Source::Quads => None,
-                    Source::Seen => return None,
-                    Source::Sorted(page) => Some(sorted_page(page)),
-                };
+        let mut groups = 0;
+        for &(source, first, count) in &self.segments {
+            let sorted = match source {
+                Source::Quads => None,
+                Source::Seen => continue,
+                Source::Sorted(page) => Some(sorted_page(page)),
+            };
+            let buffers = [
+                &self.ranges,
+                sorted.as_ref().unwrap_or(&self.empty),
+                &self.indices,
+            ];
+            if self
+                .groups
+                .get(groups)
+                .is_none_or(|cached| !cached.key.matches(first, count, buffers))
+            {
                 let group = device.create_bind_group(&wgpu::BindGroupDescriptor {
                     label: Some("Flatten section draws"),
                     layout: &self.compute_layout,
@@ -845,7 +883,7 @@ impl Flat {
                         },
                         wgpu::BindGroupEntry {
                             binding: 1,
-                            resource: sorted.as_ref().unwrap_or(&self.empty).as_entire_binding(),
+                            resource: buffers[1].as_entire_binding(),
                         },
                         wgpu::BindGroupEntry {
                             binding: 2,
@@ -853,17 +891,32 @@ impl Flat {
                         },
                     ],
                 });
-                Some((group, count as u32))
-            })
-            .collect();
+                let cached = CachedGroup {
+                    key: BindingKey {
+                        first,
+                        count,
+                        buffers: buffers.map(|b| b.clone()),
+                    },
+                    group,
+                };
+                if groups < self.groups.len() {
+                    self.groups[groups] = cached;
+                } else {
+                    self.groups.push(cached);
+                }
+            }
+            groups += 1;
+        }
+        self.groups.truncate(groups);
         let mut pass = encoder.begin_compute_pass(&wgpu::ComputePassDescriptor {
             label: Some("Flatten section draws"),
             timestamp_writes: timing.and_then(|t| t.compute_writes("Flatten")),
         });
         pass.set_pipeline(&self.flatten);
-        for (group, count) in &groups {
-            pass.set_bind_group(0, group, &[]);
-            pass.dispatch_workgroups((*count).min(GROUP_LIMIT), count.div_ceil(GROUP_LIMIT), 1);
+        for cached in &self.groups {
+            let count = cached.key.count as u32;
+            pass.set_bind_group(0, &cached.group, &[]);
+            pass.dispatch_workgroups(count.min(GROUP_LIMIT), count.div_ceil(GROUP_LIMIT), 1);
         }
         drop(pass);
         true
@@ -919,16 +972,17 @@ impl Flat {
         encoder: &mut wgpu::CommandEncoder,
         timing: Option<&mut super::pack_timing::PassTiming>,
     ) {
-        let Some((group, count)) = &self.phase2_group else {
+        let Some(cached) = &self.phase2_group else {
             return;
         };
+        let count = cached.key.count as u32;
         let mut pass = encoder.begin_compute_pass(&wgpu::ComputePassDescriptor {
             label: Some("Flatten phase 2 section draws"),
             timestamp_writes: timing.and_then(|t| t.compute_writes("Flatten phase 2")),
         });
         pass.set_pipeline(&self.flatten_seen);
-        pass.set_bind_group(0, group, &[]);
-        pass.dispatch_workgroups((*count).min(GROUP_LIMIT), count.div_ceil(GROUP_LIMIT), 1);
+        pass.set_bind_group(0, &cached.group, &[]);
+        pass.dispatch_workgroups(count.min(GROUP_LIMIT), count.div_ceil(GROUP_LIMIT), 1);
     }
 
     /// The camera's translucent calls.

crates/horizon-client-render/src/gfx/hdr.rs

@@ -169,7 +169,8 @@ pub struct Hdr {
     hand_mark: wgpu::RenderPipeline,
     params: wgpu::Buffer,
     /// The same pass drawing HDR10 for a screenshot (`capture`), with its own parameters,
-    /// so it can differ from the swapchain's in one frame.
+    /// so it can differ from the swapchain's in one frame, and without the swapchain's dither:
+    /// a screenshot keeps the exact codes.
     capture_pipeline: wgpu::RenderPipeline,
     capture_params: wgpu::Buffer,
     pub output: Output,
@@ -191,7 +192,7 @@ pub struct Hdr {
     pub masks: Masks,
     /// HDR lighting, whether Horizon lifts this frame's world: off under a Horizon shader pack
     /// that draws, while a `shaders/` pack's post or material stage runs (the pack's own),
-    /// with HDR Lighting (`look`) off, and with `HORIZON_HDR_LIGHTING=0`, to compare.
+    /// and with HDR Lighting (`look`) off.
     pub lighting: bool,
     /// The HDR Lighting setting: off, nothing in the world is lifted, light sources and the
     /// sun included, so the picture is SDR's on the HDR canvas.
@@ -286,8 +287,9 @@ impl Hdr {
                 entries: &entries,
             })
         };
-        // One full-screen pass of hdr.wgsl's `entry` into `format`, reading `layout`.
-        let pass = |label, layout: &wgpu::BindGroupLayout, entry, format| {
+        // One full-screen pass of hdr.wgsl's `entry` into `format`, reading `layout`; `dither`
+        // for the last pass into the HDR10 swapchain (`pq_dither`).
+        let pass = |label, layout: &wgpu::BindGroupLayout, entry, format, dither: bool| {
             let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
                 label: Some(label),
                 bind_group_layouts: &[Some(layout)],
@@ -308,7 +310,10 @@ impl Hdr {
                 fragment: Some(wgpu::FragmentState {
                     module: &shader,
                     entry_point: Some(entry),
-                    compilation_options: Default::default(),
+                    compilation_options: wgpu::PipelineCompilationOptions {
+                        constants: &[("pq_dither", f64::from(u8::from(dither)))],
+                        ..Default::default()
+                    },
                     targets: &[Some(wgpu::ColorTargetState {
                         format,
                         blend: None,
@@ -321,7 +326,8 @@ impl Hdr {
         };
         let layout_bindings: &[u32] = if coverage { &[0, 3, 4, 5] } else { &[0, 1, 3] };
         let display = layout("Horizon HDR bindings", layout_bindings, true);
-        let pipeline_for = |format| pass("Horizon HDR", &display, entry_point, format);
+        let pipeline_for =
+            |format, dither| pass("Horizon HDR", &display, entry_point, format, dither);
         let params = || {
             device.create_buffer(&wgpu::BufferDescriptor {
                 label: Some("Horizon HDR parameters"),
@@ -333,7 +339,7 @@ impl Hdr {
         let layered = coverage.then(|| {
             let with = |label, textures: &[u32], params, entry, format| {
                 let layout = layout(label, textures, params);
-                let pipeline = pass(label, &layout, entry, format);
+                let pipeline = pass(label, &layout, entry, format, false);
                 (layout, pipeline)
             };
             let hud = super::hud_coverage::HUD_FORMAT;
@@ -395,8 +401,8 @@ impl Hdr {
         );
         Self {
             logo: logo_mask(device, queue),
-            pipeline: pipeline_for(output.format()),
-            capture_pipeline: pipeline_for(Output::Pq.format()),
+            pipeline: pipeline_for(output.format(), output == Output::Pq),
+            capture_pipeline: pipeline_for(Output::Pq.format(), false),
             layout: display,
             clear_alpha,
             hand_mark,
@@ -1001,12 +1007,14 @@ impl Hdr {
     }
 }
 
-/// Horizon's icon (horizon-theme) as a 1-bit mask: its white strokes, one colour with hard
-/// edges, are the logo; everything else is not.
+/// The windows' icon (`window::set_icon_png`: Horizon's in the official game) as a 1-bit mask:
+/// its white strokes, one colour with hard edges, are the logo; everything else is not. No icon
+/// given: an empty mask.
 fn logo_mask(device: &wgpu::Device, queue: &wgpu::Queue) -> wgpu::TextureView {
     use wgpu::util::DeviceExt;
-    let (w, h, rgba) =
-        crate::hud::decode_bytes(horizon_theme::ICON_PNG).unwrap_or((1, 1, vec![0; 4]));
+    let (w, h, rgba) = horizon_client_input::window::icon_png()
+        .and_then(|png| crate::hud::decode_bytes(png).ok())
+        .unwrap_or((1, 1, vec![0; 4]));
     let mask: Vec<u8> = rgba
         .as_chunks::<4>()
         .0
@@ -1707,19 +1715,32 @@ struct ReferenceParams { peak: f32, scene: f32, world: f32, debug: f32, share: v
                     super::super::hud_coverage::clear(&mut encoder, &hdr.coverage_view().unwrap());
                     hdr.begin(&queue, true);
                     hdr.present(&queue, &mut encoder, &target, true, None);
-                    let got = texel(&device, &queue, encoder, &target);
-                    for c in &got[..3] {
-                        let c = f64::from(*c);
-                        let ok = match output {
-                            // 10-bit codes, a step either way for rounding.
-                            Output::Pq => (c - 1023.0 * pq(want)).abs() <= 1.0,
-                            // 80 nits a unit, in half floats.
-                            Output::ScRgb => (c * 80.0 - want).abs() <= 2e-3 * want + 1e-4,
+                    // HDR10's exact codes are a screenshot's copy: the swapchain's own get a
+                    // code of dither either way.
+                    let exact = (output == Output::Pq)
+                        .then(|| hdr.capture(&device, &queue, &mut encoder, true).unwrap());
+                    let presented = texel(&device, &queue, encoder, &target);
+                    let exact = exact.map(|copy| {
+                        let encoder = device.create_command_encoder(&Default::default());
+                        texel(&device, &queue, encoder, &copy)
+                    });
+                    for (got, codes) in [(Some(presented), 2.0), (exact, 1.0)] {
+                        let Some(got) = got else {
+                            continue;
                         };
-                        assert!(
-                            ok,
-                            "{output:?} black {black}, light {light}: {got:?}, not {want} nits"
-                        );
+                        for c in &got[..3] {
+                            let c = f64::from(*c);
+                            let ok = match output {
+                                // 10-bit codes, a step either way for rounding.
+                                Output::Pq => (c - 1023.0 * pq(want)).abs() <= codes,
+                                // 80 nits a unit, in half floats.
+                                Output::ScRgb => (c * 80.0 - want).abs() <= 2e-3 * want + 1e-4,
+                            };
+                            assert!(
+                                ok,
+                                "{output:?} black {black}, light {light}: {got:?}, not {want} nits"
+                            );
+                        }
                     }
                 }
             }
@@ -2076,3 +2097,7 @@ mod lighting_tests {
 #[cfg(test)]
 #[path = "hdr_written_tests.rs"]
 mod written_tests;
+
+#[cfg(test)]
+#[path = "hdr_dither_tests.rs"]
+mod dither_tests;

crates/horizon-client-render/src/gfx/hdr_dither_tests.rs

@@ -0,0 +1,313 @@
+//! HDR10's dither (`hdr.wgsl`, `dithered`): the last pass into the 10-bit swapchain, and what
+//! must stay without it.
+use super::{
+    Hdr, Output,
+    tests::{fill, gpu},
+};
+use wgpu::TextureFormat as F;
+
+const SIZE: [u32; 2] = [64, 1024];
+/// The ramp: grey rising by one half-float step every `ROWS` rows from `FIRST / 2048`. That is
+/// three PQ codes down the picture around 91 nits: as slow as a clear sky, and as fine as the
+/// float frame holds.
+const FIRST: u32 = 1434;
+const ROWS: u32 = 52;
+
+/// SMPTE ST 2084: nits as a 10-bit PQ code, before rounding.
+fn code(nits: f64) -> f64 {
+    let y = (nits / 10_000.0).powf(0.1593017578125);
+    1023.0 * ((0.8359375 + 18.8515625 * y) / (1.0 + 18.6875 * y)).powf(78.84375)
+}
+
+/// The ramp's row `y` as a PQ code, at the 200-nit paper white `Hdr` starts with.
+fn ramp_code(y: u32) -> f64 {
+    code(200.0 * (f64::from(FIRST + y / ROWS) / 2048.0).powf(2.2))
+}
+
+fn ramp(device: &wgpu::Device, encoder: &mut wgpu::CommandEncoder, frame: &wgpu::Texture) {
+    let shader = device.create_shader_module(wgpu::ShaderModuleDescriptor {
+        label: None,
+        source: wgpu::ShaderSource::Wgsl(
+            format!(
+                r#"
+@vertex fn vs(@builtin(vertex_index) i: u32) -> @builtin(position) vec4<f32> {{
+    return vec4(vec2(f32((i << 1u) & 2u), f32(i & 2u)) * 2.0 - 1.0, 0.0, 1.0);
+}}
+@fragment fn fs(@builtin(position) pos: vec4<f32>) -> @location(0) vec4<f32> {{
+    return vec4(vec3(f32({FIRST}u + u32(pos.y) / {ROWS}u) / 2048.0), 1.0);
+}}
+"#
+            )
+            .into(),
+        ),
+    });
+    let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+        label: None,
+        layout: None,
+        vertex: wgpu::VertexState {
+            module: &shader,
+            entry_point: Some("vs"),
+            compilation_options: Default::default(),
+            buffers: &[],
+        },
+        primitive: Default::default(),
+        depth_stencil: None,
+        multisample: Default::default(),
+        fragment: Some(wgpu::FragmentState {
+            module: &shader,
+            entry_point: Some("fs"),
+            compilation_options: Default::default(),
+            targets: &[Some(frame.format().into())],
+        }),
+        multiview_mask: None,
+        cache: None,
+    });
+    let view = frame.create_view(&Default::default());
+    let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+        color_attachments: &[Some(super::super::hud_coverage::attachment(&view))],
+        ..Default::default()
+    });
+    pass.set_pipeline(&pipeline);
+    pass.draw(0..3, 0..1);
+}
+
+/// What `hdr` writes for the float frame `paint` fills, with no HUD over it: its last pass into
+/// a swapchain image of its output (`Hdr::present`), or a screenshot's HDR10 copy
+/// (`Hdr::capture`). Every pixel's bytes, row by row.
+fn shown(
+    (device, queue): &(wgpu::Device, wgpu::Queue),
+    hdr: &mut Hdr,
+    screenshot: bool,
+    paint: impl Fn(&mut wgpu::CommandEncoder, &wgpu::Texture),
+) -> Vec<u8> {
+    let frame = hdr.frame(device, SIZE);
+    let mut encoder = device.create_command_encoder(&Default::default());
+    paint(&mut encoder, &frame);
+    hdr.keep_world(&mut encoder, None);
+    super::super::hud_coverage::clear(&mut encoder, &hdr.coverage_view().unwrap());
+    let image = if screenshot {
+        hdr.capture(device, queue, &mut encoder, true).unwrap()
+    } else {
+        let image = device.create_texture(&wgpu::TextureDescriptor {
+            label: None,
+            size: frame.size(),
+            mip_level_count: 1,
+            sample_count: 1,
+            dimension: wgpu::TextureDimension::D2,
+            format: hdr.output.format(),
+            usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_SRC,
+            view_formats: &[],
+        });
+        hdr.present(queue, &mut encoder, &image, true, None);
+        image
+    };
+    let row = SIZE[0] * image.format().block_copy_size(None).unwrap();
+    let buffer = device.create_buffer(&wgpu::BufferDescriptor {
+        label: None,
+        size: u64::from(row * SIZE[1]),
+        usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ,
+        mapped_at_creation: false,
+    });
+    encoder.copy_texture_to_buffer(
+        image.as_image_copy(),
+        wgpu::TexelCopyBufferInfo {
+            buffer: &buffer,
+            layout: wgpu::TexelCopyBufferLayout {
+                offset: 0,
+                bytes_per_row: Some(row),
+                rows_per_image: None,
+            },
+        },
+        image.size(),
+    );
+    queue.submit([encoder.finish()]);
+    buffer.map_async(wgpu::MapMode::Read, .., |r| r.unwrap());
+    device.poll(wgpu::PollType::wait_indefinitely()).unwrap();
+    buffer.get_mapped_range(..).unwrap().to_vec()
+}
+
+fn float_hdr((device, queue): &(wgpu::Device, wgpu::Queue), output: Output) -> Hdr {
+    Hdr::with_debug(device, queue, F::Rgba16Float, output, true, None)
+}
+
+/// An HDR10 picture's 10-bit codes, red, green and blue.
+fn codes(bytes: &[u8]) -> Vec<[u32; 3]> {
+    let pixels = bytes.as_chunks::<4>().0.iter();
+    pixels
+        .map(|p| [0, 10, 20].map(|shift| (u32::from_le_bytes(*p) >> shift) & 0x3ff))
+        .collect()
+}
+
+/// Down every column of a channel: the longest run of rows with one code, and the runs' mean
+/// length.
+fn runs(codes: &[[u32; 3]], channel: usize) -> (u32, f64) {
+    let (mut longest, mut count) = (0, 0);
+    for x in 0..SIZE[0] {
+        let mut run = 0;
+        for y in 0..SIZE[1] {
+            let at = |y: u32| codes[(y * SIZE[0] + x) as usize][channel];
+            if y > 0 && at(y) != at(y - 1) {
+                (longest, count, run) = (longest.max(run), count + 1, 0);
+            }
+            run += 1;
+        }
+        (longest, count) = (longest.max(run), count + 1);
+    }
+    (longest, f64::from(SIZE[0] * SIZE[1]) / f64::from(count))
+}
+
+/// Whether every row of a picture is one value from side to side: no noise in it.
+fn rows_are_flat(bytes: &[u8]) -> bool {
+    let pixel = bytes.len() / (SIZE[0] * SIZE[1]) as usize;
+    bytes
+        .chunks(pixel * SIZE[0] as usize)
+        .all(|row| row.chunks(pixel).all(|p| p == &row[..pixel]))
+}
+
+#[test]
+fn a_slow_gradient_gets_grain_instead_of_bands_on_hdr10() {
+    let Some(gpu) = gpu() else {
+        return;
+    };
+    let ramp = |encoder: &mut wgpu::CommandEncoder, frame: &wgpu::Texture| {
+        ramp(&gpu.0, encoder, frame);
+    };
+    let mut hdr = float_hdr(&gpu, Output::Pq);
+    // The ramp is what the test says: three codes, top to bottom.
+    let span = ramp_code(SIZE[1] - 1) - ramp_code(0);
+    assert!((2.9..3.2).contains(&span), "{span}");
+    // Without dither, as a screenshot's copy stays: each row its nearest code, in bands hundreds
+    // of rows tall. A GPU need not round at exactly half a code: an NVIDIA one rounds up from
+    // 0.55 here, which shows as 0.05 of a code less, so the bounds below leave a quarter code.
+    let plain = codes(&shown(&gpu, &mut hdr, true, ramp));
+    let dithered = codes(&shown(&gpu, &mut hdr, false, ramp));
+    let want = |i: usize| ramp_code(i as u32 / SIZE[0]);
+    for channel in 0..3 {
+        for (i, p) in plain.iter().enumerate() {
+            let off = (f64::from(p[channel]) - want(i)).abs();
+            assert!(
+                off <= 0.75,
+                "plain {channel} at {i}: {p:?}, not {}",
+                want(i)
+            );
+        }
+        let (longest, _) = runs(&plain, channel);
+        assert!(longest >= 250, "plain {channel}: bands of {longest} rows");
+        // With it: each pixel within the noise's one code of its light (and half a code of
+        // rounding), no column holds a code for long, and a run is a few rows on average.
+        for (i, d) in dithered.iter().enumerate() {
+            let off = (f64::from(d[channel]) - want(i)).abs();
+            assert!(
+                off <= 1.75,
+                "dithered {channel} at {i}: {d:?}, not {}",
+                want(i)
+            );
+        }
+        let (longest, mean) = runs(&dithered, channel);
+        eprintln!(
+            "HDR10 dither GPU, channel {channel}: longest run {longest} rows, mean {mean:.2}"
+        );
+        assert!(longest <= 64, "dithered {channel}: a run of {longest} rows");
+        assert!(mean < 4.0, "dithered {channel}: runs of {mean} rows");
+        // The mean of each 64-row block is the light meant.
+        let mut worst = 0.0_f64;
+        for block in 0..SIZE[1] / 64 {
+            let rows = (block * 64 * SIZE[0]) as usize..((block + 1) * 64 * SIZE[0]) as usize;
+            let n = rows.len() as f64;
+            let got = dithered[rows.clone()]
+                .iter()
+                .map(|d| f64::from(d[channel]))
+                .sum::<f64>()
+                / n;
+            let meant = rows.map(want).sum::<f64>() / n;
+            worst = worst.max((got - meant).abs());
+            assert!(
+                (got - meant).abs() < 0.25,
+                "block {block} of {channel}: {got}, not {meant}"
+            );
+        }
+        eprintln!("HDR10 dither GPU, channel {channel}: block means within {worst:.3} of a code");
+    }
+}
+
+#[test]
+fn hdr10s_dither_keeps_both_ends_exact_and_leans_to_them_in_their_last_code() {
+    let Some(gpu) = gpu() else {
+        return;
+    };
+    let mut hdr = float_hdr(&gpu, Output::Pq);
+    let grey = |g: f64| {
+        move |encoder: &mut wgpu::CommandEncoder, frame: &wgpu::Texture| {
+            fill(encoder, frame, [g, g, g, 1.0]);
+        }
+    };
+    // How far the picture's mean code is from `end`.
+    let mean_from = |picture: &[[u32; 3]], end: f64| {
+        let sum: f64 = picture.iter().flatten().map(|c| f64::from(*c)).sum();
+        (sum / (picture.len() * 3) as f64 - end).abs()
+    };
+    // Within a code of an end the noise shrinks to the distance to it. A third of a code from
+    // the end, the signal plus that noise passes half a code only where the noise is over half
+    // its range, an eighth of a triangle: so the picture's mean is an eighth of a code from the
+    // end, not a third. That lean to the end, in the last code alone, is the price of keeping
+    // the end itself exact. Bound: a GPU that rounds a tenth of a code off the half (as above)
+    // shows between 0.02 and 0.32 of a code, always short of the third.
+    let leans = |mean: f64| (0.015..0.325).contains(&mean);
+
+    // Black gets no noise: every pixel stays off.
+    let black = codes(&shown(&gpu, &mut hdr, false, grey(0.0)));
+    assert!(black.iter().all(|p| *p == [0; 3]));
+    // A third of a code above black (this grey is a half float): 0 or 1, never lifted past it.
+    let dim = 0.00038433074951171875;
+    let meant = code(200.0 * f64::powf(dim, 2.2));
+    assert!((meant - 1.0 / 3.0).abs() < 0.001, "{meant}");
+    let near_black = codes(&shown(&gpu, &mut hdr, false, grey(dim)));
+    assert!(near_black.iter().flatten().all(|c| *c <= 1));
+    let mean = mean_from(&near_black, 0.0);
+    eprintln!("HDR10 dither GPU: a third of a code above black shows as {mean:.3}");
+    assert!(leans(mean), "{mean} above black");
+
+    // The top of the range, PQ's 10 000 nits, stays the top: nothing wraps or dims. Light past
+    // the peak is held at it, so the Peak setting is the signal here.
+    hdr.peak = 10_000.0;
+    let top = codes(&shown(&gpu, &mut hdr, false, grey(20.0)));
+    assert!(top.iter().all(|p| *p == [1023; 3]));
+    // A third of a code under the top, mirrored: 1022 or 1023.
+    let (mut under, mut over) = (9000.0, 10_000.0);
+    for _ in 0..60 {
+        let middle = (under + over) / 2.0;
+        if code(middle) < 1023.0 - 1.0 / 3.0 {
+            under = middle;
+        } else {
+            over = middle;
+        }
+    }
+    hdr.peak = under as f32;
+    let meant = code(f64::from(hdr.peak));
+    assert!((1023.0 - meant - 1.0 / 3.0).abs() < 0.001, "{meant}");
+    let near_top = codes(&shown(&gpu, &mut hdr, false, grey(20.0)));
+    assert!(near_top.iter().flatten().all(|c| *c >= 1022));
+    let mean = mean_from(&near_top, 1023.0);
+    eprintln!("HDR10 dither GPU: a third of a code under the top shows as {mean:.3} under");
+    assert!(leans(mean), "{mean} under the top");
+}
+
+#[test]
+fn scrgb_and_screenshots_get_no_dither() {
+    let Some(gpu) = gpu() else {
+        return;
+    };
+    let ramp = |encoder: &mut wgpu::CommandEncoder, frame: &wgpu::Texture| {
+        ramp(&gpu.0, encoder, frame);
+    };
+    let (mut hdr10, mut scrgb) = (float_hdr(&gpu, Output::Pq), float_hdr(&gpu, Output::ScRgb));
+    // scRGB's swapchain is float: every row is one value from side to side.
+    assert!(rows_are_flat(&shown(&gpu, &mut scrgb, false, ramp)));
+    // A screenshot's HDR10 copy is the same bytes whichever swapchain is presented, the
+    // dithered one included, and has no noise in it.
+    let screenshot = shown(&gpu, &mut hdr10, true, ramp);
+    assert!(rows_are_flat(&screenshot));
+    assert_eq!(screenshot, shown(&gpu, &mut scrgb, true, ramp));
+    // The swapchain's own picture differs from it: the dither is on there.
+    assert_ne!(screenshot, shown(&gpu, &mut hdr10, false, ramp));
+}

crates/horizon-client-render/src/gfx/native_post.rs

@@ -8,7 +8,7 @@
 
 use glam::{Mat4, Vec3};
 use horizon_shader_api::{
-    Api, Frame as FrameInputs, StageKind, check::CheckedStage, stages::GROUP,
+    Api, Frame as FrameInputs, Primaries, StageKind, check::CheckedStage, stages::GROUP,
 };
 
 use super::Frame;
@@ -1596,7 +1596,11 @@ pub fn frame_inputs(
         paper_white: 80.0,
         peak: 80.0,
         black_level: 0.0,
-        padding: [0; 3],
+        // No pack is served another space yet (`[frame] primaries`).
+        primaries: Primaries::Bt709 as u32,
+        luminance_gap: [0; 2],
+        luminance: Primaries::Bt709.luminance(),
+        padding: 0,
     }
 }
 

crates/horizon-client-render/src/gfx/output.rs

@@ -144,6 +144,9 @@ pub struct EffectiveOutput {
     pub(crate) nits: [f32; 3],
     /// The HUD and menus' brightness, as a share of paper white: their nits over its.
     pub(crate) ui_brightness: f32,
+    /// The running shader pack lights the world itself: Horizon lifts none of it, so HDR
+    /// Lighting has nothing to switch (`with_pack`).
+    pub(crate) pack_lights: bool,
 }
 impl Default for EffectiveOutput {
     fn default() -> Self {
@@ -166,7 +169,22 @@ impl EffectiveOutput {
         },
         nits: [203.0, 1000.0, 0.0],
         ui_brightness: 1.0,
+        pack_lights: false,
     };
+    /// This output under the running shader pack: a `shaders/` one (`shaders`), or one of
+    /// Horizon's own of API `native`. Under a 0.1 pack on the 8- or 16-bit frame the last pass
+    /// still lifts the light sources and the sun its marks hold (`lifts_world` in
+    /// `Renderer::render`); under the rest Horizon lifts nothing.
+    pub(crate) fn with_pack(self, shaders: bool, native: Option<horizon_shader_api::Api>) -> Self {
+        let pack_lights = shaders
+            || native.is_some_and(|api| {
+                api != horizon_shader_api::Api::V0_1 || self.frame.format == super::LINEAR_FRAME
+            });
+        Self {
+            pack_lights,
+            ..self
+        }
+    }
     /// Whether the destination offers HDR output.
     pub fn hdr_offered(&self) -> bool {
         self.offered.is_some()
@@ -273,6 +291,7 @@ pub(crate) fn resolve_output(
         ],
         ui_brightness: settings.ui_nits(reading.luminance) as f32
             / settings.paper_white_nits(reading.luminance) as f32,
+        pack_lights: false,
     }
 }
 

crates/horizon-client-render/src/gfx/pack_atlas.rs

@@ -548,27 +548,107 @@ impl PackAtlas {
     }
 }
 
-/// A `TerrainVertex` of flat draws' arena page (`hz_vertices`, six words each) into the vertex
-/// inputs, for vertex `hz_vertex_index`.
-pub const PULL: &str = "        uint hz_pw = hz_vertex_index * 6u;\n        \
-    hz_v_pos = uintBitsToFloat(uvec3(hz_vertices[hz_pw], hz_vertices[hz_pw + 1u], hz_vertices[hz_pw + 2u]));\n        \
-    hz_v_uv = uvec2(hz_vertices[hz_pw + 3u] & 65535u, hz_vertices[hz_pw + 3u] >> 16u);\n        \
-    hz_v_layer = hz_vertices[hz_pw + 4u] & 65535u;\n        \
-    uint hz_pl = hz_vertices[hz_pw + 4u] >> 16u;\n        \
-    hz_v_light = uvec2(hz_pl & 255u, hz_pl >> 8u);\n        \
-    hz_v_color = unpackUnorm4x8(hz_vertices[hz_pw + 5u]);\n";
+/// GLSL: terrain.wgsl's `section_corner` over the arena page (`hz_vertices`), by quad: a
+/// vertex's words as `TerrainVertex` holds them (position, then UV, layer with light, colour),
+/// from vertices below `PACKED_BASE` or a compact record (`mesher/packed.rs`) past it. Records
+/// give back their quad's vertices bit for bit, so packs read either layout alike.
+/// `hz_arena_corner`: a vertex's position and UV words; `hz_record_corner`: corner `k`'s of the
+/// record `lo`, `hi`; `hz_record_rest`: its layer-with-light and colour words.
+const CORNER_FN: &str = "void hz_arena_corner(uint hz_av, out uvec3 hz_p, out uint hz_uv) {\n    \
+    uint hz_w = hz_av * 6u;\n    \
+    hz_p = uvec3(hz_vertices[hz_w], hz_vertices[hz_w + 1u], hz_vertices[hz_w + 2u]);\n    \
+    hz_uv = hz_vertices[hz_w + 3u];\n\
+}\n\
+uint hz_corner_offset(uint hz_rel, uint hz_side, uint hz_du, uint hz_dw) {\n    \
+    return hz_rel == 0u ? hz_side : (hz_rel == 1u ? hz_du : hz_dw);\n\
+}\n\
+void hz_record_corner(uvec3 hz_lo, uvec3 hz_hi, uint hz_k, out uvec3 hz_p, out uint hz_uv) {\n    \
+    uint hz_o = (hz_hi.z >> 12u) & 0x3ffffu;\n    \
+    uvec3 hz_block = uvec3(hz_o & 15u, (hz_o >> 4u) & 15u, (hz_o >> 8u) & 15u);\n    \
+    uint hz_axis = (hz_o >> 12u) & 3u;\n    \
+    uint hz_side = (hz_o >> 14u) & 1u;\n    \
+    uint hz_step = (((hz_o >> 15u) & 3u) + (((hz_o >> 17u) & 1u) == 1u ? 4u - hz_k : hz_k)) & 3u;\n    \
+    uint hz_du = (hz_step == 1u || hz_step == 2u) ? 1u : 0u;\n    \
+    uint hz_dw = hz_step >= 2u ? 1u : 0u;\n    \
+    uvec3 hz_pos = hz_block + uvec3(hz_corner_offset((3u - hz_axis) % 3u, hz_side, hz_du, hz_dw),\n        \
+        hz_corner_offset((4u - hz_axis) % 3u, hz_side, hz_du, hz_dw),\n        \
+        hz_corner_offset((5u - hz_axis) % 3u, hz_side, hz_du, hz_dw));\n    \
+    uint hz_sel = hz_lo.z >> 24u;\n    \
+    uint hz_u = (hz_lo.z >> (6u * ((hz_sel >> (2u * hz_k)) & 1u))) & 63u;\n    \
+    uint hz_v = (hz_lo.z >> (12u + 6u * ((hz_sel >> (2u * hz_k + 1u)) & 1u))) & 63u;\n    \
+    hz_p = floatBitsToUint(vec3(hz_pos));\n    \
+    hz_uv = (hz_u << 10u) | (hz_v << 26u);\n\
+}\n\
+uvec2 hz_record_rest(uvec3 hz_lo, uvec3 hz_hi, uint hz_k) {\n    \
+    uint hz_l = hz_k == 0u ? hz_hi.x >> 16u : (hz_k == 1u ? hz_hi.y : (hz_k == 2u ? hz_hi.y >> 12u : hz_hi.z));\n    \
+    hz_l &= 0xfffu;\n    \
+    uint hz_pl = ((hz_l & 63u) << 2u) | (((hz_l >> 6u) & 63u) << 10u);\n    \
+    uint hz_g = (hz_lo.y >> (8u * hz_k)) & 255u;\n    \
+    uint hz_t = hz_lo.x;\n    \
+    uint hz_code = hz_k == 1u ? (hz_hi.x >> 28u) & 7u : (hz_k == 2u ? (hz_hi.y >> 24u) & 7u\n        \
+        : (hz_k == 3u ? (hz_hi.y >> 27u) & 7u : 0u));\n    \
+    uint hz_alpha = hz_code == 0u ? hz_t & 0xff000000u : (hz_code * 51u) << 24u;\n    \
+    uint hz_c = (hz_g * ((hz_t >> 16u) & 255u) / 255u) | ((hz_g * ((hz_t >> 8u) & 255u) / 255u) << 8u)\n        \
+        | ((hz_g * (hz_t & 255u) / 255u) << 16u) | hz_alpha;\n    \
+    return uvec2((hz_hi.x & 0xffffu) | (hz_pl << 16u), hz_c);\n\
+}\n";
+
+/// GLSL: a flat-drawn vertex's inputs, and its quad's four corners' positions (`hz_cp0`..) and
+/// UV words (`hz_uv0`..), pulled from the arena page as terrain.wgsl's `vs_section_flat` pulls
+/// them (`CORNER_FN`): a record is read once for all four, and only the vertex's own light and
+/// colour are worked out. `hz_slot`: the slot its block is found by (`hz_block_slots`, 256 a
+/// block). The colour as the vertex fetch converts a Unorm8x4 (terrain.wgsl's `unorm8x4`).
+const PULL_FLAT: &str = "    uint hz_qv = uint(gl_VertexIndex);\n    \
+    uint hz_own = hz_qv & 3u;\n    \
+    uint hz_av = hz_qv & ~3u;\n    \
+    uint hz_slot = hz_qv;\n    \
+    bool hz_rec = false;\n    \
+    uvec3 hz_lo = uvec3(0u);\n    \
+    uvec3 hz_hi = uvec3(0u);\n    \
+    if (hz_av >= 0x10000000u) {\n        \
+        hz_slot = (hz_av - 0x10000000u) >> 2u;\n        \
+        uint hz_rw = hz_slot * 6u;\n        \
+        hz_lo = uvec3(hz_vertices[hz_rw], hz_vertices[hz_rw + 1u], hz_vertices[hz_rw + 2u]);\n        \
+        hz_hi = uvec3(hz_vertices[hz_rw + 3u], hz_vertices[hz_rw + 4u], hz_vertices[hz_rw + 5u]);\n        \
+        hz_rec = (hz_hi.z & 0x80000000u) == 0u;\n        \
+        hz_av = hz_slot + hz_lo.x;\n    \
+    }\n    \
+    uvec3 hz_cp0; uvec3 hz_cp1; uvec3 hz_cp2; uvec3 hz_cp3;\n    \
+    uint hz_uv0; uint hz_uv1; uint hz_uv2; uint hz_uv3;\n    \
+    uvec2 hz_rest;\n    \
+    if (hz_rec) {\n        \
+        hz_record_corner(hz_lo, hz_hi, 0u, hz_cp0, hz_uv0);\n        \
+        hz_record_corner(hz_lo, hz_hi, 1u, hz_cp1, hz_uv1);\n        \
+        hz_record_corner(hz_lo, hz_hi, 2u, hz_cp2, hz_uv2);\n        \
+        hz_record_corner(hz_lo, hz_hi, 3u, hz_cp3, hz_uv3);\n        \
+        hz_rest = hz_record_rest(hz_lo, hz_hi, hz_own);\n    \
+    } else {\n        \
+        hz_arena_corner(hz_av, hz_cp0, hz_uv0);\n        \
+        hz_arena_corner(hz_av + 1u, hz_cp1, hz_uv1);\n        \
+        hz_arena_corner(hz_av + 2u, hz_cp2, hz_uv2);\n        \
+        hz_arena_corner(hz_av + 3u, hz_cp3, hz_uv3);\n        \
+        uint hz_ow = (hz_av + hz_own) * 6u;\n        \
+        hz_rest = uvec2(hz_vertices[hz_ow + 4u], hz_vertices[hz_ow + 5u]);\n    \
+    }\n    \
+    uvec3 hz_vp = hz_own == 0u ? hz_cp0 : (hz_own == 1u ? hz_cp1 : (hz_own == 2u ? hz_cp2 : hz_cp3));\n    \
+    uvec3 hz_vr = uvec3(hz_own == 0u ? hz_uv0 : (hz_own == 1u ? hz_uv1 : (hz_own == 2u ? hz_uv2 : hz_uv3)), hz_rest);\n    \
+    hz_v_pos = uintBitsToFloat(hz_vp);\n    \
+    hz_v_uv = uvec2(hz_vr.x & 65535u, hz_vr.x >> 16u);\n    \
+    hz_v_layer = hz_vr.y & 65535u;\n    \
+    hz_v_light = uvec2((hz_vr.y >> 16u) & 255u, hz_vr.y >> 24u);\n    \
+    hz_v_color = vec4(float(hz_vr.z & 255u), float((hz_vr.z >> 8u) & 255u), float((hz_vr.z >> 16u) & 255u),\n        \
+        float(hz_vr.z >> 24u)) * (1.0 / 255.0);\n";
 
 /// GLSL: the face normal and tangent of a flat-drawn vertex, from its quad's first three corners
-/// (quads are four consecutive vertices of the page; position words 0-2, UV word 3).
-const FACE: &str = "    uint hz_q = (uint(gl_VertexIndex) & ~3u) * 6u;\n    \
-    vec3 hz_p0 = uintBitsToFloat(uvec3(hz_vertices[hz_q], hz_vertices[hz_q + 1u], hz_vertices[hz_q + 2u]));\n    \
-    vec3 hz_p1 = uintBitsToFloat(uvec3(hz_vertices[hz_q + 6u], hz_vertices[hz_q + 7u], hz_vertices[hz_q + 8u]));\n    \
-    vec3 hz_p2 = uintBitsToFloat(uvec3(hz_vertices[hz_q + 12u], hz_vertices[hz_q + 13u], hz_vertices[hz_q + 14u]));\n    \
-    uvec3 hz_w = uvec3(hz_vertices[hz_q + 3u], hz_vertices[hz_q + 9u], hz_vertices[hz_q + 15u]);\n    \
+/// (`PULL_FLAT`'s corners: four consecutive vertex indices, in either layout).
+const FACE: &str = "    vec3 hz_p0 = uintBitsToFloat(hz_cp0);\n    \
+    vec3 hz_p1 = uintBitsToFloat(hz_cp1);\n    \
+    vec3 hz_p2 = uintBitsToFloat(hz_cp2);\n    \
+    uvec3 hz_w = uvec3(hz_uv0, hz_uv1, hz_uv2);\n    \
     vec2 hz_t0 = vec2(hz_w.x & 65535u, hz_w.x >> 16u);\n    \
     vec2 hz_d1 = vec2(hz_w.y & 65535u, hz_w.y >> 16u) - hz_t0;\n    \
     vec2 hz_d2 = vec2(hz_w.z & 65535u, hz_w.z >> 16u) - hz_t0;\n    \
-    uint hz_w3 = hz_vertices[hz_q + 21u];\n    \
+    uint hz_w3 = hz_uv3;\n    \
     vec2 hz_t3 = vec2(hz_w3 & 65535u, hz_w3 >> 16u);\n    \
     hz_mid = (clamp(hz_t0 * hz_uv_scale, 0.0, 1.0) + clamp((hz_t0 + hz_d1) * hz_uv_scale, 0.0, 1.0)\n        \
         + clamp((hz_t0 + hz_d2) * hz_uv_scale, 0.0, 1.0) + clamp(hz_t3 * hz_uv_scale, 0.0, 1.0)) * 0.25;\n    \
@@ -620,11 +700,19 @@ impl PackAtlas {
     /// The vertex inputs of a gbuffers program drawing terrain (`TerrainVertex`, terrain.wgsl's
     /// `vs_terrain` or, for `flat` draws, `vs_terrain_flat`), in atlas coordinates.
     pub fn terrain_inputs(&self, flat: bool) -> horizon_shaders::GbuffersInputs {
-        let mut declarations = String::from(
-            "layout(location = 0) in vec3 hz_v_pos;\nlayout(location = 1) in uvec2 hz_v_uv;\n\
-             layout(location = 2) in uint hz_v_layer;\nlayout(location = 3) in vec4 hz_v_color;\n\
-             layout(location = 4) in uvec2 hz_v_light;\n",
-        );
+        // Flat draws pull their vertices from the arena page (`PULL_FLAT`), which may hold
+        // solid quads in the compact layout; others read them as vertex attributes.
+        let mut declarations = if flat {
+            String::from(
+                "vec3 hz_v_pos; uvec2 hz_v_uv; uint hz_v_layer; vec4 hz_v_color; uvec2 hz_v_light;\n",
+            )
+        } else {
+            String::from(
+                "layout(location = 0) in vec3 hz_v_pos;\nlayout(location = 1) in uvec2 hz_v_uv;\n\
+                 layout(location = 2) in uint hz_v_layer;\nlayout(location = 3) in vec4 hz_v_color;\n\
+                 layout(location = 4) in uvec2 hz_v_light;\n",
+            )
+        };
         let origin = if flat {
             declarations.push_str(
                 "layout(set = 1, binding = 0) readonly buffer HzBlockSlots { uint hz_block_slots[]; };\n\
@@ -637,7 +725,8 @@ impl PackAtlas {
                  layout(set = 3, binding = 1) readonly buffer HzVertices { uint hz_vertices[]; };\n\
                  layout(set = 3, binding = 2) readonly buffer HzTerrainTables { int hz_tables[]; };\n",
             );
-            "hz_slot_origins[hz_block_slots[uint(gl_VertexIndex) >> 8u]]"
+            declarations.push_str(CORNER_FN);
+            "hz_slot_origins[hz_block_slots[hz_slot >> 8u]]"
         } else {
             declarations.push_str("layout(location = 5) in vec4 hz_v_origin;\n");
             "hz_v_origin"
@@ -700,6 +789,7 @@ impl PackAtlas {
         );
         let mut body = body;
         if flat {
+            body.insert_str(0, PULL_FLAT);
             body.push_str(FACE);
             body.push_str(
                 "    uint hz_quad = uint(gl_VertexIndex) / 4u;\n    \

crates/horizon-client-render/src/gfx/pack_atlas/fade_test.rs

@@ -125,7 +125,7 @@ fn terrain_fade_reaches_pack_pixels_through_real_instances() {
                         terrain: Some(atlas.terrain_inputs(flat)),
                         terrain_geometry: geometry.then(|| horizon_shaders::GeometryInputs {
                             inputs: atlas.terrain_inputs(true),
-                            pull: super::PULL.to_owned(),
+                            pull: String::new(),
                             index: "@".to_owned(),
                         }),
                         ..Default::default()

crates/horizon-client-render/src/gfx/pack_atlas/midpoint_test.rs

@@ -245,6 +245,135 @@ fn terrain_vertices_go_down_to_the_32768th_below_them() {
     assert!(failures.is_empty(), "{}", failures.join("\n"));
 }
 
+/// A shader pack's flat terrain inputs read a compact record (`mesher::packed`) as the four
+/// vertices it holds: a whole tinted face with its own ambient occlusion per corner
+/// (`separateAo`), two more, and a slab's top kept as its vertices (`packed::FULL`).
+#[test]
+fn compact_records_feed_a_pack_the_vertices_they_hold() {
+    use crate::mesher::packed;
+    let instance = crate::gfx::test_gpu::instance();
+    let Ok(adapter) = pollster::block_on(instance.request_adapter(&Default::default())) else {
+        return;
+    };
+    let (device, queue) = pollster::block_on(adapter.request_device(&Default::default())).unwrap();
+    let texture = device.create_texture(&wgpu::TextureDescriptor {
+        label: None,
+        size: wgpu::Extent3d {
+            width: 16,
+            height: 16,
+            depth_or_array_layers: 1,
+        },
+        mip_level_count: 1,
+        sample_count: 1,
+        dimension: wgpu::TextureDimension::D2,
+        format: wgpu::TextureFormat::Rgba8Unorm,
+        usage: wgpu::TextureUsages::TEXTURE_BINDING | wgpu::TextureUsages::COPY_SRC,
+        view_formats: &[],
+    });
+    let mut encoder = device.create_command_encoder(&Default::default());
+    let mut atlas = PackAtlas::new(&device, &mut encoder, &[texture], 1, 1, 16).unwrap();
+    queue.submit([encoder.finish()]);
+    atlas.separate_ao = true;
+    let tint = 0x7F_B238u32;
+    let ao = [255u32, 153, 102, 204];
+    let face = |x: f32, y: f32| {
+        let pos = [
+            [x, y, 5.0],
+            [x, y, 6.0],
+            [x + 1.0, y, 6.0],
+            [x + 1.0, y, 5.0],
+        ];
+        let uv = [[0, 0], [16 << 10, 0], [16 << 10, 16 << 10], [0, 16 << 10]];
+        (0..4).map(move |i| {
+            let [r, g, b] = [16, 8, 0].map(|s| 200 * (tint >> s & 255) / 255);
+            TerrainVertex {
+                pos: pos[i],
+                uv: uv[i],
+                layer: 0x8000,
+                light: 0xF0 | 0x40 << 8,
+                color: r | g << 8 | b << 16 | ao[i] << 24,
+            }
+        })
+    };
+    let solid: Vec<_> = [(3.0, 16.0), (5.0, 16.0), (7.0, 16.0), (3.0, 8.5)]
+        .into_iter()
+        .flat_map(|(x, y)| face(x, y))
+        .collect();
+    let records = packed::layout(&solid, &[tint; 4]);
+    assert_eq!(
+        packed::packed_quads(&records, 4),
+        3,
+        "whole faces pack, the slab doesn't"
+    );
+    let page = bytemuck::cast_slice(&records);
+    let packed_range = packed::PACKED_BASE..packed::PACKED_BASE + 16;
+    let origin = f32::from_bits((1. / UV_STEPS).to_bits());
+    let mut failures = Vec::new();
+    for expression in [
+        "gl_Vertex",
+        "gl_Color",
+        "vec4(gl_MultiTexCoord0.xy, gl_MultiTexCoord1.xy)",
+        "vec4(gl_Normal, 0.0)",
+        "at_tangent",
+        "at_midBlock",
+        "vec4(mc_midTexCoord, mc_Entity.xy)",
+    ] {
+        for shadow in [false, true] {
+            let flags = [true, shadow];
+            let wide = sample_probe(&device, &queue, &atlas, &solid, origin, flags, expression);
+            let compact = sample_page(
+                &device,
+                &queue,
+                &atlas,
+                page,
+                packed_range.clone(),
+                origin,
+                flags,
+                expression,
+            );
+            let bits = |v: &[[f32; 4]]| v.iter().flatten().map(|f| f.to_bits()).collect::<Vec<_>>();
+            if bits(&wide) != bits(&compact) {
+                failures.push(format!(
+                    "{expression} shadow={shadow}: {wide:?} != {compact:?}"
+                ));
+            }
+            if expression == "gl_Color" {
+                for (corner, want) in ao.iter().enumerate() {
+                    let got = compact[corner][3];
+                    if (got - *want as f32 / 255.0).abs() > 1e-6 {
+                        failures.push(format!("corner {corner}'s alpha {got} != {want}/255"));
+                    }
+                }
+            }
+        }
+    }
+    // A pack's frames keep the translucent quads in the section arena after the solid range: three
+    // records and no `FULL` quad, then a water quad, whose corners must read as its own.
+    let mut page: Vec<[u32; 6]> = packed::layout(&solid[..12], &[tint; 3]);
+    let water: Vec<_> = face(9.0, 15.0).collect();
+    let at = page.len() as u32;
+    page.extend(water.iter().map(|v| bytemuck::cast::<_, [u32; 6]>(*v)));
+    for expression in ["vec4(gl_Normal, 0.0)", "at_tangent", "at_midBlock"] {
+        let flags = [true, false];
+        let wide = sample_probe(&device, &queue, &atlas, &water, origin, flags, expression);
+        let page = bytemuck::cast_slice(&page);
+        let after = sample_page(
+            &device,
+            &queue,
+            &atlas,
+            page,
+            at..at + 4,
+            origin,
+            flags,
+            expression,
+        );
+        if wide != after {
+            failures.push(format!("water {expression}: {wide:?} != {after:?}"));
+        }
+    }
+    assert!(failures.is_empty(), "{}", failures.join("\n"));
+}
+
 fn sample(
     device: &wgpu::Device,
     queue: &wgpu::Queue,
@@ -271,18 +400,38 @@ fn sample_probe(
     atlas: &PackAtlas,
     vertices: &[TerrainVertex],
     scale: f32,
+    flags: [bool; 2],
+    expression: &str,
+) -> Vec<[f32; 4]> {
+    let page = bytemuck::cast_slice(vertices);
+    let drawn = 0..vertices.len() as u32;
+    sample_page(device, queue, atlas, page, drawn, scale, flags, expression)
+}
+
+/// `sample_probe` of the vertex indices `drawn` of an arena page holding `page`.
+#[allow(clippy::too_many_arguments)]
+fn sample_page(
+    device: &wgpu::Device,
+    queue: &wgpu::Queue,
+    atlas: &PackAtlas,
+    page: &[u8],
+    drawn: std::ops::Range<u32>,
+    scale: f32,
     [flat, shadow]: [bool; 2],
     expression: &str,
 ) -> Vec<[f32; 4]> {
+    let count = drawn.len() as u32;
     let pp = |code| horizon_shaders::Preprocessed {
         code,
         ..Default::default()
     };
     let vertex = pp(format!(
-        "attribute vec2 mc_midTexCoord;\nvarying vec4 probe;\nvoid main() {{\n\
+        "attribute vec2 mc_midTexCoord;\nattribute vec4 at_tangent;\n\
+         attribute vec4 at_midBlock;\nattribute vec4 mc_Entity;\nvarying vec4 probe;\nvoid main() {{\n\
          probe = {expression};\n\
-         gl_Position = vec4((float(gl_VertexID) + 0.5) * {} - 1.0, 0.0, 0.0, 1.0);\n}}",
-        2. / vertices.len() as f32,
+         gl_Position = vec4((float(gl_VertexID - {}) + 0.5) * {} - 1.0, 0.0, 0.0, 1.0);\n}}",
+        drawn.start,
+        2. / count as f32,
     ));
     // Integer attachments retain the float bits without requiring float-render-target
     // capabilities on the adapter that the test runner picks.
@@ -369,7 +518,8 @@ fn sample_probe(
             module: &vs,
             entry_point: Some("main"),
             compilation_options: Default::default(),
-            buffers: &vertex_layouts[..if flat { 1 } else { 2 }],
+            // Flat draws pull their vertices from the page (`PULL_FLAT`), as in the game.
+            buffers: if flat { &[] } else { &vertex_layouts[..] },
         },
         primitive: wgpu::PrimitiveState {
             topology: wgpu::PrimitiveTopology::PointList,
@@ -408,7 +558,7 @@ fn sample_probe(
     );
     let ids = buffer(bytemuck::bytes_of(&[0u32; 2]), wgpu::BufferUsages::STORAGE);
     let data = buffer(
-        bytemuck::cast_slice(vertices),
+        page,
         wgpu::BufferUsages::STORAGE | wgpu::BufferUsages::VERTEX,
     );
     let rects = buffer(
@@ -444,7 +594,7 @@ fn sample_probe(
     let output = device.create_texture(&wgpu::TextureDescriptor {
         label: None,
         size: wgpu::Extent3d {
-            width: vertices.len() as u32,
+            width: count,
             height: 1,
             depth_or_array_layers: 1,
         },
@@ -457,7 +607,7 @@ fn sample_probe(
     });
     let read = device.create_buffer(&wgpu::BufferDescriptor {
         label: None,
-        size: vertices.len() as u64 * 16,
+        size: u64::from(count) * 16,
         usage: wgpu::BufferUsages::MAP_READ | wgpu::BufferUsages::COPY_DST,
         mapped_at_creation: false,
     });
@@ -481,11 +631,11 @@ fn sample_probe(
         for (k, group) in groups.iter().enumerate() {
             pass.set_bind_group(k as u32, group, &[]);
         }
-        pass.set_vertex_buffer(0, data.slice(..));
         if !flat {
+            pass.set_vertex_buffer(0, data.slice(..));
             pass.set_vertex_buffer(1, origin.slice(..));
         }
-        pass.draw(0..vertices.len() as u32, 0..1);
+        pass.draw(drawn, 0..1);
     }
     encoder.copy_texture_to_buffer(
         output.as_image_copy(),

crates/horizon-client-render/src/gfx/pack_uniforms.rs

@@ -1137,6 +1137,10 @@ fn components(name: &str) -> usize {
         | "endFlashPosition" => 3,
         "eyeBrightness" | "eyeBrightnessSmooth" | "atlasSize" => 2,
         "entityColor" => 4,
+        // Horizon's own vec4s, a dynamic light and half a boat's water patch box; their counts
+        // are ints.
+        n if n.starts_with("horizonDynamicLight") && n != "horizonDynamicLightCount" => 4,
+        n if n.starts_with("horizonWaterPatch") && n != "horizonWaterPatchCount" => 4,
         n if n.starts_with("gbuffer") || n.starts_with("shadow") && n != "shadowAngle" => 16,
         _ => 1,
     }
@@ -1208,6 +1212,28 @@ mod tests {
             (&matrix, "gbufferModelView", "mat4", true),
             (&matrix, "gbufferModelView", "mat3", false),
             (&Value::i(&[1]), GBUFFERS_FOG_MODE, "int", true),
+            // Horizon's own: a dynamic light and a water patch box half are vec4s, their counts
+            // ints.
+            (
+                &Value::f(&[1.0, 64.0, 2.0, 14.0]),
+                "horizonDynamicLight0",
+                "vec4",
+                true,
+            ),
+            (
+                &Value::f(&[1.0, 64.0, 2.0, 14.0]),
+                "horizonDynamicLight0",
+                "float",
+                false,
+            ),
+            (
+                &Value::f(&[0.5, -1.0, 62.0, 62.5]),
+                "horizonWaterPatch0",
+                "vec4",
+                true,
+            ),
+            (&Value::i(&[3]), "horizonDynamicLightCount", "int", true),
+            (&Value::i(&[1]), "horizonWaterPatchCount", "int", true),
         ] {
             assert_eq!(value.read_as(name, ty), kept, "{ty} {name}");
         }

crates/horizon-client-render/src/gfx/screenshot_save.rs

@@ -0,0 +1,321 @@
+//! Writing a screenshot's PNG once its frame is read back: on the render thread for the
+//! requests that want the result with the frame (an agent's, a `screenshot-sequence`'s),
+//! on a thread of its own for F2's and the world icon's (`ScreenshotRequest::background`).
+//! The render thread then neither waits for the GPU to finish the frame nor encodes the
+//! PNG, which at 4K or a Screenshot Quality above 1x froze the game for a second or more.
+use super::{ScreenshotRequest, hdr_icc, hdr10_to_rgb16, padded_row, square_downscale};
+use std::path::PathBuf;
+use std::sync::mpsc::{Receiver, Sender, channel};
+use std::time::Duration;
+
+/// What a frame's readback holds and where its PNG goes.
+pub(super) struct Shot {
+    pub path: PathBuf,
+    /// `ScreenshotRequest::size`: the world icon's square.
+    pub size: Option<[u32; 2]>,
+    /// The frame's size, which the readback's rows hold (padded to `padded_row`).
+    pub frame: [u32; 2],
+    /// Blue first (`Bgra8Unorm`), swapped to PNG's red first.
+    pub bgra: bool,
+    /// The HDR10 copy's readback and its PNG's path, beside the SDR one.
+    pub hdr: Option<(PathBuf, wgpu::Buffer)>,
+}
+impl Shot {
+    pub fn new(
+        request: &ScreenshotRequest,
+        frame: [u32; 2],
+        format: wgpu::TextureFormat,
+        hdr: Option<(PathBuf, wgpu::Buffer)>,
+    ) -> Self {
+        Self {
+            path: request.path.clone(),
+            size: request.size,
+            frame,
+            bgra: format.remove_srgb_suffix() == wgpu::TextureFormat::Bgra8Unorm,
+            hdr,
+        }
+    }
+}
+/// A written screenshot: its path, its size or the error, and the HDR copy written beside it.
+pub struct Saved {
+    pub path: PathBuf,
+    pub result: Result<[u32; 2], String>,
+    pub hdr: Option<PathBuf>,
+}
+/// Waits for `buffer`'s mapping on the render thread and writes the PNG there.
+pub(super) fn save_now(device: &wgpu::Device, shot: Shot, buffer: &wgpu::Buffer) -> Saved {
+    let (sender, receiver) = channel();
+    map(buffer, &sender);
+    if let Some((_, hdr)) = &shot.hdr {
+        map(hdr, &sender);
+    }
+    let waited = device
+        .poll(wgpu::PollType::wait_indefinitely())
+        .map_err(|e| e.to_string());
+    let count = 1 + usize::from(shot.hdr.is_some());
+    let mapped = waited.and_then(|_| wait_mapped(&receiver, count));
+    write(shot, buffer, mapped)
+}
+/// Screenshots being written on their thread.
+pub(super) struct Saves {
+    device: wgpu::Device,
+    sender: Sender<Saved>,
+    receiver: Receiver<Saved>,
+    in_flight: usize,
+}
+impl Saves {
+    pub fn new(device: &wgpu::Device) -> Self {
+        let (sender, receiver) = channel();
+        Self {
+            device: device.clone(),
+            sender,
+            receiver,
+            in_flight: 0,
+        }
+    }
+    /// Maps `buffer` (and the HDR copy's), whose copy was just submitted, and writes the
+    /// PNG on a thread of its own once the GPU has finished the frame.
+    pub fn start(&mut self, shot: Shot, buffer: wgpu::Buffer) {
+        let (mapped, on_mapped) = channel();
+        map(&buffer, &mapped);
+        if let Some((_, hdr)) = &shot.hdr {
+            map(hdr, &mapped);
+        }
+        let done = self.sender.clone();
+        let path = shot.path.clone();
+        let spawned = std::thread::Builder::new()
+            .name("Screenshot writer".into())
+            .spawn(move || {
+                let count = 1 + usize::from(shot.hdr.is_some());
+                let ready = wait_mapped(&on_mapped, count);
+                let _ = done.send(write(shot, &buffer, ready));
+            });
+        match spawned {
+            Ok(_) => {}
+            Err(e) => {
+                let _ = self.sender.send(Saved {
+                    path,
+                    result: Err(format!("no thread to write it: {e}")),
+                    hdr: None,
+                });
+            }
+        }
+        self.in_flight += 1;
+    }
+    /// The screenshots written since the last call. Polls the device so a finished frame's
+    /// mapping reaches its writer: the render thread never waits for it.
+    pub fn finished(&mut self) -> Vec<Saved> {
+        if self.in_flight == 0 {
+            return Vec::new();
+        }
+        let _ = self.device.poll(wgpu::PollType::Poll);
+        let saved: Vec<Saved> = self.receiver.try_iter().collect();
+        self.in_flight -= saved.len();
+        saved
+    }
+}
+impl Drop for Saves {
+    /// A screenshot taken right before quitting is still written whole.
+    fn drop(&mut self) {
+        let deadline = std::time::Instant::now() + Duration::from_secs(10);
+        while self.in_flight > 0 && std::time::Instant::now() < deadline {
+            let _ = self.device.poll(wgpu::PollType::Poll);
+            if let Ok(saved) = self.receiver.recv_timeout(Duration::from_millis(20)) {
+                log_saved(&saved);
+                self.in_flight -= 1;
+            }
+        }
+    }
+}
+fn log_saved(saved: &Saved) {
+    match &saved.result {
+        Ok(_) => log::info!("Saved screenshot to {}", saved.path.display()),
+        Err(e) => log::warn!("Horizon renderer: screenshot {}: {e}", saved.path.display()),
+    }
+}
+fn map(buffer: &wgpu::Buffer, mapped: &Sender<Result<(), String>>) {
+    let mapped = mapped.clone();
+    buffer.map_async(wgpu::MapMode::Read, .., move |r| {
+        let _ = mapped.send(r.map_err(|e| e.to_string()));
+    });
+}
+/// `count` mappings done, or the first one that failed. A frame the GPU never finishes
+/// (a lost device) gives up after a while instead of keeping its thread.
+fn wait_mapped(mapped: &Receiver<Result<(), String>>, count: usize) -> Result<(), String> {
+    for _ in 0..count {
+        mapped
+            .recv_timeout(Duration::from_secs(30))
+            .map_err(|_| "the frame never came back from the GPU".to_string())??;
+    }
+    Ok(())
+}
+/// The PNG (and the HDR copy's beside it) from the mapped readbacks.
+fn write(shot: Shot, buffer: &wgpu::Buffer, mapped: Result<(), String>) -> Saved {
+    let mut hdr_written = None;
+    let result = mapped.and_then(|()| {
+        if let Some((hdr_path, hdr_buffer)) = &shot.hdr {
+            let pixels = read_rows(hdr_buffer, shot.frame);
+            match pixels.and_then(|p| write_hdr_png(hdr_path, shot.frame, &p)) {
+                Ok(()) => {
+                    log::info!("Saved HDR screenshot to {}", hdr_path.display());
+                    hdr_written = Some(hdr_path.clone());
+                }
+                Err(e) => log::warn!(
+                    "Horizon renderer: HDR screenshot {}: {e}",
+                    hdr_path.display()
+                ),
+            }
+        }
+        let pixels = read_rows(buffer, shot.frame)?;
+        write_png(&shot, &pixels)
+    });
+    Saved {
+        path: shot.path,
+        result,
+        hdr: hdr_written,
+    }
+}
+/// The pixels `copy_frame` read back into the mapped `buffer`, 4 bytes each, row after
+/// row; unmaps it.
+fn read_rows(buffer: &wgpu::Buffer, [width, height]: [u32; 2]) -> Result<Vec<[u8; 4]>, String> {
+    let (width, height, row) = (width as usize, height as usize, padded_row(width) as usize);
+    let mut pixels = Vec::with_capacity(width * height);
+    {
+        let data = buffer.get_mapped_range(..).map_err(|e| e.to_string())?;
+        for y in 0..height {
+            pixels.extend_from_slice(data[y * row..y * row + width * 4].as_chunks::<4>().0);
+        }
+    }
+    buffer.unmap();
+    Ok(pixels)
+}
+fn write_png(shot: &Shot, frame: &[[u8; 4]]) -> Result<[u32; 2], String> {
+    let [frame_w, frame_h] = shot.frame;
+    let mut pixels = Vec::with_capacity(frame.len() * 4);
+    for px in frame {
+        let (r, b) = if shot.bgra {
+            (px[2], px[0])
+        } else {
+            (px[0], px[2])
+        };
+        pixels.extend_from_slice(&[r, px[1], b, 255]);
+    }
+    // NativeImage.resizeSubRectTo on takeAutoScreenshot's grab: the icon
+    // is the frame's centre square averaged down to its size.
+    let (width, height, pixels) = match shot.size {
+        Some(size) => (
+            size[0],
+            size[1],
+            square_downscale(&pixels, frame_w, frame_h, size),
+        ),
+        None => (frame_w, frame_h, pixels),
+    };
+    let file = std::fs::File::create(&shot.path).map_err(|e| e.to_string())?;
+    let mut encoder = png::Encoder::new(std::io::BufWriter::new(file), width, height);
+    encoder.set_color(png::ColorType::Rgba);
+    encoder.set_depth(png::BitDepth::Eight);
+    encoder
+        .write_header()
+        .and_then(|mut w| w.write_image_data(&pixels))
+        .map_err(|e| e.to_string())?;
+    Ok([width, height])
+}
+/// The HDR10 copy (`Hdr::capture`) as a 16-bit PNG tagged BT.2020 with PQ (cICP, PNG's
+/// third edition), with the content light levels its pixels hold (cLLI), and
+/// an ICC profile for the programs that don't read cICP (`hdr_icc`).
+fn write_hdr_png(
+    path: &std::path::Path,
+    [width, height]: [u32; 2],
+    frame: &[[u8; 4]],
+) -> Result<(), String> {
+    let pixels = hdr10_to_rgb16(frame);
+    let mut info = png::Info::with_size(width, height);
+    info.color_type = png::ColorType::Rgb;
+    info.bit_depth = png::BitDepth::Sixteen;
+    info.icc_profile = Some(hdr_icc::profile().into());
+    let file = std::fs::File::create(path).map_err(|e| e.to_string())?;
+    let written = png::Encoder::with_info(std::io::BufWriter::new(file), info)
+        .and_then(|encoder| encoder.write_header())
+        .and_then(|mut writer| {
+            // BT.2020 primaries, PQ, RGB, full range.
+            writer.write_chunk(png::chunk::cICP, &[9, 16, 0, 1])?;
+            writer.write_chunk(png::chunk::cLLI, &hdr_icc::content_light_levels(&pixels))?;
+            writer.write_image_data(&pixels)
+        });
+    written.map_err(|e| e.to_string())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn a_background_save_writes_the_png_off_the_render_thread() {
+        let instance = crate::gfx::test_gpu::instance();
+        let Ok(adapter) = pollster::block_on(instance.request_adapter(&Default::default())) else {
+            return;
+        };
+        let Ok((device, queue)) = pollster::block_on(adapter.request_device(&Default::default()))
+        else {
+            return;
+        };
+        let dir = std::env::temp_dir().join(format!("horizon-shot-{}", std::process::id()));
+        std::fs::create_dir_all(&dir).unwrap();
+        let path = dir.join("shot.png");
+        let [w, h] = [3u32, 2];
+        // A frame of blue-first pixels, each row padded as `copy_frame` reads them back.
+        let row = padded_row(w) as usize;
+        let mut bytes = vec![0u8; row * h as usize];
+        for y in 0..h as usize {
+            for x in 0..w as usize {
+                bytes[y * row + x * 4..][..4].copy_from_slice(&[10 * x as u8, 20, 200, 0]);
+            }
+        }
+        let source = wgpu::util::DeviceExt::create_buffer_init(
+            &device,
+            &wgpu::util::BufferInitDescriptor {
+                label: None,
+                contents: &bytes,
+                usage: wgpu::BufferUsages::COPY_SRC,
+            },
+        );
+        let buffer = device.create_buffer(&wgpu::BufferDescriptor {
+            label: None,
+            size: bytes.len() as u64,
+            usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ,
+            mapped_at_creation: false,
+        });
+        let mut encoder = device.create_command_encoder(&Default::default());
+        encoder.copy_buffer_to_buffer(&source, 0, &buffer, 0, bytes.len() as u64);
+        queue.submit([encoder.finish()]);
+        let request = ScreenshotRequest {
+            path: path.clone(),
+            size: None,
+            scaled: false,
+            background: true,
+        };
+        let mut saves = Saves::new(&device);
+        saves.start(
+            Shot::new(&request, [w, h], wgpu::TextureFormat::Bgra8Unorm, None),
+            buffer,
+        );
+        let deadline = std::time::Instant::now() + Duration::from_secs(10);
+        let saved = loop {
+            if let Some(saved) = saves.finished().pop() {
+                break saved;
+            }
+            assert!(std::time::Instant::now() < deadline, "never written");
+            std::thread::sleep(Duration::from_millis(5));
+        };
+        assert_eq!(saved.path, path);
+        assert_eq!(saved.result, Ok([w, h]));
+        let decoder =
+            png::Decoder::new(std::io::BufReader::new(std::fs::File::open(&path).unwrap()));
+        let mut reader = decoder.read_info().unwrap();
+        let mut out = vec![0; reader.output_buffer_size().unwrap()];
+        reader.next_frame(&mut out).unwrap();
+        // Red first, opaque: the last pixel of the first row was [20, 20, 200] blue-first.
+        assert_eq!(&out[8..12], &[200, 20, 20, 255]);
+        std::fs::remove_dir_all(&dir).unwrap();
+    }
+}

crates/horizon-client-render/src/gfx/section_fade.rs

@@ -0,0 +1,60 @@
+//! How far through vanilla's chunk fade-in a section is, and the instance that carries it to `terrain.wgsl`.
+use crate::fast_hash::FxHashMap;
+use std::time::Instant;
+
+/// A section's instance: its camera-relative origin and its UV step, negated
+/// past its fade code while it fades in over far terrain (`lod::instance`).
+pub(super) fn section_instance(origin: [f32; 3], fade: u32, visibility: f32) -> [f32; 4] {
+    let step = 1.0 / crate::mesher::UV_STEPS;
+    [
+        origin[0],
+        origin[1],
+        origin[2],
+        if fade == 0 {
+            // The step is a power of two, so its mantissa is free: it holds the vanilla
+            // chunk fade-in's `1 - visibility` in 23 bits (terrain.wgsl's `instance_step` and
+            // `instance_visibility` read it back). A whole section is the bare step.
+            let faded = ((1.0 - visibility) * 8_388_608.0)
+                .round()
+                .clamp(0.0, 8_388_607.0) as u32;
+            f32::from_bits(step.to_bits() | faded)
+        } else {
+            -(fade as f32 + step)
+        },
+    ]
+}
+/// `SectionRenderDispatcher.RenderSection.getVisibility`: how far through its fade-in a section
+/// uploaded `elapsed_ms` ago is.
+pub(super) fn chunk_visibility(elapsed_ms: u64, fade_ms: u64) -> f32 {
+    if elapsed_ms >= fade_ms {
+        1.0
+    } else {
+        elapsed_ms as f32 / fade_ms as f32
+    }
+}
+/// `Util.toMillis`: `Mth.floor(seconds * 1000.0)`.
+pub(super) fn fade_millis(seconds: f32) -> u64 {
+    (f64::from(seconds) * 1000.0).floor().max(0.0) as u64
+}
+/// `chunk_visibility` at `now` of a section first uploaded at `uploaded`
+/// (`Renderer::section_uploaded`; none: one that fades in over far terrain, or
+/// whose column left), with the chunk fade-in `fade_ms`.
+pub(super) fn section_visibility(uploaded: Option<&Instant>, fade_ms: u64, now: Instant) -> f32 {
+    uploaded.map_or(1.0, |&t| {
+        let elapsed = now.saturating_duration_since(t).as_millis() as u64;
+        chunk_visibility(elapsed, fade_ms)
+    })
+}
+/// What a section's fade depends on besides the section itself
+/// (`SectionGpu::drawn_faded`): the time, the chunk fade-in time, the sections'
+/// first uploads (`Renderer::section_uploaded`) and those held while far
+/// terrain comes in (`Renderer::lod_retiring`).
+#[derive(Clone, Copy)]
+pub(super) struct FadeInputs<'a> {
+    pub(super) now: Instant,
+    pub(super) fade_ms: u64,
+    pub(super) uploaded: &'a FxHashMap<super::SectionKey, Instant>,
+    pub(super) retiring: &'a crate::fast_hash::FxHashSet<super::SectionKey>,
+}
+/// `LevelRenderer.CHUNK_VISIBILITY_THRESHOLD`: a section's block entities wait for it.
+pub(super) const CHUNK_VISIBILITY_THRESHOLD: f32 = 0.3;

crates/horizon-client-render/src/graphics.rs

@@ -30,8 +30,9 @@ fn marker_driver(text: &str) -> &str {
 pub struct Reported {
     pub paper_white: u32,
     pub peak: u32,
-    /// The peak is the display's own claim (DXGI's `MaxLuminance`, mostly its EDID figure),
-    /// which often runs high: Auto still uses it, but the HDR page asks to calibrate.
+    /// The peak is the system's own figure (DXGI's `MaxLuminance`): the display's, or a
+    /// calibration profile's (Windows HDR Calibration), which Horizon can't tell apart. Auto
+    /// uses it, and the HDR page offers calibration.
     pub peak_guessed: bool,
 }
 
@@ -40,7 +41,7 @@ pub struct Reported {
 pub enum HdrSetup {
     /// The system says nothing: the player calibrates.
     Unknown,
-    /// The system says, but only guesses the peak: the player calibrates.
+    /// The system says, but not where its peak comes from: the page offers calibration.
     Guessed,
     /// Peak Brightness and Paper White follow the system.
     Automatic,
@@ -1355,7 +1356,7 @@ mod tests {
     }
 
     #[test]
-    fn hdr_setup_asks_to_calibrate_where_the_peak_is_guessed() {
+    fn hdr_setup_offers_calibration_where_the_peaks_source_is_unknown() {
         let wayland = Reported {
             paper_white: 203,
             peak: 1015,
@@ -1370,7 +1371,7 @@ mod tests {
         assert_eq!(g.hdr_setup(None), HdrSetup::Unknown);
         assert_eq!(g.hdr_setup(Some(wayland)), HdrSetup::Automatic);
         assert_eq!(g.hdr_setup(Some(windows)), HdrSetup::Guessed);
-        // Auto still takes the guess, over the 1000-nit default.
+        // Auto still takes the reported peak, over the 1000-nit default.
         assert_eq!(g.peak_nits(Some(windows)), 1000);
         assert_eq!(g.paper_white_nits(Some(windows)), 400);
         for (peak, paper_white) in [(800, 0), (0, 240)] {

crates/horizon-client-render/src/graphics_style.rs

@@ -2,16 +2,21 @@
 //! colours and the controls it draws with. The screen (`graphics_ui`) only
 //! lays out rows and handles input; a menu theme replaces this module.
 //!
-//! It takes the design system's Blocks palette (`horizon_theme::BLOCKS_DARK`,
-//! `docs/design-system.md`) in a lighter form: square panels of dark glass
-//! with a thin edge, so the world shows through, flat controls, and the violet
-//! face on the one main button, in vanilla's font.
+//! Its colours come from `menu_style`, given at startup (in the official game the design
+//! system's Blocks palette, `docs/design-system.md`), in a lighter form: square panels of
+//! dark glass with a thin edge, so the world shows through, flat controls, and the face on
+//! the one main button, in vanilla's font.
+use crate::menu_style::{self, SettingsColours};
 use crate::{
     hud::{HudAtlas, HudBatch},
     text::Text,
     ui,
 };
-use horizon_theme::BLOCKS_DARK as B;
+
+/// The settings pages' colours (`menu_style`, given at startup).
+fn b() -> &'static SettingsColours {
+    &menu_style::get().settings
+}
 
 /// What a setting costs in frame time, shown with its description.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -36,54 +41,91 @@ impl Cost {
     /// `0xRRGGBB`: the palette's success, warn and danger.
     pub fn rgb(self) -> u32 {
         match self {
-            Cost::None => B.ink_soft,
-            Cost::Low | Cost::Saves => B.success,
-            Cost::Medium => B.warn,
-            Cost::High => B.danger,
+            Cost::None => b().ink_soft,
+            Cost::Low | Cost::Saves => b().success,
+            Cost::Medium => b().warn,
+            Cost::High => b().danger,
         }
     }
 }
 
-/// `0xRRGGBB` and an alpha in the HUD's colour encoding.
-const fn hex(c: u32, a: u8) -> u32 {
-    (a as u32) << 24 | (c & 0xff) << 16 | (c >> 8 & 0xff) << 8 | (c >> 16 & 0xff)
-}
+use menu_style::hud_colour as hex;
 /// The plate and the strip: the page's dark, see-through, so the world shows behind them.
-const GLASS: u32 = hex(B.page, 118);
+fn glass() -> u32 {
+    hex(b().page, 118)
+}
 /// Their 1 px edge.
-const EDGE: u32 = hex(B.ink, 26);
+pub fn edge() -> u32 {
+    hex(b().ink, 26)
+}
 /// A group's panel, a little lighter than the plate it sits on.
-const GROUP: u32 = hex(B.ink, 11);
+fn group_fill() -> u32 {
+    hex(b().ink, 11)
+}
 /// A hovered or focused row, lit on its group's panel.
-pub const HOVER: u32 = hex(B.ink, 18);
+pub fn hover() -> u32 {
+    hex(b().ink, 18)
+}
 /// The open page in the page list.
-pub const OPEN: u32 = hex(B.ink, 26);
+pub fn open() -> u32 {
+    hex(b().ink, 26)
+}
 /// The rule under the plate's heading, and between two rows of a group.
-pub const HEAD_RULE: u32 = hex(B.ink, 31);
-pub const ROW_RULE: u32 = hex(B.ink, 15);
+pub fn head_rule() -> u32 {
+    hex(b().ink, 31)
+}
+pub fn row_rule() -> u32 {
+    hex(b().ink, 15)
+}
 /// Fields, boxes and the value stepper: sunk, see-through.
-const WELL: u32 = hex(B.outline, 102);
+fn well_fill() -> u32 {
+    hex(b().outline, 102)
+}
 /// A button, a slider's track, the scroller's thumb.
-const BUTTON: u32 = hex(B.ink, 20);
-const BUTTON_HOVER: u32 = hex(B.ink, 41);
-const TRACK: u32 = hex(B.ink, 64);
-const HANDLE: u32 = hex(B.ink, 255);
+fn button_fill() -> u32 {
+    hex(b().ink, 20)
+}
+fn button_hover() -> u32 {
+    hex(b().ink, 41)
+}
+fn track_fill() -> u32 {
+    hex(b().ink, 64)
+}
+fn handle_fill() -> u32 {
+    hex(b().ink, 255)
+}
 /// The one main button.
-const FACE: u32 = hex(B.face, 255);
-const FACE_HOVER: u32 = hex(0x6a50e6, 255);
+pub fn face() -> u32 {
+    hex(b().face, 255)
+}
+fn face_hover() -> u32 {
+    hex(b().face_hover, 255)
+}
 /// A tick box's edge when off.
-const BOX_EDGE: u32 = hex(B.ink_soft, 89);
-const OUTLINE: u32 = hex(B.outline, 255);
-pub const ACCENT: u32 = hex(B.accent, 255);
+fn box_edge() -> u32 {
+    hex(b().ink_soft, 89)
+}
+fn outline() -> u32 {
+    hex(b().outline, 255)
+}
+pub fn accent() -> u32 {
+    hex(b().accent, 255)
+}
 /// Vanilla's white text, and its grey for what can't be used now.
 pub const WHITE: u32 = u32::MAX;
-pub const MUTED: u32 = hex(B.muted, 255);
+pub fn muted() -> u32 {
+    hex(b().muted, 255)
+}
 /// A page that isn't open, a value at rest.
-pub const SOFT: u32 = hex(B.ink_soft, 255);
+pub fn soft() -> u32 {
+    hex(b().ink_soft, 255)
+}
 /// Vanilla's grey for a tooltip's lines under its first (`ChatFormatting.GRAY`).
 pub const GREY: u32 = hex(0xaaaaaa, 255);
 /// A light veil over the backdrop, under the panels.
-pub const VEIL: u32 = hex(B.page, 77);
+pub fn veil() -> u32 {
+    hex(b().page, 77)
+}
 
 /// Sizes in GUI pixels.
 /// Shorter screens than this (a 720p window at scale 3) keep a narrower margin on top.
@@ -120,21 +162,21 @@ pub fn ring(batch: &mut HudBatch, atlas: &HudAtlas, [x, y, w, h]: [f32; 4], colo
 }
 /// The screen's plate, and the strip under it: dark glass with a thin edge.
 pub fn panel(batch: &mut HudBatch, atlas: &HudAtlas, rect: [f32; 4]) {
-    fill(batch, atlas, rect, GLASS);
-    ring(batch, atlas, rect, EDGE);
+    fill(batch, atlas, rect, glass());
+    ring(batch, atlas, rect, edge());
 }
 /// A group's panel on the plate, its rows on it.
 pub fn group(batch: &mut HudBatch, atlas: &HudAtlas, rect: [f32; 4]) {
-    fill(batch, atlas, rect, GROUP);
+    fill(batch, atlas, rect, group_fill());
 }
 /// A sunk well: the search field, the value stepper.
 pub fn well(batch: &mut HudBatch, atlas: &HudAtlas, rect: [f32; 4]) {
-    fill(batch, atlas, rect, WELL);
+    fill(batch, atlas, rect, well_fill());
 }
 /// The scroller: a faint track and its thumb.
 pub fn scroller(batch: &mut HudBatch, atlas: &HudAtlas, track: [f32; 4], thumb: [f32; 4]) {
-    fill(batch, atlas, track, ROW_RULE);
-    fill(batch, atlas, thumb, TRACK);
+    fill(batch, atlas, track, row_rule());
+    fill(batch, atlas, thumb, track_fill());
 }
 /// `text` cut to `width` with an ellipsis, as a long name gives way to its control: the HUD
 /// kit's `fit::ellipsize`.
@@ -142,11 +184,11 @@ pub use crate::hud_kit::fit::ellipsize as fit;
 /// A 12 px tick box ending at `right`, centred in the row at `y`: its edge in the accent when on.
 pub fn checkbox(batch: &mut HudBatch, atlas: &HudAtlas, right: f32, y: f32, on: bool, live: bool) {
     let rect = [right - 12.0, y + 4.0, 12.0, 12.0];
-    fill(batch, atlas, rect, WELL);
+    fill(batch, atlas, rect, well_fill());
     let edge = match (on, live) {
-        (true, true) => ACCENT,
-        (true, false) => MUTED,
-        (false, _) => BOX_EDGE,
+        (true, true) => accent(),
+        (true, false) => muted(),
+        (false, _) => box_edge(),
     };
     ring(batch, atlas, rect, edge);
     if on {
@@ -169,7 +211,7 @@ fn tick(batch: &mut HudBatch, atlas: &HudAtlas, x: f32, y: f32, color: u32) {
         for (i, c) in row.chars().enumerate() {
             if c == '#' {
                 let (px, py) = (x + i as f32, y + j as f32);
-                fill(batch, atlas, [px + 1.0, py + 1.0, 1.0, 1.0], OUTLINE);
+                fill(batch, atlas, [px + 1.0, py + 1.0, 1.0, 1.0], outline());
                 fill(batch, atlas, [px, py, 1.0, 1.0], color);
             }
         }
@@ -198,17 +240,17 @@ pub fn button_with_room(
 ) {
     let [x, y, w, h] = rect;
     let face = match (live, primary, hover) {
-        (false, _, _) => WELL,
-        (true, true, false) => FACE,
-        (true, true, true) => FACE_HOVER,
-        (true, false, false) => BUTTON,
-        (true, false, true) => BUTTON_HOVER,
+        (false, _, _) => well_fill(),
+        (true, true, false) => face(),
+        (true, true, true) => face_hover(),
+        (true, false, false) => button_fill(),
+        (true, false, true) => button_hover(),
     };
     fill(batch, atlas, rect, face);
     if hover && live {
         ring(batch, atlas, rect, WHITE);
     }
-    let color = if live { WHITE } else { MUTED };
+    let color = if live { WHITE } else { muted() };
     let ty = y + ((h - 8.0) / 2.0).floor();
     let left = x + 2.0 + room;
     scrolling_label(
@@ -252,7 +294,7 @@ pub fn slider(
     (hover, live): (bool, bool),
 ) {
     let [x, y, w, h] = rect;
-    let color = if live { WHITE } else { MUTED };
+    let color = if live { WHITE } else { muted() };
     scrolling_label(
         batch,
         atlas,
@@ -263,17 +305,22 @@ pub fn slider(
     );
     let line = y + h - 3.0;
     let at = x + (position.clamp(0.0, 1.0) * (w - 4.0)).round();
-    fill(batch, atlas, [x, line, w, 2.0], TRACK);
+    fill(batch, atlas, [x, line, w, 2.0], track_fill());
     fill(
         batch,
         atlas,
         [x, line, at - x, 2.0],
-        if live { ACCENT } else { MUTED },
+        if live { accent() } else { muted() },
     );
     let handle = [at, line - 3.0, 4.0, 8.0];
-    fill(batch, atlas, handle, if live { HANDLE } else { MUTED });
+    fill(
+        batch,
+        atlas,
+        handle,
+        if live { handle_fill() } else { muted() },
+    );
     if hover && live {
-        ring(batch, atlas, [at - 1.0, line - 4.0, 6.0, 10.0], ACCENT);
+        ring(batch, atlas, [at - 1.0, line - 4.0, 6.0, 10.0], accent());
     }
 }
 /// A value that a press steps through: in a well, between the arrows that say so.
@@ -290,13 +337,13 @@ pub fn cycler(
         ring(batch, atlas, rect, WHITE);
     }
     let ty = y + ((h - 8.0) / 2.0).floor();
-    let arrows = if hover && live { WHITE } else { MUTED };
+    let arrows = if hover && live { WHITE } else { muted() };
     batch.text_styled(atlas, &Text::literal("<"), x + 3.0, ty, arrows, true);
     batch.text_styled(atlas, &Text::literal(">"), x + w - 8.0, ty, arrows, true);
     let color = match (live, hover) {
-        (false, _) => MUTED,
+        (false, _) => muted(),
         (true, true) => WHITE,
-        (true, false) => SOFT,
+        (true, false) => soft(),
     };
     scrolling_label(batch, atlas, value, [x + 9.0, ty, w - 18.0], (y, h), color);
 }

crates/horizon-client-render/src/graphics_ui.rs

@@ -697,7 +697,7 @@ fn description(
             "Your display didn't say how bright it gets: calibrate to set it up."
         }
         (Item::Horizon(H::HdrCalibrate), Setup::Guessed) => {
-            "Your display's reported peak is often too high: calibrate to set it up."
+            "Auto uses the peak Windows reports. Calibrate if highlights look clipped."
         }
         (Item::Horizon(H::HdrCalibrate), Setup::Automatic) => {
             "Already set up for your display. Only calibrate if HDR looks wrong."
@@ -705,7 +705,7 @@ fn description(
         (Item::Horizon(H::HdrCalibrate), Setup::Changed) => {
             "Puts Peak Brightness and Paper White back to your display's setup."
         }
-        // A guessed peak's Auto is what calibration replaced; paper white is the player's own.
+        // A peak of unknown source isn't said to be set up; paper white is the player's own.
         (Item::Horizon(h @ (H::HdrPeak | H::HdrPaperWhite)), Setup::Automatic | Setup::Changed)
             if h == H::HdrPaperWhite || out.reported.is_some_and(|r| !r.peak_guessed) =>
         {
@@ -1110,7 +1110,8 @@ impl Item {
     /// active; saved values wait for it. Translucent Batching switches where the device can batch
     /// (`graphics::translucent_batching_offered`), its saved value waiting for one that can,
     /// Smooth Gradients only where it can draw the 16-bit frame, the same way, and GPU Culling
-    /// only where it is offered (`graphics::gpu_culling_offer`), with the reason it isn't.
+    /// only where it is offered (`graphics::gpu_culling_offer`), with the reason it isn't. HDR
+    /// Lighting has nothing to switch where the running shader pack lights the world itself.
     fn blocked(self, s: &Settings, out: &EffectiveOutput) -> Option<&'static str> {
         if !self.available() {
             return Some("This feature is not yet available in Horizon.");
@@ -1141,6 +1142,9 @@ impl Item {
             } else {
                 "Turn HDR on to use it."
             }),
+            Item::Horizon(H::HdrLighting) if out.pack_lights => {
+                Some("The shader pack lights the world itself.")
+            }
             Item::Horizon(H::TranslucentBatching)
                 if !crate::graphics::translucent_batching_offered() =>
             {
@@ -1215,10 +1219,13 @@ impl Item {
     }
     pub fn label(self, s: &Settings, out: &EffectiveOutput) -> Text {
         match self {
-            Item::Vanilla(Opt::RenderDistance) if s.horizon.lod_distance > 0 => labelled(
-                "Full Detail Distance",
-                lang::tr("%s chunks", &[&s.render_distance]),
-            ),
+            // Far terrain renames the row; its value stays vanilla's `options.chunks`.
+            Item::Vanilla(Opt::RenderDistance) if s.horizon.lod_distance > 0 => {
+                Text::option_name_value(
+                    Text::literal(lang::get("Full Detail Distance")),
+                    Text::tr("options.chunks", &[&s.render_distance]),
+                )
+            }
             Item::Vanilla(o) => o.label(s),
             Item::Horizon(h) => h.label(s, out),
             Item::Extra(e) => Text::option_name_value(
@@ -1314,7 +1321,11 @@ impl Item {
 
 /// Whether a setting is on the screen now: Upscaling only while TAA is, which does it.
 fn shown(item: Item, s: &Settings) -> bool {
-    item != Item::Horizon(H::Upscaling) || s.horizon.taa
+    match item {
+        Item::Horizon(H::Upscaling) => s.horizon.taa,
+        Item::Extra(crate::extras::Item::Fullbright) => !s.fullbright_held,
+        _ => true,
+    }
 }
 /// A control's label as its name and its value ("Render Distance" and "12 chunks").
 fn parts(item: Item, s: &Settings, out: &EffectiveOutput) -> (String, Option<String>) {
@@ -1426,7 +1437,7 @@ impl Screen for GraphicsScreen {
             g::gpu_culling_offer(),
             g::reduced_far_detail_suggested(),
         );
-        shell::stamp_of(&(read(s), offers))
+        shell::stamp_of(&(read(s), s.fullbright_held, offers))
     }
     fn sheets(&self, s: &Settings) -> Vec<Sheet<Page, Item>> {
         let sheet = |(page, groups): (Page, Vec<(&'static str, Vec<Setting>)>)| Sheet {
@@ -1986,6 +1997,31 @@ mod tests {
         assert_eq!(key(&mut ui, &mut s, K::Escape), [Output::Done]);
     }
 
+    /// On another's server Fullbright's row is gone and the screen draws again; its choice is
+    /// kept for the next world that allows it (#3823).
+    #[test]
+    fn fullbright_row_is_hidden_while_held_and_keeps_its_choice() {
+        let mut s = Settings::default();
+        s.extras.fullbright = true;
+        let screen = GraphicsScreen::default();
+        let listed = |s: &Settings, item| {
+            let sheets = screen.sheets(s);
+            let groups = sheets.into_iter().flat_map(|sheet| sheet.groups);
+            groups.flat_map(|group| group.rows).any(|r| r.id == item)
+        };
+        let fullbright = Item::Extra(crate::extras::Item::Fullbright);
+        let lights = Item::Extra(crate::extras::Item::DynamicLights);
+        assert!(listed(&s, fullbright));
+        let free = screen.stamp(&s);
+        s.fullbright_held = true;
+        assert!(!listed(&s, fullbright));
+        assert!(listed(&s, lights));
+        assert_ne!(screen.stamp(&s), free);
+        assert!(s.extras.fullbright);
+        s.fullbright_held = false;
+        assert!(listed(&s, fullbright));
+    }
+
     /// The strip says what a row does, what its chosen value does where that differs, and why a
     /// greyed row can't be used; the search finds a row by what it does.
     #[test]
@@ -2106,10 +2142,36 @@ mod tests {
         assert_eq!(item.slider(&s), Some(13.0 / 23.0));
         s.horizon.lod_distance = 12;
         assert_eq!(item.slider(&s), Some(1.0 / 23.0));
-        assert_eq!(
-            Item::Vanilla(Opt::RenderDistance).label(&s, &NONE).plain(),
-            format!("Full Detail Distance: {near} chunks")
-        );
+    }
+
+    /// With far terrain on, Render Distance reads "Full Detail Distance" but keeps vanilla's
+    /// `options.chunks` value: it was Horizon's "%s chunks", so "12 Chunks" became "12 chunks"
+    /// (#14880).
+    #[test]
+    fn full_detail_distance_keeps_the_vanilla_chunk_count() {
+        struct Vanilla;
+        impl lang::ResourceSource for Vanilla {
+            fn read(&self, path: &str) -> Option<Vec<u8>> {
+                (path == "assets/minecraft/lang/en_us.json").then(|| {
+                    serde_json::to_vec(&serde_json::json!({
+                        "options.renderDistance": "Render Distance",
+                        "options.chunks": "%s Chunks",
+                        "options.generic_value": "%s: %s"
+                    }))
+                    .unwrap()
+                })
+            }
+        }
+        let mut s = Settings::default();
+        let near = s.render_distance;
+        let render = Item::Vanilla(Opt::RenderDistance);
+        let ((off, on), _) = lang::scoped(lang::Language::load(&[&Vanilla], "en_us"), || {
+            let off = render.label(&s, &NONE).plain();
+            s.horizon.lod_distance = 256;
+            (off, render.label(&s, &NONE).plain())
+        });
+        assert_eq!(off, format!("Render Distance: {near} Chunks"));
+        assert_eq!(on, format!("Full Detail Distance: {near} Chunks"));
     }
 
     #[test]

crates/horizon-client-render/src/graphics_ui_hdr_tests.rs

@@ -31,6 +31,49 @@ fn smooth_gradients_wait_for_a_device_that_draws_the_16_bit_frame() {
     assert_eq!(item.blocked(&s, &out), Some("Turn HDR on to use it."));
 }
 
+#[test]
+fn hdr_lighting_is_greyed_only_where_the_running_pack_lights_the_world() {
+    use horizon_shader_api::Api;
+    let mut s = Settings::default();
+    s.horizon.hdr = HdrMode::On;
+    let item = Item::Horizon(H::HdrLighting);
+    let lights = Some("The shader pack lights the world itself.");
+    let out = offering(true, None);
+    // No pack running, as with one picked but refused, missing or its mod off: live.
+    assert_eq!(item.blocked(&s, &out.with_pack(false, None)), None);
+    // A 0.1 pack on the 16-bit frame: the light sources and the sun still shine.
+    assert_eq!(
+        item.blocked(&s, &out.with_pack(false, Some(Api::V0_1))),
+        None
+    );
+    assert_eq!(
+        item.blocked(&s, &out.with_pack(false, Some(Api::V0_2))),
+        lights
+    );
+    assert_eq!(item.blocked(&s, &out.with_pack(true, None)), lights);
+    let float = EffectiveOutput {
+        frame: crate::gfx::FrameConfiguration {
+            format: wgpu::TextureFormat::Rgba16Float,
+            ..out.frame
+        },
+        ..out
+    };
+    assert_eq!(
+        item.blocked(&s, &float.with_pack(false, Some(Api::V0_1))),
+        lights
+    );
+    // HDR's own reasons come first.
+    assert_eq!(
+        item.blocked(&s, &NONE.with_pack(true, None)),
+        Some("Your display or system doesn't offer HDR output.")
+    );
+    s.horizon.hdr = HdrMode::Off;
+    assert_eq!(
+        item.blocked(&s, &out.with_pack(true, None)),
+        Some("Turn HDR on to use it.")
+    );
+}
+
 #[test]
 fn hdr_auto_can_be_selected_before_querying_and_brightness_waits_for_output() {
     let mut s = Settings::default();
@@ -121,7 +164,7 @@ fn auto_levels_and_setup_read_their_own_renderers_report() {
 }
 
 /// The setup rows' label and description for each kind of report: none, a compositor's
-/// (Wayland), and Windows', whose peak is the display's own guess.
+/// (Wayland), and Windows', whose peak may be the display's or a calibration profile's.
 #[test]
 fn the_setup_rows_ask_to_calibrate_unless_the_system_set_the_display_up() {
     let trusted = offering(true, Some(true));
@@ -157,7 +200,7 @@ fn the_setup_rows_ask_to_calibrate_unless_the_system_set_the_display_up() {
         [
             (
                 calibrate.into(),
-                "Your display's reported peak is often too high: calibrate to set it up."
+                "Auto uses the peak Windows reports. Calibrate if highlights look clipped."
             ),
             ("Peak Brightness: Auto (1000)".into(), "-"),
             ("Paper White: Auto (400)".into(), "-"),
@@ -176,7 +219,7 @@ fn the_setup_rows_ask_to_calibrate_unless_the_system_set_the_display_up() {
     );
     // Calibrated or set by hand, either report offers its automatic setup back.
     s.horizon.hdr_peak = 800;
-    // Peak's Auto stays a guess on Windows: only Paper White is said to be set up there.
+    // Peak's Auto has no known source on Windows: only Paper White is said to be set up there.
     let changed = |peak| {
         [
             (
@@ -305,3 +348,30 @@ fn undo_never_restores_a_held_hdr_start() {
     screen.undo(&mut s, &opened);
     assert_eq!(s.horizon, opened.horizon);
 }
+
+/// The Calibrate row's descriptions fit the strip's two lines at vanilla's 427-wide GUI (a
+/// 1080p window at scale 4 is wider): a longer one would end in "…".
+#[test]
+fn the_calibrate_descriptions_fit_the_strip() {
+    let atlas = crate::hud::HudAtlas::build(std::path::Path::new("/nonexistent")).unwrap();
+    let mut guessed = offering(true, Some(true));
+    guessed.reported = guessed.reported.map(|r| crate::graphics::Reported {
+        peak_guessed: true,
+        ..r
+    });
+    let mut changed = Settings::default();
+    changed.horizon.hdr_peak = 800;
+    let item = Item::Horizon(H::HdrCalibrate);
+    let width = Columns::of(427.0, 240.0).dock[2] - 24.0;
+    for (s, out) in [
+        (Settings::default(), NONE),
+        (Settings::default(), guessed),
+        (Settings::default(), offering(true, Some(true))),
+        (changed, guessed),
+    ] {
+        let text = description(item, &s, &out, "-");
+        assert_ne!(text, "-");
+        let lines = atlas.font.split(&Text::literal(text.to_owned()), width);
+        assert!(lines.len() <= 2, "{text}");
+    }
+}

crates/horizon-client-render/src/hdr.wgsl

@@ -173,13 +173,52 @@ fn calibration_picture(pos: vec4<f32>) -> vec4<f32> {
     return vec4(nits / 80.0, 1.0);
 }
 
-// Light in units of paper white, as the swapchain takes it: HDR10 or scRGB, the black level
-// lifted.
-fn display(light: vec3<f32>) -> vec4<f32> {
+// On for the HDR10 swapchain alone (Hdr::new): its 10 bits get dither. A screenshot's HDR10 copy
+// (Hdr::capture) keeps the exact codes, and scRGB's floats need none.
+override pq_dither: bool = false;
+
+// Three even random values in [0, 1) for `at`: PCG's 3D hash (Jarzynski and Olano, "Hash Functions
+// for GPU Rendering", JCGT 2020). Integers only, so it is the same on every GPU and at every
+// resolution, where hashes built on `fract(sin())` repeat or streak at 4K's coordinates.
+// Copyright 2020 Mark Jarzynski & Marc Olano, MIT (github.com/markjarzynski/PCG3D; the license is in
+// THIRD_PARTY_NOTICES.md).
+fn hash3(at: vec3<u32>) -> vec3<f32> {
+    var v = at * 1664525u + 1013904223u;
+    v.x += v.y * v.z;
+    v.y += v.z * v.x;
+    v.z += v.x * v.y;
+    v ^= v >> vec3(16u);
+    v.x += v.y * v.z;
+    v.y += v.z * v.x;
+    v.z += v.x * v.y;
+    return vec3<f32>(v >> vec3(8u)) / 16777216.0;
+}
+
+// The PQ signal `e` with dither for its 10 bits: triangular noise of one code either way, each
+// channel's own, so a slow gradient (a clear sky is a few codes tall) shows as grain a code deep
+// instead of bands, and its mean is the light meant. The noise is the pixel's alone: no frame
+// counter, so a still picture stays still. Within a code of black or of the top it shrinks to
+// what fits: the signal never leaves 0..1, and black stays exactly black (an OLED's pixel off).
+// The price is in that last code alone: the smaller noise keeps the signal's mean but not the
+// rounded one, which leans to the end (a third of a code from it shows as an eighth). Under
+// 0.00004 nits at black, that is the accepted cost of a true 0.
+fn dithered(e: vec3<f32>, pixel: vec2<f32>) -> vec3<f32> {
+    let at = vec2<u32>(pixel);
+    let noise = hash3(vec3(at, 0u)) + hash3(vec3(at, 1u)) - 1.0;
+    return e + noise * min(min(e, 1.0 - e), vec3(1.0 / 1023.0));
+}
+
+// Light in units of paper white at the pixel `pos`, as the swapchain takes it: HDR10 or scRGB,
+// the black level lifted.
+fn display(light: vec3<f32>, pos: vec4<f32>) -> vec4<f32> {
     let scrgb = light * params.paper;
     if params.pq > 0.5 {
         let e = pq(BT709_TO_BT2020 * scrgb * 80.0);
-        return vec4(select(e, lift_black(e), params.black > 0.0), 1.0);
+        let lifted = select(e, lift_black(e), params.black > 0.0);
+        if pq_dither {
+            return vec4(dithered(lifted, pos.xy), 1.0);
+        }
+        return vec4(lifted, 1.0);
     }
     if params.black > 0.0 {
         return vec4(pq_nits(lift_black(pq(scrgb * 80.0))) / 80.0, 1.0);
@@ -209,7 +248,7 @@ fn display(light: vec3<f32>) -> vec4<f32> {
     // The HUD and menus at their own brightness, by how much they cover, no brighter than the
     // peak (as `fs_hdr_layered`): UI Brightness can pass paper white.
     light = min(light * mix(1.0, params.ui, ui), vec3(params.peak));
-    return display(light);
+    return display(light, pos);
 }
 
 // The tone curve's knee: up to it light stays as it is. Where HDR lighting eased into the peak
@@ -328,5 +367,5 @@ override screenshot_shoulder: bool = true;
     if calibrating(pos) {
         return calibration_picture(pos);
     }
-    return display(min(pow(layered(vec2<i32>(pos.xy)), vec3(2.2)), vec3(params.peak)));
+    return display(min(pow(layered(vec2<i32>(pos.xy)), vec3(2.2)), vec3(params.peak)), pos);
 }

crates/horizon-client-render/src/hud.rs

@@ -52,7 +52,7 @@ pub struct TextureFlags {
 impl TextureFlags {
     /// The `texture` section of a `.png.mcmeta` file, if it sets either flag.
     pub fn from_mcmeta(json: &str) -> Option<Self> {
-        let meta: serde_json::Value = serde_json::from_str(json).ok()?;
+        let meta = crate::packs::first_json(json.as_bytes())?;
         let section = meta.get("texture")?;
         let flag = |key| section.get(key).and_then(serde_json::Value::as_bool) == Some(true);
         let flags = Self {
@@ -387,7 +387,7 @@ fn strip_frame(pixels: &[u8], stride: u32, x: u32, y: u32, w: u32, h: u32) -> Ve
 }
 /// The `animation` section of a texture's `.mcmeta`.
 fn animation_of(mcmeta: Option<&str>) -> Option<AnimationMetadata> {
-    let meta: serde_json::Value = serde_json::from_str(mcmeta?).ok()?;
+    let meta = crate::packs::first_json(mcmeta?.as_bytes())?;
     AnimationMetadata::from_json(&meta.get("animation")?.to_string()).ok()
 }
 /// An animated strip's first frame: the region the mcmeta's frame size picks
@@ -3110,6 +3110,18 @@ mod coverage_tests;
 mod tests {
     use super::*;
 
+    #[test]
+    fn animated_texture_metadata_ignores_trailing_pack_signature() {
+        let meta = r#"{"animation":{"frametime":2,"width":2,"height":2}}
+// High Contrast pack signature"#;
+        let animation = animation_of(Some(meta)).expect("the first JSON value is metadata");
+        assert_eq!(animation.frame_size(8, 4), [2, 2]);
+        let pixels = (0..8 * 4).flat_map(|i| [i as u8, 0, 0, 255]).collect();
+        let (_, height, first) = first_frame((8, 4, pixels), Some(&animation));
+        assert_eq!(height, 2);
+        assert_eq!(first.len(), 2 * 2 * 4);
+    }
+
     #[test]
     fn object_skin_revision_tracks_changes_and_capacity_clear() {
         let mut atlas = HudAtlas::boot();

crates/horizon-client-render/src/hud_kit/motion.rs

@@ -3,8 +3,9 @@
 //! where a tween is at the frame's [`Clock`]; nothing here holds state or runs on its own, and
 //! no motion ever decides what input does.
 //!
-//! The curves are the design system's (`horizon_theme::QUICK`, `MOVE`): a [`Tween`] takes one
-//! of them, at the theme's duration or a shorter one of its own.
+//! A [`Tween`] takes a duration and a CSS `cubic-bezier` curve: Horizon's overlays use the design
+//! system's (`horizon_theme::QUICK`, `MOVE`), at the theme's duration or a shorter one of their
+//! own.
 //!
 //! The game builds the clock once a frame (`Clock::new(now, still)`). A still clock (the game is
 //! paused, frame-stepped by `HORIZON_STILL` or a screenshot sequence, or a repro recording or
@@ -16,7 +17,7 @@
 //! use std::time::{Duration, Instant};
 //!
 //! let opened = Instant::now();
-//! let open = Tween::new(Duration::from_millis(90), horizon_theme::QUICK);
+//! let open = Tween::new(Duration::from_millis(90), [0.4, 0.0, 0.2, 1.0]);
 //! // Half way through: partly faded in, partly grown from 94%.
 //! let clock = Clock::new(opened + Duration::from_millis(45), false);
 //! let alpha = motion::fade(open, clock, opened);
@@ -26,7 +27,6 @@
 //! let still = Clock::new(opened, true);
 //! assert_eq!(motion::fade(open, still, opened), 1.0);
 //! ```
-use horizon_theme::Motion;
 use std::time::{Duration, Instant};
 
 /// The time a frame shows, built once a frame by the game.
@@ -50,28 +50,20 @@ impl Clock {
     }
 }
 
-/// A duration and one of the design system's easing curves.
+/// A duration and an easing curve.
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub struct Tween {
     /// How long it runs.
     pub duration: Duration,
-    /// The CSS `cubic-bezier` control points of its curve (a `horizon_theme::Motion`'s).
+    /// The CSS `cubic-bezier` control points of its curve.
     pub curve: [f32; 4],
 }
 
 impl Tween {
-    /// `motion`'s curve over `duration`: the dial's motions are shorter than the launcher's, on
-    /// the same curves.
-    pub const fn new(duration: Duration, motion: Motion) -> Self {
-        Self {
-            duration,
-            curve: motion.curve,
-        }
-    }
-
-    /// A theme motion as it is: its own duration and curve.
-    pub const fn of(motion: Motion) -> Self {
-        Self::new(motion.duration(), motion)
+    /// `curve` over `duration`: the dial's motions are shorter than the launcher's, on the same
+    /// curves.
+    pub const fn new(duration: Duration, curve: [f32; 4]) -> Self {
+        Self { duration, curve }
     }
 
     /// The linear progress, 0 to 1, `since` a start at this clock; 1 on a still clock.
@@ -84,7 +76,7 @@ impl Tween {
 
     /// The eased progress, 0 to 1, on the tween's curve.
     pub fn progress(self, clock: Clock, since: Instant) -> f32 {
-        horizon_theme::bezier(self.curve, self.linear(clock, since))
+        bezier(self.curve, self.linear(clock, since))
     }
 
     /// Whether it has finished (always, on a still clock).
@@ -98,6 +90,29 @@ impl Tween {
     }
 }
 
+/// A CSS `cubic-bezier(x1, y1, x2, y2)` at `t` in 0..1: solves x for the curve parameter,
+/// returns y.
+pub fn bezier([x1, y1, x2, y2]: [f32; 4], t: f32) -> f32 {
+    let t = t.clamp(0.0, 1.0);
+    if t == 0.0 || t == 1.0 {
+        return t;
+    }
+    let at = |a: f32, b: f32, s: f32| {
+        let u = 1.0 - s;
+        3.0 * u * u * s * a + 3.0 * u * s * s * b + s * s * s
+    };
+    let (mut lo, mut hi) = (0f32, 1f32);
+    for _ in 0..24 {
+        let mid = (lo + hi) / 2.0;
+        if at(x1, x2, mid) < t {
+            lo = mid;
+        } else {
+            hi = mid;
+        }
+    }
+    at(y1, y2, (lo + hi) / 2.0)
+}
+
 /// An alpha from 0 to 1 as something fades in.
 pub fn fade(tween: Tween, clock: Clock, since: Instant) -> f32 {
     tween.progress(clock, since)
@@ -145,7 +160,7 @@ mod tests {
     #[test]
     fn a_tween_runs_from_its_start_to_its_end_and_holds() {
         let t0 = Instant::now();
-        let tween = Tween::new(MS(80), horizon_theme::MOVE);
+        let tween = Tween::new(MS(80), horizon_theme::MOVE.curve);
         assert_eq!(tween.progress(at(t0, 0), t0), 0.0);
         assert_eq!(tween.progress(at(t0, 80), t0), 1.0);
         assert_eq!(tween.progress(at(t0, 500), t0), 1.0);
@@ -160,8 +175,7 @@ mod tests {
     fn a_still_clock_shows_every_motion_settled() {
         let t0 = Instant::now();
         let still = Clock::new(t0, true);
-        let tween = Tween::of(horizon_theme::QUICK);
-        assert_eq!(tween.duration, horizon_theme::QUICK.duration());
+        let tween = Tween::new(horizon_theme::QUICK.duration(), horizon_theme::QUICK.curve);
         assert_eq!(fade(tween, still, t0), 1.0);
         assert_eq!(fade_out(tween, still, t0), 0.0);
         assert_eq!(scale_in(tween, still, t0, 0.94), 1.0);
@@ -173,7 +187,7 @@ mod tests {
     #[test]
     fn the_helpers_start_where_they_say() {
         let t0 = Instant::now();
-        let tween = Tween::new(MS(100), horizon_theme::QUICK);
+        let tween = Tween::new(MS(100), horizon_theme::QUICK.curve);
         let c = at(t0, 0);
         assert_eq!(fade(tween, c, t0), 0.0);
         assert_eq!(fade_out(tween, c, t0), 1.0);
@@ -184,10 +198,25 @@ mod tests {
         assert!((flash(tween, at(t0, 25), t0) - 0.75).abs() < 1e-6);
     }
 
+    #[test]
+    fn the_curve_is_the_design_systems() {
+        for motion in horizon_theme::MOTION {
+            for i in 0..=20 {
+                let t = i as f32 / 20.0;
+                assert_eq!(
+                    bezier(motion.curve, t),
+                    motion.ease(t),
+                    "{} at {t}",
+                    motion.name
+                );
+            }
+        }
+    }
+
     #[test]
     fn a_turn_takes_the_short_way_round() {
         let t0 = Instant::now();
-        let tween = Tween::new(MS(80), horizon_theme::MOVE);
+        let tween = Tween::new(MS(80), horizon_theme::MOVE.curve);
         // From up-left (7/8 of a turn) to up-right: through up, not round the bottom.
         let from = 7.0 * FRAC_PI_4;
         let half = turn(tween, at(t0, 1), t0, from, FRAC_PI_4);

crates/horizon-client-render/src/hud_kit/room.rs

@@ -1,6 +1,7 @@
 //! Room: what of a view Horizon's own HUD overlays may use. Vanilla's HUD elements are
 //! keep-outs; an overlay asks the room where it fits instead of assuming a fixed spot, so it
-//! doesn't cover them. Today the only keep-out is the boss bars at the top centre.
+//! doesn't cover them. The keep-outs: the boss bars at the top centre, and the status rows above
+//! the hotbar at the bottom centre.
 //!
 //! The room is built once a frame from what the HUD shows (`Game::hud_room` in gameplay). With
 //! nothing showing it is empty, and every overlay stays exactly where it always was.
@@ -34,6 +35,16 @@ pub const GAP: f32 = 2.0;
 pub enum Keep {
     /// The boss bars and their names at the top centre (`hud_overlays::boss_bars_bottom`).
     BossBars,
+    /// The survival rows above the hotbar at the bottom centre: health with its absorption rows,
+    /// armour, food or the mount's hearts, and air; from the highest row's top to the view's
+    /// bottom.
+    StatusRows,
+}
+impl Keep {
+    /// It sits at the top of the view, not the bottom.
+    fn at_top(self) -> bool {
+        matches!(self, Self::BossBars)
+    }
 }
 
 /// A view and the keep-outs its HUD shows this frame.
@@ -90,10 +101,20 @@ impl Room {
     /// bars' bottom, or 0 with none.
     pub fn top(&self) -> f32 {
         self.keeps()
-            .map(|(Keep::BossBars, [_, y, _, h])| y + h)
+            .filter(|(keep, _)| keep.at_top())
+            .map(|(_, [_, y, _, h])| y + h)
             .fold(0.0, f32::max)
     }
 
+    /// How far, in GUI px from the view's top, the keep-outs at the bottom reach up: the status
+    /// rows' top, or the view's height with none.
+    pub fn bottom(&self) -> f32 {
+        self.keeps()
+            .filter(|(keep, _)| !keep.at_top())
+            .map(|(_, [_, y, _, _])| y)
+            .fold(self.height, f32::min)
+    }
+
     /// Where a centred overlay that wants its top at `wanted` (GUI px) goes: at `wanted` unless
     /// a keep-out reaches past it (`top() > wanted`, a real overlap; touching isn't one), else
     /// `GAP` below that keep-out.
@@ -134,4 +155,15 @@ mod tests {
         assert_eq!(bars(36.0).below_top(18.0), 38.0);
         assert_eq!(bars(36.0).usable(), [0.0, 38.0, 500.0, 262.0]);
     }
+
+    #[test]
+    fn the_status_rows_are_kept_at_the_bottom_and_leave_the_top_alone() {
+        let room = Room::new(427.0, 240.0);
+        assert_eq!(room.bottom(), 240.0);
+        // Hearts and armour from y 191 down.
+        let rows = room.with(Keep::StatusRows, [122.0, 191.0, 182.0, 49.0]);
+        assert_eq!(rows.bottom(), 191.0);
+        assert_eq!(rows.top(), 0.0);
+        assert_eq!(rows.below_top(18.0), 18.0);
+    }
 }

crates/horizon-client-render/src/hud_kit/tabs.rs

@@ -38,6 +38,12 @@
 //! ```
 use crate::hud::{HudAtlas, HudBatch};
 use crate::hud_kit::{colour, fit};
+use crate::menu_style::{self, OverlayColours};
+
+/// The overlays' colours (`menu_style`, given at startup).
+fn overlay() -> &'static OverlayColours {
+    &menu_style::get().overlay
+}
 
 /// A pip under the strip: its size and the step from one to the next, in GUI px.
 pub const PIP: [f32; 2] = [3.0, 2.0];
@@ -45,8 +51,12 @@ pub const PIP_STEP: f32 = 5.0;
 /// How far, in GUI px, the arrows sit from the name.
 pub const ARROW_GAP: f32 = 4.0;
 /// An arrow with a page that way, and one at an end, with none.
-pub const ARROW: u32 = colour(horizon_theme::BACKDROP_MUTED, 255);
-pub const ARROW_OFF: u32 = colour(horizon_theme::BACKDROP_MUTED, 77);
+pub fn arrow_colour() -> u32 {
+    colour(overlay().backdrop_muted, 255)
+}
+pub fn arrow_off_colour() -> u32 {
+    colour(overlay().backdrop_muted, 77)
+}
 /// The pips (the selected one is white).
 pub const PIP_OFF: u32 = colour(0xFFFFFF, 89);
 pub const PIP_ON: u32 = colour(0xFFFFFF, 255);
@@ -65,9 +75,15 @@ pub const EDGE_FADE: f32 = 12.0;
 pub const FADE: [f32; 5] = [1.0, 0.7, 0.35, 0.15, 0.1];
 /// The selected tab's fill and text, and the others'.
 pub const SELECTED_FILL: u32 = colour(0xFFFFFF, 242);
-pub const SELECTED_TEXT: u32 = colour(horizon_theme::DARK.page, 255);
-pub const TAB_FILL: u32 = colour(horizon_theme::DARK.page, 191);
-pub const TAB_TEXT: u32 = colour(horizon_theme::BACKDROP_MUTED, 255);
+pub fn selected_text() -> u32 {
+    colour(overlay().page, 255)
+}
+pub fn tab_fill() -> u32 {
+    colour(overlay().page, 191)
+}
+pub fn tab_text() -> u32 {
+    colour(overlay().backdrop_muted, 255)
+}
 /// The line of text's height in GUI px (vanilla's font, without its shadow).
 const LINE: f32 = 8.0;
 
@@ -144,7 +160,11 @@ pub fn draw(batch: &mut HudBatch, atlas: &HudAtlas, strip: &Strip) {
             arrow,
             ax,
             ay,
-            if on { ARROW } else { ARROW_OFF },
+            if on {
+                arrow_colour()
+            } else {
+                arrow_off_colour()
+            },
             true,
         );
     }
@@ -282,9 +302,9 @@ pub fn draw_tabs(batch: &mut HudBatch, atlas: &HudAtlas, strip: &TabStrip, alpha
     for tab in &row.tabs {
         let [tx, ty, tw, th] = tab.area;
         let (fill, text) = if tab.selected {
-            (SELECTED_FILL, SELECTED_TEXT)
+            (SELECTED_FILL, selected_text())
         } else {
-            (TAB_FILL, TAB_TEXT)
+            (tab_fill(), tab_text())
         };
         let tab_start = batch.vertices.len();
         // Cut where the edges' fades start, so each fade runs over its own piece.
@@ -380,15 +400,16 @@ mod tests {
             let [ax, _] = strip.arrows[i];
             (batch.vertices.iter())
                 .filter(|v| {
-                    (v.pos[0] - ax).abs() < 4.0 && v.color & 0x00FF_FFFF == ARROW & 0x00FF_FFFF
+                    (v.pos[0] - ax).abs() < 4.0
+                        && v.color & 0x00FF_FFFF == arrow_colour() & 0x00FF_FFFF
                 })
                 .map(|v| v.color >> 24)
                 .max()
                 .unwrap_or(0)
         };
         let first = collapsed(&atlas, &pages, 0, AREA);
-        assert_eq!(alpha(&first, 0), ARROW_OFF >> 24);
-        assert_eq!(alpha(&first, 1), ARROW >> 24);
+        assert_eq!(alpha(&first, 0), arrow_off_colour() >> 24);
+        assert_eq!(alpha(&first, 1), arrow_colour() >> 24);
     }
 
     #[test]

crates/horizon-client-render/src/hud_layout.rs

@@ -131,6 +131,23 @@ pub enum GuiDraw {
 
 pub const WHITE: u32 = 0xFFFF_FFFF;
 
+/// The highest top, in GUI px, of the draws that sit on the view (`None` for none): where a row
+/// of the HUD begins.
+pub fn draws_top(draws: &[GuiDraw]) -> Option<i32> {
+    draws
+        .iter()
+        .filter_map(|d| match *d {
+            GuiDraw::Sprite { y, .. }
+            | GuiDraw::AtlasSprite { y, .. }
+            | GuiDraw::Blit { y, .. }
+            | GuiDraw::Text { y, .. }
+            | GuiDraw::Item { y, .. } => Some(y),
+            GuiDraw::Fill { y0, .. } => Some(y0),
+            GuiDraw::Push(_) | GuiDraw::Pop => None,
+        })
+        .min()
+}
+
 fn sprite(sprite: &'static str, x: i32, y: i32, w: i32, h: i32) -> GuiDraw {
     GuiDraw::Sprite {
         sprite: Cow::Borrowed(sprite),

crates/horizon-client-render/src/hud_overlays.rs

@@ -583,6 +583,9 @@ pub const BOSS_BAR_STEP: i32 = 10 + 9;
 pub const BOSS_BAR_HEIGHT: i32 = 5;
 /// A boss bar's sprite width, in GUI px; it is centred on the view.
 pub const BOSS_BAR_WIDTH: i32 = 182;
+/// Half the hotbar's width, in GUI px (`Hud`'s `screenWidth / 2 - 91`): the status rows above it
+/// span the same.
+pub const HOTBAR_HALF_WIDTH: i32 = 91;
 
 /// How many of `n` boss bars `BossHealthOverlay.extractRenderState` draws on a view `h` GUI px
 /// tall: it stops once the next bar's top reaches a third of the height (integer division,

crates/horizon-client-render/src/lib.rs

@@ -74,6 +74,7 @@ pub mod light;
 pub mod lod;
 pub mod logging;
 pub mod menu_blur;
+pub mod menu_style;
 pub mod mesher;
 pub mod minimap;
 pub mod mipmap;
@@ -109,6 +110,8 @@ pub mod preedit;
 pub mod providers;
 pub mod pvp;
 pub mod pvp_hud;
+pub mod radial_editor;
+pub mod radial_overlay;
 pub mod random_source;
 pub mod screen_draw;
 pub mod screen_effects;
@@ -169,6 +172,7 @@ pub use horizon_client_input::key_names;
 pub use horizon_client_input::keybinds;
 pub use horizon_client_input::keymapping;
 pub use horizon_client_input::mouse;
+pub use horizon_client_input::radial;
 pub use horizon_client_input::window;
 pub use horizon_command as command;
 pub use horizon_items::blocks;

crates/horizon-client-render/src/light.rs

@@ -22,6 +22,7 @@ use crate::{
 use horizon_core::geometry::{Direction, ShapeOp, VoxelShape};
 use horizon_world::registry::{BlockRegistry, BlockStateId};
 use std::{
+    cell::RefCell,
     collections::{HashMap, VecDeque},
     path::Path,
     sync::Arc,
@@ -365,6 +366,48 @@ fn give_scratch(scratch: LightScratch) {
     }
 }
 
+thread_local! {
+    static RELIGHT_SCRATCH: RefCell<RelightScratch> = RefCell::new(RelightScratch::new());
+}
+
+struct RelightScratch {
+    decrease: VecDeque<(Pos, u8)>,
+    cleared: Vec<Pos>,
+    increase: VecDeque<Pos>,
+    sources: FxHashMap<(i32, i32), i32>,
+}
+
+impl RelightScratch {
+    fn new() -> Self {
+        Self {
+            decrease: VecDeque::new(),
+            cleared: Vec::new(),
+            increase: VecDeque::new(),
+            sources: FxHashMap::default(),
+        }
+    }
+
+    fn clear(&mut self) {
+        const MAX_CAPACITY: usize = 16_384;
+        self.decrease.clear();
+        if self.decrease.capacity() > MAX_CAPACITY {
+            self.decrease.shrink_to(MAX_CAPACITY);
+        }
+        self.cleared.clear();
+        if self.cleared.capacity() > MAX_CAPACITY {
+            self.cleared.shrink_to(MAX_CAPACITY);
+        }
+        self.increase.clear();
+        if self.increase.capacity() > MAX_CAPACITY {
+            self.increase.shrink_to(MAX_CAPACITY);
+        }
+        self.sources.clear();
+        if self.sources.capacity() > MAX_CAPACITY {
+            self.sources.shrink_to(MAX_CAPACITY);
+        }
+    }
+}
+
 /// Where a section sits in the 48-wide region.
 #[derive(Clone, Copy)]
 struct At {
@@ -880,12 +923,12 @@ impl<'w> Region<'w> {
         Self {
             layout: world.layout(),
             world,
-            slots: Vec::new(),
+            slots: Vec::with_capacity(16),
             index: FxHashMap::default(),
             last: ((i32::MIN, 0, 0), NONE),
         }
     }
-    #[inline]
+    #[inline(always)]
     fn slot(&mut self, x: i32, y: i32, z: i32) -> Option<usize> {
         let s = self.layout.section_index(y)?;
         let key = (x >> 4, s as i32, z >> 4);
@@ -1142,10 +1185,25 @@ pub fn relight(
     force: bool,
     changed: &mut LightChanges,
 ) {
-    let mut region = Region::new(world);
-    changed.keyed(region.layout);
-    relight_region(&mut region, tables, sky_light, positions, force, changed);
-    region.finish();
+    changed.keyed(world.layout());
+    if positions.is_empty() {
+        return;
+    }
+    RELIGHT_SCRATCH.with_borrow_mut(|scratch| {
+        scratch.clear();
+        let mut region = Region::new(world);
+        relight_region(
+            &mut region,
+            tables,
+            sky_light,
+            positions,
+            force,
+            scratch,
+            changed,
+        );
+        region.finish();
+        scratch.clear();
+    });
 }
 /// The columns `changed` touched that border a loaded column not lit yet
 /// (`unlit`). `relight` reads and writes only lit columns, so an edit's
@@ -1170,10 +1228,11 @@ fn relight_region(
     sky_light: bool,
     positions: &[Pos],
     force: bool,
+    scratch: &mut RelightScratch,
     changed: &mut LightChanges,
 ) {
     crate::spans::time("lt_block", || {
-        relight_layer(world, tables, false, positions.to_vec(), force, changed)
+        relight_layer(world, tables, false, positions, force, scratch, changed)
     });
     if sky_light {
         let (min_y, max_y) = (world.layout.min_y(), world.layout.max_y());
@@ -1201,7 +1260,7 @@ fn relight_region(
             }
         });
         crate::spans::time("lt_sky", || {
-            relight_layer(world, tables, true, seeds, force, changed)
+            relight_layer(world, tables, true, &seeds, force, scratch, changed)
         });
     }
 }
@@ -1209,14 +1268,30 @@ fn relight_layer(
     world: &mut Region,
     tables: &LightTables,
     sky: bool,
-    seeds: Vec<Pos>,
+    seeds: &[Pos],
     force: bool,
+    scratch: &mut RelightScratch,
     changed: &mut LightChanges,
 ) {
-    let mut decrease: VecDeque<(Pos, u8)> = VecDeque::new();
-    let mut cleared: Vec<Pos> = Vec::new();
-    let mut increase: VecDeque<Pos> = VecDeque::new();
-    for p in seeds {
+    scratch.decrease.clear();
+    scratch.cleared.clear();
+    scratch.increase.clear();
+    scratch.sources.clear();
+
+    if seeds.len() > scratch.decrease.capacity() {
+        scratch.decrease.reserve(seeds.len());
+    }
+    if seeds.len() > scratch.cleared.capacity() {
+        scratch.cleared.reserve(seeds.len());
+    }
+    if seeds.len() > scratch.increase.capacity() {
+        scratch.increase.reserve(seeds.len());
+    }
+
+    let decrease = &mut scratch.decrease;
+    let cleared = &mut scratch.cleared;
+    let increase = &mut scratch.increase;
+    for &p in seeds {
         let Some(old) = level(world, sky, p) else {
             continue;
         };
@@ -1267,13 +1342,22 @@ fn relight_layer(
         }
     }
     // Sources inside the cleared area light up again.
-    let mut sources: FxHashMap<(i32, i32), i32> = FxHashMap::default();
+    let sources = &mut scratch.sources;
+    let mut last_xz = (i32::MIN, i32::MIN);
+    let mut last_lowest = 0;
     crate::spans::time("lt_sources", || {
-        for p in cleared {
+        for &p in cleared.iter() {
             let seed = if sky {
-                let lowest = *sources
-                    .entry((p.0, p.2))
-                    .or_insert_with(|| lowest_sky_source(world, tables, p.0, p.2));
+                let lowest = if (p.0, p.2) == last_xz {
+                    last_lowest
+                } else {
+                    let lowest = *sources
+                        .entry((p.0, p.2))
+                        .or_insert_with(|| lowest_sky_source(world, tables, p.0, p.2));
+                    last_xz = (p.0, p.2);
+                    last_lowest = lowest;
+                    lowest
+                };
                 if p.1 >= lowest { 15 } else { 0 }
             } else {
                 world
@@ -2119,9 +2203,39 @@ pub(crate) mod tests {
             relight(&mut w, &t, true, &positions, false, &mut changed);
         }
         println!(
-            "relight_bench: {:?}, {} sections",
-            start.elapsed(),
-            changed.sections().count()
+            "relight_bench (large batch: 400 rounds x 32 blocks): {:?}",
+            start.elapsed()
+        );
+    }
+
+    #[test]
+    #[ignore]
+    fn relight_single_block_bench() {
+        let mut w: FxHashMap<_, _> = world(|_| {}).into_iter().collect();
+        let t = tables();
+        let mut rng = 0x2545_f491_u32;
+        let mut next = |n: i32| {
+            rng ^= rng << 13;
+            rng ^= rng >> 17;
+            rng ^= rng << 5;
+            (rng % n as u32) as i32
+        };
+        let start = std::time::Instant::now();
+        let mut changed = LightChanges::default();
+        for round in 0..2000 {
+            let state = [TORCH, SLAB, AIR][round % 3];
+            let pos = (next(32) - 8, next(12), next(32) - 8);
+            Arc::make_mut(w.get_mut(&(pos.0 >> 4, pos.2 >> 4)).unwrap()).set(
+                pos.0 & 15,
+                pos.1,
+                pos.2 & 15,
+                state,
+            );
+            relight(&mut w, &t, true, &[pos], false, &mut changed);
+        }
+        println!(
+            "relight_single_block_bench (single block: 2000 rounds): {:?}",
+            start.elapsed()
         );
     }
 

crates/horizon-client-render/src/menu_style.rs

@@ -0,0 +1,150 @@
+//! The look of the screens vanilla doesn't have that the engine still draws: the settings pages
+//! (`graphics_style`), the HUD kit's tab strip, and the overlays drawn with `ui_theme` (the
+//! on-screen keyboard, the boot screen, the missing-resources window). Vanilla's screens never
+//! read it.
+//!
+//! The layer above gives it once at startup ([`install`]), before the first frame; the
+//! official game gives Horizon's design system (`docs/design-system.md`). With none given, the
+//! screens draw in [`NEUTRAL`]: vanilla's greys and chat colours, and no text where they would
+//! use their own fonts. A read is one atomic load, and only those screens make it.
+use std::sync::OnceLock;
+
+/// Colours as `0xRRGGBB`, sizes in dp (the launcher's logical pixels).
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct MenuStyle {
+    pub settings: SettingsColours,
+    pub overlay: OverlayColours,
+    pub sizes: Sizes,
+    /// The overlays' TrueType faces; none: they draw no text.
+    pub fonts: Option<Fonts>,
+}
+
+/// The settings pages: square panels of dark glass over the world, flat controls, one face.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct SettingsColours {
+    /// The plate behind everything, drawn see-through.
+    pub page: u32,
+    /// Text, and the light the panels, rules, hovers and controls are drawn in.
+    pub ink: u32,
+    /// Secondary text and values.
+    pub ink_soft: u32,
+    /// Labels, descriptions, what can't be used.
+    pub muted: u32,
+    /// Wells and the dark edge of small marks.
+    pub outline: u32,
+    /// Focus, a checked box, a slider's fill.
+    pub accent: u32,
+    /// The one main button, and while hovered.
+    pub face: u32,
+    pub face_hover: u32,
+    pub success: u32,
+    pub warn: u32,
+    pub danger: u32,
+}
+
+/// Overlays drawn over the game (the HUD kit's tab strip, `ui_theme`'s overlays).
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct OverlayColours {
+    /// The dark page under text and tabs.
+    pub page: u32,
+    /// Muted text over a veiled backdrop.
+    pub backdrop_muted: u32,
+    /// Text and the light hover and pressed plates are drawn in.
+    pub ink: u32,
+    /// Secondary text and values.
+    pub ink_soft: u32,
+    /// One-pixel rules between rows.
+    pub rule: u32,
+    /// The main action, and its text.
+    pub accent: u32,
+    pub on_accent: u32,
+    /// A lit choice and its bright edge (the controller dial's sector).
+    pub lit: u32,
+    pub lit_edge: u32,
+}
+
+/// `ui_theme`'s type scale and shapes, in dp.
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Sizes {
+    pub caption: f32,
+    pub label: f32,
+    pub ui: f32,
+    pub body: f32,
+    pub title: f32,
+    /// The boot screen's wordmark at its smallest, and its console lines.
+    pub display: f32,
+    pub micro: f32,
+    /// Fields; plates (hover rows, selection); a large control's height.
+    pub radius: f32,
+    pub radius_plate: f32,
+    pub control_large: f32,
+}
+
+/// TrueType faces (`ui_theme::Face`).
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub struct Fonts {
+    pub regular: &'static [u8],
+    pub medium: &'static [u8],
+    pub semibold: &'static [u8],
+    pub mono: &'static [u8],
+}
+
+/// The look with nothing given: vanilla's greys and chat colours.
+pub const NEUTRAL: MenuStyle = MenuStyle {
+    settings: SettingsColours {
+        page: 0x101010,
+        ink: 0xffffff,
+        ink_soft: 0xe0e0e0,
+        muted: 0xa0a0a0,
+        outline: 0x000000,
+        accent: 0xffffff,
+        face: 0x555555,
+        face_hover: 0x6f6f6f,
+        success: 0x55ff55,
+        warn: 0xffff55,
+        danger: 0xff5555,
+    },
+    overlay: OverlayColours {
+        page: 0x101010,
+        backdrop_muted: 0xa0a0a0,
+        ink: 0xffffff,
+        ink_soft: 0xe0e0e0,
+        rule: 0x303030,
+        accent: 0xffffff,
+        on_accent: 0x000000,
+        lit: 0xffffff,
+        lit_edge: 0xffffff,
+    },
+    sizes: Sizes {
+        caption: 12.0,
+        label: 13.0,
+        ui: 14.0,
+        body: 15.0,
+        title: 28.0,
+        display: 44.0,
+        micro: 11.0,
+        radius: 0.0,
+        radius_plate: 0.0,
+        control_large: 40.0,
+    },
+    fonts: None,
+};
+
+static STYLE: OnceLock<MenuStyle> = OnceLock::new();
+
+/// Give the menus their look: call it once at startup. A second call keeps the first look and
+/// returns false.
+pub fn install(style: MenuStyle) -> bool {
+    STYLE.set(style).is_ok()
+}
+
+/// The look given to [`install`], or [`NEUTRAL`].
+#[inline]
+pub fn get() -> &'static MenuStyle {
+    STYLE.get().unwrap_or(&NEUTRAL)
+}
+
+/// `0xRRGGBB` and an alpha in the HUD's colour encoding (`0xAABBGGRR`).
+pub const fn hud_colour(rgb: u32, alpha: u8) -> u32 {
+    (alpha as u32) << 24 | (rgb & 0xff) << 16 | (rgb >> 8 & 0xff) << 8 | (rgb >> 16 & 0xff)
+}

crates/horizon-client-render/src/mesher/packed.rs

@@ -13,8 +13,9 @@
 //! - word 1: each corner's grey level before the tint;
 //! - word 2: the UV rectangle in 1/32 of the sprite (u0, u1, v0, v1, 6 bits each) and, per
 //!   corner, which edge of it its u and v take;
-//! - word 3: the layer, and corner 0's light (sky and block light over 4, 6 bits each);
-//! - word 4: corners 1 and 2's light;
+//! - word 3: the layer, corner 0's light (sky and block light over 4, 6 bits each), and
+//!   corner 1's alpha code (`ALPHA_STEP` times it; 0: word 0's alpha);
+//! - word 4: corners 1 and 2's light, and corners 2 and 3's alpha codes;
 //! - word 5: corner 3's light, the face (block x, y, z, the axis it faces along, which side
 //!   of the block, and where and which way its corners go round), and `FULL` clear.
 use super::TerrainVertex;
@@ -27,6 +28,8 @@ pub const WHITE: u32 = 0xFF_FFFF;
 /// Word 5's bit of a quad kept as four vertices; word 0 is then the slots from the record
 /// to its first vertex.
 pub const FULL: u32 = 1 << 31;
+/// The step of a corner's own alpha (words 3 and 4's codes): 255 / 5.
+pub const ALPHA_STEP: u32 = 51;
 /// The draws' base vertex of a compact mesh: `PACKED_BASE + 4 * slot + corner` is a corner of
 /// the quad whose record is at `slot`; below it, vertex indices name vertices.
 pub const PACKED_BASE: u32 = 1 << 28;
@@ -133,12 +136,24 @@ pub fn pack_quad(quad: &[TerrainVertex; 4], tint: u32) -> Option<[u32; 6]> {
     for (i, v) in quad.iter().enumerate() {
         grays |= gray_of(v.color, tint)? << (8 * i);
     }
+    // Corners 1 to 3's alpha (a shader pack's `separateAo`: each corner's ambient occlusion,
+    // multiples of 51 on a whole face): `ALPHA_STEP` times the code, 0 for corner 0's.
+    let mut codes = [0u32; 3];
+    for (code, v) in codes.iter_mut().zip(&quad[1..]) {
+        let a = v.color >> 24;
+        if v.color & 0xFF00_0000 != alpha {
+            if a == 0 || a % ALPHA_STEP != 0 {
+                return None;
+            }
+            *code = a / ALPHA_STEP;
+        }
+    }
     let words = [
         tint | alpha,
         grays,
         rect | select << 24,
-        u32::from(quad[0].layer) | light[0] << 16,
-        light[1] | light[2] << 12,
+        u32::from(quad[0].layer) | light[0] << 16 | codes[0] << 28,
+        light[1] | light[2] << 12 | codes[1] << 24 | codes[2] << 27,
         light[3] | orient << 12,
     ];
     let exact = (0..4).all(|c| {
@@ -190,12 +205,18 @@ pub fn packed_vertex(words: &[u32; 6], corner: usize) -> TerrainVertex {
     let light = ((light & 63) << 2 | (light >> 6 & 63) << 10) as u16;
     let g = w1 >> (8 * i) & 255;
     let [r, gr, b] = channels(w0).map(|t| g * t / 255);
+    let code = [0, w3 >> 28 & 7, w4 >> 24 & 7, w4 >> 27 & 7][corner];
+    let alpha = if code == 0 {
+        w0 & 0xFF00_0000
+    } else {
+        (code * ALPHA_STEP) << 24
+    };
     TerrainVertex {
         pos: pos.map(|c| c as f32),
         uv,
         layer: (w3 & 0xFFFF) as u16,
         light,
-        color: r | gr << 8 | b << 16 | (w0 & 0xFF00_0000),
+        color: r | gr << 8 | b << 16 | alpha,
     }
 }
 
@@ -247,11 +268,10 @@ pub fn place_into(
     let n = quads.len();
     let packed = records.iter().filter(|r| r.is_some()).count();
     let full = n - packed;
-    let pad = if full > 0 {
-        n.next_multiple_of(4) - n
-    } else {
-        0
-    };
+    // Whole quads of slots: what follows (a quad's own vertices, the translucent ones after
+    // the solid range) then starts a quad, as a shader pack's vertex stage reads its quad's
+    // corners from the vertex index (`pack_atlas::PULL_FLAT`).
+    let pad = n.next_multiple_of(4) - n;
     if n + pad + 4 * full >= 4 * n {
         return;
     }
@@ -334,6 +354,22 @@ mod tests {
         }
     }
 
+    #[test]
+    fn each_corners_ambient_occlusion_alpha_packs_on_its_steps() {
+        // A shader pack's `separateAo`: the alpha byte is each corner's occlusion.
+        let mut quad = top([0, 1, 2, 3]);
+        for (v, a) in quad.iter_mut().zip([153u32, 255, 51, 204]) {
+            v.color = v.color & 0x00FF_FFFF | a << 24;
+        }
+        let words = pack_quad(&quad, TINT).expect("occlusion on the 51 steps packs");
+        for (corner, v) in quad.iter().enumerate() {
+            assert!(same(&packed_vertex(&words, corner), v), "corner {corner}");
+        }
+        // A partial face's blended occlusion falls between the steps.
+        quad[2].color = quad[2].color & 0x00FF_FFFF | 140 << 24;
+        assert!(pack_quad(&quad, TINT).is_none());
+    }
+
     #[test]
     fn quads_off_the_grid_or_the_steps_keep_their_vertices() {
         // Half a block up: a slab's top.
@@ -375,4 +411,13 @@ mod tests {
         // Nothing smaller to gain: no layout at all.
         assert!(layout(&odd, &[TINT]).is_empty());
     }
+
+    #[test]
+    fn the_records_end_on_a_whole_quad_of_slots() {
+        // Five whole faces, every one a record: the translucent vertices after them start a quad.
+        let solid: Vec<TerrainVertex> = (0..5).flat_map(|_| top([0, 1, 2, 3])).collect();
+        let out = layout(&solid, &[TINT; 5]);
+        assert_eq!(packed_quads(&out, 5), 5);
+        assert_eq!(out.len(), 8);
+    }
 }

crates/horizon-client-render/src/options_ui.rs

@@ -18,6 +18,8 @@ use crate::{
     ui,
 };
 
+mod shell_pages;
+
 fn tr(key: &str) -> Text {
     Text::translate(key, &[])
 }
@@ -322,6 +324,8 @@ impl Opt {
             Opt::PadNintendoButtons => "horizon.options.nintendo_buttons",
             Opt::PadKeyboard => "horizon.options.on_screen_keyboard",
             Opt::PadGameplayGuide => "horizon.options.gameplay_guide",
+            Opt::PadRadialMode => "horizon.options.radial_mode",
+            Opt::PadRadialStick => "horizon.options.radial_stick",
             Opt::ModelPart(i) => [
                 "options.modelPart.cape",
                 "options.modelPart.jacket",
@@ -880,6 +884,7 @@ impl Opt {
                 gamepad::TextKeyboard::Horizon => "horizon.options.keyboard.horizon",
                 gamepad::TextKeyboard::Steam => "horizon.options.keyboard.steam",
             }),
+            Opt::PadRadialMode | Opt::PadRadialStick => self.radial_text(s),
             Opt::Page(page, row) => pages::slider_text(page, row),
             _ => Text::empty(),
         }
@@ -1201,6 +1206,7 @@ impl Opt {
                     .unwrap_or(0) as u8;
                 s.controller.keyboard = all[usize::from(next(i, 3))];
             }
+            Opt::PadRadialMode | Opt::PadRadialStick => self.radial_step(s, back),
             _ => {}
         }
         if self.affects_preset() {
@@ -1352,6 +1358,11 @@ pub enum Page {
     /// Horizon's controller settings and button binds.
     Controller,
     PadBinds,
+    /// The radial menu's pages (`radial_editor`), on the settings shell, and a page's name.
+    ControllerRadial,
+    ControllerRadialName,
+    /// The list of every action for one of its slots.
+    ControllerRadialPick,
     Extras,
     /// PvP & HUD (`pvp`): the extras a PvP player sets, on their own page.
     Pvp,
@@ -1683,6 +1694,10 @@ pub struct OptionsUi {
     controller: shell::Shell<crate::controller_ui::ControllerScreen>,
     /// Horizon Extras, on the settings shell.
     extras: shell::Shell<crate::extras_ui::ExtrasScreen>,
+    /// The radial menu's pages, on the settings shell.
+    radial: shell::Shell<crate::radial_editor::RadialScreen>,
+    /// The list of actions for one of the radial menu's slots.
+    radial_pick: shell::Shell<crate::radial_editor::PickScreen>,
     /// Shaders: the shader packs and the picked one's options, on the settings shell.
     shader: shell::Shell<crate::shader_ui::ShaderScreen>,
     /// The Pack Options page, and the packs' Polytone config entries by pack id (the game
@@ -1767,6 +1782,8 @@ impl Default for OptionsUi {
             graphics: Default::default(),
             controller: Default::default(),
             extras: Default::default(),
+            radial: Default::default(),
+            radial_pick: Default::default(),
             shader: Default::default(),
             pack_options: Default::default(),
             pack_configs: Default::default(),
@@ -2112,6 +2129,7 @@ impl OptionsUi {
                     .pack_screen
                     .as_ref()
                     .is_some_and(|p| p.search_focused()),
+                Page::ControllerRadialName => self.radial_name_typing(),
                 _ => match self.shell() {
                     Some(shell) => shell.typing(),
                     None => self.settings_search_active(),
@@ -2244,95 +2262,16 @@ impl OptionsUi {
             self.studio.refresh();
         }
     }
-    /// The open page's screen on the settings shell. This, with `shell_mut`, is all a screen
-    /// needs here: drawing, clicks, the wheel, a stick's scrolling, keys and typing all go
-    /// through them, so no input path can miss one.
-    fn shell(&self) -> Option<&dyn shell::Hosted> {
-        match self.page() {
-            Page::Extras => Some(&self.extras),
-            page if Self::graphics_page(page).is_some() => Some(&self.graphics),
-            page if Self::controller_page(page).is_some() => Some(&self.controller),
-            page if Self::shader_page(page).is_some() => Some(&self.shader),
-            _ => None,
-        }
-    }
-    fn shell_mut(&mut self) -> Option<&mut dyn shell::Hosted> {
-        self.graphics.screen.output = self.output;
-        match self.page() {
-            Page::Extras => Some(&mut self.extras),
-            page if Self::graphics_page(page).is_some() => Some(&mut self.graphics),
-            page if Self::controller_page(page).is_some() => Some(&mut self.controller),
-            page if Self::shader_page(page).is_some() => Some(&mut self.shader),
-            _ => None,
-        }
-    }
     /// A controller's or the keyboard's focus landed on `rect`: a row of a shell screen's list
     /// that is partly hidden scrolls all into view. How far it moved down, when it moved.
     pub fn reveal(&mut self, s: &Settings, size: (f32, f32), rect: [f32; 4]) -> Option<f32> {
         self.shell_mut()?.reveal(s, size, rect)
     }
-    /// The window's size, for the graphics and controller screens' rows that step an option
-    /// (`Opt::cycle`, which a fullscreen resolution needs): before each input that can press one.
-    fn shell_framebuffers(&mut self) {
-        self.graphics.screen.framebuffer = self.framebuffer;
-        self.controller.screen.framebuffer = self.framebuffer;
-    }
-    /// Who and what Controller Settings is about: the game sets it before each draw.
-    pub fn set_controller_context(&mut self, context: crate::controller_ui::Context) {
-        self.controller.screen.context = context;
-    }
-    /// The binding the screen waits on: a controller button's, else a key's.
-    fn waiting(&self) -> Option<shell::Capture> {
-        let pad = self.selected_pad_action.map(shell::Capture::Pad);
-        pad.or(self.selected_key.map(shell::Capture::Key))
-    }
-    /// What a shell screen's outputs do to these options.
-    fn shell_events(&mut self, s: &mut Settings, outputs: Vec<shell::Output>) -> Vec<Event> {
-        let mut events = Vec::new();
-        for output in outputs {
-            match output {
-                shell::Output::Event(event) => events.push(event),
-                shell::Output::Bind(shell::Capture::Key(name)) => self.selected_key = Some(name),
-                shell::Output::Bind(shell::Capture::Pad(action)) => {
-                    self.selected_pad_action = Some(action)
-                }
-                shell::Output::Push(page) => {
-                    if page == Page::HdrCalibration {
-                        self.calibration =
-                            Some(crate::hdr_calibration::Calibration::new(s, &self.output));
-                    }
-                    self.push(page);
-                }
-                shell::Output::Done => events.extend(self.back(s)),
-            }
-        }
-        events
-    }
-    /// Where the shader screen opens for `page`, if it is one of its pages.
-    fn shader_page(page: Page) -> Option<crate::shader_ui::Tab> {
-        match page {
-            Page::ShaderPacks => Some(crate::shader_ui::Tab::Packs),
-            Page::ShaderOptions => Some(crate::shader_ui::Tab::Screen(0)),
-            _ => None,
-        }
-    }
-    /// Where the controller screen opens for `page`, if it is one of its pages.
-    fn controller_page(page: Page) -> Option<crate::controller_ui::Page> {
-        match page {
-            Page::Controller => Some(crate::controller_ui::Page::General),
-            Page::PadBinds => Some(crate::controller_ui::Page::Bindings),
-            _ => None,
-        }
-    }
     /// Whether a video settings screen is open, Horizon's or vanilla's: the fullscreen mode
     /// waits for it to close, and Ctrl with the wheel steps the GUI scale.
     pub fn video_open(&self) -> bool {
         self.page() == Page::Video || Self::graphics_page(self.page()).is_some()
     }
-    /// Whether the controller screen is open: a controller button pressed now may bind.
-    pub fn controller_open(&self) -> bool {
-        Self::controller_page(self.page()).is_some()
-    }
     /// Where the graphics screen opens for `page`, if it is one of its pages.
     fn graphics_page(page: Page) -> Option<crate::graphics_ui::Page> {
         match page {
@@ -2369,6 +2308,9 @@ impl OptionsUi {
                 "options.videoTitle"
             }
             Page::Controller | Page::PadBinds => "horizon.pages.controller",
+            Page::ControllerRadial => "horizon.pages.controller_radial",
+            Page::ControllerRadialName => "horizon.radial.name_title",
+            Page::ControllerRadialPick => "horizon.radial.pick_title",
             Page::Extras => "horizon.pages.extras",
             Page::Pvp => "horizon.pages.pvp",
             Page::Credits => "credits_and_attribution.screen.title",
@@ -3602,6 +3544,9 @@ impl OptionsUi {
         }
         let waiting = self.waiting();
         let in_world = self.in_world;
+        if self.draw_radial_name(batch, atlas, cursor, in_world) {
+            return;
+        }
         if let Some(shell) = self.shell_mut() {
             shell.draw(s, batch, atlas, cursor, in_world, waiting);
             // The keys lay the screen out at the size it was drawn at.
@@ -3953,6 +3898,9 @@ impl OptionsUi {
             let outcome = c.click(&atlas.font, (x, y), size, drag);
             return self.calibration_outcome(s, outcome);
         }
+        if self.page() == Page::ControllerRadialName {
+            return self.click_radial_name(s, atlas, (x, y), size, drag || right);
+        }
         if self.shell().is_some() {
             // Waiting on a controller button: a click cancels the wait.
             if !drag && self.selected_pad_action.take().is_some() {
@@ -4648,6 +4596,8 @@ impl OptionsUi {
             self.scroll = 0.0;
         } else if self.page() == Page::SplitProfiles {
             self.split_profiles.type_text(text);
+        } else if self.page() == Page::ControllerRadialName {
+            self.type_radial_name(text);
         } else if let Some(shell) = self.shell_mut() {
             if shell.typing() {
                 shell.type_text(text);
@@ -4683,6 +4633,9 @@ impl OptionsUi {
         if self.page() == Page::SplitProfiles {
             return self.split_profiles.shortcut(shortcut, clipboard);
         }
+        if self.page() == Page::ControllerRadialName {
+            return self.radial_name_shortcut(shortcut, clipboard);
+        }
         if let Some(shell) = self.shell_mut() {
             return shell.shortcut(shortcut, clipboard);
         }
@@ -4786,6 +4739,9 @@ impl OptionsUi {
         if self.page() == Page::SplitProfiles && self.split_profiles.key(key, text) {
             return Vec::new();
         }
+        if self.page() == Page::ControllerRadialName {
+            return self.radial_name_key(s, key, text);
+        }
 
         // The size it was drawn at; before the first draw, one its keys can lay out at.
         let gui = if self.size.0 > 0.0 && self.size.1 > 0.0 {

crates/horizon-client-render/src/options_ui/shell_pages.rs

@@ -0,0 +1,302 @@
+//! The pages Options shows on the settings shell (`settings_shell`): which shell each page
+//! opens, what a shell's outputs do here, and the radial menu's pages (`radial_editor`), whose
+//! name entry is drawn here in place of a shell, and whose rows of Controller Settings step here.
+use super::{Event, OptionsUi, Page, tr};
+use crate::{
+    gamepad,
+    hud::{HudAtlas, HudBatch},
+    radial_editor::Named,
+    settings::{Opt, Settings},
+    settings_shell as shell,
+    text::Text,
+};
+
+impl OptionsUi {
+    /// The open page's screen on the settings shell. This, with `shell_mut`, is all a screen
+    /// needs here: drawing, clicks, the wheel, a stick's scrolling, keys and typing all go
+    /// through them, so no input path can miss one.
+    pub(super) fn shell(&self) -> Option<&dyn shell::Hosted> {
+        match self.page() {
+            Page::Extras => Some(&self.extras),
+            page if Self::graphics_page(page).is_some() => Some(&self.graphics),
+            Page::ControllerRadial => Some(&self.radial),
+            Page::ControllerRadialPick => Some(&self.radial_pick),
+            page if Self::controller_page(page).is_some() => Some(&self.controller),
+            page if Self::shader_page(page).is_some() => Some(&self.shader),
+            _ => None,
+        }
+    }
+    pub(super) fn shell_mut(&mut self) -> Option<&mut dyn shell::Hosted> {
+        self.graphics.screen.output = self.output;
+        match self.page() {
+            Page::Extras => Some(&mut self.extras),
+            page if Self::graphics_page(page).is_some() => Some(&mut self.graphics),
+            Page::ControllerRadial => Some(&mut self.radial),
+            Page::ControllerRadialPick => Some(&mut self.radial_pick),
+            page if Self::controller_page(page).is_some() => Some(&mut self.controller),
+            page if Self::shader_page(page).is_some() => Some(&mut self.shader),
+            _ => None,
+        }
+    }
+    /// Where the open shell screen asked the focus to open (a radial slot's list, on the slot's
+    /// action), for a controller's focus to land there.
+    pub fn shell_opened_focus(&self) -> Option<[f32; 4]> {
+        self.shell()?.opened_focus()
+    }
+    /// The clicks until it is set back are a controller's Left or Right on a row: a choice of a
+    /// settings shell steps, rather than opens.
+    pub fn pad_clicks_step(&mut self, on: bool) {
+        if on {
+            if let Some(shell) = self.shell_mut() {
+                shell.clicks_step(true);
+            }
+            return;
+        }
+        // Every shell: the click may have changed the page.
+        let shells: [&mut dyn shell::Hosted; 6] = [
+            &mut self.extras,
+            &mut self.graphics,
+            &mut self.controller,
+            &mut self.radial,
+            &mut self.radial_pick,
+            &mut self.shader,
+        ];
+        for shell in shells {
+            shell.clicks_step(false);
+        }
+    }
+    /// The controller's focus landed there.
+    pub fn clear_shell_opened_focus(&mut self) {
+        if let Some(shell) = self.shell_mut() {
+            shell.clear_opened_focus();
+        }
+    }
+    /// The window's size, for the graphics and controller screens' rows that step an option
+    /// (`Opt::cycle`, which a fullscreen resolution needs): before each input that can press one.
+    pub(super) fn shell_framebuffers(&mut self) {
+        self.graphics.screen.framebuffer = self.framebuffer;
+        self.controller.screen.framebuffer = self.framebuffer;
+    }
+    /// Who and what Controller Settings is about: the game sets it before each draw.
+    pub fn set_controller_context(&mut self, context: crate::controller_ui::Context) {
+        self.controller.screen.context = context;
+    }
+    /// The binding the screen waits on: a controller button's, else a key's.
+    pub(super) fn waiting(&self) -> Option<shell::Capture> {
+        let pad = self.selected_pad_action.map(shell::Capture::Pad);
+        pad.or(self.selected_key.map(shell::Capture::Key))
+    }
+    /// What a shell screen's outputs do to these options.
+    pub(super) fn shell_events(
+        &mut self,
+        s: &mut Settings,
+        outputs: Vec<shell::Output>,
+    ) -> Vec<Event> {
+        let mut events = Vec::new();
+        for output in outputs {
+            match output {
+                shell::Output::Event(event) => events.push(event),
+                shell::Output::Bind(shell::Capture::Key(name)) => self.selected_key = Some(name),
+                shell::Output::Bind(shell::Capture::Pad(action)) => {
+                    self.selected_pad_action = Some(action)
+                }
+                shell::Output::Push(page) => {
+                    if page == Page::HdrCalibration {
+                        self.calibration =
+                            Some(crate::hdr_calibration::Calibration::new(s, &self.output));
+                    }
+                    self.push(page);
+                    // A slot's list, for the slot, opening on what it holds.
+                    if page == Page::ControllerRadialPick
+                        && let Some(at) = self.radial.screen.picking.take()
+                    {
+                        let row = self.radial_pick.screen.open_on(at, &s.controller.radial);
+                        self.radial_pick.focus_soon(row);
+                    }
+                }
+                shell::Output::Done => {
+                    // Back from a slot's list, the focus is on the slot.
+                    let slot = (self.page() == Page::ControllerRadialPick)
+                        .then(|| self.radial_pick.screen.at());
+                    events.extend(self.back(s));
+                    if let Some((page, slot)) = slot {
+                        self.radial
+                            .focus_soon(crate::radial_editor::RadialRow::Slot(page, slot));
+                    }
+                }
+            }
+        }
+        // A pick on a slot's list is a change of the radial page's, which its Undo takes back.
+        if self.radial_pick.screen.take_picked() {
+            self.radial.changed_elsewhere();
+        }
+        // A radial page added or deleted: the one to show now.
+        if let Some(page) = self.radial.screen.take_shown() {
+            self.radial.show(page);
+        }
+        events
+    }
+    /// What a press on a radial page's name does here.
+    pub(super) fn name_events(
+        &mut self,
+        named: crate::radial_editor::Named,
+        s: &mut Settings,
+    ) -> Vec<Event> {
+        use crate::radial_editor::Named;
+        let mut events = vec![Event::ButtonClick];
+        match named {
+            Named::Nothing => return Vec::new(),
+            Named::Done => {
+                let entry = self.radial.screen.naming.take();
+                if entry.is_some_and(|entry| entry.apply(&mut s.controller.radial)) {
+                    self.radial.changed_elsewhere();
+                }
+                events.push(Event::Changed);
+                events.extend(self.back(s));
+            }
+            Named::Back => events.extend(self.back(s)),
+        }
+        events
+    }
+    /// Where the shader screen opens for `page`, if it is one of its pages.
+    pub(super) fn shader_page(page: Page) -> Option<crate::shader_ui::Tab> {
+        match page {
+            Page::ShaderPacks => Some(crate::shader_ui::Tab::Packs),
+            Page::ShaderOptions => Some(crate::shader_ui::Tab::Screen(0)),
+            _ => None,
+        }
+    }
+    /// Where the controller screen opens for `page`, if it is one of its pages.
+    pub(super) fn controller_page(page: Page) -> Option<crate::controller_ui::Page> {
+        match page {
+            Page::Controller => Some(crate::controller_ui::Page::General),
+            Page::PadBinds => Some(crate::controller_ui::Page::Bindings),
+            _ => None,
+        }
+    }
+    /// Whether the controller screen is open: a controller button pressed now may bind.
+    pub fn controller_open(&self) -> bool {
+        Self::controller_page(self.page()).is_some()
+    }
+    /// The radial screens' glyphs this frame, and the name of a radial page being typed, drawn
+    /// in place of a shell: whether it was.
+    pub(super) fn draw_radial_name(
+        &mut self,
+        batch: &mut HudBatch,
+        atlas: &HudAtlas,
+        cursor: (f32, f32),
+        in_world: bool,
+    ) -> bool {
+        self.radial.screen.glyphs = self.pad_glyphs;
+        if self.page() == Page::ControllerRadialName
+            && let Some(entry) = &mut self.radial.screen.naming
+        {
+            entry.draw(batch, atlas, cursor, in_world);
+            return true;
+        }
+        false
+    }
+    /// A click on a radial page's name entry (`ignored`: a drag or a right click).
+    pub(super) fn click_radial_name(
+        &mut self,
+        s: &mut Settings,
+        atlas: &HudAtlas,
+        at: (f32, f32),
+        size: (f32, f32),
+        ignored: bool,
+    ) -> Vec<Event> {
+        let entry = self.radial.screen.naming.as_mut();
+        let named = match entry.filter(|_| !ignored) {
+            Some(entry) => entry.click(atlas, at, size),
+            None => Named::Nothing,
+        };
+        self.name_events(named, s)
+    }
+    /// Whether a radial page's name is being typed.
+    pub(super) fn radial_name_typing(&self) -> bool {
+        self.radial
+            .screen
+            .naming
+            .as_ref()
+            .is_some_and(|n| n.typing())
+    }
+    /// Text typed into a radial page's name.
+    pub(super) fn type_radial_name(&mut self, text: &str) {
+        if let Some(entry) = &mut self.radial.screen.naming {
+            entry.type_text(text);
+        }
+    }
+    /// An edit shortcut in a radial page's name: whether it did something.
+    pub(super) fn radial_name_shortcut(
+        &mut self,
+        shortcut: crate::clipboard::EditShortcut,
+        clipboard: &mut dyn crate::clipboard::Clipboard,
+    ) -> bool {
+        let entry = self.radial.screen.naming.as_mut();
+        entry.is_some_and(|entry| entry.shortcut(shortcut, clipboard))
+    }
+    /// A key on a radial page's name entry.
+    pub(super) fn radial_name_key(
+        &mut self,
+        s: &mut Settings,
+        key: winit::keyboard::KeyCode,
+        text: Option<&str>,
+    ) -> Vec<Event> {
+        let named = match &mut self.radial.screen.naming {
+            Some(entry) => entry.key(key, text),
+            // Nothing to name: Escape still leaves.
+            None if key == winit::keyboard::KeyCode::Escape => Named::Back,
+            None => Named::Nothing,
+        };
+        self.name_events(named, s)
+    }
+}
+
+impl Opt {
+    /// The radial menu's rows of Controller Settings: their value.
+    pub(super) fn radial_text(self, s: &Settings) -> Text {
+        match self {
+            Opt::PadRadialMode => tr(match s.controller.radial_mode {
+                gamepad::RadialMode::Hold => "options.key.hold",
+                gamepad::RadialMode::Toggle => "options.key.toggle",
+            }),
+            Opt::PadRadialStick => tr(match s.controller.radial_stick {
+                gamepad::RadialStick::Right => "horizon.options.radial_stick.right",
+                gamepad::RadialStick::Left => "horizon.options.radial_stick.left",
+                gamepad::RadialStick::Either => "horizon.options.radial_stick.either",
+            }),
+            _ => Text::empty(),
+        }
+    }
+    /// The radial menu's rows of Controller Settings: a step, back or on.
+    pub(super) fn radial_step(self, s: &mut Settings, back: bool) {
+        let next = |n: u8, count: u8| {
+            if back {
+                (n + count - 1) % count
+            } else {
+                (n + 1) % count
+            }
+        };
+        match self {
+            Opt::PadRadialMode => {
+                let all = gamepad::RadialMode::ALL;
+                let i = all
+                    .iter()
+                    .position(|m| *m == s.controller.radial_mode)
+                    .unwrap_or(0) as u8;
+                s.controller.radial_mode = all[usize::from(next(i, all.len() as u8))];
+            }
+            Opt::PadRadialStick => {
+                let all = gamepad::RadialStick::ALL;
+                let i = all
+                    .iter()
+                    .position(|k| *k == s.controller.radial_stick)
+                    .unwrap_or(0) as u8;
+                // An opener under the thumb that now selects goes unbound.
+                s.controller
+                    .set_radial_stick(all[usize::from(next(i, all.len() as u8))]);
+            }
+            _ => {}
+        }
+    }
+}

crates/horizon-client-render/src/options_ui_pages.rs

@@ -124,21 +124,15 @@ impl OptionsUi {
                 Some(open("horizon.pages.open.studio", Page::Studio)),
             ),
             // No AI hides the AI Agent page and everything AI.
-            Row::Buttons(
-                self.extra_button(s, crate::extras::Item::DiscordPresence),
-                Some(if s.extras.no_ai {
-                    self.extra_button(s, crate::extras::Item::NoAi)
-                } else {
-                    open("horizon.pages.open.agent", Page::Agent)
-                }),
-            ),
-        ]
-        .into_iter()
-        .chain(
-            (!s.extras.no_ai)
-                .then(|| Row::Buttons(self.extra_button(s, crate::extras::Item::NoAi), None)),
-        )
-        .collect();
+            if s.extras.no_ai {
+                Row::Buttons(self.extra_button(s, crate::extras::Item::NoAi), None)
+            } else {
+                Row::Buttons(
+                    open("horizon.pages.open.agent", Page::Agent),
+                    Some(self.extra_button(s, crate::extras::Item::NoAi)),
+                )
+            },
+        ];
         self.added_entries(&mut rows);
         rows
     }

crates/horizon-client-render/src/pack_formats/colors.rs

@@ -7,6 +7,14 @@ use horizon_polytone::colors::PackColors;
 use crate::block_entity_render::DYES;
 use crate::pack_palette::{self, Environment};
 
+fn fluid(fog: horizon_polytone::colors::FluidFog) -> pack_palette::FluidFog {
+    pack_palette::FluidFog {
+        color: fog.color,
+        radius: fog.radius,
+        fade: fog.fade,
+    }
+}
+
 /// The colours of every namespace's file under the pack overlay at `root`.
 pub fn read(root: &Path) -> pack_palette::PackColors {
     let colors = PackColors::read(root);
@@ -29,6 +37,10 @@ pub fn read(root: &Path) -> pack_palette::PackColors {
             water_fog_brightening_time: env.water_fog_brightening_time,
             horizon_height: env.horizon_height,
         },
+        fluid_fog: pack_palette::FluidFogs {
+            water: colors.fluid_fog.water.map(fluid),
+            lava: colors.fluid_fog.lava.map(fluid),
+        },
     }
 }
 

crates/horizon-client-render/src/pack_palette.rs

@@ -59,6 +59,24 @@ pub struct PackColors {
     pub xp_bar: [Option<u32>; 2],
     /// The effect fogs' settings: the fog reads them every frame.
     pub env: Environment,
+    /// The fog the packs' fluid modifiers give water and lava.
+    pub fluid_fog: FluidFogs,
+}
+
+/// A fluid modifier's fog: a flat colour (RGB), and the fog's radius and fade multipliers (1 is
+/// vanilla's).
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct FluidFog {
+    pub color: Option<u32>,
+    pub radius: f32,
+    pub fade: f32,
+}
+
+/// The fog the packs' fluid modifiers give water and lava.
+#[derive(Clone, Copy, Debug, Default, PartialEq)]
+pub struct FluidFogs {
+    pub water: Option<FluidFog>,
+    pub lava: Option<FluidFog>,
 }
 
 impl Default for PackColors {
@@ -72,6 +90,7 @@ impl Default for PackColors {
             entity_shadows: true,
             xp_bar: [None; 2],
             env: Environment::default(),
+            fluid_fog: FluidFogs::default(),
         }
     }
 }

crates/horizon-client-render/src/pack_screen.rs

@@ -368,6 +368,57 @@ pub struct PackScreen {
     browser_search: TextField,
     /// The browser's search box has the keyboard.
     browser_focus: bool,
+    /// Which atlas slot holds which icon, kept from one frame to the next
+    /// ([`PackScreen::bind_icons`]).
+    icon_slots: std::cell::RefCell<IconSlots>,
+}
+
+/// The atlas's pack icon slots and the icon each holds. The atlas keeps what is
+/// written into a slot, so an icon is sent once, when it takes a slot, and not
+/// again every frame it is drawn.
+#[derive(Clone, Debug, Default)]
+struct IconSlots {
+    /// The atlas the pixels went into ([`HudAtlas::revision`]); a new atlas holds none of them.
+    revision: u64,
+    /// Frames bound so far: an icon drawn in this one keeps its slot.
+    frame: u64,
+    /// Least recently drawn first: the icon's texture key, its slot, its pixels, and the
+    /// frame it was last drawn in.
+    held: Vec<(String, usize, Arc<[u8]>, u64)>,
+}
+
+impl IconSlots {
+    /// Starts a frame on `atlas`; an atlas that is not the one the slots were filled in empties them.
+    fn begin(&mut self, atlas: &HudAtlas) {
+        if self.revision != atlas.revision {
+            self.held.clear();
+            self.revision = atlas.revision;
+        }
+        self.frame += 1;
+    }
+
+    /// The slot for the icon drawn under `texture`, and whether its pixels have to be sent. A new
+    /// icon takes a free slot, else the slot of the icon drawn longest ago; none when every slot
+    /// holds an icon drawn in this frame, and that icon keeps `unknown_pack`.
+    fn slot_for(&mut self, texture: &str, icon: &Arc<[u8]>) -> Option<(usize, bool)> {
+        if let Some(at) = self.held.iter().position(|h| h.0 == texture) {
+            let mut kept = self.held.remove(at);
+            let same = Arc::ptr_eq(&kept.2, icon);
+            kept.2 = icon.clone();
+            kept.3 = self.frame;
+            let slot = kept.1;
+            self.held.push(kept);
+            return Some((slot, !same));
+        }
+        let slot = match (0..PACK_ICON_SLOTS).find(|i| !self.held.iter().any(|h| h.1 == *i)) {
+            Some(free) => free,
+            None if self.held.first().is_some_and(|h| h.3 < self.frame) => self.held.remove(0).1,
+            None => return None,
+        };
+        self.held
+            .push((texture.to_owned(), slot, icon.clone(), self.frame));
+        Some((slot, true))
+    }
 }
 
 fn tr(key: &str) -> Text {
@@ -459,6 +510,7 @@ impl PackScreen {
                 field
             },
             browser_focus: false,
+            icon_slots: Default::default(),
             changed: false,
         };
         s.reposition(m);
@@ -931,10 +983,13 @@ impl PackScreen {
         self.model.commit()
     }
     /// Points the icon blits of `draws` at the atlas's pack icon slots and
-    /// writes the icons into them, one slot per icon drawn (vanilla registers a
-    /// texture per pack). Icons past the last slot keep `unknown_pack`.
+    /// writes the icons into them (vanilla registers a texture per pack). An
+    /// icon keeps its slot from one frame to the next and is sent when it takes
+    /// the slot, not every frame; the slot of the icon drawn longest ago is
+    /// taken first. Icons past the last slot in one frame keep `unknown_pack`.
     pub fn bind_icons(&self, draws: &mut [Draw], atlas: &HudAtlas, patches: &mut Vec<Patch>) {
-        let mut slots = 0..PACK_ICON_SLOTS;
+        let mut slots = self.icon_slots.borrow_mut();
+        slots.begin(atlas);
         for draw in draws {
             let Draw::Blit { texture, .. } = draw else {
                 continue;
@@ -942,20 +997,23 @@ impl PackScreen {
             let Some(icon) = self.icons.get(texture.as_str()) else {
                 continue;
             };
-            let Some(slot) = slots.next() else {
-                return;
+            let Some((slot, send)) = slots.slot_for(texture, icon) else {
+                continue;
             };
             let sprite = format!("horizon/pack-icon{slot}");
             let Some(rect) = atlas.sprites.get(&sprite) else {
+                slots.held.pop();
                 return;
             };
-            patches.push(Patch {
-                x: (rect.u0 * atlas.width as f32).round() as u32,
-                y: (rect.v0 * atlas.height as f32).round() as u32,
-                width: PACK_ICON_SIZE,
-                height: PACK_ICON_SIZE,
-                rgba: icon.to_vec(),
-            });
+            if send {
+                patches.push(Patch {
+                    x: (rect.u0 * atlas.width as f32).round() as u32,
+                    y: (rect.v0 * atlas.height as f32).round() as u32,
+                    width: PACK_ICON_SIZE,
+                    height: PACK_ICON_SIZE,
+                    rgba: icon.to_vec(),
+                });
+            }
             *texture = sprite;
         }
     }
@@ -1618,6 +1676,12 @@ impl PackScreen {
                         let hover = hovered == Some(i)
                             && d::inside(mouse, bx, by, OPTIONS_SIZE, OPTIONS_SIZE);
                         Self::draw_options_button(out, bx, by, hover);
+                        // A control for a pad's crosshair to glide onto and its D-pad to hop to,
+                        // while the list shows it whole.
+                        let mark = crate::widgets::targets_mark();
+                        let size = OPTIONS_SIZE as f32;
+                        crate::widgets::target([bx as f32, by as f32, size, size]);
+                        crate::widgets::clip_targets(mark, l.y as f32, l.bottom() as f32);
                         if hover {
                             tooltip = Some(tr("horizon.pack.optionsInfo"));
                         }
@@ -1745,9 +1809,14 @@ mod icon_tests {
             .unwrap();
         assert_eq!(id, "file/Configurable");
         let (cx, cy) = (bx + OPTIONS_SIZE / 2, by + OPTIONS_SIZE / 2);
-        // Hovered, it explains itself.
+        // Hovered, it explains itself; a pad's crosshair reaches it as a control.
         let draws = screen.draw(&m, (cx, cy), 0, 0);
         assert!(draws.iter().any(|d| matches!(d, Draw::Tooltip { .. })));
+        crate::widgets::end_frame(crate::widgets::generation() + 1);
+        let size = OPTIONS_SIZE as f32;
+        let button = [bx as f32, by as f32, size, size];
+        let targets = crate::widgets::last_targets();
+        assert!(targets.iter().any(|t| t.rect == button), "{targets:?}");
         assert_eq!(
             screen.click(&m, cx as f64, cy as f64),
             Action::Options("file/Configurable".into())
@@ -2070,3 +2139,177 @@ mod footer_label_tests {
         assert_eq!(lang::code(), before, "the global language was left alone");
     }
 }
+
+#[cfg(test)]
+mod icon_slot_tests {
+    use super::*;
+
+    fn atlas() -> HudAtlas {
+        HudAtlas::build(std::path::Path::new("/nonexistent/horizon-test-assets")).unwrap()
+    }
+
+    /// `count` packs with an icon each, the pixels of icon `i` all `i`.
+    fn packs(count: usize) -> Vec<PackInfo> {
+        let side = PACK_ICON_SIZE as usize;
+        (0..count)
+            .map(|i| PackInfo {
+                id: format!("file/pack{i:03}"),
+                title: Text::literal(format!("pack{i:03}")),
+                description: Text::literal(""),
+                description_style: Style::default(),
+                source: Source::BuiltIn,
+                compat: Compat::Compatible,
+                icon: Some(vec![i as u8; side * side * 4].into()),
+                required: false,
+                position: Position::Top,
+                fixed: false,
+            })
+            .collect()
+    }
+
+    /// One frame as `options_ui` draws it: the calls, then the icons bound. The icons drawn
+    /// (their texture keys before binding), the textures after, and the patches sent.
+    fn frame(screen: &PackScreen, atlas: &HudAtlas) -> (Vec<String>, Vec<String>, Vec<Patch>) {
+        let m = Measure(&atlas.font);
+        let mut draws = screen.draw(&m, (0, 0), 0, 0);
+        let drawn: Vec<String> = draws
+            .iter()
+            .filter_map(|d| match d {
+                Draw::Blit { texture, .. } if screen.icons.contains_key(texture) => {
+                    Some(texture.clone())
+                }
+                _ => None,
+            })
+            .collect();
+        let mut patches = Vec::new();
+        screen.bind_icons(&mut draws, atlas, &mut patches);
+        let bound = draws
+            .iter()
+            .filter_map(|d| match d {
+                Draw::Blit { texture, .. } if texture.contains("pack-icon") => {
+                    Some(texture.clone())
+                }
+                _ => None,
+            })
+            .collect();
+        (drawn, bound, patches)
+    }
+
+    /// Only the available list has packs: one row of 36 for each of `count` icons fits in a
+    /// window `height` high.
+    fn screen(m: &Measure, count: usize, height: i32) -> PackScreen {
+        PackScreen::new(
+            m,
+            tr("resourcePack.title"),
+            480,
+            height,
+            false,
+            packs(count),
+            &[],
+        )
+    }
+
+    /// Every frame sent every drawn icon again (a 128 by 128 RGBA copy each) into the same
+    /// atlas, which keeps what it is given: an icon is sent when it takes a slot, once.
+    #[test]
+    fn an_icon_is_sent_once_and_not_every_frame() {
+        let atlas = atlas();
+        let screen = screen(&Measure(&atlas.font), 5, 400);
+        let (drawn, bound, patches) = frame(&screen, &atlas);
+        assert_eq!((drawn.len(), bound.len(), patches.len()), (5, 5, 5));
+        for again in 0..3 {
+            let (_, rebound, resent) = frame(&screen, &atlas);
+            assert_eq!(rebound, bound, "frame {again}");
+            assert_eq!(resent.len(), 0, "frame {again}");
+        }
+    }
+
+    /// More icons drawn in one frame than there are slots: the first 64 get one, the rest keep
+    /// `unknown_pack`, and the next frame does not move them or send anything.
+    #[test]
+    fn past_the_slots_in_one_frame_the_rest_keep_unknown_pack() {
+        let atlas = atlas();
+        let screen = screen(&Measure(&atlas.font), PACK_ICON_SLOTS + 6, 4000);
+        let (drawn, bound, patches) = frame(&screen, &atlas);
+        assert_eq!(
+            drawn.len(),
+            PACK_ICON_SLOTS + 6,
+            "the window shows every row"
+        );
+        assert_eq!(
+            (bound.len(), patches.len()),
+            (PACK_ICON_SLOTS, PACK_ICON_SLOTS)
+        );
+        let (_, rebound, resent) = frame(&screen, &atlas);
+        assert_eq!((rebound, resent.len()), (bound, 0));
+    }
+
+    /// Scrolling through more packs than slots: every icon drawn gets a slot, each one is sent
+    /// once on the way down, and a frame that draws what the last one drew sends nothing.
+    #[test]
+    fn scrolling_sends_only_the_icons_that_come_into_view() {
+        let atlas = atlas();
+        let m = Measure(&atlas.font);
+        let mut screen = screen(&m, 70, 330);
+        let mut seen = std::collections::HashSet::new();
+        let mut sent = 0;
+        // 150 wheel steps of 18 are more than the 2520 high list.
+        for step in 0..150 {
+            let (drawn, bound, patches) = frame(&screen, &atlas);
+            assert_eq!(bound.len(), drawn.len(), "step {step}: none falls back");
+            let new = drawn.iter().filter(|t| seen.insert((*t).clone())).count();
+            assert_eq!(patches.len(), new, "step {step}");
+            sent += patches.len();
+            assert_eq!(frame(&screen, &atlas).2.len(), 0, "step {step}: same view");
+            screen.scroll(100.0, 200.0, -1.0);
+        }
+        assert_eq!((seen.len(), sent), (70, 70));
+    }
+
+    /// The slot of the icon drawn longest ago is the one taken, and the icon that left it is
+    /// sent again when it comes back.
+    #[test]
+    fn the_icon_drawn_longest_ago_gives_up_its_slot() {
+        let icons: Vec<Arc<[u8]>> = packs(PACK_ICON_SLOTS + 1)
+            .into_iter()
+            .map(|p| p.icon.unwrap())
+            .collect();
+        let mut slots = IconSlots::default();
+        let key = |i: usize| format!("k{i}");
+        slots.begin(&atlas());
+        for i in 0..PACK_ICON_SLOTS {
+            assert_eq!(slots.slot_for(&key(i), &icons[i]), Some((i, true)));
+        }
+        // The next frame draws icon 0 first, then a new one: slot 1, the oldest left, is taken.
+        slots.frame += 1;
+        assert_eq!(slots.slot_for(&key(0), &icons[0]), Some((0, false)));
+        assert_eq!(
+            slots.slot_for("new", &icons[PACK_ICON_SLOTS]),
+            Some((1, true))
+        );
+        // Icon 1 comes back: it is sent again, into the slot of the next oldest.
+        assert_eq!(slots.slot_for(&key(1), &icons[1]), Some((2, true)));
+    }
+
+    /// New pixels under the same key take the same slot and are sent; a new atlas holds none
+    /// of the icons, so all are sent again.
+    #[test]
+    fn changed_pixels_and_a_new_atlas_send_again() {
+        let atlas = atlas();
+        let mut screen = screen(&Measure(&atlas.font), 3, 400);
+        let (_, bound, patches) = frame(&screen, &atlas);
+        assert_eq!(patches.len(), 3);
+        let key = icon_texture("file/pack001");
+        screen
+            .icons
+            .insert(key, vec![200; patches[1].rgba.len()].into());
+        let (_, rebound, resent) = frame(&screen, &atlas);
+        assert_eq!(rebound, bound);
+        assert_eq!(resent.len(), 1);
+        assert_eq!((resent[0].x, resent[0].y), (patches[1].x, patches[1].y));
+        assert_eq!(resent[0].rgba[0], 200);
+        let other = self::atlas();
+        assert_ne!(other.revision, atlas.revision);
+        assert_eq!(frame(&screen, &other).2.len(), 3);
+    }
+}

crates/horizon-client-render/src/packs.rs

@@ -466,6 +466,13 @@ fn read_meta(source: &Source) -> Option<serde_json::Value> {
 /// file with a comment after the closing brace. Gson reads past a UTF-8 byte order mark;
 /// serde_json rejects it.
 pub(crate) fn parse_meta(bytes: &[u8]) -> Option<serde_json::Value> {
+    first_json(bytes)
+}
+
+/// Reads the first JSON value from resource metadata, matching Gson's
+/// `JsonReader` (which ignores a trailing signature or comment). Resource
+/// packs commonly append such text to texture metadata as well as pack.mcmeta.
+pub(crate) fn first_json(bytes: &[u8]) -> Option<serde_json::Value> {
     serde_json::Deserializer::from_slice(bytes.strip_prefix(b"\xEF\xBB\xBF").unwrap_or(bytes))
         .into_iter()
         .next()?

crates/horizon-client-render/src/particles.rs

@@ -31,8 +31,10 @@ mod native;
 pub mod polytone;
 mod polytone_gpu;
 mod polytone_model;
+mod simple;
 mod spawn;
 pub use native::{ParticleController, ParticleUpdate};
+use simple::{PARALLEL_MIN, parallel_threads, sprite_from_age_in, tick_simple};
 
 /// `ParticleOptions` with the parameters of the option classes used here.
 #[derive(Clone, Debug)]
@@ -524,6 +526,8 @@ pub struct Particle {
     no_render: bool,
     /// Ticked once when created (`CritParticle` constructor).
     pre_tick: bool,
+    /// A Polytone particle with physics, which joins only where its box is clear of blocks.
+    spawn_check: bool,
     /// `Particle.random`: the particle's own generator (`RandomSource.create()`).
     random: LegacyRandom,
     controller: Option<Box<dyn native::Controller>>,
@@ -893,6 +897,7 @@ impl Particle {
             behaviour: Behaviour::Base,
             no_render: false,
             pre_tick: false,
+            spawn_check: false,
             frame_ticks: 0,
             random: LegacyRandom::new(0),
             controller: None,
@@ -1325,6 +1330,9 @@ pub struct ParticleEngine {
     /// A native mod's sprite sets, by namespaced particle name.
     mod_sets: HashMap<String, (u32, Option<ModBehaviour>)>,
     set_sprites: Vec<Vec<u32>>,
+    /// How many live particles it takes to tick them on several threads (`tick_all`), and how many threads.
+    parallel_min: usize,
+    parallel_threads: usize,
     /// Resource packs' Polytone custom particle types (#11486).
     polytone: Option<std::sync::Arc<polytone::Registry>>,
     /// Vanilla particle types a pack replaces with a custom one of the same id
@@ -1527,6 +1535,8 @@ impl ParticleEngine {
             sets: HashMap::new(),
             mod_sets: HashMap::new(),
             set_sprites: Vec::new(),
+            parallel_min: PARALLEL_MIN,
+            parallel_threads: parallel_threads(),
             polytone: None,
             polytone_overrides: HashMap::new(),
             polytone_gpu: Vec::new(),
@@ -1752,28 +1762,6 @@ impl ParticleEngine {
         particle.controller = Some(Box::new(controller));
         Some(particle)
     }
-    /// Sets (or clears) the resource packs' Polytone custom particle types.
-    pub fn set_polytone(&mut self, registry: Option<std::sync::Arc<polytone::Registry>>) {
-        let registry = registry.filter(|r| !r.is_empty());
-        let same = match (&self.polytone, &registry) {
-            (Some(a), Some(b)) => std::sync::Arc::ptr_eq(a, b),
-            (None, None) => true,
-            _ => false,
-        };
-        if !same {
-            self.polytone_gpu.clear();
-            self.polytone_overrides = registry
-                .iter()
-                .flat_map(|r| {
-                    ParticleType::ALL.iter().filter_map(|&ty| {
-                        let id = format!("minecraft:{}", ty.name());
-                        r.get(&id).is_some().then_some((ty, id))
-                    })
-                })
-                .collect();
-        }
-        self.polytone = registry;
-    }
     /// The quads the last render blends additively (`RenderPipelines` additive, src alpha and
     /// one), for the frame's additive pass.
     pub fn take_additive(&self) -> Vec<Vertex> {
@@ -2121,23 +2109,7 @@ impl ParticleEngine {
     }
     /// `SingleQuadParticle.setSpriteFromAge`.
     fn sprite_from_age(&self, p: &mut Particle) {
-        if p.removed {
-            return;
-        }
-        if let Some(set) = p.set {
-            // A sprite set's index can outlive the reload that rebuilt them.
-            let Some(sprites) = self.set_sprites.get(set as usize) else {
-                return;
-            };
-            let lifetime = p.lifetime.max(1);
-            let index = if p.frame_ticks > 0 {
-                (p.age.max(0) as i64 / i64::from(p.frame_ticks)) % sprites.len() as i64
-            } else {
-                (p.age.max(0) as i64 * (sprites.len() as i64 - 1) / i64::from(lifetime))
-                    .clamp(0, sprites.len() as i64 - 1)
-            };
-            p.sprite = Sprite::Index(sprites[index as usize]);
-        }
+        sprite_from_age_in(&self.set_sprites, p);
     }
     #[allow(clippy::too_many_lines)]
     /// `ParticleProvider.createParticle`: provider draws use the engine's
@@ -3630,13 +3602,14 @@ impl ParticleEngine {
         self.sprite_from_age(&mut q);
         q
     }
-    /// ClientLevel.createFireworks: a Starter (or poofs without explosions).
+    /// ClientLevel.createFireworks: a Starter (or poofs without explosions) with `playSound`.
     pub fn fireworks(
         &mut self,
         at: [f64; 3],
         v: [f64; 3],
         explosions: Vec<FireworkExplosion>,
         camera: [f64; 3],
+        play_sound: bool,
     ) {
         if explosions.is_empty() {
             for _ in 0..self.random.next_int_bound(3).unwrap_or(0) + 2 {
@@ -3660,17 +3633,17 @@ impl ParticleEngine {
             life: 0,
             lifetime,
             twinkle_delay: twinkle,
-            far,
+            sound: play_sound.then_some(far),
         });
     }
     fn tick_starters(&mut self) {
         for mut s in std::mem::take(&mut self.starters) {
-            if s.life == 0 {
+            if s.life == 0 && s.sound.is_some() {
                 let large = s.explosions.len() >= 3
                     || s.explosions
                         .iter()
                         .any(|e| e.shape == FireworkShape::LargeBall);
-                let sound = match (large, s.far) {
+                let sound = match (large, s.sound == Some(true)) {
                     (true, true) => "minecraft:entity.firework_rocket.large_blast_far",
                     (true, false) => "minecraft:entity.firework_rocket.large_blast",
                     (false, true) => "minecraft:entity.firework_rocket.blast_far",
@@ -3713,16 +3686,13 @@ impl ParticleEngine {
                     (c & 255) as f32 / 255.0,
                     ((c >> 24) & 255) as f32 / 255.0,
                 ];
-                self.create(
-                    &ParticleOptions::colored(ParticleType::Flash, rgba),
-                    s.at,
-                    [0.0; 3],
-                );
+                let flash = ParticleOptions::colored(ParticleType::Flash, rgba);
+                self.create(&flash, s.at, [0.0; 3]);
             }
             s.life += 1;
             if s.life > s.lifetime {
-                if s.twinkle_delay {
-                    let sound = if s.far {
+                if s.twinkle_delay && s.sound.is_some() {
+                    let sound = if s.sound == Some(true) {
                         "minecraft:entity.firework_rocket.twinkle_far"
                     } else {
                         "minecraft:entity.firework_rocket.twinkle"
@@ -3847,9 +3817,7 @@ impl ParticleEngine {
         self.emitters = emitters;
         let mut particles = std::mem::take(&mut self.particles);
         self.spawned_in_tick = Some(Vec::new());
-        for p in &mut particles {
-            self.tick_particle(p, level);
-        }
+        self.tick_all(&mut particles, level);
         particles.retain(|p| !p.removed);
         self.particles = particles;
         for (options, pos, velocity) in self.spawned_in_tick.take().unwrap_or_default() {
@@ -3857,6 +3825,9 @@ impl ParticleEngine {
         }
         let pending = std::mem::take(&mut self.pending);
         for mut p in pending {
+            if p.spawn_check && !polytone::unobstructed(level, p.bb) {
+                continue;
+            }
             if p.pre_tick {
                 p.pre_tick = false;
                 self.tick_particle(&mut p, level);
@@ -3954,7 +3925,15 @@ impl ParticleEngine {
     #[allow(clippy::too_many_lines)]
     fn tick_particle(&mut self, p: &mut Particle, level: &ParticleLevel) {
         match p.behaviour {
-            Behaviour::Base => p.base_tick(level),
+            Behaviour::Base
+            | Behaviour::Mod { .. }
+            | Behaviour::Animated
+            | Behaviour::Snowflake
+            | Behaviour::Crit
+            | Behaviour::Spark { .. } => {
+                let simple = tick_simple(&self.set_sprites, p, level);
+                self.finish_simple(p, simple);
+            }
             Behaviour::Controlled { .. } => {
                 if let Some(mut controller) = p.controller.take() {
                     let update = controller.tick(p, level);
@@ -3973,23 +3952,6 @@ impl ParticleEngine {
                     p.remove();
                 }
             }
-            Behaviour::Mod { size, alpha } => {
-                p.base_tick(level);
-                p.size = mod_curve(size, p.age, p.lifetime);
-                p.rgba[3] = mod_curve(alpha, p.age, p.lifetime);
-                self.sprite_from_age(p);
-            }
-            Behaviour::Animated => {
-                p.base_tick(level);
-                self.sprite_from_age(p);
-            }
-            Behaviour::Snowflake => {
-                p.base_tick(level);
-                self.sprite_from_age(p);
-                p.velocity[0] *= f64::from(0.95f32);
-                p.velocity[1] *= f64::from(0.9f32);
-                p.velocity[2] *= f64::from(0.95f32);
-            }
             Behaviour::Lava => {
                 p.base_tick(level);
                 if !p.removed && p.random.next_float() > p.age as f32 / p.lifetime as f32 {
@@ -4000,11 +3962,6 @@ impl ParticleEngine {
                     );
                 }
             }
-            Behaviour::Crit => {
-                p.base_tick(level);
-                p.rgba[1] *= 0.96;
-                p.rgba[2] *= 0.9;
-            }
             Behaviour::Drip {
                 fluid,
                 stage,
@@ -4475,27 +4432,6 @@ impl ParticleEngine {
                     }
                 }
             }
-            Behaviour::Spark {
-                fade,
-                trail,
-                twinkle,
-            } => {
-                p.base_tick(level);
-                self.sprite_from_age(p);
-                if p.age > p.lifetime / 2 {
-                    p.rgba[3] = 1.0 - (p.age as f32 - (p.lifetime / 2) as f32) / p.lifetime as f32;
-                    if let Some(f) = fade {
-                        for i in 0..3 {
-                            p.rgba[i] += (f[i] - p.rgba[i]) * 0.2;
-                        }
-                    }
-                }
-                if trail && p.age < p.lifetime / 2 && (p.age + p.lifetime) % 2 == 0 {
-                    let mut child = self.spark(p.position, [0.0; 3], p.rgba, fade, false, twinkle);
-                    child.age = child.lifetime / 2;
-                    self.pending.push(child);
-                }
-            }
             Behaviour::Spell { original_alpha } => {
                 p.base_tick(level);
                 self.sprite_from_age(p);
@@ -5100,7 +5036,9 @@ struct Starter {
     life: i32,
     lifetime: i32,
     twinkle_delay: bool,
-    far: bool,
+    /// `FireworkParticles.Starter.playSound`, with `isFarAwayFromCamera` when
+    /// it plays: `None` for a silent rocket.
+    sound: Option<bool>,
 }
 const STAR: [[f64; 2]; 6] = [
     [0.0, 1.0],

crates/horizon-client-render/src/particles/polytone.rs

@@ -774,7 +774,7 @@ impl Host for Ctx<'_, '_> {
                 // `r.noise(x, y)`: one simplex noise (named noises aren't read yet).
                 let mut coords = args.iter().filter(|v| !matches!(v, V::Str(_))).map(V::num);
                 let (x, y) = (coords.next().unwrap_or(0.0), coords.next().unwrap_or(0.0));
-                num(f64::from(crate::environment::polytone_noise().get2(x, y)))
+                num(crate::environment::polytone_noise().get(x, y))
             }
             (id, _) if id >= BLOCKS => {
                 let at = *self
@@ -801,6 +801,26 @@ impl Host for Ctx<'_, '_> {
             _ => Err(format!("{name} is not available here")),
         }
     }
+
+    /// A particle's own fields, as `particle_method` answers them.
+    fn field(&mut self, root: Root, field: horizon_polytone::expr::Field) -> Option<V> {
+        use horizon_polytone::expr::Field as F;
+        let Subject::Particle(p) = &self.subject else {
+            return None;
+        };
+        if root != Root::Object {
+            return None;
+        }
+        Some(V::Num(match field {
+            F::Age => f64::from(p.age),
+            F::Life => f64::from(p.lifetime),
+            F::Custom => *self.custom,
+            F::X => p.position[0],
+            F::Y => p.position[1],
+            F::Z => p.position[2],
+            F::Temperature | F::Downfall => return None,
+        }))
+    }
 }
 
 fn eval(program: &Program, ctx: &mut Ctx) -> Option<f64> {
@@ -1070,6 +1090,16 @@ const INITIALIZED: [&str; 13] = [
     "dz",
 ];
 
+/// Whether no block's collision shape overlaps `bb` (where the query fails, nothing does).
+pub(super) fn unobstructed(level: &ParticleLevel<'_>, bb: horizon_core::geometry::Aabb) -> bool {
+    let mut scene = crate::collisions::SceneCollisions {
+        world: level.world,
+        binding: level.collision,
+        subject: None,
+    };
+    scene.cells_without_collision(bb) || scene.unobstructed(bb).unwrap_or(true)
+}
+
 impl super::ParticleController for Controller {
     fn tick(&mut self, p: &mut Particle, level: &ParticleLevel<'_>) -> ParticleUpdate {
         let mut update = ParticleUpdate::default();
@@ -1300,6 +1330,10 @@ pub(super) fn make(
     particle.polytone_type =
         (def.limit.is_some() || def.exclusion_radius > 0.0).then(|| Arc::from(name));
     particle.bb = super::aabb_at(position, particle.bb_width, particle.bb_height);
+    // A particle with physics whose box starts inside a block's collision never joins the world:
+    // it is not drawn and none of its emitters run (measured on the mod: one spawned just under a
+    // block, where falling leaves start, never shows; one 0.01 clear of it does).
+    particle.spawn_check = def.has_physics;
     particle.controller = Some(Box::new(Controller {
         def: def.clone(),
         registry: registry.clone(),
@@ -1511,6 +1545,31 @@ impl ParticleEngine {
     }
 }
 
+impl ParticleEngine {
+    /// Sets (or clears) the resource packs' Polytone custom particle types.
+    pub fn set_polytone(&mut self, registry: Option<Arc<Registry>>) {
+        let registry = registry.filter(|r| !r.is_empty());
+        let same = match (&self.polytone, &registry) {
+            (Some(a), Some(b)) => Arc::ptr_eq(a, b),
+            (None, None) => true,
+            _ => false,
+        };
+        if !same {
+            self.polytone_gpu.clear();
+            self.polytone_overrides = registry
+                .iter()
+                .flat_map(|r| {
+                    ParticleType::ALL.iter().filter_map(|&ty| {
+                        let id = format!("minecraft:{}", ty.name());
+                        r.get(&id).is_some().then_some((ty, id))
+                    })
+                })
+                .collect();
+        }
+        self.polytone = registry;
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -2224,6 +2283,144 @@ mod tests {
         std::fs::remove_dir_all(root).unwrap();
     }
 
+    /// `scene`, with the torch a full block of collision: something a particle's box can start in.
+    fn solid_scene(blocks: &'static BlockRegistry) -> Scene {
+        use horizon_core::geometry::{Axis, VoxelShape};
+        let tag = |shape: VoxelShape| {
+            let sizes = shape.sizes();
+            let occupied = (0..sizes[2])
+                .flat_map(|z| {
+                    (0..sizes[1]).flat_map(move |y| (0..sizes[0]).map(move |x| (x, y, z)))
+                })
+                .map(|(x, y, z)| u8::from(shape.is_full(x as i32, y as i32, z as i32)))
+                .collect();
+            let (min, max) = shape.discrete_bounds();
+            let axes = shape
+                .cube_coordinate_axes()
+                .iter()
+                .enumerate()
+                .fold(0, |mask, (i, on)| mask | (i8::from(*on) << i));
+            let mut fields = vec![
+                ("occupied", Tag::ByteArray(occupied)),
+                ("cube", Tag::Byte(i8::from(shape.is_cube()))),
+                ("cube_axes", Tag::Byte(axes)),
+                ("discrete_min", Tag::IntArray(min.to_vec())),
+                ("discrete_max", Tag::IntArray(max.to_vec())),
+            ];
+            for (axis, name) in [(Axis::X, "x"), (Axis::Y, "y"), (Axis::Z, "z")] {
+                let bits = shape.coordinates(axis).iter().map(|v| v.to_bits() as i64);
+                fields.push((name, Tag::LongArray(bits.collect())));
+            }
+            Tag::compound(fields)
+        };
+        let names = || Tag::List(STATES.iter().map(|s| Tag::String((*s).into())).collect());
+        let cached = CachedCollisionRegistry::from_nbt(
+            &Tag::compound([
+                ("DataVersion", Tag::Int(DATA_VERSION)),
+                ("states", names()),
+                (
+                    "shapes",
+                    Tag::List(vec![tag(VoxelShape::empty()), tag(VoxelShape::block())]),
+                ),
+                ("cached_shapes", Tag::IntArray(vec![0, 1])),
+            ]),
+            blocks,
+        )
+        .unwrap();
+        Scene {
+            collision: BlockCollisionRegistry::new(Arc::new(cached)).unwrap(),
+            ..scene(blocks)
+        }
+    }
+
+    #[test]
+    fn a_particle_with_physics_born_inside_a_block_never_joins() {
+        let blocks = blocks();
+        let leaf = |physics| {
+            serde_json::json!({"has_physics": physics, "render_type": "invisible",
+                "initializer": {"lifetime": "20", "hitbox_size": "0.08"},
+                "particle_emitters": [{"particle": "test:mark", "chance": "1"}]})
+        };
+        let root = pack(&[
+            (
+                "assets/test/polytone/custom_particles/leaf.json",
+                leaf(true),
+            ),
+            (
+                "assets/test/polytone/custom_particles/ghost.json",
+                leaf(false),
+            ),
+            (
+                "assets/test/polytone/custom_particles/mark.json",
+                serde_json::json!({"render_type": "invisible", "has_physics": false}),
+            ),
+            (
+                "assets/minecraft/polytone/entity_modifiers/player.json",
+                serde_json::json!({"emitters": [{"particle": "test:leaf", "chance": "1"}]}),
+            ),
+            (
+                "assets/test/polytone/custom_particles/wide.json",
+                serde_json::json!({"has_physics": true, "render_type": "invisible",
+                    "initializer": {"lifetime": "20", "hitbox_size": 10},
+                    "particle_emitters": [{"particle": "test:mark", "chance": "1"}]}),
+            ),
+            (
+                "assets/test/polytone/custom_particles/parent.json",
+                serde_json::json!({"has_physics": true, "render_type": "invisible",
+                    "initializer": {"lifetime": "20", "hitbox_size": "0.08"},
+                    "particle_emitters": [{"particle": "test:wide", "chance": "1", "y": "-0.05"}]}),
+            ),
+            (
+                "assets/minecraft/polytone/entity_modifiers/skeleton.json",
+                serde_json::json!({"emitters": [{"particle": "test:parent", "chance": "1", "x": "-4.5"}]}),
+            ),
+            (
+                "assets/minecraft/polytone/entity_modifiers/creeper.json",
+                serde_json::json!({"emitters": [{"particle": "test:wide", "chance": "1", "x": "-4.5"}]}),
+            ),
+            (
+                "assets/minecraft/polytone/entity_modifiers/zombie.json",
+                serde_json::json!({"emitters": [{"particle": "test:ghost", "chance": "1"}]}),
+            ),
+        ]);
+        let scene = solid_scene(blocks);
+        let level = ParticleLevel {
+            world: &scene.world,
+            facts: &scene.facts,
+            collision: &scene.collision,
+            player: None,
+            cached_chunk: std::cell::Cell::new(None),
+        };
+        let mut engine = engine(Registry::read(&root, Default::default(), blocks));
+        // The solid block is at (1, 64, 1): its bottom face is y 64.
+        // Spawns one particle, lets the engine take it in and tick it: whether it joined, and
+        // how many particles it emitted.
+        let mut spawn = |entity: &str, y: f64| {
+            engine.particles.clear();
+            engine.pending.clear();
+            engine.polytone_entity(&level, entity, [1.5, y, 1.5]);
+            engine.tick(&level);
+            let joined = engine.particles.len();
+            engine.tick(&level);
+            (
+                joined,
+                engine.particles.len() + engine.pending.len() - joined,
+            )
+        };
+        // The solid block is at (1, 64, 1): its bottom face is y 64.
+        // 0.05 under the block, a 0.08 box reaches into it: it never joins, nothing emitted.
+        assert_eq!(spawn("minecraft:player", 63.95), (0, 0));
+        // 0.01 clear of it, it joins and emits.
+        assert_eq!(spawn("minecraft:player", 63.91), (1, 1));
+        // Without physics nothing collides.
+        assert_eq!(spawn("minecraft:zombie", 63.95), (1, 1));
+        // A wide box reaching a block from five blocks away does not join either.
+        assert_eq!(spawn("minecraft:creeper", 60.0), (0, 0));
+        // Nor does one a clear particle emits there: the small one joins, its wide copy never.
+        assert_eq!(spawn("minecraft:skeleton", 60.0), (1, 0));
+        std::fs::remove_dir_all(root).unwrap();
+    }
+
     #[test]
     fn a_pack_custom_particle_replaces_the_vanilla_type_of_its_id() {
         let root = pack(&[(

crates/horizon-client-render/src/particles/simple.rs

@@ -0,0 +1,161 @@
+//! The particles that tick on their own (`tick_simple`): the behaviours that read and write only
+//! their own particle, the world and the sprite sets, which `ParticleEngine::tick_all` runs on several
+//! threads in a busy scene.
+use super::{Behaviour, Particle, ParticleEngine, ParticleLevel, Sprite, mod_curve};
+
+/// The live particles it takes before `tick_all` uses more than one thread: a scoped thread costs
+/// tens of microseconds to start and join, and a simple particle about a tenth of one.
+pub(super) const PARALLEL_MIN: usize = 2048;
+/// Threads for ticking particles: half the machine's workers, at most four (the chunk workers and
+/// the render thread need cores too); `HORIZON_WORKER_THREADS` caps them as it does every pool.
+pub(super) fn parallel_threads() -> usize {
+    (horizon_threads::worker_count() / 2).clamp(1, 4)
+}
+pub(super) fn sprite_from_age_in(set_sprites: &[Vec<u32>], p: &mut Particle) {
+    if p.removed {
+        return;
+    }
+    if let Some(set) = p.set {
+        // A sprite set's index can outlive the reload that rebuilt them.
+        let Some(sprites) = set_sprites.get(set as usize) else {
+            return;
+        };
+        let lifetime = p.lifetime.max(1);
+        let index = if p.frame_ticks > 0 {
+            (p.age.max(0) as i64 / i64::from(p.frame_ticks)) % sprites.len() as i64
+        } else {
+            (p.age.max(0) as i64 * (sprites.len() as i64 - 1) / i64::from(lifetime))
+                .clamp(0, sprites.len() as i64 - 1)
+        };
+        p.sprite = Sprite::Index(sprites[index as usize]);
+    }
+}
+/// The tick of the behaviours that read and write only their own particle, the world and the engine's
+/// sprite sets: no particle spawned, no sound, nothing drawn from the engine's random. Those are the
+/// bulk of a busy scene (flames, smoke, poofs, dust, crits), and `ParticleEngine::tick` runs them on
+/// several threads. Any other behaviour is left alone, for `ParticleEngine::tick_particle`.
+pub(super) fn tick_simple(
+    set_sprites: &[Vec<u32>],
+    p: &mut Particle,
+    level: &ParticleLevel,
+) -> Simple {
+    match p.behaviour {
+        Behaviour::Base => p.base_tick(level),
+        Behaviour::Mod { size, alpha } => {
+            p.base_tick(level);
+            p.size = mod_curve(size, p.age, p.lifetime);
+            p.rgba[3] = mod_curve(alpha, p.age, p.lifetime);
+            sprite_from_age_in(set_sprites, p);
+        }
+        Behaviour::Animated => {
+            p.base_tick(level);
+            sprite_from_age_in(set_sprites, p);
+        }
+        Behaviour::Snowflake => {
+            p.base_tick(level);
+            sprite_from_age_in(set_sprites, p);
+            p.velocity[0] *= f64::from(0.95f32);
+            p.velocity[1] *= f64::from(0.9f32);
+            p.velocity[2] *= f64::from(0.95f32);
+        }
+        Behaviour::Crit => {
+            p.base_tick(level);
+            p.rgba[1] *= 0.96;
+            p.rgba[2] *= 0.9;
+        }
+        Behaviour::Spark { fade, trail, .. } => {
+            p.base_tick(level);
+            sprite_from_age_in(set_sprites, p);
+            if p.age > p.lifetime / 2 {
+                p.rgba[3] = 1.0 - (p.age as f32 - (p.lifetime / 2) as f32) / p.lifetime as f32;
+                if let Some(f) = fade {
+                    for i in 0..3 {
+                        p.rgba[i] += (f[i] - p.rgba[i]) * 0.2;
+                    }
+                }
+            }
+            if trail && p.age < p.lifetime / 2 && (p.age + p.lifetime) % 2 == 0 {
+                return Simple::SparkTrail;
+            }
+        }
+        _ => return Simple::No,
+    }
+    Simple::Done
+}
+/// The same world with a one-chunk lookup cache of its own, for a worker thread.
+///
+/// `ParticleLevel::cached_chunk` is a `Cell`, which a level shared between threads may not hold:
+/// each thread gets a view with an empty cache, built here on the engine thread and moved in. A
+/// cache they shared could not hold "the last chunk looked up" for any one of them in any case.
+fn thread_view<'a>(level: &ParticleLevel<'a>) -> ParticleLevel<'a> {
+    ParticleLevel {
+        world: level.world,
+        facts: level.facts,
+        collision: level.collision,
+        player: level.player,
+        cached_chunk: std::cell::Cell::new(None),
+    }
+}
+/// What `tick_simple` did with a particle.
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub(super) enum Simple {
+    /// Not one of its behaviours: the engine ticks it.
+    No,
+    /// Ticked completely.
+    Done,
+    /// Ticked, except that a firework spark's trail wants a child. Only the engine can make one:
+    /// it takes the next seed, so the children come in the order the sparks have.
+    SparkTrail,
+}
+impl ParticleEngine {
+    /// What `tick_simple` leaves to the engine: a spark's trail child.
+    pub(super) fn finish_simple(&mut self, p: &Particle, simple: Simple) {
+        if simple != Simple::SparkTrail {
+            return;
+        }
+        if let Behaviour::Spark { fade, twinkle, .. } = p.behaviour {
+            let mut child = self.spark(p.position, [0.0; 3], p.rgba, fade, false, twinkle);
+            child.age = child.lifetime / 2;
+            self.pending.push(child);
+        }
+    }
+    /// One tick of every live particle. The ones `tick_simple` covers are independent of each
+    /// other and of the engine, so with enough of them they tick on several threads; every other
+    /// one then ticks here, in the order it had, so the particles, the engine's random and what
+    /// is spawned come out as when all of them ticked one after another.
+    pub(super) fn tick_all(&mut self, particles: &mut [Particle], level: &ParticleLevel) {
+        if particles.is_empty() || particles.len() < self.parallel_min || self.parallel_threads < 2
+        {
+            for p in particles {
+                self.tick_particle(p, level);
+            }
+            return;
+        }
+        let sets = &self.set_sprites;
+        let per = particles.len().div_ceil(self.parallel_threads);
+        let mut handled = vec![Simple::No; particles.len()];
+        std::thread::scope(|scope| {
+            let run = |part: &mut [Particle], done: &mut [Simple], level: &ParticleLevel| {
+                for (p, done) in part.iter_mut().zip(done) {
+                    *done = tick_simple(sets, p, level);
+                }
+            };
+            let mut parts = particles.chunks_mut(per).zip(handled.chunks_mut(per));
+            let own = parts.next();
+            for (part, done) in parts {
+                let view = thread_view(level);
+                scope.spawn(move || run(part, done, &view));
+            }
+            // This thread takes the first share, instead of waiting for the others.
+            if let Some((part, done)) = own {
+                run(part, done, level);
+            }
+        });
+        for (p, done) in particles.iter_mut().zip(handled) {
+            match done {
+                Simple::No => self.tick_particle(p, level),
+                simple => self.finish_simple(p, simple),
+            }
+        }
+    }
+}

crates/horizon-client-render/src/particles/tick_bench.rs

@@ -1,8 +1,12 @@
-//! The particle stress scene's load on `ParticleEngine`, outside the game: `cargo test --profile fast
-//! -p horizon-client-render --lib particle_tick_cost -- --ignored --nocapture` (prepared resources;
-//! `PARTICLE_BENCH_SECS` sets the run, default 5). It spawns what tools/stress_scenes.py's `particles`
-//! scene makes each tick (flames, cosy smoke, end rods, TNT debris) over its stone floor and times the
-//! spawns and the engine tick apart, once the engine holds as many particles as it will.
+//! The particle stress scene's load on `ParticleEngine`, outside the game.
+//!
+//! - `parallel_tick_matches_serial_tick`: the engine ticking on several threads (`tick_all`) leaves
+//!   every particle, the engine's random and its sounds exactly as ticking them one after another.
+//! - `particle_tick_cost` (`cargo test --profile fast -p horizon-client-render --lib
+//!   particle_tick_cost -- --ignored --nocapture`, prepared resources; `PARTICLE_BENCH_SECS` sets
+//!   the run, default 2): spawns what tools/stress_scenes.py's `particles` scene makes each tick
+//!   (flames, cosy smoke, end rods, TNT debris, rockets) over its stone floor and times the spawns
+//!   and the engine tick apart, once the engine holds as many particles as it will.
 use super::*;
 use crate::{blocks::BlockFacts, chunk::Chunk, collisions, world::World};
 use std::sync::Arc;
@@ -25,6 +29,7 @@ impl Lcg {
     }
 }
 
+/// What to spawn each tick: a type, how many, around where, how far, how fast.
 type Emitter = (ParticleType, usize, [f64; 3], [f64; 3], f64);
 
 fn spawn_tick(engine: &mut ParticleEngine, rng: &mut Lcg, types: &[Emitter], rockets: usize) {
@@ -38,7 +43,7 @@ fn spawn_tick(engine: &mut ParticleEngine, rng: &mut Lcg, types: &[Emitter], roc
             twinkle: false,
         };
         let at = [-5.5 + rng.next() * 12.0, f64::from(FLOOR_Y + 20), 20.5];
-        engine.fireworks(at, [0.0, 0.1, 0.0], vec![explosion], engine.camera);
+        engine.fireworks(at, [0.0, 0.1, 0.0], vec![explosion], engine.camera, true);
     }
     for &(ty, count, center, delta, speed) in types {
         let options = ParticleOptions::simple(ty);
@@ -58,9 +63,29 @@ fn spawn_tick(engine: &mut ParticleEngine, rng: &mut Lcg, types: &[Emitter], roc
     }
 }
 
-#[test]
-#[ignore = "a measurement, not a check"]
-fn particle_tick_cost() {
+/// The scene's emitters, per tick: flames, cosy smoke, end rods, and TNT's debris (poof and smoke).
+fn emitters() -> [Emitter; 5] {
+    let ty = |name: &str| ParticleType::from_name(name).unwrap();
+    let (fx, fy, fz) = (0.5, f64::from(FLOOR_Y + 5), 20.5);
+    let tnt = [0.5, f64::from(FLOOR_Y + 24), 26.5];
+    [
+        (ty("flame"), 320, [fx, fy, fz], [8.0, 4.0, 8.0], 0.01),
+        (
+            ty("campfire_cosy_smoke"),
+            8,
+            [fx, fy, fz],
+            [8.0, 4.0, 8.0],
+            0.0,
+        ),
+        (ty("end_rod"), 80, [fx, fy, fz], [8.0, 4.0, 8.0], 0.05),
+        (ty("poof"), 258, tnt, [3.0, 3.0, 3.0], 0.4),
+        (ty("smoke"), 238, tnt, [3.0, 3.0, 3.0], 0.4),
+    ]
+}
+
+/// Runs `f` over the stress scene's world (a stone floor at y 289 under the particles). Skipped
+/// without prepared resources.
+fn with_scene(f: impl FnOnce(&ParticleLevel)) {
     let root = Path::new(env!("CARGO_MANIFEST_DIR"))
         .join("../../.local/horizon-client")
         .join(horizon_core::VANILLA_VERSION);
@@ -88,69 +113,127 @@ fn particle_tick_cost() {
             world.set(x, FLOOR_Y, z, floor).unwrap();
         }
     }
-    let level = ParticleLevel {
+    f(&ParticleLevel {
         world: &world,
         facts: &facts,
         collision: &collision,
         player: None,
         cached_chunk: std::cell::Cell::new(None),
-    };
-    let ty = |name: &str| ParticleType::from_name(name).unwrap();
-    let (fx, fy, fz) = (0.5, f64::from(FLOOR_Y + 5), 20.5);
-    let tnt = [0.5, f64::from(FLOOR_Y + 24), 26.5];
-    // The scene's emitters, per tick, and TNT's debris (poof and smoke).
-    let flame: Emitter = (ty("flame"), 320, [fx, fy, fz], [8.0, 4.0, 8.0], 0.01);
-    let cosy: Emitter = (
-        ty("campfire_cosy_smoke"),
-        8,
-        [fx, fy, fz],
-        [8.0, 4.0, 8.0],
-        0.0,
+    });
+}
+
+fn engine(parallel_min: usize, threads: usize) -> ParticleEngine {
+    let mut engine = ParticleEngine::new(Path::new(""), &HashMap::new(), &HashSet::new());
+    engine.camera = [0.5, 298.0, 0.5];
+    engine.parallel_min = parallel_min;
+    engine.parallel_threads = threads;
+    engine
+}
+
+/// Every live particle's fields, as text.
+fn state(engine: &ParticleEngine) -> Vec<String> {
+    engine
+        .particles
+        .iter()
+        .map(|p| format!("{:?}", engine.snapshot(p)))
+        .collect()
+}
+
+#[test]
+fn parallel_tick_matches_serial_tick() {
+    with_scene(|level| {
+        let types = emitters();
+        // One engine ticks every particle in turn; the other on three threads. Same seeds, same spawns.
+        let mut serial = engine(usize::MAX, 1);
+        let mut threaded = engine(0, 3);
+        for e in [&mut serial, &mut threaded] {
+            e.seed_randoms(7, 8, 9);
+        }
+        let (mut a, mut b) = (Lcg(99), Lcg(99));
+        for tick in 0..90 {
+            spawn_tick(&mut serial, &mut a, &types, 3);
+            spawn_tick(&mut threaded, &mut b, &types, 3);
+            serial.tick(level);
+            threaded.tick(level);
+            assert_eq!(serial.len(), threaded.len(), "tick {tick}");
+            if tick % 10 == 9 {
+                assert_eq!(state(&serial), state(&threaded), "tick {tick}");
+            }
+        }
+        assert!(serial.len() > 1000, "{} particles", serial.len());
+        assert_eq!(serial.sounds.len(), threaded.sounds.len());
+        assert_eq!(serial.next_randoms(), threaded.next_randoms());
+    });
+}
+
+/// Spawns and ticks `types` once the engine is full, for `secs`, and prints the cost per tick.
+fn measure(
+    level: &ParticleLevel,
+    name: &str,
+    (types, rockets): (&[Emitter], usize),
+    (parallel_min, threads): (usize, usize),
+    secs: f64,
+) {
+    let mut engine = engine(parallel_min, threads);
+    let mut rng = Lcg(1234);
+    for _ in 0..600 {
+        spawn_tick(&mut engine, &mut rng, types, rockets);
+        engine.tick(level);
+    }
+    let (mut spawn, mut tick, mut ticks, mut alive) =
+        (Duration::ZERO, Duration::ZERO, 0u64, 0usize);
+    let end = Instant::now() + Duration::from_secs_f64(secs);
+    while Instant::now() < end {
+        let t = Instant::now();
+        spawn_tick(&mut engine, &mut rng, types, rockets);
+        spawn += t.elapsed();
+        let t = Instant::now();
+        engine.tick(level);
+        tick += t.elapsed();
+        alive += engine.len();
+        ticks += 1;
+    }
+    let per = |d: Duration| d.as_secs_f64() * 1000.0 / ticks as f64;
+    let alive = alive / ticks as usize;
+    eprintln!(
+        "{name:24} alive {alive:6} | per tick: spawn {:6.3} ms, engine tick {:6.3} ms | {:5.0} ns per particle",
+        per(spawn),
+        per(tick),
+        per(tick) * 1.0e6 / alive.max(1) as f64
     );
-    let rod: Emitter = (ty("end_rod"), 80, [fx, fy, fz], [8.0, 4.0, 8.0], 0.05);
-    let poof: Emitter = (ty("poof"), 258, tnt, [3.0, 3.0, 3.0], 0.4);
-    let smoke: Emitter = (ty("smoke"), 238, tnt, [3.0, 3.0, 3.0], 0.4);
-    let cases: [(&str, Vec<Emitter>, usize); 7] = [
-        ("flame 320/tick", vec![flame], 0),
-        ("cosy smoke 8/tick", vec![cosy], 0),
-        ("end rod 80/tick", vec![rod], 0),
-        ("poof 258/tick", vec![poof], 0),
-        ("smoke 238/tick", vec![smoke], 0),
-        ("3 rockets/tick", vec![], 3),
-        ("the whole scene", vec![flame, cosy, rod, poof, smoke], 3),
-    ];
-    let secs: f64 = std::env::var("PARTICLE_BENCH_SECS")
-        .ok()
-        .and_then(|s| s.parse().ok())
-        .unwrap_or(2.0);
-    for (name, types, rockets) in cases {
-        let mut engine = ParticleEngine::new(Path::new(""), &HashMap::new(), &HashSet::new());
-        engine.camera = [0.5, 298.0, 0.5];
-        let mut rng = Lcg(1234);
-        for _ in 0..600 {
-            spawn_tick(&mut engine, &mut rng, &types, rockets);
-            engine.tick(&level);
+}
+
+#[test]
+#[ignore = "a measurement, not a check"]
+fn particle_tick_cost() {
+    with_scene(|level| {
+        let [flame, cosy, rod, poof, smoke] = emitters();
+        let all = [flame, cosy, rod, poof, smoke];
+        let secs: f64 = std::env::var("PARTICLE_BENCH_SECS")
+            .ok()
+            .and_then(|s| s.parse().ok())
+            .unwrap_or(2.0);
+        let one = (usize::MAX, 1);
+        eprintln!("default threads: {}", parallel_threads());
+        for (name, types, rockets) in [
+            ("flame 320/tick", vec![flame], 0),
+            ("cosy smoke 8/tick", vec![cosy], 0),
+            ("end rod 80/tick", vec![rod], 0),
+            ("poof 258/tick", vec![poof], 0),
+            ("smoke 238/tick", vec![smoke], 0),
+            ("3 rockets/tick", vec![], 3),
+        ] {
+            measure(level, name, (&types, rockets), one, secs);
         }
-        let (mut spawn, mut tick, mut ticks, mut alive) =
-            (Duration::ZERO, Duration::ZERO, 0u64, 0usize);
-        let end = Instant::now() + Duration::from_secs_f64(secs);
-        while Instant::now() < end {
-            let t = Instant::now();
-            spawn_tick(&mut engine, &mut rng, &types, rockets);
-            spawn += t.elapsed();
-            let t = Instant::now();
-            engine.tick(&level);
-            tick += t.elapsed();
-            alive += engine.len();
-            ticks += 1;
+        measure(level, "whole scene, 1 thread", (&all, 3), one, secs);
+        for threads in [2, 3, 4, 6] {
+            measure(
+                level,
+                &format!("whole scene, {threads} threads"),
+                (&all, 3),
+                (PARALLEL_MIN, threads),
+                secs,
+            );
         }
-        let per = |d: Duration| d.as_secs_f64() * 1000.0 / ticks as f64;
-        let alive = alive / ticks as usize;
-        eprintln!(
-            "{name:20} alive {alive:6} | per tick: spawn {:6.3} ms, engine tick {:6.3} ms | {:5.0} ns per particle",
-            per(spawn),
-            per(tick),
-            per(tick) * 1.0e6 / alive.max(1) as f64
-        );
-    }
+    });
 }

crates/horizon-client-render/src/poi_sections.rs

@@ -7,7 +7,10 @@
 //! sections are immutable behind `Arc` and edited through `Arc::make_mut`, so
 //! a weak reference tells an edited or replaced section from the one the list
 //! was built from (see `random_tick_sections`), without keeping its blocks.
-use crate::{chunk::Section, fast_hash::FxHashMap};
+use crate::{
+    chunk::{Chunk, Section},
+    fast_hash::FxHashMap,
+};
 use std::sync::{Arc, Mutex, Weak};
 
 /// A section's POIs: the block index in the section (`y << 8 | z << 4 | x`)
@@ -18,13 +21,16 @@ struct Cached<T> {
     section: Weak<Section>,
     pois: SectionPois<T>,
 }
-/// Cached POI lists by section, `(chunk x, section index, chunk z)`.
+/// Cached POI lists by chunk column `(chunk x, chunk z)`, each by section
+/// index: a search through a column looks it up once.
 pub struct PoiSections<T> {
     sections: Mutex<Lists<T>>,
 }
 struct Lists<T> {
-    by_section: FxHashMap<(i32, i32, i32), Cached<T>>,
-    /// Size above which lists of sections no longer resident are dropped.
+    by_column: FxHashMap<(i32, i32), Vec<Option<Cached<T>>>>,
+    /// How many section lists are kept, and the count above which the lists
+    /// of sections no longer resident are dropped.
+    len: usize,
     prune_at: usize,
 }
 const MIN_PRUNE: usize = 4096;
@@ -32,27 +38,61 @@ impl<T> Default for PoiSections<T> {
     fn default() -> Self {
         Self {
             sections: Mutex::new(Lists {
-                by_section: FxHashMap::default(),
+                by_column: FxHashMap::default(),
+                len: 0,
                 prune_at: MIN_PRUNE,
             }),
         }
     }
 }
-impl<T: Copy> PoiSections<T> {
-    /// The POIs of `section`, whose block states `kind` classifies. `kind`
-    /// must give the same answer for a state on every call.
-    pub fn get(
-        &self,
-        key: (i32, i32, i32),
-        section: &Arc<Section>,
-        mut kind: impl FnMut(u32) -> Option<T>,
-    ) -> SectionPois<T> {
-        let mut lists = self.sections.lock().unwrap_or_else(|e| e.into_inner());
-        if let Some(cached) = lists.by_section.get(&key)
-            && cached.section.as_ptr() == Arc::as_ptr(section)
-        {
-            return cached.pois.clone();
+impl<T: Copy> Lists<T> {
+    /// The column's lists, for sections up to `last`, after dropping the
+    /// lists of sections no longer resident if there are too many.
+    fn column(
+        &mut self,
+        column: (i32, i32),
+        last: usize,
+    ) -> (&mut [Option<Cached<T>>], &mut usize) {
+        if self.len >= self.prune_at {
+            self.prune();
         }
+        let lists = self.by_column.entry(column).or_default();
+        if lists.len() <= last {
+            lists.resize_with(last + 1, || None);
+        }
+        (lists, &mut self.len)
+    }
+
+    /// Drops the lists of sections no longer resident.
+    fn prune(&mut self) {
+        let mut len = 0;
+        self.by_column.retain(|_, lists| {
+            for c in lists.iter_mut() {
+                if c.as_ref().is_some_and(|c| c.section.strong_count() == 0) {
+                    *c = None;
+                }
+            }
+            let kept = lists.iter().filter(|c| c.is_some()).count();
+            len += kept;
+            kept > 0
+        });
+        self.len = len;
+        self.prune_at = (len * 2).max(MIN_PRUNE);
+    }
+}
+
+/// The POIs of `section` from `slot`, listed again (and kept there) unless
+/// `slot` was listed from this very section; `len` counts the slots filled.
+fn list<'a, T: Copy>(
+    slot: &'a mut Option<Cached<T>>,
+    len: &mut usize,
+    section: &Arc<Section>,
+    kind: &mut impl FnMut(u32) -> Option<T>,
+) -> &'a SectionPois<T> {
+    let fresh = slot
+        .as_ref()
+        .is_some_and(|c| c.section.as_ptr() == Arc::as_ptr(section));
+    if !fresh {
         let pois: SectionPois<T> = if section.blocks.maybe_has(|v| kind(v).is_some()) {
             let mut states = [0u32; 4096];
             section.unpack(&mut states);
@@ -64,18 +104,56 @@ impl<T: Copy> PoiSections<T> {
         } else {
             Arc::from([])
         };
-        if lists.by_section.len() >= lists.prune_at {
-            lists.by_section.retain(|_, c| c.section.strong_count() > 0);
-            lists.prune_at = (lists.by_section.len() * 2).max(MIN_PRUNE);
+        *len += usize::from(slot.is_none());
+        *slot = Some(Cached {
+            section: Arc::downgrade(section),
+            pois,
+        });
+    }
+    &slot.as_ref().expect("just listed").pois
+}
+
+impl<T: Copy> PoiSections<T> {
+    /// The POIs of `section`, the `key.1`-th section of the column
+    /// `(key.0, key.2)`, whose block states `kind` classifies. `kind` must give
+    /// the same answer for a state on every call.
+    pub fn get(
+        &self,
+        key: (i32, i32, i32),
+        section: &Arc<Section>,
+        mut kind: impl FnMut(u32) -> Option<T>,
+    ) -> SectionPois<T> {
+        let mut lists = self.sections.lock().unwrap_or_else(|e| e.into_inner());
+        let s = usize::try_from(key.1).expect("a section index");
+        let (column, len) = lists.column((key.0, key.2), s);
+        list(&mut column[s], len, section, &mut kind).clone()
+    }
+
+    /// The POIs of `chunk` from block Y `y0` to `y1`, its first section at
+    /// `min_y`, as [`Self::get`] gives them: each section that has any, with
+    /// the Y of its lowest blocks, in order, put in `out`. One lookup of the
+    /// column.
+    pub fn column(
+        &self,
+        chunk: &Chunk,
+        min_y: i32,
+        (y0, y1): (i32, i32),
+        mut kind: impl FnMut(u32) -> Option<T>,
+        out: &mut Vec<(i32, SectionPois<T>)>,
+    ) {
+        out.clear();
+        let (first, last) = ((y0 - min_y) >> 4, (y1 - min_y) >> 4);
+        if first > last {
+            return;
+        }
+        let mut lists = self.sections.lock().unwrap_or_else(|e| e.into_inner());
+        let (slots, len) = lists.column((chunk.x, chunk.z), last as usize);
+        for s in first as usize..=last as usize {
+            let pois = list(&mut slots[s], len, &chunk.sections[s], &mut kind);
+            if !pois.is_empty() {
+                out.push((min_y + s as i32 * 16, pois.clone()));
+            }
         }
-        lists.by_section.insert(
-            key,
-            Cached {
-                section: Arc::downgrade(section),
-                pois: pois.clone(),
-            },
-        );
-        pois
     }
 }
 
@@ -143,6 +221,48 @@ mod tests {
         assert!(index.get((0, 0, 0), &chunk.sections[0], kind).is_empty());
     }
 
+    /// A column gives each section's list as `get` does, the sections
+    /// without any left out, and keeps them until a section changes.
+    #[test]
+    fn a_column_gives_what_each_section_gives() {
+        let index = PoiSections::<u8>::default();
+        let kind = |v: u32| (v == 5).then_some(5);
+        let mut chunk = Arc::new(Chunk::empty(2, -3));
+        for (x, y, z) in [(1, MIN_Y + 2, 3), (4, MIN_Y + 40, 0), (0, MIN_Y + 41, 15)] {
+            Arc::make_mut(&mut chunk).set(x, y, z, 5);
+        }
+        let mut out = Vec::new();
+        index.column(&chunk, MIN_Y, (MIN_Y, MIN_Y + 63), kind, &mut out);
+        let bases: Vec<i32> = out.iter().map(|(base, _)| *base).collect();
+        assert_eq!(bases, [MIN_Y, MIN_Y + 32]);
+        for (base, pois) in &out {
+            let s = (base - MIN_Y) / 16;
+            let one = index.get((2, s, -3), &chunk.sections[s as usize], kind);
+            assert!(Arc::ptr_eq(pois, &one));
+        }
+        // Kept: no rescan.
+        index.column(
+            &chunk,
+            MIN_Y,
+            (MIN_Y, MIN_Y + 63),
+            |_| panic!("rescanned"),
+            &mut out,
+        );
+        assert_eq!(out.len(), 2);
+        // An edit lists that section again.
+        Arc::make_mut(&mut chunk).set(4, MIN_Y + 40, 0, 1);
+        let mut rescans = 0;
+        let counted = |v: u32| {
+            rescans += 1;
+            kind(v)
+        };
+        index.column(&chunk, MIN_Y, (MIN_Y + 20, MIN_Y + 63), counted, &mut out);
+        assert!(rescans > 0);
+        assert_eq!(out.len(), 1);
+        assert_eq!(out[0].0, MIN_Y + 32);
+        assert_eq!(&*out[0].1, &[(9 << 8 | 15 << 4, 5)]);
+    }
+
     #[test]
     fn unloaded_sections_are_dropped() {
         let index = PoiSections::<u8>::default();
@@ -153,7 +273,7 @@ mod tests {
             index.get((1, i, 0), &Arc::new(Section::default()), kind);
         }
         let lists = index.sections.lock().unwrap();
-        assert!(lists.by_section.len() <= 2);
-        assert!(lists.by_section.contains_key(&(0, 0, 0)));
+        assert!(lists.len <= 2);
+        assert!(lists.by_column[&(0, 0)][0].is_some());
     }
 }

crates/horizon-client-render/src/potent_sulfur.rs

@@ -7,13 +7,16 @@ use horizon_core::{
     geometry::{Vec3, traverse_blocks},
     position::BlockPos,
 };
+use horizon_world::collision_context::CollisionContext;
 
 /// `PotentSulfurBlock.ALLOWED_WATER_BLOCKS_ABOVE`.
 const ALLOWED_WATER_BLOCKS_ABOVE: i32 = 4;
 
 /// `PotentSulfurBlockEntity.isGeyserPassableBlock`: air, water, or a block
-/// with no collision shape.
-pub fn is_geyser_passable_block(level: &ParticleLevel, pos: [i32; 3]) -> bool {
+/// with no collision shape for `CollisionContext.positionContext(context_y)`.
+/// Vanilla passes the height of the block under the column it reads, so
+/// scaffolding seen from below lets the gas and the geyser through.
+pub fn is_geyser_passable_block(level: &ParticleLevel, pos: [i32; 3], context_y: i32) -> bool {
     let state = level.world.block(pos[0], pos[1], pos[2]);
     if level.facts.is_air(state) || &*level.facts.get(state).name == "minecraft:water" {
         return true;
@@ -23,7 +26,9 @@ pub fn is_geyser_passable_block(level: &ParticleLevel, pos: [i32; 3]) -> bool {
         binding: level.collision,
         subject: None,
     };
-    match level.collision.collision_shape(&mut scene, state, pos) {
+    let context = CollisionContext::position(f64::from(context_y));
+    let position = BlockPos::new(pos[0], pos[1], pos[2]);
+    match (level.collision).collision_shape_with_context(&mut scene, state, position, &context) {
         Ok(shape) => shape.is_empty(),
         Err(_) => !level.facts.get(state).full_collision,
     }
@@ -46,9 +51,9 @@ pub fn find_noxious_gas_source_block(level: &ParticleLevel, origin: [i32; 3]) ->
         let state = level.world.block(pos[0], pos[1], pos[2]);
         let is_water_block = &*level.facts.get(state).name == "minecraft:water";
         if !is_water_source(level, pos)
-            || (!is_water_block && !is_geyser_passable_block(level, pos))
+            || (!is_water_block && !is_geyser_passable_block(level, pos, origin[1]))
         {
-            if level.facts.is_air(state) || is_geyser_passable_block(level, pos) {
+            if level.facts.is_air(state) || is_geyser_passable_block(level, pos, origin[1]) {
                 return Some(pos);
             }
             break;
@@ -63,7 +68,7 @@ pub fn find_noxious_gas_source_block(level: &ParticleLevel, origin: [i32; 3]) ->
 pub fn unobstructed_block_count(level: &ParticleLevel, pos: [i32; 3], water_blocks: i32) -> i32 {
     let geyser_force_height = 6 * water_blocks;
     for i in 0..geyser_force_height {
-        if !is_geyser_passable_block(level, [pos[0], pos[1] + i, pos[2]]) {
+        if !is_geyser_passable_block(level, [pos[0], pos[1] + i, pos[2]], pos[1] - 1) {
             return i;
         }
     }
@@ -79,7 +84,7 @@ pub fn can_be_reached_by_noxious_gas(
     pos: [f64; 3],
 ) -> bool {
     let block = ParticleLevel::block_at(pos);
-    if !is_geyser_passable_block(level, block) {
+    if !is_geyser_passable_block(level, block, block[1] - 1) {
         return false;
     }
     let center = source_block.map(|c| f64::from(c) + 0.5);

crates/horizon-client-render/src/radial_editor.rs

@@ -0,0 +1,844 @@
+//! The radial menu's pages in the controller settings (Horizon's own; `radial.rs` has their
+//! rules, `radial_overlay.rs` draws them in play), on the settings shell (`settings_shell`): a
+//! sheet per page with its eight slots, what changes the page, and what changes them all. A
+//! page's own name is typed on a small page of its own, [`NameEntry`].
+use crate::{
+    gamepad::{self, GlyphOf, MenuJob},
+    graphics_style::{self as style, BUTTON_H},
+    hud::{HudAtlas, HudBatch},
+    lang,
+    options_ui::{Event, Page},
+    pad_glyph::{Glyph, Glyphs},
+    radial::{self, Pages, RadialAction, SLOTS, Slot},
+    radial_overlay::{page_label, slot_caption},
+    settings::Settings,
+    settings_shell::{
+        self as shell, Binding, Capture, Group, Output, Reset, Row, Screen, Sheet, Shown, Value,
+    },
+    text::Text,
+    ui,
+};
+
+const TITLE: &str = "horizon.pages.controller_radial";
+const SLOTS_GROUP: &str = "horizon.radial.group.slots";
+const PAGE_GROUP: &str = "horizon.radial.group.page";
+const ALL_GROUP: &str = "horizon.radial.group.all";
+/// The opener's row binds the menu's own pad action, in place.
+const OPENER: &str = gamepad::RADIAL;
+
+/// A row of a page; `usize`s are the page and the slot.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(crate) enum RadialRow {
+    Slot(usize, usize),
+    Rename(usize),
+    NewPage,
+    Delete(usize),
+    Reset,
+    Opener,
+}
+
+/// A slot's action, that it holds none, or that its action is missing.
+fn slot_label(slot: &Slot) -> String {
+    slot_caption(slot).unwrap_or_else(|| lang::get("horizon.radial.empty"))
+}
+
+/// What the slot after `slot` (before, `back`) holds: Empty between the last action and the first.
+/// A missing action steps as Empty does.
+fn step(slot: &Slot, back: bool) -> Slot {
+    let order: Vec<_> = std::iter::once(None)
+        .chain(RadialAction::ALL.map(Some))
+        .collect();
+    let at = order
+        .iter()
+        .position(|entry| *entry == slot.action())
+        .unwrap_or(0);
+    let next = if back { at + order.len() - 1 } else { at + 1 };
+    order[next % order.len()].into()
+}
+
+fn page_of(page: usize, pages: usize) -> String {
+    lang::tr("horizon.radial.page_of", &[&(page + 1), &pages])
+}
+
+/// The opener's row: a binding of the menu's own pad action, in place, on its button's art. Its
+/// strip says what stands in the way (no button, or one another action shares); while it waits,
+/// the shell says how to bind it.
+fn opener_row(s: &Settings, glyphs: Glyphs) -> Row<RadialRow> {
+    let pad = &s.controller;
+    // Through the player's glyphs, so a Nintendo pad going by its letters names its own button.
+    let glyph = Glyph::of(GlyphOf::Bound(OPENER), pad, glyphs);
+    let warning = match pad.binding(OPENER) {
+        None => Some(lang::get("horizon.radial.unbound")),
+        Some(_) => pad
+            .conflicts(OPENER)
+            .then(|| lang::get("horizon.radial.conflict")),
+    };
+    let binding = Binding {
+        capture: Capture::Pad(OPENER),
+        shown: Shown::Pad {
+            glyph,
+            cancel: Glyph::menu(MenuJob::Start, glyphs),
+        },
+        shared: Vec::new(),
+        // The default (D-pad Right) is refused with some sticks: no reset, only a new button.
+        reset: Reset::None,
+    };
+    let name = lang::get("horizon.radial.opener");
+    Row {
+        chosen: warning,
+        ..Row::new(RadialRow::Opener, name, Value::Binding(binding))
+            .about(lang::get(opener_about(pad.radial_stick)))
+    }
+}
+
+/// What the opener's row says it can be, with the stick that selects: never under that thumb.
+fn opener_about(stick: gamepad::RadialStick) -> &'static str {
+    match stick {
+        gamepad::RadialStick::Right => "horizon.radial.opener.about",
+        gamepad::RadialStick::Left => "horizon.radial.opener.about.left",
+        gamepad::RadialStick::Either => "horizon.radial.opener.about.either",
+    }
+}
+
+/// The page's rows: its slots, then what changes it.
+fn page_groups(pages: &Pages, page: usize) -> [Group<RadialRow>; 2] {
+    let slots = (0..SLOTS).map(|slot| {
+        let name = lang::get(&format!("horizon.radial.slot.{slot}"));
+        let cell = pages.page(page).slot(slot);
+        let value = Value::Choice(slot_label(cell));
+        let missing = match cell {
+            Slot::Missing(id) => Some(lang::tr("horizon.radial.missing.about", &[id])),
+            _ => None,
+        };
+        Row {
+            chosen: missing,
+            ..Row::new(RadialRow::Slot(page, slot), name, value)
+                .about(lang::get("horizon.radial.slot.about"))
+        }
+    });
+    let full = (pages.len() >= radial::MAX_PAGES)
+        .then(|| lang::tr("horizon.radial.new_page.full", &[&radial::MAX_PAGES]));
+    let last = (pages.len() <= 1).then(|| lang::get("horizon.radial.delete_page.last"));
+    let changes = vec![
+        Row::new(
+            RadialRow::Rename(page),
+            lang::get("horizon.radial.rename"),
+            Value::Press,
+        )
+        .about(lang::get("horizon.radial.rename.about")),
+        Row::new(
+            RadialRow::NewPage,
+            lang::get(radial::NEW_PAGE_NAME),
+            Value::Press,
+        )
+        .about(lang::get("horizon.radial.new_page.about"))
+        .blocked(full),
+        Row::new(
+            RadialRow::Delete(page),
+            lang::get("horizon.radial.delete_page"),
+            Value::Press,
+        )
+        .about(lang::get("horizon.radial.delete_page.about"))
+        .blocked(last),
+    ];
+    [
+        Group {
+            name: SLOTS_GROUP,
+            rows: slots.collect(),
+        },
+        Group {
+            name: PAGE_GROUP,
+            rows: changes,
+        },
+    ]
+}
+
+/// The screen's own state; the pages are the player's settings.
+#[derive(Default)]
+pub(crate) struct RadialScreen {
+    /// The buttons' names follow the controller in use: the options screen says which.
+    pub(crate) glyphs: Glyphs,
+    /// The page to show next: one just added, or where a deleted one was.
+    show: Option<usize>,
+    /// The page whose name is being typed, on its own page (`Page::ControllerRadialName`).
+    pub(crate) naming: Option<NameEntry>,
+    /// The slot (page, slot) whose list of actions opens next (`Page::ControllerRadialPick`).
+    pub(crate) picking: Option<(usize, usize)>,
+}
+
+impl RadialScreen {
+    /// The page the shell should show now, once.
+    pub(crate) fn take_shown(&mut self) -> Option<usize> {
+        self.show.take()
+    }
+}
+
+impl Screen for RadialScreen {
+    type Page = usize;
+    type Row = RadialRow;
+    fn title(&self) -> &'static str {
+        TITLE
+    }
+    /// The rows read the pages, the opener's button, the stick that selects and the glyphs it is
+    /// named with.
+    fn stamp(&self, s: &Settings) -> u64 {
+        let pad = &s.controller;
+        let opener = (pad.binding(OPENER), pad.conflicts(OPENER));
+        shell::stamp_of(&(&pad.radial, opener, pad.radial_stick, self.glyphs))
+    }
+    fn sheets(&self, s: &Settings) -> Vec<Sheet<usize, RadialRow>> {
+        let pages = &s.controller.radial;
+        let default = *pages == Pages::default();
+        let all = Group {
+            name: ALL_GROUP,
+            rows: vec![
+                Row::new(
+                    RadialRow::Reset,
+                    lang::get("horizon.radial.reset"),
+                    Value::Press,
+                )
+                .about(lang::get("horizon.radial.reset.about"))
+                .blocked(default.then(|| lang::get("horizon.radial.reset.default"))),
+                opener_row(s, self.glyphs),
+            ],
+        };
+        (0..pages.len())
+            .map(|page| {
+                let [slots, changes] = page_groups(pages, page);
+                let all = Group {
+                    name: all.name,
+                    rows: all.rows.clone(),
+                };
+                Sheet::new(
+                    page,
+                    page_label(pages.page(page)),
+                    page_of(page, pages.len()),
+                    vec![slots, changes, all],
+                )
+            })
+            .collect()
+    }
+    fn press(&mut self, s: &mut Settings, row: RadialRow, back: bool) -> Vec<Output> {
+        let pages = &mut s.controller.radial;
+        match row {
+            RadialRow::Slot(page, slot) => {
+                let next = step(pages.page(page).slot(slot), back);
+                pages.set_slot(page, slot, next);
+            }
+            RadialRow::Rename(page) => {
+                self.naming = Some(NameEntry::new(page, &page_label(pages.page(page))));
+                return vec![Output::Push(Page::ControllerRadialName)];
+            }
+            RadialRow::NewPage => self.show = pages.add(),
+            RadialRow::Delete(page) => {
+                pages.remove(page);
+                self.show = Some(pages.clamp(page));
+            }
+            RadialRow::Reset => {
+                *pages = Pages::default();
+                self.show = Some(0);
+            }
+            // The shell starts its wait (`gamepad::opener_refused` refused, Start cancels).
+            RadialRow::Opener => return Vec::new(),
+        }
+        vec![Output::Event(Event::Changed)]
+    }
+    /// A press on a slot opens the list of every action for it; Left and Right still step it.
+    fn choose(&mut self, _s: &mut Settings, row: RadialRow) -> Option<Vec<Output>> {
+        let RadialRow::Slot(page, slot) = row else {
+            return None;
+        };
+        self.picking = Some((page, slot));
+        Some(vec![Output::Push(Page::ControllerRadialPick)])
+    }
+    /// The wheel over a slot steps it, as a press does.
+    fn wheel_step(&mut self, s: &mut Settings, row: RadialRow, back: bool) -> Option<Vec<Output>> {
+        matches!(row, RadialRow::Slot(..)).then(|| self.press(s, row, back))
+    }
+    /// Undo is how a delete or a reset is taken back: they act at once.
+    fn undoes(&self) -> bool {
+        true
+    }
+    /// The pages, and the opener's button, which its row binds.
+    fn undo(&mut self, s: &mut Settings, before: &Settings) -> Vec<Output> {
+        s.controller.radial = before.controller.radial.clone();
+        s.controller.bind(OPENER, before.controller.binding(OPENER));
+        Vec::new()
+    }
+}
+
+const PICK_TITLE: &str = "horizon.radial.pick_title";
+const PICK_GROUP: &str = "horizon.radial.group.actions";
+
+/// A row of a slot's list: the line naming the slot, then Empty and every action.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(crate) enum PickRow {
+    Slot,
+    Pick(Option<RadialAction>),
+}
+
+/// One slot's list of every action and Empty, on the settings shell: it names the slot, marks
+/// what the slot holds and opens on it; a press puts that in the slot and goes back.
+#[derive(Default)]
+pub(crate) struct PickScreen {
+    /// The page and the slot.
+    at: (usize, usize),
+    picked: bool,
+}
+
+impl PickScreen {
+    /// For `at`; the row the focus opens on, what the slot holds.
+    pub(crate) fn open_on(&mut self, at: (usize, usize), pages: &Pages) -> PickRow {
+        *self = Self { at, picked: false };
+        self.current(pages).unwrap_or(PickRow::Pick(None))
+    }
+    /// The page and the slot it is for.
+    pub(crate) fn at(&self) -> (usize, usize) {
+        self.at
+    }
+    /// A pick changed the pages since the last call, which the editor's Undo takes back.
+    pub(crate) fn take_picked(&mut self) -> bool {
+        std::mem::take(&mut self.picked)
+    }
+    /// The row of what the slot holds; none for an action this game doesn't know.
+    fn current(&self, pages: &Pages) -> Option<PickRow> {
+        match pages.page(self.at.0).slot(self.at.1) {
+            Slot::Empty => Some(PickRow::Pick(None)),
+            Slot::Action(action) => Some(PickRow::Pick(Some(*action))),
+            Slot::Missing(_) => None,
+        }
+    }
+}
+
+impl Screen for PickScreen {
+    type Page = ();
+    type Row = PickRow;
+    fn title(&self) -> &'static str {
+        PICK_TITLE
+    }
+    fn stamp(&self, s: &Settings) -> u64 {
+        let (page, slot) = self.at;
+        shell::stamp_of(&(self.at, s.controller.radial.page(page).slot(slot)))
+    }
+    fn sheets(&self, s: &Settings) -> Vec<Sheet<(), PickRow>> {
+        let pages = &s.controller.radial;
+        let (page, slot) = self.at;
+        let direction = lang::get(&format!("horizon.radial.slot.{slot}"));
+        let named = lang::tr(
+            "horizon.radial.pick.slot",
+            &[&direction, &page_label(pages.page(page))],
+        );
+        let current = self.current(pages);
+        let about = lang::get("horizon.radial.pick.about");
+        let mut rows =
+            vec![Row::new(PickRow::Slot, named.clone(), Value::Note).about(about.clone())];
+        for action in std::iter::once(None).chain(RadialAction::ALL.map(Some)) {
+            let id = PickRow::Pick(action);
+            let value = if current == Some(id) {
+                Value::Choice(lang::get("horizon.radial.pick.current"))
+            } else {
+                Value::Press
+            };
+            let name = slot_label(&action.into());
+            rows.push(Row::new(id, name, value).about(about.clone()));
+        }
+        vec![Sheet::new(
+            (),
+            named,
+            about,
+            vec![Group {
+                name: PICK_GROUP,
+                rows,
+            }],
+        )]
+    }
+    fn press(&mut self, s: &mut Settings, row: PickRow, _back: bool) -> Vec<Output> {
+        let PickRow::Pick(action) = row else {
+            return Vec::new();
+        };
+        let (page, slot) = self.at;
+        s.controller.radial.set_slot(page, slot, action.into());
+        self.picked = true;
+        vec![Output::Event(Event::Changed), Output::Done]
+    }
+}
+
+/// The name field and its buttons, centred in the screen but under the title, one row apart.
+const NAME_W: f32 = 200.0;
+const NAME_BLOCK_H: f32 = 100.0;
+const NAME_TOP_MIN: f32 = 30.0;
+const NAME_STEP: f32 = 25.0;
+
+/// What a press on the name's page did.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub(crate) enum Named {
+    Nothing,
+    /// Done: the page takes the name.
+    Done,
+    /// Cancel, keeping the old name.
+    Back,
+}
+
+/// A page's name being typed.
+pub(crate) struct NameEntry {
+    page: usize,
+    field: ui::EditBox,
+}
+
+impl NameEntry {
+    fn new(page: usize, name: &str) -> Self {
+        let mut field = ui::EditBox::new(0.0, 0.0, NAME_W, BUTTON_H);
+        field.max_length = radial::NAME_MAX;
+        field.set_value(name);
+        field.focused = true;
+        Self { page, field }
+    }
+
+    /// Done and Cancel, under the field.
+    fn buttons(w: f32, h: f32) -> [([f32; 4], Named); 2] {
+        let (x, top) = ((w / 2.0).floor() - NAME_W / 2.0, name_top(h));
+        let at = |row: f32| [x, top + row * NAME_STEP, NAME_W, BUTTON_H];
+        [(at(1.0), Named::Done), (at(2.0), Named::Back)]
+    }
+
+    pub(crate) fn draw(
+        &mut self,
+        batch: &mut HudBatch,
+        atlas: &HudAtlas,
+        cursor: (f32, f32),
+        in_world: bool,
+    ) {
+        let (w, h) = (batch.width.ceil(), batch.height.ceil());
+        ui::menu_background(batch, atlas, 0.0, 0.0, w, h, in_world);
+        let title = Text::literal(lang::get("horizon.radial.name_title"));
+        style::title(batch, atlas, &title);
+        let field = &mut self.field;
+        let (x, top) = ((w / 2.0).floor() - NAME_W / 2.0, name_top(h));
+        (field.x, field.y, field.width, field.height) = (x, top, NAME_W, BUTTON_H);
+        field.draw(batch, atlas, None);
+        for ([x, y, bw, bh], named) in Self::buttons(w, h) {
+            let (label, action) = match named {
+                Named::Done => ("gui.done", crate::widgets::Action::Done),
+                _ => ("gui.cancel", crate::widgets::Action::Cancel),
+            };
+            let hover = ui::hovered(cursor, x, y, bw, bh);
+            let text = Text::literal(lang::get(label));
+            ui::action_button(batch, atlas, action, x, y, bw, bh, &text, true, hover);
+        }
+    }
+
+    /// A press at `(x, y)` on a screen `w` x `h`.
+    pub(crate) fn click(
+        &mut self,
+        atlas: &HudAtlas,
+        (x, y): (f32, f32),
+        (w, h): (f32, f32),
+    ) -> Named {
+        let hit = Self::buttons(w, h)
+            .into_iter()
+            .find(|([bx, by, bw, bh], _)| ui::hovered((x, y), *bx, *by, *bw, *bh));
+        if let Some((_, named)) = hit {
+            return named;
+        }
+        let field = &mut self.field;
+        field.focused = ui::hovered((x, y), field.x, field.y, field.width, field.height);
+        if field.focused {
+            field.click(atlas, x, false, false);
+        }
+        Named::Nothing
+    }
+
+    /// The name field takes the keys.
+    pub(crate) fn typing(&self) -> bool {
+        self.field.focused
+    }
+
+    pub(crate) fn type_text(&mut self, text: &str) {
+        if self.field.focused {
+            self.field.insert_text(text);
+        }
+    }
+
+    /// A key: Enter is Done, Escape is Cancel, the rest the field's.
+    pub(crate) fn key(&mut self, key: winit::keyboard::KeyCode, text: Option<&str>) -> Named {
+        use winit::keyboard::KeyCode as K;
+        match key {
+            K::Escape => return Named::Back,
+            K::Enter | K::NumpadEnter => return Named::Done,
+            _ if self.field.focused => {
+                if !self.field.key(key, false, false)
+                    && let Some(t) = text
+                {
+                    let typed: String = t.chars().filter(|c| !c.is_control()).collect();
+                    self.field.insert_text(&typed);
+                }
+            }
+            _ => {}
+        }
+        Named::Nothing
+    }
+
+    /// Ctrl+A/C/V/X in the name field; false when it hasn't the focus.
+    pub(crate) fn shortcut(
+        &mut self,
+        shortcut: crate::clipboard::EditShortcut,
+        clipboard: &mut dyn crate::clipboard::Clipboard,
+    ) -> bool {
+        if self.field.focused {
+            self.field.shortcut(shortcut, clipboard);
+        }
+        self.field.focused
+    }
+
+    /// The name into the pages. Left as it was, a default page keeps following the language.
+    pub(crate) fn apply(&self, pages: &mut Pages) -> bool {
+        let changed = self.field.value != page_label(pages.page(self.page));
+        if changed {
+            pages.rename(self.page, &self.field.value);
+        }
+        changed
+    }
+}
+
+/// The name field's top.
+fn name_top(h: f32) -> f32 {
+    ((h - NAME_BLOCK_H) / 2.0).floor().max(NAME_TOP_MIN)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::gamepad::Button as PadButton;
+    use crate::radial::PageName;
+    use crate::settings_shell::{Hosted, Shell};
+    use winit::keyboard::KeyCode as K;
+
+    const SIZE: (f32, f32) = (854.0, 480.0);
+
+    fn rows_of(s: &Settings, page: usize) -> Vec<Row<RadialRow>> {
+        let sheets = RadialScreen::default().sheets(s);
+        let groups = sheets.into_iter().nth(page).unwrap().groups;
+        groups.into_iter().flat_map(|group| group.rows).collect()
+    }
+    fn row(s: &Settings, id: RadialRow) -> Row<RadialRow> {
+        let page = match id {
+            RadialRow::Slot(page, _) | RadialRow::Rename(page) | RadialRow::Delete(page) => page,
+            _ => 0,
+        };
+        rows_of(s, page).into_iter().find(|r| r.id == id).unwrap()
+    }
+    /// A click on `id` through the shell, as the mouse or a controller's A gives it.
+    fn click(shell: &mut Shell<RadialScreen>, s: &mut Settings, id: RadialRow) -> Vec<Output> {
+        let at = shell.point_at(s, SIZE, id);
+        shell.click(s, at, SIZE, false, false, false)
+    }
+
+    /// Undo, at the foot over Done.
+    fn undo(shell: &mut Shell<RadialScreen>, s: &mut Settings) {
+        let [x, y, ..] = shell::Columns::of(SIZE.0, SIZE.1).button(1);
+        shell.click(s, (x + 2.0, y + 2.0), SIZE, false, false, false);
+    }
+
+    #[test]
+    fn a_slot_steps_through_empty_and_every_action_both_ways() {
+        let mut seen = vec![Slot::Empty];
+        let mut slot = Slot::Empty;
+        for _ in RadialAction::ALL {
+            slot = step(&slot, false);
+            seen.push(slot.clone());
+        }
+        assert_eq!(step(&slot, false), Slot::Empty, "the last wraps to Empty");
+        let actions: Vec<_> = seen.iter().filter_map(Slot::action).collect();
+        assert_eq!(actions, RadialAction::ALL.to_vec());
+        assert_eq!(
+            step(&Slot::Empty, true).action(),
+            RadialAction::ALL.last().copied()
+        );
+        let chat = Slot::Action(RadialAction::Chat);
+        assert_eq!(step(&step(&chat, true), false), chat);
+        // A missing action steps on as Empty would.
+        let missing = Slot::Missing("mymod:dash".to_owned());
+        assert_eq!(step(&missing, false), step(&Slot::Empty, false));
+    }
+
+    #[test]
+    fn a_press_on_a_slot_opens_its_list_and_left_and_right_still_step_it() {
+        let mut s = Settings::default();
+        let mut shell = Shell::<RadialScreen>::default();
+        let before = s.controller.radial.clone();
+        let outputs = click(&mut shell, &mut s, RadialRow::Slot(0, 2));
+        assert!(outputs.contains(&Output::Push(Page::ControllerRadialPick)));
+        assert_eq!(shell.screen.picking, Some((0, 2)));
+        assert_eq!(
+            s.controller.radial, before,
+            "the press itself changes nothing"
+        );
+        // Right on the focused row steps it.
+        shell.set_focus(Some(shell::Target::Row(RadialRow::Slot(0, 2))));
+        shell.key(&mut s, K::ArrowRight, None, false, SIZE);
+        let stepped = step(before.page(0).slot(2), false);
+        assert_eq!(*s.controller.radial.page(0).slot(2), stepped);
+    }
+
+    #[test]
+    fn the_list_names_the_slot_marks_its_action_and_a_pick_fills_it() {
+        let mut s = Settings::default();
+        let mut picker = PickScreen::default();
+        // General's right slot holds Commands.
+        let opens_on = picker.open_on((0, 2), &s.controller.radial);
+        assert_eq!(opens_on, PickRow::Pick(Some(RadialAction::Command)));
+        let rows: Vec<_> = picker
+            .sheets(&s)
+            .into_iter()
+            .flat_map(|sheet| sheet.groups)
+            .flat_map(|group| group.rows)
+            .collect();
+        assert_eq!(rows[0].id, PickRow::Slot);
+        assert_eq!(rows[0].value, Value::Note);
+        // Empty, then every action, each once; only the slot's own marked.
+        let picks: Vec<_> = rows[1..].iter().map(|row| row.id).collect();
+        let every: Vec<_> = std::iter::once(None)
+            .chain(RadialAction::ALL.map(Some))
+            .map(PickRow::Pick)
+            .collect();
+        assert_eq!(picks, every);
+        let marked: Vec<_> = rows
+            .iter()
+            .filter(|row| matches!(row.value, Value::Choice(_)))
+            .map(|row| row.id)
+            .collect();
+        assert_eq!(marked, [opens_on]);
+        let outputs = picker.press(&mut s, PickRow::Pick(Some(RadialAction::Chat)), false);
+        assert_eq!(outputs, [Output::Event(Event::Changed), Output::Done]);
+        assert_eq!(
+            *s.controller.radial.page(0).slot(2),
+            Slot::Action(RadialAction::Chat)
+        );
+        assert!(picker.take_picked() && !picker.take_picked());
+        // Empty empties it.
+        picker.press(&mut s, PickRow::Pick(None), false);
+        assert!(s.controller.radial.page(0).slot(2).is_empty());
+    }
+
+    #[test]
+    fn a_missing_action_says_which_it_is() {
+        let mut s = Settings::default();
+        s.controller
+            .radial
+            .set_slot(0, 1, Slot::Missing("mymod:dash".to_owned()));
+        let english = lang::Language::load(&[], "en_us");
+        let (chosen, _) = lang::scoped(english, || row(&s, RadialRow::Slot(0, 1)).chosen);
+        assert!(chosen.is_some_and(|text| text.contains("mymod:dash")));
+    }
+
+    #[test]
+    fn a_slot_changes_alone_and_undo_puts_back_what_the_screen_found() {
+        let mut s = Settings::default();
+        let mut shell = Shell::<RadialScreen>::default();
+        let before = s.controller.radial.page(0).clone();
+        shell.set_focus(Some(shell::Target::Row(RadialRow::Slot(0, 0))));
+        let outputs = shell.key(&mut s, K::ArrowRight, None, false, SIZE);
+        assert!(outputs.contains(&Output::Event(Event::Changed)));
+        let after = s.controller.radial.page(0);
+        assert_eq!(*after.slot(0), step(before.slot(0), false));
+        assert_eq!(after.slots()[1..], before.slots()[1..]);
+        assert!(shell.changed());
+        undo(&mut shell, &mut s);
+        assert_eq!(s.controller.radial, Pages::default());
+        assert!(!shell.changed());
+    }
+
+    #[test]
+    fn delete_and_reset_act_at_once_and_undo_takes_them_back() {
+        let mut s = Settings::default();
+        s.controller.radial.rename(1, "Mine");
+        let found = s.controller.radial.clone();
+        let mut shell = Shell::<RadialScreen>::default();
+        click(&mut shell, &mut s, RadialRow::Delete(0));
+        assert_eq!(s.controller.radial.len(), 1);
+        assert_eq!(page_label(s.controller.radial.page(0)), "Mine");
+        // One page left: it can't go, and the strip says why.
+        let delete = row(&s, RadialRow::Delete(0));
+        assert!(!delete.live && delete.why.is_some());
+        let reset = row(&s, RadialRow::Reset);
+        assert!(reset.live);
+        shell.screen.take_shown();
+        click(&mut shell, &mut s, RadialRow::Reset);
+        assert_eq!(s.controller.radial, Pages::default());
+        assert!(!row(&s, RadialRow::Reset).live, "already the defaults");
+        assert_eq!(shell.screen.take_shown(), Some(0));
+        undo(&mut shell, &mut s);
+        assert_eq!(s.controller.radial, found);
+    }
+
+    #[test]
+    fn new_pages_stop_at_the_most_and_the_new_one_shows() {
+        let mut s = Settings::default();
+        let mut screen = RadialScreen::default();
+        while row(&s, RadialRow::NewPage).live {
+            screen.press(&mut s, RadialRow::NewPage, false);
+            assert_eq!(screen.take_shown(), Some(s.controller.radial.len() - 1));
+        }
+        assert_eq!(s.controller.radial.len(), radial::MAX_PAGES);
+        assert!(row(&s, RadialRow::NewPage).why.is_some());
+        // Every page is a sheet, named as the overlay names it.
+        let sheets = screen.sheets(&s);
+        assert_eq!(sheets.len(), radial::MAX_PAGES);
+        assert_eq!(sheets[0].name, page_label(s.controller.radial.page(0)));
+    }
+
+    #[test]
+    fn a_deleted_last_page_leaves_the_one_before_it_showing() {
+        let mut s = Settings::default();
+        let mut screen = RadialScreen::default();
+        screen.press(&mut s, RadialRow::Delete(1), false);
+        assert_eq!(screen.take_shown(), Some(0));
+    }
+
+    #[test]
+    fn rename_opens_the_name_page_and_only_done_with_a_new_name_renames() {
+        let general = Pages::default().page(0).name.clone();
+        let mut s = Settings::default();
+        let mut screen = RadialScreen::default();
+        let outputs = screen.press(&mut s, RadialRow::Rename(0), false);
+        assert_eq!(outputs, vec![Output::Push(Page::ControllerRadialName)]);
+        let entry = screen.naming.as_mut().unwrap();
+        // Done with the name as it was: a default page keeps following the language.
+        assert_eq!(entry.key(K::Enter, None), Named::Done);
+        assert!(!entry.apply(&mut s.controller.radial));
+        assert_eq!(s.controller.radial.page(0).name, general);
+        entry.type_text("!");
+        assert_eq!(entry.key(K::Escape, None), Named::Back);
+        entry.field.set_value("Mine");
+        entry.type_text("!");
+        assert!(entry.apply(&mut s.controller.radial));
+        assert_eq!(
+            s.controller.radial.page(0).name,
+            PageName::Custom("Mine!".to_owned())
+        );
+    }
+
+    #[test]
+    fn undo_puts_back_a_name_given_on_the_name_page() {
+        let mut s = Settings::default();
+        s.controller.radial.rename(1, "Mine");
+        let mut shell = Shell::<RadialScreen>::default();
+        shell.show(1);
+        click(&mut shell, &mut s, RadialRow::Rename(1));
+        let entry = shell.screen.naming.as_mut().unwrap();
+        entry.field.set_value("Building");
+        // As the options screen does on Done: the name page changed what Undo puts back.
+        let entry = shell.screen.naming.take().unwrap();
+        assert!(entry.apply(&mut s.controller.radial));
+        shell.changed_elsewhere();
+        assert_eq!(page_label(s.controller.radial.page(1)), "Building");
+        assert!(shell.changed());
+        undo(&mut shell, &mut s);
+        assert_eq!(page_label(s.controller.radial.page(1)), "Mine");
+        assert!(!shell.changed());
+    }
+
+    #[test]
+    fn a_nintendo_pad_going_by_its_letters_names_its_own_opener() {
+        let mut s = Settings::default();
+        // Selecting with the left stick, the top face button (North) can open it.
+        s.controller.radial_stick = gamepad::RadialStick::Left;
+        s.controller.bind(OPENER, Some(gamepad::Button::North));
+        s.controller.glyphs = gamepad::GlyphStyle::Nintendo;
+        let label = |s: &Settings| {
+            let glyphs = Glyphs::of(&s.controller, gamepad::GlyphStyle::Nintendo);
+            match opener_row(s, glyphs).value {
+                Value::Binding(Binding {
+                    shown: Shown::Pad { glyph, .. },
+                    ..
+                }) => glyph.expect("bound").label().to_owned(),
+                other => panic!("{other:?}"),
+            }
+        };
+        // By places, the top button: printed X on a Nintendo pad.
+        s.controller.nintendo_letters = false;
+        assert_eq!(label(&s), "X");
+        // By letters, the part is played by the button printed Y (on the left).
+        s.controller.nintendo_letters = true;
+        assert_eq!(label(&s), "Y");
+    }
+
+    #[test]
+    fn the_opener_row_names_its_button_and_says_what_gets_in_the_way() {
+        let mut s = Settings::default();
+        let glyphs = Glyphs::of(&s.controller, gamepad::GlyphStyle::Xbox);
+        let shown = |s: &Settings| match opener_row(s, glyphs).value {
+            Value::Binding(Binding {
+                capture,
+                shown: Shown::Pad { glyph, .. },
+                ..
+            }) => {
+                assert_eq!(capture, Capture::Pad(OPENER));
+                glyph
+            }
+            other => panic!("{other:?}"),
+        };
+        let bound = s.controller.binding(OPENER).unwrap();
+        // The button on its glyph.
+        let glyph = shown(&s).expect("the opener's glyph");
+        assert_eq!(glyph.part(), bound);
+        assert_eq!(glyph.label(), "→");
+        assert_eq!(opener_row(&s, glyphs).chosen, None);
+        s.controller.bind("key.chat", Some(bound));
+        let shared = opener_row(&s, glyphs).chosen;
+        assert!(shared.is_some(), "a shared button");
+        s.controller.bind(OPENER, None);
+        let unbound = opener_row(&s, glyphs).chosen;
+        assert!(unbound.is_some() && unbound != shared && shown(&s).is_none());
+        // A press waits for a button on the row, and Undo takes a new one back.
+        let mut shell = Shell::<RadialScreen>::default();
+        s.controller.bind(OPENER, Some(bound));
+        let outputs = click(&mut shell, &mut s, RadialRow::Opener);
+        assert!(outputs.contains(&Output::Bind(Capture::Pad(OPENER))));
+        assert!(shell.changed());
+        s.controller.bind(OPENER, Some(PadButton::North));
+        undo(&mut shell, &mut s);
+        assert_eq!(s.controller.binding(OPENER), Some(bound));
+    }
+
+    #[test]
+    fn every_string_has_a_horizon_key() {
+        let atlas =
+            HudAtlas::build(std::path::Path::new("/nonexistent/horizon-test-assets")).unwrap();
+        let english = lang::Language::load(&[], "en_us");
+        let ((), missed) = lang::scoped(english, || {
+            let mut s = Settings::default();
+            s.controller.bind("key.chat", Some(PadButton::DPadRight));
+            let mut shell = Shell::<RadialScreen>::default();
+            let draw = |shell: &mut Shell<RadialScreen>, s: &Settings| {
+                let mut batch = HudBatch::new([854, 480]);
+                shell.draw(s, &mut batch, &atlas, (0.0, 0.0), false, None);
+            };
+            // Every page's rows are built, with what the strip says of each.
+            draw(&mut shell, &s);
+            s.controller.bind(OPENER, None);
+            s.controller.radial.remove(1);
+            while s.controller.radial.add().is_some() {}
+            draw(&mut shell, &s);
+            s.controller.radial = Pages::default();
+            s.controller.radial.remove(1);
+            draw(&mut shell, &s);
+            let mut batch = HudBatch::new([854, 480]);
+            let waiting = Some(Capture::Pad(OPENER));
+            shell.draw(&s, &mut batch, &atlas, (0.0, 0.0), false, waiting);
+            let mut entry = NameEntry::new(0, "Mine");
+            let mut batch = HudBatch::new([854, 480]);
+            entry.draw(&mut batch, &atlas, (0.0, 0.0), false);
+            let mut picker = Shell::<PickScreen>::default();
+            picker.screen.open_on((0, 1), &s.controller.radial);
+            let mut batch = HudBatch::new([854, 480]);
+            picker.draw(&s, &mut batch, &atlas, (0.0, 0.0), false, None);
+        });
+        // Vanilla's own (gui.done...) come from the game's resources, not bundled ones.
+        let missed: Vec<_> = missed
+            .iter()
+            .filter(|key| key.starts_with("horizon.") || !key.contains('.'))
+            .collect();
+        assert!(missed.is_empty(), "no text for {missed:?}");
+    }
+}

crates/horizon-client-render/src/sculk.rs

@@ -232,6 +232,8 @@ impl Selector {
 pub struct Tick {
     /// A vibration was chosen: its travel time (the particle starts).
     pub started: Option<(Info, i32)>,
+    /// A vibration was reloaded from save: particle resumes from interpolated pos.
+    pub resumed: Option<(Info, i32)>,
     /// A vibration arrived.
     pub received: Option<Info>,
     /// `onDataChanged`.
@@ -261,6 +263,10 @@ impl Data {
             self.selector.start_over();
         }
         if let Some(info) = self.current {
+            if self.reload_particle {
+                self.reload_particle = false;
+                out.resumed = Some((info, self.travel));
+            }
             let mut changed = self.travel > 0;
             self.travel = (self.travel - 1).max(0);
             if self.travel <= 0 {
@@ -293,8 +299,11 @@ impl Data {
         Tag::compound(entries)
     }
     pub fn from_nbt(tag: &Tag) -> Self {
+        let current = tag.get("event").and_then(info_from_nbt);
+        let reload_particle = current.is_some();
         let mut data = Self {
-            current: tag.get("event").and_then(info_from_nbt),
+            current,
+            reload_particle,
             ..Self::default()
         };
         if let Some(Tag::Int(t)) = tag.get("event_delay") {
@@ -979,4 +988,30 @@ mod tests {
         assert_eq!(back.spreader.cursors[0].charge, 1000);
         assert_eq!(back.spreader.cursors[1].charge, 500);
     }
+
+    #[test]
+    fn vibration_reloads_particle() {
+        let tag = Tag::compound([
+            (
+                "event",
+                Tag::compound([
+                    ("game_event", Tag::String("minecraft:step".into())),
+                    ("distance", Tag::Float(4.0f32.to_bits())),
+                    (
+                        "pos",
+                        Tag::List(vec![
+                            Tag::Double(1.0f64.to_bits()),
+                            Tag::Double(0),
+                            Tag::Double(0),
+                        ]),
+                    ),
+                ]),
+            ),
+            ("event_delay", Tag::Int(3)),
+        ]);
+        let mut d = Data::from_nbt(&tag);
+        assert!(d.reload_particle && d.current.is_some());
+        let tick = d.tick(10, true, true, |dist| dist as i32);
+        assert!(tick.resumed.is_some() && !d.reload_particle);
+    }
 }

crates/horizon-client-render/src/settings.rs

@@ -203,6 +203,9 @@ pub struct Settings {
     pub startup_api: crate::graphics::GraphicsApi,
     /// `Monitor.videoModes` of the window's monitor, for the Video page (set by the game).
     pub video_modes: Vec<crate::window::VideoMode>,
+    /// Fullbright is held off: this window plays on another's server (set by the game, not
+    /// saved). The graphics screen hides its row; `extras.fullbright` keeps the choice.
+    pub fullbright_held: bool,
     /// Controller settings (`horizon-controller.txt`, Horizon's own).
     pub controller: crate::gamepad::PadSettings,
     /// Horizon's optional extras (`horizon-extras.txt`), all off by default.
@@ -293,6 +296,7 @@ impl Default for Settings {
             horizon: Default::default(),
             startup_api: Default::default(),
             video_modes: Vec::new(),
+            fullbright_held: false,
             controller: Default::default(),
             extras: Default::default(),
             mods: Default::default(),
@@ -337,6 +341,13 @@ impl Settings {
             .and_then(|mode| self.video_modes.iter().position(|m| *m == mode))
             .map_or(-1, |i| i as i32)
     }
+    /// Loads only the crates' settings stores (`horizon_hooks::settings`) from the files next to
+    /// `path`, into the seat whose turn it is (`horizon_hooks::seat`): a splitscreen player whose
+    /// settings were made from P1's rather than loaded.
+    pub fn load_stores(path: &Path) {
+        let dir = path.parent();
+        horizon_hooks::settings::engine::load(&mut |file| fs::read_to_string(dir?.join(file)).ok());
+    }
     pub fn load(path: &Path) -> Self {
         let mut horizon = path
             .parent()
@@ -507,6 +518,7 @@ impl Settings {
             horizon: Default::default(),
             startup_api: Default::default(),
             video_modes: Vec::new(),
+            fullbright_held: false,
             controller: Default::default(),
             extras: Default::default(),
             mods: Default::default(),
@@ -862,6 +874,10 @@ pub enum Opt {
     PadNintendoButtons,
     PadKeyboard,
     PadGameplayGuide,
+    /// The radial menu's opener held or pressed once (`PadSettings::radial_mode`).
+    PadRadialMode,
+    /// The stick the radial menu selects with (`PadSettings::radial_stick`).
+    PadRadialStick,
     /// `options.modelPart.*`: one skin layer (index into `options_file::MODEL_PARTS`).
     ModelPart(usize),
     /// A slider of a page a crate registered (`horizon_hooks::pages`): (page, row).

crates/horizon-client-render/src/settings_shell/tests.rs

@@ -0,0 +1,815 @@
+use super::*;
+use crate::options_ui::Event;
+use winit::keyboard::KeyCode as K;
+
+const SIZE: (f32, f32) = (854.0, 480.0);
+const SHORT: (f32, f32) = (480.0, 240.0);
+const CHANGED: Output = Output::Event(Event::Changed);
+
+/// A screen with what Extras doesn't have: two pages, a slider, a value with descriptions of
+/// its own, and a row a wheel steps.
+#[derive(Default)]
+struct Probe {
+    slider: f32,
+    choice: usize,
+    pressed: Vec<(u32, bool)>,
+    /// How many times its rows were built.
+    built: std::cell::Cell<usize>,
+}
+const CHOICES: [(&str, &str); 2] = [("Red", "Paints it red."), ("Blue", "Paints it blue.")];
+const SLIDER: u32 = 0;
+const CHOICE: u32 = 1;
+const FIRST_FILLER: u32 = 10;
+const FILLERS: u32 = 40;
+const GREY: u32 = 100;
+const WHY: &str = "Not here.";
+impl Screen for Probe {
+    type Page = u8;
+    type Row = u32;
+    fn title(&self) -> &'static str {
+        "Probe"
+    }
+    /// Its rows read the field of view, besides its own state.
+    fn stamp(&self, s: &Settings) -> u64 {
+        stamp_of(&s.fov)
+    }
+    fn sheets(&self, s: &Settings) -> Vec<Sheet<u8, u32>> {
+        self.built.set(self.built.get() + 1);
+        let (value, chosen) = CHOICES[self.choice];
+        let mut rows = vec![
+            Row::new(
+                SLIDER,
+                "Level".to_owned(),
+                Value::Slider {
+                    position: self.slider,
+                    steps: Some(10),
+                    text: s.fov.to_string(),
+                },
+            ),
+            Row {
+                chosen: Some(chosen.to_owned()),
+                ..Row::new(CHOICE, "Paint".to_owned(), Value::Choice(value.to_owned()))
+                    .about("Picks a colour.".to_owned())
+            },
+            Row::new(GREY, "Greyed".to_owned(), Value::Press)
+                .about("Does a thing.".to_owned())
+                .blocked(Some(WHY.to_owned())),
+        ];
+        rows.extend((0..FILLERS).map(|i| {
+            Row::new(FIRST_FILLER + i, format!("Filler {i}"), Value::Press)
+                .about("Does nothing.".to_owned())
+        }));
+        let elsewhere = vec![Row::new(99, "Elsewhere".to_owned(), Value::Press)];
+        vec![
+            Sheet::new(
+                0,
+                "One".to_owned(),
+                "The first.".to_owned(),
+                vec![Group { name: "G", rows }],
+            ),
+            Sheet::new(
+                1,
+                "Two".to_owned(),
+                "The second.".to_owned(),
+                vec![Group {
+                    name: "H",
+                    rows: elsewhere,
+                }],
+            ),
+        ]
+    }
+    fn press(&mut self, s: &mut Settings, row: u32, back: bool) -> Vec<Output> {
+        self.pressed.push((row, back));
+        match row {
+            CHOICE => self.choice = (self.choice + 1) % CHOICES.len(),
+            FIRST_FILLER => s.fov += 1.0,
+            _ => {}
+        }
+        vec![CHANGED]
+    }
+    fn undoes(&self) -> bool {
+        true
+    }
+    fn undo(&mut self, s: &mut Settings, before: &Settings) -> Vec<Output> {
+        s.fov = before.fov;
+        Vec::new()
+    }
+    fn slide(&mut self, _: &mut Settings, _: u32, position: f32) {
+        self.slider = position;
+    }
+    fn wheel_step(&mut self, _: &mut Settings, row: u32, _: bool) -> Option<Vec<Output>> {
+        (row == CHOICE).then(|| {
+            self.choice = (self.choice + 1) % CHOICES.len();
+            vec![CHANGED]
+        })
+    }
+}
+
+fn middle_of(shell: &mut Shell<Probe>, row: u32, size: (f32, f32)) -> (f32, f32) {
+    shell.point_at(&Settings::default(), size, row)
+}
+
+fn atlas() -> HudAtlas {
+    HudAtlas::build(std::path::Path::new("/nonexistent/horizon-test-assets")).unwrap()
+}
+
+/// What one frame asks of a screen: a draw, then the stick's scroll, an arrow key and the wheel
+/// away from any row, at the size it was drawn at.
+fn frame(shell: &mut Shell<Probe>, s: &mut Settings, atlas: &HudAtlas) -> (f32, f32) {
+    let mut batch = HudBatch::new([1708, 960]);
+    shell.draw(s, &mut batch, atlas, (0.0, 0.0), false, None);
+    let size = (batch.width, batch.height);
+    shell.scroll(s, size, -1.0);
+    shell.key(s, K::ArrowDown, None, false, size);
+    shell.wheel(s, size, (0.0, 0.0), 1.0);
+    size
+}
+
+#[test]
+fn rows_are_built_once_and_again_only_when_what_they_read_changes() {
+    let atlas = atlas();
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let built = |shell: &Shell<Probe>| shell.screen.built.get();
+    let reads = |shell: &mut Shell<Probe>, s: &Settings, size, end: &str| {
+        let view = shell.view(s, size);
+        let mut labels = view.rows.iter().map(|r| r.label(r.value_text().as_deref()));
+        labels.any(|label| label.ends_with(end))
+    };
+    // Each of the four built them before: now the first frame builds them once, the next none.
+    let size = frame(&mut shell, &mut s, &atlas);
+    assert_eq!(built(&shell), 1);
+    frame(&mut shell, &mut s, &atlas);
+    assert_eq!(built(&shell), 1);
+    // A press changes the screen's own state: its row reads the new value.
+    let at = middle_of(&mut shell, CHOICE, size);
+    shell.click(&mut s, at, size, false, false, false);
+    assert!(reads(&mut shell, &s, size, "Blue"));
+    // A setting changed elsewhere (a key bound, a command) shows on the next frame.
+    s.fov = 90.0;
+    frame(&mut shell, &mut s, &atlas);
+    assert!(reads(&mut shell, &s, size, "90"));
+    let before = built(&shell);
+    frame(&mut shell, &mut s, &atlas);
+    assert_eq!(built(&shell), before);
+    // Searching, and another size, build them again.
+    shell.type_text("filler");
+    shell.view(&s, size);
+    assert_eq!(built(&shell), before + 1);
+    shell.view(&s, SHORT);
+    assert_eq!(built(&shell), before + 2);
+    // So does another language, and coming back from it.
+    lang::scoped(lang::Language::load(&[], "de_de"), || shell.view(&s, SHORT));
+    assert_eq!(built(&shell), before + 3);
+    shell.view(&s, SHORT);
+    assert_eq!(built(&shell), before + 4);
+}
+
+#[test]
+fn a_row_the_list_hides_part_of_scrolls_into_view_when_focused_and_then_takes_a_press() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let cols = Columns::of(SHORT.0, SHORT.1);
+    // A filler far down, scrolled to just over the bottom: its middle is under the list's edge.
+    let cut = FIRST_FILLER + 20;
+    let view = shell.view(&s, SHORT);
+    let (_, y) = shell.placed(&view).find(|(r, _)| r.id == cut).unwrap();
+    shell.scroll.amount = y - cols.bottom + style::ROW / 2.0 - 1.0;
+    let rect = cols.row(y - shell.scroll.amount);
+    assert!(
+        rect[1] + rect[3] / 2.0 >= cols.bottom,
+        "the row's middle is hidden"
+    );
+    let moved = Hosted::reveal(&mut shell, &s, SHORT, rect).unwrap();
+    let shown = [rect[0], rect[1] + moved, rect[2], rect[3]];
+    assert!(moved < 0.0 && shown[1] + shown[3] <= cols.bottom);
+    // All in view, it stays put.
+    assert_eq!(Hosted::reveal(&mut shell, &s, SHORT, shown), None);
+    let middle = (shown[0] + 4.0, shown[1] + shown[3] / 2.0);
+    assert_eq!(
+        shell.click(&mut s, middle, SHORT, false, false, false),
+        vec![CLICK, CHANGED]
+    );
+    assert_eq!(shell.screen.pressed, [(cut, false)]);
+}
+
+#[test]
+fn undo_appears_after_a_change_and_puts_back_what_the_screen_opened_with() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let undo = Columns::of(SIZE.0, SIZE.1).button(1);
+    let on_undo = (undo[0] + 2.0, undo[1] + 2.0);
+    // Nothing changed: there is no Undo to press.
+    assert!(
+        shell
+            .click(&mut s, on_undo, SIZE, false, false, false)
+            .is_empty()
+    );
+    let at = middle_of(&mut shell, FIRST_FILLER, SIZE);
+    shell.click(&mut s, at, SIZE, false, false, false);
+    assert_eq!(s.fov, 71.0);
+    // Another option changed meanwhile isn't the screen's to put back.
+    s.chat_opacity = 0.25;
+    assert_eq!(
+        shell.click(&mut s, on_undo, SIZE, false, false, false),
+        vec![CLICK, CHANGED]
+    );
+    assert_eq!((s.fov, s.chat_opacity), (70.0, 0.25));
+    assert!(
+        shell
+            .click(&mut s, on_undo, SIZE, false, false, false)
+            .is_empty()
+    );
+    // From the keyboard: Tab reaches it, Enter undoes and leaves the focus on Done.
+    shell.click(&mut s, at, SIZE, false, false, false);
+    let reached = (0..100).any(|_| {
+        shell.key(&mut s, K::Tab, None, false, SIZE);
+        shell.focus == Some(Target::Undo)
+    });
+    assert!(reached);
+    assert_eq!(
+        shell.key(&mut s, K::Enter, None, false, SIZE),
+        vec![CLICK, CHANGED]
+    );
+    assert_eq!(s.fov, 70.0);
+    assert_eq!(shell.focus, Some(Target::Done));
+}
+
+#[test]
+fn the_strip_says_why_a_greyed_row_cant_be_used() {
+    let atlas = atlas();
+    let s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let mut batch = HudBatch::new([1708, 960]);
+    let size = (batch.width, batch.height);
+    let strip = |batch: &mut HudBatch, shell: &mut Shell<Probe>, at| {
+        shell.draw(&s, batch, &atlas, at, false, None);
+        crate::widgets::end_frame(crate::widgets::generation() + 1);
+        let dock = Columns::of(size.0, size.1).dock;
+        let labelled = crate::widgets::last_labelled();
+        let found = labelled.iter().find(|w| [w.x, w.y, w.w, w.h] == dock);
+        found.map(|w| w.label.clone())
+    };
+    let grey = middle_of(&mut shell, GREY, size);
+    assert_eq!(strip(&mut batch, &mut shell, grey).as_deref(), Some(WHY));
+    let choice = middle_of(&mut shell, CHOICE, size);
+    assert_eq!(
+        strip(&mut batch, &mut shell, choice).as_deref(),
+        Some(CHOICES[0].1)
+    );
+}
+
+#[test]
+fn growing_the_window_keeps_the_scroll_within_the_list() {
+    let s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    shell.scroll(&s, SIZE, -1000.0);
+    assert!(shell.scroll.amount > 0.0);
+    let tall = (SIZE.0, 4000.0);
+    let view = shell.view(&s, tall);
+    assert_eq!(shell.scroll.amount, 0.0);
+    let first = shell.placed(&view).next().map(|(_, y)| y).unwrap();
+    assert!(first >= view.cols.top);
+}
+
+#[test]
+fn one_scroll_path_moves_the_list_for_wheel_and_stick_alike() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let rate = SCROLL_RATE;
+    // The wheel away from any row, and `scroll`, which a stick and a D-pad use.
+    shell.wheel(&mut s, SIZE, (0.0, 0.0), -1.0);
+    assert_eq!(shell.scroll.amount, rate);
+    shell.scroll(&s, SIZE, -2.0);
+    assert_eq!(shell.scroll.amount, 3.0 * rate);
+    shell.scroll(&s, SIZE, 100.0);
+    assert_eq!(shell.scroll.amount, 0.0);
+}
+
+#[test]
+fn the_wheel_steps_a_row_only_with_the_extra_on_and_only_where_the_screen_says() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let over_choice = middle_of(&mut shell, CHOICE, SIZE);
+    shell.wheel(&mut s, SIZE, over_choice, -1.0);
+    assert_eq!(shell.screen.choice, 0);
+    assert_eq!(shell.scroll.amount, SCROLL_RATE);
+    s.extras.wheel_cycles_settings = true;
+    shell.scroll.amount = 0.0;
+    let outputs = shell.wheel(&mut s, SIZE, over_choice, -1.0);
+    assert_eq!(outputs, vec![CHANGED]);
+    assert_eq!(shell.screen.choice, 1);
+    assert_eq!(shell.scroll.amount, 0.0);
+    // A row the screen doesn't step scrolls, the greyed one too.
+    let over_grey = middle_of(&mut shell, GREY, SIZE);
+    assert!(shell.wheel(&mut s, SIZE, over_grey, -1.0).is_empty());
+    assert_eq!(shell.scroll.amount, SCROLL_RATE);
+}
+
+#[test]
+fn a_row_says_what_its_chosen_value_does_and_is_found_by_what_it_does() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let about = |shell: &mut Shell<Probe>, s: &Settings| {
+        let view = shell.view(s, SIZE);
+        let row = view.rows.iter().find(|r| r.id == CHOICE).unwrap();
+        row.described().to_owned()
+    };
+    assert_eq!(about(&mut shell, &s), "Paints it red.");
+    let at = middle_of(&mut shell, CHOICE, SIZE);
+    shell.click(&mut s, at, SIZE, false, false, false);
+    assert_eq!(about(&mut shell, &s), "Paints it blue.");
+    // The search reads the row's own description, on every page.
+    shell.type_text("colour");
+    let view = shell.view(&s, SIZE);
+    let found: Vec<u32> = view.rows.iter().map(|r| r.id).collect();
+    assert!(found.contains(&CHOICE) && !found.contains(&99));
+    shell.search.set_value("elsewhere");
+    shell.focus = None;
+    let view = shell.view(&s, SIZE);
+    assert_eq!(view.rows.iter().map(|r| r.id).collect::<Vec<_>>(), [99]);
+}
+
+#[test]
+fn a_press_on_the_track_slides_and_on_the_name_only_focuses() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let at = middle_of(&mut shell, SLIDER, SIZE);
+    assert!(
+        shell
+            .click(&mut s, at, SIZE, false, false, false)
+            .is_empty()
+    );
+    assert_eq!(shell.screen.slider, 0.0);
+    let (track, width) = Columns::of(SIZE.0, SIZE.1).track();
+    let mid = (track + width / 2.0, at.1);
+    assert_eq!(
+        shell.click(&mut s, mid, SIZE, false, false, false),
+        vec![DRAGGED]
+    );
+    assert_eq!(shell.screen.slider, 0.5);
+    let end = (track + width, at.1);
+    assert_eq!(
+        shell.click(&mut s, end, SIZE, true, false, false),
+        vec![DRAGGED]
+    );
+    assert_eq!(shell.screen.slider, 1.0);
+    assert!(shell.release().is_some());
+    assert!(shell.release().is_none());
+}
+
+#[test]
+fn the_keyboard_walks_the_live_rows_past_the_view_and_presses_them() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let mut key = |shell: &mut Shell<Probe>, k| shell.key(&mut s, k, None, false, SHORT);
+    // Tab: the search, the two pages, then the first row.
+    for _ in 0..4 {
+        key(&mut shell, K::Tab);
+    }
+    assert_eq!(shell.focus, Some(Target::Row(SLIDER)));
+    // A slider Tab reaches changes with the arrows, in its steps.
+    key(&mut shell, K::ArrowRight);
+    assert!((shell.screen.slider - 0.1).abs() < f32::EPSILON);
+    // The arrows go on past the greyed row and rows out of view, which scroll in.
+    key(&mut shell, K::ArrowDown);
+    assert_eq!(shell.focus, Some(Target::Row(CHOICE)));
+    key(&mut shell, K::ArrowDown);
+    assert_eq!(shell.focus, Some(Target::Row(FIRST_FILLER)));
+    for _ in 0..30 {
+        key(&mut shell, K::ArrowDown);
+    }
+    assert_eq!(shell.focus, Some(Target::Row(FIRST_FILLER + 30)));
+    assert!(shell.scroll.amount > 0.0);
+    assert_eq!(key(&mut shell, K::Enter), vec![CLICK, CHANGED]);
+    assert_eq!(shell.screen.pressed, [(FIRST_FILLER + 30, false)]);
+    assert_eq!(key(&mut shell, K::Escape), vec![Output::Done]);
+}
+
+#[test]
+fn left_and_right_step_a_focused_choice_and_leave_other_rows() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let mut key = |shell: &mut Shell<Probe>, k| shell.key(&mut s, k, None, false, SIZE);
+    shell.set_focus(Some(Target::Row(CHOICE)));
+    // Right is a press, Left a Shift press: the screen's own way back, and the focus stays.
+    assert_eq!(key(&mut shell, K::ArrowRight), vec![CLICK, CHANGED]);
+    assert_eq!(key(&mut shell, K::ArrowLeft), vec![CLICK, CHANGED]);
+    assert_eq!(shell.screen.pressed, [(CHOICE, false), (CHOICE, true)]);
+    assert_eq!(shell.focus, Some(Target::Row(CHOICE)));
+    assert!(shell.changed);
+    // A row that isn't a choice: Left goes to the page list, as before.
+    shell.set_focus(Some(Target::Row(FIRST_FILLER)));
+    assert!(key(&mut shell, K::ArrowLeft).is_empty());
+    assert!(matches!(shell.focus, Some(Target::Page(_))));
+    assert_eq!(shell.screen.pressed.len(), 2);
+}
+
+#[test]
+fn a_drawn_choice_tells_the_pad_its_arrows_step_it() {
+    let atlas = atlas();
+    let s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let mut batch = HudBatch::new([1708, 960]);
+    shell.draw(&s, &mut batch, &atlas, (0.0, 0.0), false, None);
+    crate::widgets::end_frame(u64::MAX);
+    let view = shell.view(&s, (batch.width, batch.height));
+    let rect_of = |id| {
+        let mut placed = shell.placed(&view);
+        view.cols.row(placed.find(|(r, _)| r.id == id).unwrap().1)
+    };
+    assert!(crate::widgets::last_steps_value(rect_of(CHOICE)));
+    assert!(!crate::widgets::last_steps_value(rect_of(SLIDER)));
+    assert!(!crate::widgets::last_steps_value(rect_of(FIRST_FILLER)));
+}
+
+/// A controller presses with a click, then moves its own focus: only keys show this one.
+#[test]
+fn leaving_the_search_field_gives_the_keys_back() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let view = shell.view(&s, SIZE);
+    let [x, y, w, h] = view.cols.search();
+    shell.click(
+        &mut s,
+        (x + w / 2.0, y + h / 2.0),
+        SIZE,
+        false,
+        false,
+        false,
+    );
+    assert!(shell.typing());
+    Hosted::blur_search(&mut shell);
+    assert!(!shell.typing());
+    // Another focus isn't dropped.
+    let at = middle_of(&mut shell, FIRST_FILLER, SIZE);
+    shell.click(&mut s, at, SIZE, false, false, false);
+    Hosted::blur_search(&mut shell);
+    shell.key(&mut s, K::ArrowDown, None, false, SIZE);
+    assert!(shell.shows_focus(Target::Row(FIRST_FILLER + 1)));
+}
+
+#[test]
+fn a_key_that_moves_nothing_shows_no_focus() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let at = middle_of(&mut shell, FIRST_FILLER, SIZE);
+    shell.click(&mut s, at, SIZE, false, false, false);
+    shell.key(&mut s, K::ShiftLeft, None, false, SIZE);
+    assert!(!shell.shows_focus(Target::Row(FIRST_FILLER)));
+}
+
+#[test]
+fn a_cut_description_says_so() {
+    assert_eq!(cut_off("off, it never "), "off, it never…");
+}
+
+#[test]
+fn a_click_leaves_no_focus_showing_until_a_key_moves_it() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let at = middle_of(&mut shell, FIRST_FILLER, SIZE);
+    shell.click(&mut s, at, SIZE, false, false, false);
+    assert!(!shell.shows_focus(Target::Row(FIRST_FILLER)));
+    // The next key goes on from the row clicked, and shows where it went.
+    shell.key(&mut s, K::ArrowDown, None, false, SIZE);
+    assert!(shell.shows_focus(Target::Row(FIRST_FILLER + 1)));
+}
+
+#[test]
+fn a_taller_strip_takes_from_the_list_as_far_as_the_list_keeps_its_height() {
+    let (wide, base) = (
+        Columns::of(480.0, 270.0).with_note_lines(4),
+        Columns::of(480.0, 270.0),
+    );
+    assert_eq!(wide.note_lines, 4);
+    assert_eq!(wide.bottom, base.bottom - 2.0 * NOTE_LINE_H);
+    assert_eq!(wide.dock[1] + wide.dock[3], base.dock[1] + base.dock[3]);
+    assert_eq!(wide.button(0), base.button(0));
+    // A 720p window at scale 4 has room for one more line, not two.
+    let short = Columns::of(320.0, 180.0).with_note_lines(4);
+    assert_eq!(short.note_lines, 3);
+    assert!(short.bottom - short.top >= MIN_LIST_H);
+}
+
+#[test]
+fn shift_presses_a_row_backwards() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let at = middle_of(&mut shell, FIRST_FILLER, SIZE);
+    shell.click(&mut s, at, SIZE, false, false, true);
+    // The right button is not a press.
+    shell.click(&mut s, at, SIZE, false, true, false);
+    assert_eq!(shell.screen.pressed, [(FIRST_FILLER, true)]);
+}
+
+#[test]
+fn a_click_on_a_greyed_row_does_nothing_and_done_leaves() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let at = middle_of(&mut shell, GREY, SIZE);
+    assert!(
+        shell
+            .click(&mut s, at, SIZE, false, false, false)
+            .is_empty()
+    );
+    assert!(shell.screen.pressed.is_empty());
+    let [x, y, w, h] = Columns::of(SIZE.0, SIZE.1).button(0);
+    let at = (x + w / 2.0, y + h / 2.0);
+    assert_eq!(
+        shell.click(&mut s, at, SIZE, false, false, false),
+        vec![CLICK, Output::Done]
+    );
+}
+
+#[test]
+fn a_page_picked_shows_alone() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let [x, y, w, h] = Columns::of(SIZE.0, SIZE.1).page(1);
+    let at = (x + w / 2.0, y + h / 2.0);
+    assert_eq!(
+        shell.click(&mut s, at, SIZE, false, false, false),
+        vec![CLICK]
+    );
+    let view = shell.view(&s, SIZE);
+    assert_eq!(view.rows.iter().map(|r| r.id).collect::<Vec<_>>(), [99]);
+}
+
+/// A screen with more pages than a short view's page list has room for: a page of its own,
+/// then a section of `PAGES` under a line, one more page out of the list that the section's
+/// first page links to, and a change that waits for Apply.
+#[derive(Default)]
+struct Pages {
+    pending: bool,
+    applied: usize,
+}
+const PAGES: u8 = 12;
+const HOME: u8 = 0;
+const DEEP: u8 = 100;
+const LINK: u32 = 1000;
+const WAITS: u32 = 1001;
+const SECTION: &str = "Section";
+impl Screen for Pages {
+    type Page = u8;
+    type Row = u32;
+    fn title(&self) -> &'static str {
+        "Pages"
+    }
+    fn stamp(&self, _: &Settings) -> u64 {
+        stamp_of(&self.pending)
+    }
+    fn sheets(&self, _: &Settings) -> Vec<Sheet<u8, u32>> {
+        let page = |id: u8, name: String, rows| {
+            Sheet::new(id, name, String::new(), vec![Group { name: "G", rows }])
+        };
+        let change = Row::new(WAITS, "Change".to_owned(), Value::Press);
+        let mut sheets = vec![page(HOME, "Home".to_owned(), vec![change])];
+        for i in 1..=PAGES {
+            let mut rows = vec![Row::new(u32::from(i), format!("Row {i}"), Value::Press)];
+            if i == 1 {
+                rows.push(Row::new(LINK, "Deeper...".to_owned(), Value::Press));
+            }
+            let mut sheet = page(i, format!("Page {i}"), rows);
+            sheet.heading = (i == 1).then(|| SECTION.to_owned());
+            sheets.push(sheet);
+        }
+        let deep = Row::new(u32::from(DEEP), "Deep".to_owned(), Value::Press);
+        let mut deeper = page(DEEP, "Deeper".to_owned(), vec![deep]);
+        deeper.listed = false;
+        sheets.push(deeper);
+        sheets
+    }
+    fn press(&mut self, _: &mut Settings, row: u32, _: bool) -> Vec<Output> {
+        self.pending |= row == WAITS;
+        vec![CHANGED]
+    }
+    fn link(&self, row: u32) -> Option<u8> {
+        (row == LINK).then_some(DEEP)
+    }
+    fn undoes(&self) -> bool {
+        true
+    }
+    fn pending(&self, _: &Settings) -> bool {
+        self.pending
+    }
+    fn apply(&mut self, _: &mut Settings) -> Vec<Output> {
+        self.pending = false;
+        self.applied += 1;
+        vec![CHANGED]
+    }
+}
+
+/// A window of 854x960 (427x480 GUI px at its automatic scale) and one of 854x480 (427x240:
+/// the page list has room for six places).
+const TALL: [u32; 2] = [854, 960];
+const SHORT_WINDOW: [u32; 2] = [854, 480];
+
+/// One frame of `shell` in a window of `window`; the GUI size it was drawn at.
+fn drawn<S: Screen + Default>(shell: &mut Shell<S>, s: &Settings, window: [u32; 2]) -> (f32, f32) {
+    let mut batch = HudBatch::new(window);
+    shell.draw(s, &mut batch, &atlas(), (0.0, 0.0), false, None);
+    crate::widgets::end_frame(crate::widgets::generation() + 1);
+    (batch.width, batch.height)
+}
+
+fn middle([x, y, w, h]: [f32; 4]) -> (f32, f32) {
+    (x + w / 2.0, y + h / 2.0)
+}
+
+#[test]
+fn pages_that_fit_are_listed_and_more_collapse_into_one_row_leaving_none_out() {
+    let s = Settings::default();
+    let mut shell = Shell::<Pages>::default();
+    // Tall enough: each page under the last, the deeper page left out as it is in no list.
+    drawn(&mut shell, &s, TALL);
+    let tall = shell.page_places();
+    let pages: Vec<u8> = tall.iter().map(|p| p.0).collect();
+    assert_eq!(pages, (HOME..=PAGES).collect::<Vec<_>>());
+    assert!(tall.iter().all(|p| p.2 == Part::Tab));
+    assert!(tall.windows(2).all(|p| p[1].1[1] > p[0].1[1]));
+    assert_eq!(shell.strip_ends(), None);
+    // Short: the first page, then the section in one row, its first page between nothing and
+    // its next. Every place is inside the column, the row's on one line under the section's.
+    let size = drawn(&mut shell, &s, SHORT_WINDOW);
+    let short = shell.page_places();
+    let parts: Vec<(u8, Part)> = short.iter().map(|p| (p.0, p.2)).collect();
+    assert_eq!(
+        parts,
+        [(HOME, Part::Tab), (1, Part::Shown), (2, Part::Next)]
+    );
+    assert_eq!(shell.strip_ends(), Some((false, true)));
+    let cols = Columns::of(size.0, size.1);
+    for (_, [x, _, w, _], _) in &short {
+        assert!(*x >= cols.side_x && x + w <= cols.side_x + style::CONTROL_W);
+    }
+    assert_eq!(short[1].1[1], short[2].1[1]);
+    assert_eq!(short[1].1[1], cols.page(2)[1]);
+    // The line naming the section stays over it.
+    let labelled = crate::widgets::last_labelled();
+    let line = labelled.iter().find(|w| w.label == SECTION).unwrap();
+    assert!(line.y > cols.page(1)[1] && line.y < cols.page(2)[1]);
+}
+
+#[test]
+fn the_collapsed_rows_arrows_walk_every_page_and_its_ends_go_no_further() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Pages>::default();
+    shell.show(1);
+    let mut seen = vec![1];
+    let size = loop {
+        let size = drawn(&mut shell, &s, SHORT_WINDOW);
+        let places = shell.page_places();
+        let Some(&(next, rect, _)) = places.iter().find(|p| p.2 == Part::Next) else {
+            break size;
+        };
+        assert_eq!(
+            shell.click(&mut s, middle(rect), size, false, false, false),
+            [CLICK]
+        );
+        assert_eq!(shell.open_page(), Some(next));
+        seen.push(next);
+    };
+    assert_eq!(seen, (1..=PAGES).collect::<Vec<_>>());
+    assert_eq!(shell.strip_ends(), Some((true, false)));
+    // At the last page, the right of the row picks nothing: its arrow is dimmed.
+    let cols = Columns::of(size.0, size.1);
+    let [x, y, w, h] = cols.page(2);
+    assert!(
+        shell
+            .click(
+                &mut s,
+                (x + w - 2.0, y + h / 2.0),
+                size,
+                false,
+                false,
+                false
+            )
+            .is_empty()
+    );
+    assert_eq!(shell.open_page(), Some(PAGES));
+    // The page before it from the keyboard: Enter on its arrow opens it, and the focus follows
+    // it to the middle of the row.
+    let before = shell
+        .page_places()
+        .iter()
+        .find(|p| p.0 == PAGES - 1)
+        .unwrap()
+        .2;
+    assert_eq!(before, Part::Prev);
+    shell.set_focus(Some(Target::Page(PAGES - 1)));
+    assert_eq!(shell.key(&mut s, K::Enter, None, false, size), [CLICK]);
+    drawn(&mut shell, &s, SHORT_WINDOW);
+    let now = shell
+        .page_places()
+        .iter()
+        .find(|p| p.0 == PAGES - 1)
+        .unwrap()
+        .2;
+    assert_eq!(now, Part::Shown);
+}
+
+#[test]
+fn while_searching_the_collapsed_rows_arrows_skip_pages_without_matches() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Pages>::default();
+    // Rows 1, 10, 11 and 12: none before the first. The first page stays, as it has no match.
+    shell.set_search("row 1");
+    let size = drawn(&mut shell, &s, SHORT_WINDOW);
+    let pages = |shell: &Shell<Pages>| shell.page_places().iter().map(|p| p.0).collect::<Vec<_>>();
+    assert_eq!(pages(&shell), [HOME, 1, 10]);
+    assert_eq!(shell.strip_ends(), Some((false, true)));
+    // Its arrow goes to the next match, which has the first one before it and the last after.
+    let next = shell.page_places()[2].1;
+    shell.click(&mut s, middle(next), size, false, false, false);
+    drawn(&mut shell, &s, SHORT_WINDOW);
+    assert_eq!(pages(&shell), [HOME, 1, 10, 11]);
+    assert_eq!(shell.strip_ends(), Some((true, true)));
+}
+
+#[test]
+fn a_controllers_bumpers_find_the_collapsed_rows_parts_as_tabs() {
+    let s = Settings::default();
+    let mut shell = Shell::<Pages>::default();
+    shell.show(5);
+    drawn(&mut shell, &s, SHORT_WINDOW);
+    let tabs: Vec<(f32, bool)> = crate::widgets::last_targets()
+        .into_iter()
+        .filter_map(|t| match t.kind {
+            crate::widgets::Kind::Tab(open) => Some((t.rect[0], open)),
+            _ => None,
+        })
+        .collect();
+    // The first page, the page before, the open one (lit) and the one after.
+    assert_eq!(tabs.len(), 4, "{tabs:?}");
+    assert_eq!(tabs.iter().filter(|t| t.1).count(), 1);
+    let (before, open, after) = (tabs[1].0, tabs[2], tabs[3].0);
+    assert!(open.1 && before < open.0 && open.0 < after);
+    // The arrows are vanilla's Previous Page and Next Page to the narrator.
+    let labels = crate::widgets::last_labelled();
+    let named = |key| {
+        labels
+            .iter()
+            .any(|w| w.label == lang::get(key) && w.enabled)
+    };
+    assert!(named(PREVIOUS_PAGE) && named(NEXT_PAGE));
+}
+
+#[test]
+fn a_link_opens_a_page_out_of_the_list_and_escape_comes_back_to_the_links_page() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Pages>::default();
+    // Found by the search from another page: back is the page the link is on.
+    shell.show(HOME);
+    shell.set_search("deeper");
+    let at = shell.point_at(&s, SIZE, LINK);
+    assert_eq!(shell.click(&mut s, at, SIZE, false, false, false), [CLICK]);
+    // The page opens alone, the search cleared; the list lights the page the link was on.
+    assert_eq!(shell.open_page(), Some(DEEP));
+    assert_eq!(shell.listed(&s, SIZE), [(DEEP, u32::from(DEEP))]);
+    drawn(&mut shell, &s, TALL);
+    assert_eq!(shell.lit_page(), Some(1));
+    assert!(shell.key(&mut s, K::Escape, None, false, SIZE).is_empty());
+    assert_eq!(shell.open_page(), Some(1));
+    assert_eq!(
+        shell.key(&mut s, K::Escape, None, false, SIZE),
+        [Output::Done]
+    );
+}
+
+#[test]
+fn apply_shows_beside_undo_while_changes_wait_and_goes_with_them() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Pages>::default();
+    let done = Columns::of(SIZE.0, SIZE.1).button(0);
+    assert_eq!(shell.foot_at(&s, SIZE), [(Target::Done, done)]);
+    let at = shell.point_at(&s, SIZE, WAITS);
+    shell.click(&mut s, at, SIZE, false, false, false);
+    let foot = shell.foot_at(&s, SIZE);
+    let targets: Vec<_> = foot.iter().map(|f| f.0).collect();
+    assert_eq!(targets, [Target::Undo, Target::Apply, Target::Done]);
+    // Side by side over Done, as wide as it together.
+    let ([ux, uy, uw, _], [ax, ay, aw, _]) = (foot[0].1, foot[1].1);
+    assert_eq!((uy, ay), (foot[2].1[1] - FOOT_GAP - style::BUTTON_H, uy));
+    assert!(ux + uw < ax && ax + aw == done[0] + done[2] && ux == done[0]);
+    assert_eq!(
+        shell.click(&mut s, middle(foot[1].1), SIZE, false, false, false),
+        [CLICK, CHANGED]
+    );
+    assert_eq!(shell.screen.applied, 1);
+    let targets: Vec<_> = shell.foot_at(&s, SIZE).iter().map(|f| f.0).collect();
+    assert_eq!(targets, [Target::Undo, Target::Done]);
+}
+
+#[test]
+fn the_right_button_steps_no_choice_as_vanillas_cycle_button() {
+    let mut s = Settings::default();
+    let mut shell = Shell::<Probe>::default();
+    let choice = middle_of(&mut shell, CHOICE, SIZE);
+    assert!(
+        shell
+            .click(&mut s, choice, SIZE, false, true, false)
+            .is_empty()
+    );
+    assert!(shell.screen.pressed.is_empty());
+}

crates/horizon-client-render/src/skins.rs

@@ -932,7 +932,56 @@ pub struct Downloader {
     failed: std::collections::HashMap<(Kind, String), std::time::Instant>,
     /// How long a failed texture download waits before it is tried again.
     retry_after: std::time::Duration,
+    /// The `states` keys, oldest first, so the oldest settled one can go ([`Bounds::states`]).
+    state_order: std::collections::VecDeque<(Kind, String)>,
+    /// The `resources` keys, oldest first ([`Bounds::resources`]).
+    resource_order: std::collections::VecDeque<String>,
+    /// Downloads started whose answer `state` has not taken yet: one thread each.
+    in_flight: usize,
+    /// Fetches a texture's body; the HTTP GET, but for a test.
+    fetch: fn(&str) -> Option<Vec<u8>>,
+    bounds: Bounds,
 }
+/// A download thread's answer to `state`. If the thread panics before giving it (a body that
+/// breaks the decoder, say), dropping this answers "failed" instead: the download's place in
+/// `in_flight` is given back and the texture is retried after the wait, where an answer that never
+/// came kept the key `Pending` for good and, with the bound, the place taken for the session.
+struct Answer {
+    send: std::sync::mpsc::Sender<((Kind, String), Option<Vec<u8>>)>,
+    key: Option<(Kind, String)>,
+}
+impl Answer {
+    fn give(&mut self, image: Option<Vec<u8>>) {
+        if let Some(key) = self.key.take() {
+            let _ = self.send.send((key, image));
+        }
+    }
+}
+impl Drop for Answer {
+    fn drop(&mut self) {
+        self.give(None);
+    }
+}
+
+/// What the downloader keeps and runs at most. Every texture URL a server (or a tab list of
+/// hundreds of players) names used to add a `states` entry and a thread of its own, and every
+/// `texture` id a `resources` entry, none of them ever dropped.
+#[derive(Clone, Copy, Debug)]
+struct Bounds {
+    /// Entries of `states`; the oldest settled (ready or failed) one is dropped past this. A
+    /// dropped texture is loaded again from the disk cache when it is asked for.
+    states: usize,
+    /// Entries of `resources`; the oldest is dropped past this, and read from the packs again.
+    resources: usize,
+    /// Downloads running at once. Past this `state` says `Pending` and starts nothing, so the
+    /// caller, which asks again every frame, starts it when one has finished.
+    downloads: usize,
+}
+const BOUNDS: Bounds = Bounds {
+    states: 4096,
+    resources: 4096,
+    downloads: 16,
+};
 /// `images` is bounded only so a long session on a busy server does not grow
 /// without end; the disk cache holds everything it drops.
 const MAX_SKIN_IMAGES: usize = 1024;
@@ -964,6 +1013,11 @@ impl Downloader {
             resources: Default::default(),
             failed: Default::default(),
             retry_after: std::time::Duration::from_secs(60),
+            state_order: Default::default(),
+            resource_order: Default::default(),
+            in_flight: 0,
+            fetch: http_get,
+            bounds: BOUNDS,
         }
     }
     /// The resource packs changed (or were first loaded) at `root`: patch
@@ -973,6 +1027,7 @@ impl Downloader {
             self.images.remove(&location);
             self.image_order.retain(|l| *l != location);
         }
+        self.resource_order.clear();
         self.resource_root = root;
     }
     /// `ClientAsset.ResourceTexture`: loads `<namespace>:textures/<path>.png`
@@ -1002,12 +1057,47 @@ impl Downloader {
             }
             None => Download::Failed,
         };
-        self.resources.insert(location.to_owned(), state);
+        if self.resources.insert(location.to_owned(), state).is_none() {
+            self.resource_order.push_back(location.to_owned());
+            while self.resources.len() > self.bounds.resources
+                && let Some(old) = self.resource_order.pop_front()
+            {
+                self.resources.remove(&old);
+            }
+        }
+    }
+    /// Forgets how `location` loaded, so `resource` reads it again.
+    fn forget_resource(&mut self, location: &str) {
+        if self.resources.remove(location).is_some() {
+            self.resource_order.retain(|l| l != location);
+        }
+    }
+    /// Records how `key` stands. A new key may push the oldest settled one out of `states`;
+    /// downloads running are never dropped, so their answer has a key to land on.
+    fn set_state(&mut self, key: (Kind, String), state: Download) {
+        if self.states.insert(key.clone(), state).is_some() {
+            return;
+        }
+        self.state_order.push_back(key);
+        while self.states.len() > self.bounds.states {
+            let Some(at) = self
+                .state_order
+                .iter()
+                .position(|k| self.states.get(k) != Some(&Download::Pending))
+            else {
+                break;
+            };
+            if let Some(old) = self.state_order.remove(at) {
+                self.states.remove(&old);
+                self.failed.remove(&old);
+            }
+        }
     }
     /// How the download of `url` stands, starting it the first time. A
     /// failure is permanent for `retry_after`, then tried again.
     pub fn state(&mut self, kind: Kind, url: &str) -> Download {
         while let Ok((key, image)) = self.done.try_recv() {
+            self.in_flight = self.in_flight.saturating_sub(1);
             let state = match image {
                 Some(rgba) => {
                     match key.0 {
@@ -1023,29 +1113,42 @@ impl Downloader {
                     Download::Failed
                 }
             };
-            self.states.insert(key, state);
+            self.set_state(key, state);
         }
         let Some(hash) = texture_hash(url) else {
             return Download::Failed;
         };
         let key = (kind, hash);
+        let full = self.in_flight >= self.bounds.downloads;
         if let Some(state) = self.states.get(&key).copied() {
             let due = self
                 .failed
                 .get(&key)
                 .is_none_or(|at| at.elapsed() >= self.retry_after);
-            if state != Download::Failed || !due {
+            // A failure that is due waits for a free download like a new texture does.
+            if state != Download::Failed || !due || full {
                 return state;
             }
             self.states.remove(&key);
             self.failed.remove(&key);
+            self.state_order.retain(|k| *k != key);
         }
-        self.states.insert(key.clone(), Download::Pending);
+        if full {
+            // Not recorded: the next call asks again, and starts it once one has finished.
+            return Download::Pending;
+        }
+        self.in_flight += 1;
+        self.set_state(key.clone(), Download::Pending);
         let digest: String = skin_location(&key.1)["skins/".len()..].to_owned();
         let (url, send, root) = (url.to_owned(), self.send.clone(), self.root.clone());
+        let fetch = self.fetch;
         std::thread::spawn(move || {
-            let image = Self::load_texture(&root, kind, &digest, &url, http_get);
-            let _ = send.send((key, image));
+            let mut answer = Answer {
+                send,
+                key: Some(key),
+            };
+            let image = Self::load_texture(&root, kind, &digest, &url, fetch);
+            answer.give(image);
         });
         Download::Pending
     }
@@ -1108,7 +1211,7 @@ impl Downloader {
         if location.starts_with("patch/") {
             let Some(image) = self.images.get(location).cloned() else {
                 // Dropped from memory: read from the packs again.
-                self.resources.remove(location);
+                self.forget_resource(location);
                 return false;
             };
             self.queue(location.to_owned(), image);
@@ -1925,3 +2028,225 @@ mod tests {
         assert_eq!(served.load(Ordering::SeqCst), 2);
     }
 }
+
+#[cfg(test)]
+mod download_bound_tests {
+    use super::{Bounds, Download, Downloader, Kind};
+    use std::sync::atomic::{AtomicUsize, Ordering};
+
+    fn downloader(name: &str, bounds: Bounds, fetch: fn(&str) -> Option<Vec<u8>>) -> Downloader {
+        let root =
+            std::env::temp_dir().join(format!("horizon-test-skin-{name}-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&root);
+        let mut d = Downloader::new(root);
+        d.fetch = fetch;
+        d.bounds = bounds;
+        d
+    }
+
+    fn url(i: usize) -> String {
+        format!("https://textures.example/texture/skin{i:05}")
+    }
+
+    /// Asks again until the texture's download has settled.
+    fn wait(d: &mut Downloader, url: &str) -> Download {
+        let deadline = std::time::Instant::now() + std::time::Duration::from_secs(10);
+        loop {
+            let state = d.state(Kind::Skin, url);
+            if state != Download::Pending || std::time::Instant::now() > deadline {
+                return state;
+            }
+            std::thread::sleep(std::time::Duration::from_millis(2));
+        }
+    }
+
+    static RUNNING: AtomicUsize = AtomicUsize::new(0);
+    static PEAK: AtomicUsize = AtomicUsize::new(0);
+
+    /// A fetch that is slow enough for the others to pile up behind it, and counts how many run.
+    fn slow_failure(_: &str) -> Option<Vec<u8>> {
+        let now = RUNNING.fetch_add(1, Ordering::SeqCst) + 1;
+        PEAK.fetch_max(now, Ordering::SeqCst);
+        std::thread::sleep(std::time::Duration::from_millis(20));
+        RUNNING.fetch_sub(1, Ordering::SeqCst);
+        None
+    }
+
+    /// The same, not counted: tests run side by side, and the count is another test's.
+    fn sleepy_failure(_: &str) -> Option<Vec<u8>> {
+        std::thread::sleep(std::time::Duration::from_millis(20));
+        None
+    }
+
+    /// A tab list of 60 players names 60 textures at once: no more than the bound run together,
+    /// the ones that waited start as the others finish, and every one ends. Every frame asks again.
+    #[test]
+    fn downloads_run_a_few_at_a_time_and_the_late_ones_start_later() {
+        let bounds = Bounds {
+            states: 4096,
+            resources: 4096,
+            downloads: 4,
+        };
+        let mut d = downloader("threads", bounds, slow_failure);
+        let urls: Vec<String> = (0..60).map(url).collect();
+        let deadline = std::time::Instant::now() + std::time::Duration::from_secs(20);
+        let mut first = true;
+        loop {
+            let states: Vec<Download> = urls.iter().map(|u| d.state(Kind::Skin, u)).collect();
+            if first {
+                // Asked all at once: four started, and the others were not even recorded.
+                assert_eq!(d.in_flight, 4);
+                assert_eq!(d.states.len(), 4);
+                assert!(states.iter().all(|s| *s == Download::Pending));
+                first = false;
+            }
+            if states.iter().all(|s| *s == Download::Failed) {
+                break;
+            }
+            assert!(
+                std::time::Instant::now() < deadline,
+                "{} still pending",
+                states.len()
+            );
+            std::thread::sleep(std::time::Duration::from_millis(2));
+        }
+        assert!(
+            PEAK.load(Ordering::SeqCst) <= 4,
+            "{}",
+            PEAK.load(Ordering::SeqCst)
+        );
+        assert_eq!(d.states.len(), 60);
+        assert_eq!(d.in_flight, 0);
+    }
+
+    /// More textures than `states` holds: the map keeps to its bound, the oldest settled ones go
+    /// (and their failure time with them), and one that went is asked again as a new texture.
+    #[test]
+    fn the_states_keep_to_their_bound_and_drop_the_oldest() {
+        let bounds = Bounds {
+            states: 8,
+            resources: 4096,
+            downloads: 16,
+        };
+        let mut d = downloader("states", bounds, |_| None);
+        for i in 0..40 {
+            let u = url(i);
+            assert_eq!(wait(&mut d, &u), Download::Failed, "{i}");
+            assert!(d.states.len() <= 8 && d.state_order.len() == d.states.len());
+            assert!(d.failed.len() <= 8);
+        }
+        let kept: Vec<usize> = (0..40)
+            .filter(|i| {
+                d.states
+                    .contains_key(&(Kind::Skin, super::texture_hash(&url(*i)).unwrap()))
+            })
+            .collect();
+        assert_eq!(kept, (32..40).collect::<Vec<_>>());
+        // The first one went: asked again, it starts again (and fails again).
+        assert_eq!(d.state(Kind::Skin, &url(0)), Download::Pending);
+        assert_eq!(d.in_flight, 1);
+    }
+
+    /// A fetch that panics, as a decoder can on a body a server chose.
+    fn panicking(_: &str) -> Option<Vec<u8>> {
+        panic!("a fetch that panics, on purpose");
+    }
+
+    /// A thread that panics before it answers still gives its place back: with two places and six
+    /// textures whose fetch panics, every one settles as failed instead of the places staying
+    /// taken for good.
+    #[test]
+    fn a_download_that_panics_gives_its_place_back() {
+        let bounds = Bounds {
+            states: 4096,
+            resources: 4096,
+            downloads: 2,
+        };
+        let mut d = downloader("panics", bounds, panicking);
+        for i in 0..6 {
+            assert_eq!(wait(&mut d, &url(i)), Download::Failed, "{i}");
+        }
+        assert_eq!(d.in_flight, 0);
+        assert_eq!(d.states.len(), 6);
+    }
+
+    /// A fetch long enough for a test to ask between its start and its end.
+    fn slowish_failure(_: &str) -> Option<Vec<u8>> {
+        std::thread::sleep(std::time::Duration::from_millis(150));
+        None
+    }
+
+    /// A failure whose wait is over is retried like a new texture: not while every place is taken
+    /// (it keeps answering `Failed`, and starts nothing), and as soon as one is free.
+    #[test]
+    fn a_failure_that_is_due_waits_for_a_free_place() {
+        let bounds = Bounds {
+            states: 4096,
+            resources: 4096,
+            downloads: 1,
+        };
+        let mut d = downloader("due", bounds, slowish_failure);
+        let wait_time = d.retry_after;
+        assert_eq!(wait(&mut d, &url(0)), Download::Failed);
+        // Another texture takes the only place; the first one's retry becomes due but has to wait.
+        assert_eq!(d.state(Kind::Skin, &url(1)), Download::Pending);
+        d.retry_after = std::time::Duration::ZERO;
+        assert_eq!(d.state(Kind::Skin, &url(0)), Download::Failed);
+        assert_eq!(d.in_flight, 1);
+        d.retry_after = wait_time;
+        assert_eq!(wait(&mut d, &url(1)), Download::Failed);
+        // The place is free: the retry starts.
+        d.retry_after = std::time::Duration::ZERO;
+        assert_eq!(d.state(Kind::Skin, &url(0)), Download::Pending);
+        assert_eq!(d.in_flight, 1);
+    }
+
+    /// A texture that is running is never the one dropped, however many settle behind it.
+    #[test]
+    fn a_running_download_keeps_its_place_in_the_states() {
+        let bounds = Bounds {
+            states: 2,
+            resources: 4096,
+            downloads: 16,
+        };
+        let mut d = downloader("running", bounds, sleepy_failure);
+        assert_eq!(d.state(Kind::Skin, &url(0)), Download::Pending);
+        for i in 1..6 {
+            d.set_state((Kind::Cape, format!("settled{i}")), Download::Ready);
+        }
+        assert_eq!(
+            d.states
+                .get(&(Kind::Skin, super::texture_hash(&url(0)).unwrap())),
+            Some(&Download::Pending)
+        );
+        assert!(d.states.len() <= 3);
+        assert_eq!(wait(&mut d, &url(0)), Download::Failed);
+    }
+
+    /// `resources` keeps to its bound too: a server's `texture` ids, one for each unique one, no
+    /// longer pile up, and one that was dropped is read from the packs again.
+    #[test]
+    fn the_resource_textures_keep_to_their_bound() {
+        let bounds = Bounds {
+            states: 4096,
+            resources: 8,
+            downloads: 16,
+        };
+        let mut d = downloader("resources", bounds, |_| None);
+        for i in 0..40 {
+            d.resource(&format!("patch/n/{i}"), "n", &format!("t{i}"));
+            assert!(d.resources.len() <= 8 && d.resource_order.len() == d.resources.len());
+        }
+        let kept: Vec<usize> = (0..40)
+            .filter(|i| d.resources.contains_key(&format!("patch/n/{i}")))
+            .collect();
+        assert_eq!(kept, (32..40).collect::<Vec<_>>());
+        // Forgetting one by hand (as `again` does) leaves no stale key behind.
+        d.forget_resource("patch/n/35");
+        assert_eq!(d.resource_order.len(), d.resources.len());
+        assert!(!d.resource_order.iter().any(|l| l == "patch/n/35"));
+        // New packs start the count over.
+        d.set_resource_root(std::env::temp_dir());
+        assert!(d.resources.is_empty() && d.resource_order.is_empty());
+    }
+}

crates/horizon-client-render/src/sound_engine.rs

@@ -913,6 +913,20 @@ pub trait Backend {
     fn unpause(&mut self, channel: ChannelId);
     /// `Channel.stopped`.
     fn stopped(&mut self, channel: ChannelId) -> bool;
+    /// Update volume, pitch, and position in a single backend call.
+    fn update_channel(&mut self, channel: ChannelId, volume: f32, pitch: f32, position: [f64; 3]) {
+        self.set_volume(channel, volume);
+        self.set_pitch(channel, pitch);
+        self.set_position(channel, position);
+    }
+    /// Filter which handles have stopped playing in a single pass.
+    fn filter_stopped(&mut self, live: &[(u64, ChannelId)], stopped: &mut Vec<u64>) {
+        for &(h, c) in live {
+            if self.stopped(c) {
+                stopped.push(h);
+            }
+        }
+    }
     /// Whether the channel plays clearly through a mod's muffle (`Audio::muffle`): its sound
     /// event is one the mod exempted. A backend without a muffle ignores it.
     fn set_unmuffled(&mut self, _channel: ChannelId, _unmuffled: bool) {}
@@ -1494,13 +1508,14 @@ impl SoundEngine {
                 .iter()
                 .filter_map(|(h, handle)| handle.channel.map(|c| (*h, c))),
         );
-        for (h, c) in live.drain(..) {
-            if backend.stopped(c) {
-                self.release_handle(h, backend);
-            }
+        let mut stopped = std::mem::take(&mut self.mapped_scratch);
+        stopped.clear();
+        backend.filter_stopped(&live, &mut stopped);
+        for h in stopped.drain(..) {
+            self.release_handle(h, backend);
         }
         // Released handles nobody maps any more.
-        let mut mapped = std::mem::take(&mut self.mapped_scratch);
+        let mut mapped = stopped;
         mapped.clear();
         mapped.extend(self.instance_to_channel.iter().map(|(_, h)| *h));
         self.handles
@@ -1550,9 +1565,7 @@ impl SoundEngine {
                 h.pitch_edited = pitch_edited;
             }
             if let Some(c) = self.handles.get(&handle).and_then(handle_channel) {
-                backend.set_volume(c, volume);
-                backend.set_pitch(c, pitch);
-                backend.set_position(c, position);
+                backend.update_channel(c, volume, pitch, position);
             }
             let instance = self.instances.get_mut(&id).expect("present");
             if instance.looping

crates/horizon-client-render/src/sprites.rs

@@ -127,6 +127,9 @@ pub struct Sprites {
     /// textures under their own names, and one layer serves them all (the GPU's array may
     /// hold as few as 2048).
     still: std::collections::HashMap<StillKey, u32>,
+    /// Names a connected-texture rule matches by name (`matchTiles`, `connectTiles`): each keeps a
+    /// layer of its own ([`Sprites::keep_apart`]).
+    apart: std::collections::HashSet<String>,
     /// Decoded textures kept on disk between launches ([`Sprites::with_disk_cache`]).
     disk: Option<crate::sprite_cache::SpriteCache>,
     /// Textures [`Sprites::prefetch`] decoded ahead of their insert, by sprite name or
@@ -218,6 +221,13 @@ impl Sprites {
             ..Self::default()
         }
     }
+    /// Keeps each of `names` on a layer of its own, never shared with an identical texture: the
+    /// connected-texture rules that name them find their faces by layer, so a texture sharing it
+    /// would be matched too (a tile a rule chains onto, and a model's transparent placeholder
+    /// with the same pixels). Before the textures that bear these names are inserted.
+    pub fn keep_apart(&mut self, names: impl IntoIterator<Item = String>) {
+        self.apart.extend(names);
+    }
     /// Write what this run decoded to the cache file.
     pub fn save_disk_cache(&mut self) {
         if let Some(disk) = &mut self.disk {
@@ -287,8 +297,13 @@ impl Sprites {
         let mut resized = Vec::with_capacity(self.native.len());
         self.pixels.clear();
         for (from, frames, initial) in &self.native {
-            let frames: Arc<Vec<Vec<u8>>> =
-                Arc::new(frames.iter().map(|f| resample(f, *from, size)).collect());
+            // Native frames already match the atlas size: share the immutable
+            // buffers with animations rather than copying every frame again.
+            let frames: Arc<Vec<Vec<u8>>> = if *from == size {
+                Arc::clone(frames)
+            } else {
+                Arc::new(frames.iter().map(|f| resample(f, *from, size)).collect())
+            };
             self.pixels.extend_from_slice(&frames[*initial]);
             resized.push(frames);
         }
@@ -686,23 +701,24 @@ impl Sprites {
                     .is_some_and(|(_, p)| p.starts_with("item/")),
             dither_cutouts: crate::mipmap::dither_cutouts(),
         };
-        let still = (animation.is_none() && frames.len() == 1).then(|| {
-            use std::hash::{Hash, Hasher};
-            let mut frame = std::collections::hash_map::DefaultHasher::new();
-            frames[0].hash(&mut frame);
-            let mut maps = std::collections::hash_map::DefaultHasher::new();
-            pbr.hash(&mut maps);
-            StillKey {
-                frame: frame.finish(),
-                pbr: maps.finish(),
-                side,
-                settings: [
-                    settings.strategy as u32,
-                    settings.alpha_cutoff_bias.to_bits(),
-                ],
-                flags: [settings.has_transparent, settings.item, opaque, translucent],
-            }
-        });
+        let still =
+            (animation.is_none() && frames.len() == 1 && !self.apart.contains(name)).then(|| {
+                use std::hash::{Hash, Hasher};
+                let mut frame = std::collections::hash_map::DefaultHasher::new();
+                frames[0].hash(&mut frame);
+                let mut maps = std::collections::hash_map::DefaultHasher::new();
+                pbr.hash(&mut maps);
+                StillKey {
+                    frame: frame.finish(),
+                    pbr: maps.finish(),
+                    side,
+                    settings: [
+                        settings.strategy as u32,
+                        settings.alpha_cutoff_bias.to_bits(),
+                    ],
+                    flags: [settings.has_transparent, settings.item, opaque, translucent],
+                }
+            });
         if let Some(&same) = still.as_ref().and_then(|k| self.still.get(k)) {
             self.layers.insert(name.to_owned(), same);
             return Ok(same);
@@ -872,6 +888,35 @@ mod tests {
     use super::*;
     use std::fs::{self, File};
     #[test]
+    fn native_frames_at_atlas_size_are_shared_without_resampling() {
+        let pixels = vec![
+            [10, 20, 30, 255].repeat((SPRITE_SIZE * SPRITE_SIZE) as usize),
+            [40, 50, 60, 255].repeat((SPRITE_SIZE * SPRITE_SIZE) as usize),
+        ];
+        let native = Arc::new(pixels.clone());
+        let smaller = Arc::new(vec![vec![12; 8 * 8 * 4], vec![34; 8 * 8 * 4]]);
+        let metadata = r#"{"frametime":2}"#;
+        let mut sprites = Sprites {
+            native: vec![
+                (SPRITE_SIZE, Arc::clone(&native), 1),
+                (8, Arc::clone(&smaller), 0),
+            ],
+            pbr: vec![[None, None], [None, None]],
+            animations: vec![
+                test_frames(0, pixels.clone(), metadata),
+                test_frames(1, smaller.as_ref().clone(), metadata),
+            ],
+            ..Default::default()
+        };
+        sprites.finish();
+        assert!(Arc::ptr_eq(&sprites.animations[0].frames, &native));
+        assert!(!Arc::ptr_eq(&sprites.animations[1].frames, &smaller));
+        assert_eq!(sprites.animations[0].pixels(1), pixels[1].as_slice());
+        let resized = resample(&smaller[0], 8, SPRITE_SIZE);
+        assert_eq!(sprites.animations[1].pixels(0), resized.as_slice());
+        assert_eq!(&sprites.pixels[..pixels[1].len()], pixels[1].as_slice());
+    }
+    #[test]
     fn the_texture_budget_picks_the_largest_side_that_fits() {
         // 1300 layers: vanilla's count, about.
         assert_eq!(side_within(512, 1300, DEFAULT_TEXTURE_BUDGET), 128);
@@ -1282,6 +1327,40 @@ mod tests {
         assert_eq!(sprites.pixels.len(), 3 * 16 * 16 * 4);
     }
     #[test]
+    fn a_texture_a_connected_rule_matches_keeps_a_layer_of_its_own() {
+        // A resource pack's transparent placeholders: a model's layer and a tile another
+        // connected-texture rule chains onto (`matchTiles=./19.png`) have the same pixels. The
+        // rule finds its faces by layer, so the one it names can't share the others'.
+        let root =
+            std::env::temp_dir().join(format!("horizon-sprite-apart-{}", std::process::id()));
+        let directory = root.join("assets/a/textures/block");
+        fs::create_dir_all(&directory).unwrap();
+        let write = |name: &str| {
+            let mut encoder =
+                png::Encoder::new(File::create(directory.join(name)).unwrap(), 16, 16);
+            encoder.set_color(png::ColorType::Rgba);
+            encoder.set_depth(png::BitDepth::Eight);
+            encoder
+                .write_header()
+                .unwrap()
+                .write_image_data(&[0; 16 * 16 * 4])
+                .unwrap();
+        };
+        for name in ["placeholder.png", "named.png", "again.png"] {
+            write(name);
+        }
+        let mut sprites = Sprites::default();
+        sprites.keep_apart(["a:block/named".to_owned()]);
+        let placeholder = sprites.insert(&root, "a:block/placeholder").unwrap();
+        let named = sprites.insert(&root, "a:block/named").unwrap();
+        let again = sprites.insert(&root, "a:block/again").unwrap();
+        fs::remove_dir_all(&root).unwrap();
+        // The named one alone; the others still share.
+        assert_ne!(named, placeholder);
+        assert_eq!(again, placeholder);
+        assert_eq!(sprites.count(), 2);
+    }
+    #[test]
     fn a_32px_only_atlas_does_not_add_an_extra_mipmap() {
         let mut sprites = Sprites {
             native: vec![

crates/horizon-client-render/src/streaming.rs

@@ -605,6 +605,9 @@ pub struct Streaming {
     /// Set while `update` runs, after it refreshed `cover`: nothing else can
     /// change `extra` meanwhile, so `cover` answers without comparing them.
     cover_current: bool,
+    /// `forced` and `mod_forced` as each column's distance to the nearest one, made again when
+    /// they change; read like `cover`, while `cover_current`.
+    forced_cover: Option<ForcedCover>,
     /// Mesh the sections for drawing (false on a server thread).
     pub mesh: bool,
     /// The pregeneration band (`set_band`).
@@ -806,6 +809,7 @@ impl GenerationScan {
                 forced: input.ranges.forced,
                 mod_forced: input.ranges.mod_forced,
                 cover: input.ranges.cover,
+                forced_cover: None,
                 band: input.ranges.band,
             };
             self.remember(ranges, input.world);
@@ -1066,8 +1070,10 @@ pub struct WorkerContext {
     pub light: Arc<LightTables>,
 }
 mod bounded;
+mod forced_cover;
 mod relight_now;
 use bounded::nearest_first;
+use forced_cover::ForcedCover;
 impl Streaming {
     pub fn new<G: ChunkGenerator>(
         generator: Arc<G>,
@@ -1176,6 +1182,7 @@ impl Streaming {
             extra: Vec::new(),
             cover: None,
             cover_current: false,
+            forced_cover: None,
             mesh: true,
             band: None,
             band_ranked: None,
@@ -1691,6 +1698,7 @@ impl Streaming {
         let mut columns = std::mem::take(&mut self.mesh_columns_scratch);
         columns.clear();
         ExtraCover::refresh(&mut self.cover, &self.extra);
+        ForcedCover::refresh(&mut self.forced_cover, &self.forced, &self.mod_forced);
         self.cover_current = true;
         // The sweeps below walk every loaded column and proto chunk. Run them
         // at once when the view moves and every eighth tick otherwise: a
@@ -1870,6 +1878,7 @@ impl Streaming {
                 forced: &self.forced,
                 mod_forced: &self.mod_forced,
                 cover: ExtraCover::current(&self.cover, &self.extra, self.cover_current),
+                forced_cover: self.forced_cover.as_ref().filter(|_| self.cover_current),
                 band: self.band.as_ref(),
             };
             let (protos, generating) = (&self.protos, &self.generating);
@@ -2040,6 +2049,7 @@ impl Streaming {
                 forced: &self.forced,
                 mod_forced: &self.mod_forced,
                 cover: ExtraCover::current(&self.cover, &self.extra, self.cover_current),
+                forced_cover: self.forced_cover.as_ref().filter(|_| self.cover_current),
                 band: self.band.as_ref(),
             };
             self.waiting.retain(|&(x, sy, z)| {
@@ -2145,6 +2155,7 @@ impl Streaming {
                 forced: &self.forced,
                 mod_forced: &self.mod_forced,
                 cover: ExtraCover::current(&self.cover, &self.extra, self.cover_current),
+                forced_cover: self.forced_cover.as_ref().filter(|_| self.cover_current),
                 band: self.band.as_ref(),
             },
             world,
@@ -2283,6 +2294,7 @@ impl Streaming {
             forced: &self.forced,
             mod_forced: &self.mod_forced,
             cover: ExtraCover::current(&self.cover, &self.extra, self.cover_current),
+            forced_cover: self.forced_cover.as_ref().filter(|_| self.cover_current),
             band: self.band.as_ref(),
         }
     }
@@ -2563,6 +2575,8 @@ struct Ranges<'a> {
     /// `extra` indexed by a grid or buckets: coverage queries without a
     /// scan of every area.
     cover: Option<&'a ExtraCover>,
+    /// `forced` and `mod_forced` by distance (`Streaming::forced_cover`), while they match it.
+    forced_cover: Option<&'a ForcedCover>,
     band: Option<&'a Band>,
 }
 /// The chunks a pregeneration task (`/pregen`) wants lit now: rows `z0..=z1`
@@ -2611,6 +2625,7 @@ impl Band {
             + i64::from(x - self.x0 + 8).max(0)
     }
 }
+
 /// For every column near the extra areas, how far it lies outside the
 /// nearest one's square (Chebyshev distance less its radius; 0 inside). A server has an area per player, and streaming asks of every
 /// loaded and wanted column whether one reaches it, several times a tick:
@@ -2918,16 +2933,6 @@ impl Ranges<'_> {
             .iter()
             .any(|&(c, radius)| (x - c.0).abs().max((z - c.1).abs()) <= radius + margin)
     }
-    /// Whether a `/forceload` or a native mod's ticket holds the chunk.
-    fn is_forced(&self, x: i32, z: i32) -> bool {
-        self.forced.contains(&(x, z)) || self.mod_forced.contains(&(x, z))
-    }
-    /// Every chunk a `/forceload` or a native mod's ticket holds, once each.
-    fn forced_chunks(&self) -> impl Iterator<Item = &(i32, i32)> + '_ {
-        self.forced
-            .iter()
-            .chain(self.mod_forced.iter().filter(|c| !self.forced.contains(c)))
-    }
     /// The columns meshed for drawing: those vanilla draws around the
     /// player (`in_view_distance`), and forced ones.
     fn in_view(&self, x: i32, z: i32) -> bool {
@@ -2939,18 +2944,7 @@ impl Ranges<'_> {
         if self.radius >= 0 && dx * dx + dz * dz <= r * r {
             return true;
         }
-        // A forced chunk holds a FORCED ticket at level 31
-        // (`ChunkMap.FORCED_TICKET_LEVEL`), and the level rises one per ring
-        // (`ChunkTracker.computeLevelFromNeighbor`): the margin is the
-        // vanilla status ring the caller asks for.
-        let reach = match margin {
-            1 => FORCED_FULL_RING,
-            2 => FORCED_FEATURES_RING,
-            3 => FORCED_TERRAIN_RING,
-            _ => margin + 1,
-        };
-        self.forced_chunks()
-            .any(|f| (x - f.0).abs() <= reach && (z - f.1).abs() <= reach)
+        self.near_forced(x, z, margin)
     }
 }
 impl Drop for Streaming {
@@ -3484,6 +3478,7 @@ mod tests {
             forced: &forced,
             mod_forced: &NO_CHUNKS,
             cover: None,
+            forced_cover: None,
             band: None,
         };
         let generate = |x, z, priority, order| Queued {
@@ -3724,6 +3719,7 @@ mod tests {
                     forced: &self.forced,
                     mod_forced: &NO_CHUNKS,
                     cover: None,
+                    forced_cover: None,
                     band: None,
                 },
                 world: &self.world,
@@ -4107,6 +4103,7 @@ mod tests {
                     forced: &forced,
                     mod_forced: &NO_CHUNKS,
                     cover: None,
+                    forced_cover: None,
                     band: None,
                 };
                 let square = |x: i32, z: i32, n: i32| {
@@ -4164,6 +4161,7 @@ mod tests {
                     forced: &forced,
                     mod_forced: &NO_CHUNKS,
                     cover: None,
+                    forced_cover: None,
                     band: None,
                 };
                 let span = radius * 3 + 20;
@@ -4201,6 +4199,7 @@ mod tests {
             forced: &forced,
             mod_forced: &NO_CHUNKS,
             cover: None,
+            forced_cover: None,
             band: None,
         };
         for x in -5i32..=15 {
@@ -4235,6 +4234,7 @@ mod tests {
                 forced: &forced,
                 mod_forced: &NO_CHUNKS,
                 cover: None,
+                forced_cover: None,
                 band: None,
             };
             let level = |x: i32, z: i32| 31 + ((x - 40).abs().max((z + 9).abs()) - view).max(0);
@@ -4290,6 +4290,7 @@ mod tests {
             forced: &forced,
             mod_forced: &NO_CHUNKS,
             cover: None,
+            forced_cover: None,
             band: None,
         };
         let level = |x: i32, z: i32| 31 + (x - 40).abs().max((z + 40).abs());
@@ -4430,6 +4431,7 @@ mod cover_tests {
                 forced: &forced,
                 mod_forced: &NO_CHUNKS,
                 cover,
+                forced_cover: None,
                 band: None,
             };
             let (scan, grid) = (ranges(None), ranges(Some(&cover)));
@@ -4473,6 +4475,7 @@ mod cover_tests {
                 forced: &forced,
                 mod_forced: &NO_CHUNKS,
                 cover,
+                forced_cover: None,
                 band: None,
             };
             let (scan, buckets) = (ranges(None), ranges(Some(&cover)));
@@ -4539,6 +4542,7 @@ mod cover_tests {
                 forced: &forced,
                 mod_forced: &NO_CHUNKS,
                 cover,
+                forced_cover: None,
                 band: None,
             };
             // The columns streaming asks about: everything kept, and the

crates/horizon-client-render/src/streaming/forced_cover.rs

@@ -0,0 +1,165 @@
+//! The chunks a `/forceload` or a native mod's ticket holds, as `Ranges` reads them, and their
+//! distance map.
+use super::{FORCED_FEATURES_RING, FORCED_FULL_RING, FORCED_TERRAIN_RING, Ranges};
+use crate::fast_hash::FxHashMap;
+use std::collections::HashSet;
+
+/// `Streaming::forced` and `mod_forced` as the Chebyshev distance from each column within
+/// `REACH` of one to the nearest: `Ranges::in_main_range` answers by one lookup instead of going
+/// through every forced chunk (it is asked for every column, several times a tick).
+pub(super) struct ForcedCover {
+    forced: HashSet<(i32, i32)>,
+    mod_forced: HashSet<(i32, i32)>,
+    near: FxHashMap<(i32, i32), u8>,
+}
+impl ForcedCover {
+    /// The widest ring `in_main_range` asks of a forced chunk (margins 1 to 4).
+    const REACH: i32 = FORCED_TERRAIN_RING + 1;
+    /// Past this many forced chunks the cover is not made: the scan answers.
+    const MOST: usize = 4096;
+    pub(super) fn refresh(
+        cover: &mut Option<Self>,
+        forced: &HashSet<(i32, i32)>,
+        mod_forced: &HashSet<(i32, i32)>,
+    ) {
+        if cover
+            .as_ref()
+            .is_some_and(|c| c.forced == *forced && c.mod_forced == *mod_forced)
+        {
+            return;
+        }
+        if forced.len() + mod_forced.len() > Self::MOST {
+            *cover = None;
+            return;
+        }
+        let mut near = FxHashMap::default();
+        for &(fx, fz) in forced.iter().chain(mod_forced) {
+            for dx in -Self::REACH..=Self::REACH {
+                for dz in -Self::REACH..=Self::REACH {
+                    let d = dx.abs().max(dz.abs()) as u8;
+                    near.entry((fx + dx, fz + dz))
+                        .and_modify(|e: &mut u8| *e = (*e).min(d))
+                        .or_insert(d);
+                }
+            }
+        }
+        *cover = Some(Self {
+            forced: forced.clone(),
+            mod_forced: mod_forced.clone(),
+            near,
+        });
+    }
+    /// Whether a forced chunk lies within `reach` of `(x, z)`, or `None` past `REACH`.
+    pub(super) fn within(&self, x: i32, z: i32, reach: i32) -> Option<bool> {
+        (reach <= Self::REACH).then(|| {
+            self.near
+                .get(&(x, z))
+                .is_some_and(|&d| i32::from(d) <= reach)
+        })
+    }
+}
+
+impl Ranges<'_> {
+    /// Whether a `/forceload` or a native mod's ticket holds the chunk.
+    pub(super) fn is_forced(&self, x: i32, z: i32) -> bool {
+        self.forced.contains(&(x, z)) || self.mod_forced.contains(&(x, z))
+    }
+    /// Every chunk a `/forceload` or a native mod's ticket holds, once each.
+    pub(super) fn forced_chunks(&self) -> impl Iterator<Item = &(i32, i32)> + '_ {
+        self.forced
+            .iter()
+            .chain(self.mod_forced.iter().filter(|c| !self.forced.contains(c)))
+    }
+    /// `in_main_range` past the player's circle: whether a forced chunk lies within the ring
+    /// `margin` asks for.
+    pub(super) fn near_forced(&self, x: i32, z: i32, margin: i32) -> bool {
+        // A forced chunk holds a FORCED ticket at level 31
+        // (`ChunkMap.FORCED_TICKET_LEVEL`), and the level rises one per ring
+        // (`ChunkTracker.computeLevelFromNeighbor`): the margin is the
+        // vanilla status ring the caller asks for.
+        let reach = match margin {
+            1 => FORCED_FULL_RING,
+            2 => FORCED_FEATURES_RING,
+            3 => FORCED_TERRAIN_RING,
+            _ => margin + 1,
+        };
+        if let Some(hit) = self.forced_cover.and_then(|c| c.within(x, z, reach)) {
+            return hit;
+        }
+        self.forced_chunks()
+            .any(|f| (x - f.0).abs() <= reach && (z - f.1).abs() <= reach)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn chunks(seed: &mut u64, n: usize, spread: i32) -> HashSet<(i32, i32)> {
+        let mut next = |m: i32| {
+            *seed ^= *seed << 13;
+            *seed ^= *seed >> 7;
+            *seed ^= *seed << 17;
+            (*seed % (2 * m as u64 + 1)) as i32 - m
+        };
+        (0..n).map(|_| (next(spread), next(spread))).collect()
+    }
+
+    /// With the forced chunks by distance, every column gets the answer the scan of every forced
+    /// chunk gives, at every margin streaming asks (and those past the map's reach), after the
+    /// forced chunks change too.
+    #[test]
+    fn the_distances_answer_as_the_scan() {
+        let mut seed = 0x2545_F491_4F6C_DD1Du64;
+        let mut cover = None;
+        for case in 0..24 {
+            let spread = [3, 12, 40][case % 3];
+            let forced = chunks(&mut seed, 1 + case % 9, spread);
+            // Some mod tickets on forced chunks, some apart.
+            let mut mod_forced = chunks(&mut seed, case % 4, spread);
+            mod_forced.extend(forced.iter().take(case % 2));
+            ForcedCover::refresh(&mut cover, &forced, &mod_forced);
+            let made = cover.as_ref().expect("a few forced chunks get a map");
+            let ranges = |forced_cover| Ranges {
+                // The player's circle far away: only the forced chunks answer.
+                center: (10_000, 10_000),
+                radius: 2,
+                extra: &[],
+                forced: &forced,
+                mod_forced: &mod_forced,
+                cover: None,
+                forced_cover,
+                band: None,
+            };
+            let (scan, map) = (ranges(None), ranges(Some(made)));
+            let span = spread + 10;
+            for z in -span..=span {
+                for x in -span..=span {
+                    for margin in 0..=7 {
+                        assert_eq!(
+                            map.in_main_range(x, z, margin),
+                            scan.in_main_range(x, z, margin),
+                            "case {case} ({x}, {z}) margin {margin}"
+                        );
+                    }
+                    for d in [false, true] {
+                        assert_eq!(map.requested(x, z, d), scan.requested(x, z, d));
+                        assert_eq!(map.chunk_kept(x, z, d), scan.chunk_kept(x, z, d));
+                        assert_eq!(map.unloaded(x, z, d), scan.unloaded(x, z, d));
+                    }
+                }
+            }
+        }
+    }
+
+    /// Too many forced chunks for a map: none is made, and the scan answers.
+    #[test]
+    fn past_the_most_no_map_is_made() {
+        let forced: HashSet<(i32, i32)> = (0..=ForcedCover::MOST as i32).map(|x| (x, 0)).collect();
+        let mut cover = None;
+        ForcedCover::refresh(&mut cover, &HashSet::new(), &HashSet::from([(0, 0)]));
+        assert!(cover.is_some());
+        ForcedCover::refresh(&mut cover, &forced, &HashSet::new());
+        assert!(cover.is_none());
+    }
+}

crates/horizon-client-render/src/studio_ui.rs

@@ -304,19 +304,19 @@ impl StudioUi {
 
                 // Card background & highlight
                 if is_selected {
-                    style::fill(batch, atlas, rect, style::OPEN);
+                    style::fill(batch, atlas, rect, style::open());
                 } else if is_hovered {
-                    style::fill(batch, atlas, rect, style::HOVER);
+                    style::fill(batch, atlas, rect, style::hover());
                 } else {
                     style::well(batch, atlas, rect);
                 }
 
                 let border_color = if is_selected {
-                    style::ACCENT
+                    style::accent()
                 } else if is_hovered {
                     style::WHITE
                 } else {
-                    style::ROW_RULE
+                    style::row_rule()
                 };
                 style::ring(batch, atlas, rect, border_color);
 

crates/horizon-client-render/src/terrain.wgsl

@@ -524,8 +524,18 @@ fn packed_corner(lo: vec3<u32>, hi: vec3<u32>, corner: u32) -> ArenaCorner {
     let packed_light = ((light & 63u) << 2u) | (((light >> 6u) & 63u) << 10u);
     let g = (lo.y >> (8u * corner)) & 255u;
     let t = lo.x;
+    // Corners 1 to 3's own alpha (`packed::ALPHA_STEP` times the code; 0: word 0's).
+    var code = 0u;
+    if corner == 1u {
+        code = (hi.x >> 28u) & 7u;
+    } else if corner == 2u {
+        code = (hi.y >> 24u) & 7u;
+    } else if corner == 3u {
+        code = (hi.y >> 27u) & 7u;
+    }
+    let alpha = select((code * 51u) << 24u, t & 0xff000000u, code == 0u);
     let color = (g * ((t >> 16u) & 255u) / 255u) | ((g * ((t >> 8u) & 255u) / 255u) << 8u)
-        | ((g * (t & 255u) / 255u) << 16u) | (t & 0xff000000u);
+        | ((g * (t & 255u) / 255u) << 16u) | alpha;
     return ArenaCorner(bitcast<vec3<u32>>(vec3<f32>(pos)),
         vec3((u << 10u) | (v << 26u), (hi.x & 0xffffu) | (packed_light << 16u), color));
 }
@@ -955,13 +965,13 @@ const PI: f32 = 3.14159265;
 fn disc_distance(d: vec3<f32>, y: f32) -> vec2<f32> {
     if d.y * y <= 0.0 { return vec2(-1.0); }
     let p = d * (y / d.y);
-    let h = length(p.xz);
-    let phi = atan2(p.z, p.x);
-    let sector = PI / 4.0;
-    let delta = phi - (floor(phi / sector) * sector + sector * 0.5);
-    let edge = 512.0 * cos(sector * 0.5) / cos(delta);
-    if h > edge { return vec2(-1.0); }
-    let s = h / edge;
+    // The regular octagon's edge parameter, directly from its half planes.
+    // max(|x| + tan(pi/8)*|z|, |z| + tan(pi/8)*|x|) / radius
+    // equals length(p.xz) / edge without atan2, floor or cos per pixel.
+    let a = abs(p.xz);
+    let diagonal = 0.41421356237309503;
+    let s = max(a.x + diagonal * a.y, a.y + diagonal * a.x) / 512.0;
+    if s > 1.0 { return vec2(-1.0); }
     let ay = abs(y);
     let rim = sqrt(512.0 * 512.0 + y * y);
     return vec2(ay + s * (rim - ay), ay + s * (512.0 - ay));

crates/horizon-client-render/src/ui.rs

@@ -1251,6 +1251,9 @@ pub struct EditBox {
     /// `getMessage`: what the narrator calls the box ("<message> edit box:
     /// <value>").
     pub message: String,
+    /// `EditBox.setInvertHighlightedTextColor`: a selection draws its text
+    /// inverted (the default) or in the box's own colour (`AnvilScreen`).
+    pub invert_highlighted_text_color: bool,
     /// Where a borderless box drawn in a frame of its own focuses: a controller's outline goes
     /// round the frame, not over the text.
     pub frame: Option<[f32; 4]>,
@@ -1543,6 +1546,7 @@ impl EditBox {
             text_color_uneditable: rgba(112, 112, 112, 255),
             editable: true,
             message: String::new(),
+            invert_highlighted_text_color: true,
             frame: None,
         }
     }
@@ -1918,7 +1922,11 @@ impl EditBox {
             let right = self.x + self.width;
             let (x0, x1) = (cursor_x.min(right), (hx - 1.0).min(right));
             let (a, b) = (x0.min(x1), x0.max(x1));
-            batch.text_highlight(atlas, (a, ty - 1.0, b - a, 11.0), true);
+            batch.text_highlight(
+                atlas,
+                (a, ty - 1.0, b - a, 11.0),
+                self.invert_highlighted_text_color,
+            );
         }
         if show_cursor {
             if insert {
@@ -2628,6 +2636,20 @@ mod tests {
         );
     }
 
+    /// `EditBox.setInvertHighlightedTextColor`: a selection inverts its text
+    /// unless the box asks it not to (the anvil's rename box).
+    #[test]
+    fn a_selection_inverts_its_text_unless_the_box_says_not_to() {
+        let mut edit = EditBox::new(0.0, 0.0, 100.0, 20.0);
+        assert!(edit.invert_highlighted_text_color);
+        edit.invert_highlighted_text_color = false;
+        edit.set_value("name");
+        edit.set_cursor(0, false);
+        edit.set_cursor(4, true);
+        assert_eq!(edit.selected_text(), "name");
+        assert!(!edit.invert_highlighted_text_color);
+    }
+
     /// `EditBox.setEditable(false)`: the box keeps the focus, the caret keys
     /// and copy, but `charTyped`/paste/Backspace/Delete do nothing, and Cut
     /// copies without taking the text out. A value and the caret still show,

crates/horizon-client-render/src/widgets.rs

@@ -14,6 +14,8 @@ pub enum Cursor {
     Arrow,
     PointingHand,
     NotAllowed,
+    /// `CursorTypes.RESIZE_NS`: a scroller held vertically (`MerchantScreen`).
+    ResizeNs,
 }
 
 thread_local! {