Merge pull request #2773 from ludovic111/feat/sculk-sidebar-card

🤖 Agent: merging the Sculk sidebar card (Ludovic approved the screenshots); fmt, clippy -D warnings and launcher tests pass on the head merged with main.
Merge pull request #2769 from ludovic111/refactor/cut-villager-poi
2026-11-07 11:06:11 -10:00 · 2026-10-27 13:04:06 +01:00 · 2026-10-27 12:54:54 +01:00 · 2026-10-27 12:52:56 +01:00 · 2026-10-27 12:46:09 +01:00 · 2026-10-27 12:46:06 +01:00
1901 changed files with 160352 additions and 57346 deletions
@@ -2,7 +2,6 @@
 target/
 .local/
 **/node_modules/
-website/
 benchmarks/
 packs/
 mods/
@@ -0,0 +1,6 @@
+# Generated files that tests compare byte for byte with what they generate: LF on every OS, also
+# where Git for Windows' core.autocrlf would check them out with CRLF.
+docs/launcher-commands.md text eol=lf
+docs/horizon-ctl-commands.md text eol=lf
+crates/horizon-theme/tokens.css text eol=lf
+docs/api/*-reference.md text eol=lf
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec python3 tools/check_public_tree.py --history
+exec python3 tools/check_public_tree.py --pre-push
@@ -6,7 +6,6 @@
 /.github/                                @ludovic111
 /tools/ci/                               @ludovic111
 /tools/release_train.py                  @ludovic111
-/tools/release_channels.py               @ludovic111
 /crates/horizon-release-sign/            @ludovic111
 /crates/horizon-server/src/update.rs     @ludovic111
 /crates/horizon-server/Cargo.toml        @ludovic111
@@ -3,7 +3,8 @@ name: checks
 # check main requires, so it never has a condition: a skipped job counts as passed, and every run of this workflow
 # must report a real verify (a pull request that changes no Rust finishes it in seconds instead).
 # parity: the vanilla harnesses a pull request's changes can affect, on the Mac mini's runner, which holds the
-# maintainer's own Minecraft files (Horizon never downloads the game); .github/workflows/parity.yml. A fork's pull
+# maintainer's own Minecraft files (Horizon never downloads the game); .github/workflows/parity.yml. Only for a pull
+# request that changes a harness, oracle, probe or the runner: the rest are checked on main by parity-main. A fork's pull
 # request runs it only when a maintainer adds the run-parity label (.github/workflows/run-parity.yml), so labels
 # never start this workflow. See docs/release-flow.md.
 on:
@@ -61,18 +62,92 @@ jobs:
        if: steps.rust.outputs.required != 'false'
        run: |
          cargo +stable fmt --all -- --check
-          cargo +stable clippy --workspace --all-targets -- -D warnings
+          # With the game's code mods (on in every release build, off by default).
+          cargo +stable clippy --workspace --all-targets --features horizon-client/mods -- -D warnings
          # The server build (released as horizon-engine): the game without sound or controllers.
          cargo +stable clippy -p horizon-client --all-targets --no-default-features -- -D warnings
+      # Libraries, binaries and integration tests, then doc tests: not the ~275 examples, which clippy above already
+      # type-checks and the parity job builds and runs (they were most of this step's build and link time).
      - name: Test Rust core and voxel kernel correctness
        if: steps.rust.outputs.required != 'false'
-        run: cargo +stable test --workspace
-  parity:
+        run: |
+          cargo +stable test --workspace --lib --bins --tests --features horizon-client/mods,horizon-mods/pack
+          # The full content-root tests (#[ignore]d: minutes each on a laptop). The same build as above; they need the
+          # prepared vanilla data, so without it they pass at once.
+          cargo +stable test --workspace --lib --features horizon-client/mods,horizon-mods/pack mod_content::tests:: -- --ignored
+          cargo +stable test --workspace --doc --features horizon-client/mods,horizon-mods/pack
+  # The launcher is its own workspace (launcher/Cargo.toml), so verify's cargo runs never build it. A pull request that
+  # changes it or a crate it builds is checked here, and so is every push to main: two pull requests can each pass
+  # alone and break it together (#2059 and the registry ratings did, 2026-10-26).
+  launcher:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Does this pull request change the launcher or a crate it builds?
+        if: github.event_name == 'pull_request'
+        id: launcher
+        env:
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+        run: python3 tools/ci/rust_changes.py --launcher "$BASE_SHA" "$HEAD_SHA" >> "$GITHUB_OUTPUT"
+      - name: Install Rust and the headers GPUI links against
+        if: steps.launcher.outputs.required != 'false'
+        run: |
+          sudo apt-get update && sudo apt-get install -y --no-install-recommends libxkbcommon-x11-dev libwayland-dev \
+            libx11-xcb-dev libfontconfig-dev libvulkan-dev libasound2-dev libudev-dev
+          rustup toolchain install stable --profile minimal --component rustfmt --component clippy
+      - uses: Swatinem/rust-cache@v2
+        if: steps.launcher.outputs.required != 'false'
+        with:
+          workspaces: launcher
+          shared-key: launcher
+          save-if: ${{ github.ref == 'refs/heads/main' }}
+      - name: Check the launcher's formatting, lint and tests
+        if: steps.launcher.outputs.required != 'false'
+        working-directory: launcher
+        run: |
+          cargo +stable fmt --check
+          cargo +stable clippy --all-targets --locked -- -D warnings
+          cargo +stable test --locked --lib
+  # Most pull requests leave the harnesses to parity-main, which runs them on main a batch of merges at a time
+  # (.github/workflows/parity-main.yml; releases wait for it). A pull request still runs them itself when it changes
+  # a harness, an oracle, a probe or the runner, or carries the run-parity label (run-parity.yml, when it is added).
+  parity-scope:
    if: github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: ubuntu-latest
+    outputs:
+      run: ${{ steps.scope.outputs.run }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+          fetch-depth: 0
+          persist-credentials: false
+      - id: scope
+        env:
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          LABELS: ${{ join(github.event.pull_request.labels.*.name, ' ') }}
+        run: |
+          changed=$(git diff --name-only "$(git merge-base "$BASE_SHA" HEAD)" HEAD)
+          harness=$(grep -E '^(tools/test_[a-z0-9_]+_parity\.py|tools/(parity[a-z_]*|lab)\.py|tools/parity_hosts\.json|mods/horizon/src/test/|crates/[^/]+/examples/|crates/horizon-client/src/game/[a-z_]*(fixture|harness)\.rs|\.github/workflows/parity[a-z-]*\.yml)' <<< "$changed" || true)
+          if [ -n "$harness" ] || [[ " $LABELS " == *" run-parity "* ]]; then
+            echo "run=true" >> "$GITHUB_OUTPUT"
+            echo "The pull request runs its harnesses: ${harness:-label run-parity}"
+          else
+            echo "run=false" >> "$GITHUB_OUTPUT"
+            echo "No harness, oracle, probe or runner change: parity-main checks this on main"
+          fi
+  parity:
+    needs: parity-scope
+    if: needs.parity-scope.outputs.run == 'true'
    uses: ./.github/workflows/parity.yml
    with:
      base: ${{ github.event.pull_request.base.sha }}
      head: ${{ github.event.pull_request.head.sha }}
+      full: ${{ contains(github.event.pull_request.labels.*.name, 'full-parity') }}
  # Horizon never downloads the game. These jobs need a self-hosted Linux runner
  # (label horizon-game) holding the maintainer's own copy: the official launcher's
  # game directory in HORIZON_MINECRAFT_DIR and the pinned server jar in
@@ -425,7 +500,7 @@ jobs:
        env:
          RUSTUP_TOOLCHAIN: stable
        run: python tools/test_float_log_parity.py
-  portable-mod:
+  jfr-analysis:
    if: github.event_name == 'workflow_dispatch'
    runs-on: [self-hosted, linux, horizon-game]
    steps:
@@ -437,101 +512,7 @@ jobs:
        with:
          distribution: temurin
          java-version: '25'
-      - name: Compile original mod and test metrics
-        run: python tools/build_mod.py
      - name: Verify streaming JFR analysis against the JDK exporter
        run: python tools/test_jfr.py
      - name: Verify ZGC pause and allocation event interpretation
        run: python tools/test_jfr.py --gc zgc
-      - name: Build pinned portable packs
-        run: python tools/build_pack.py
-      - name: Measure isolated worker pacing on this platform
-        run: python -c "from tools.build_mod import benchmark_workers; benchmark_workers()"
-      - name: Measure isolated debounce queue polling
-        run: python -c "from tools.build_mod import benchmark_debounce; benchmark_debounce()"
-      - name: Measure wakeable idle queue latency
-        run: python -c "from tools.build_mod import benchmark_idle; benchmark_idle()"
-      - name: Measure object allocations with compact headers off and on
-        run: python -c "from tools.build_mod import benchmark_headers; benchmark_headers()"
-      - name: Test pack integrity and comparisons
-        run: python -m unittest discover -s tests -v
-      - name: Start recommended OpenGL macOS clients and verify framebuffer readback
-        if: runner.os == 'macOS'
-        run: |
-          python tools/test_client_graphics.py --native-display
-          cp dist/client-graphics-smoke.json dist/client-graphics-macos-title.json
-          python tools/test_client_graphics.py --native-display --world
-          cp dist/client-graphics-smoke.json dist/client-graphics-macos-world.json
-      - name: Compile the private dispatch fixture
-        run: python -c "from tools.build_mod import build_dispatch_fixture; build_dispatch_fixture()"
-      - name: Compile the private integrated-server graphics fixture
-        run: python -c "from tools.build_mod import build_integration_fixture; build_integration_fixture('server-graphics', 'dev.horizonlab.metrics.ServerGraphicsIntegration', fixture_dependencies={})"
-      - name: Compile the private tick-manager state fixture
-        run: python -c "from tools.build_mod import build_integration_fixture; build_integration_fixture('tick-state', 'dev.horizonlab.metrics.TickStateIntegration')"
-      - name: Compile the private terrain tick membership fixture
-        run: python -c "from tools.build_mod import build_tick_dedup_fixture; build_tick_dedup_fixture()"
-      - name: Compile the private culling whitelist fixture
-        run: python -c "from tools.build_mod import build_culling_empty_fixture; build_culling_empty_fixture()"
-      - name: Compile the private culling ray geometry fixture
-        run: python -c "from tools.build_mod import build_integration_fixture; build_integration_fixture('culling-rays', 'dev.horizonlab.dispatch.CullingRayIntegration', ['entityculling'], ['CullingRayAccess'])"
-      - name: Compile the private terrain position lookup fixture
-        run: python -c "from tools.build_mod import build_integration_fixture; build_integration_fixture('terrain-position', 'dev.horizonlab.dispatch.PositionIntegration')"
-      - name: Compile the private terrain quad reuse fixture
-        run: python -c "from tools.build_mod import build_integration_fixture; build_integration_fixture('quad-reuse', 'dev.horizonlab.dispatch.QuadReuseIntegration')"
-      - name: Compile the private object-size agent and terrain quad fixture
-        run: python -c "from tools.test_quad_sizes import build_agent; from tools.build_mod import build_integration_fixture; build_agent(); build_integration_fixture('quad-size', 'dev.horizonlab.dispatch.QuadSizeIntegration')"
-      - name: Compile the private terrain read shutdown fixture
-        run: python -c "from tools.build_mod import build_integration_fixture; build_integration_fixture('terrain-read', 'dev.horizonlab.dispatch.TerrainReadIntegration')"
-      - name: Install headless graphics libraries for applied-hook checks
-        if: runner.os == 'Linux'
-        run: sudo apt-get update && sudo apt-get install -y xvfb libgl1 libegl1 libvulkan1 mesa-vulkan-drivers libasound2t64 libxkbcommon0
-      - name: Verify integrated-server graphics report against the actual device
-        run: python tools/test_server_graphics.py ${{ runner.os == 'macOS' && '--native-display' || '' }}
-      - name: Exercise the applied dispatcher hooks and upstream rejection path
-        if: runner.os == 'Linux'
-        run: python tools/test_dispatch.py
-      - name: Verify applied tick membership transitions and allocation
-        if: runner.os == 'Linux'
-        run: python tools/test_tick_dedup.py
-      - name: Verify live culling whitelist registration and empty iteration
-        if: runner.os == 'Linux'
-        run: python tools/test_culling_empty.py
-      - name: Compare applied culling ray geometry and provider queries
-        if: runner.os == 'Linux'
-        run: python tools/test_culling_rays.py
-      - name: Verify actual full-data position lookup equivalence
-        if: runner.os == 'Linux'
-        run: python tools/test_terrain_position.py
-      - name: Verify actual terrain quad geometry and allocation
-        if: runner.os == 'Linux'
-        run: python tools/test_quad_reuse.py
-      - name: Measure actual builder and quad shallow sizes in both header modes
-        if: runner.os == 'Linux'
-        run: python tools/test_quad_sizes.py
-      - name: Verify interrupted DH reads and preserved shared futures
-        if: runner.os == 'Linux'
-        run: python tools/test_terrain_read.py
-      - name: Upload original mod and pack manifests only
-        uses: actions/upload-artifact@v4
-        with:
-          name: horizon-linux
-          path: |
-            dist/*.mrpack
-            dist/horizon-*.jar
-            dist/worker-pacing-benchmark.txt
-            dist/debounce-queue-benchmark.txt
-            dist/idle-queue-benchmark.txt
-            dist/object-header-benchmark.txt
-            dist/dispatch-integration.json
-            dist/tick-dedup-integration.json
-            dist/culling-empty-integration.json
-            dist/terrain-read-integration.json
-            dist/culling-rays-integration.json
-            dist/terrain-position-integration.json
-            dist/quad-reuse-integration.json
-            dist/quad-size-integration.json
-            dist/server-graphics-smoke.json
-            dist/client-graphics-smoke.json
-            dist/client-graphics-macos-title.json
-            dist/client-graphics-macos-world.json
-          retention-days: 3
@@ -0,0 +1,34 @@
+name: mod-registry
+# The submission service is its own workspace (crates/horizon-mod-registry), so the checks job doesn't build
+# it: this one does, when it or horizon-mods (the checks it shares with the launcher and the game) changes.
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'crates/horizon-mods/**'
+      - 'crates/horizon-mod-registry/**'
+      - '.github/workflows/mod-registry.yml'
+  pull_request:
+    paths:
+      - 'crates/horizon-mods/**'
+      - 'crates/horizon-mod-registry/**'
+      - '.github/workflows/mod-registry.yml'
+permissions:
+  contents: read
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    defaults:
+      run:
+        working-directory: crates/horizon-mod-registry
+    steps:
+      - uses: actions/checkout@v4
+      - run: rustup toolchain install stable --profile minimal --component rustfmt --component clippy
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: crates/horizon-mod-registry
+          save-if: ${{ github.ref == 'refs/heads/main' }}
+      - run: cargo +stable fmt --check
+      - run: cargo +stable clippy --all-targets --locked -- -D warnings
+      - run: cargo +stable test --locked
@@ -8,7 +8,7 @@ name: nightly audit
 #   gh workflow run "nightly audit" -f dry_run=true    # the audit, without touching issues
 on:
  schedule:
-    # GitHub's schedules are in UTC: both, and the first step keeps the one that is 03:00 in Paris.
+    # GitHub's schedules are in UTC: both, and the first step keeps the one that is 03:07 in Paris today.
    - cron: '7 1 * * *'
    - cron: '7 2 * * *'
  workflow_dispatch:
@@ -29,15 +29,21 @@ env:

 jobs:
  audit:
-    runs-on: [self-hosted, horizon-game]
-    timeout-minutes: 150
+    # The Mac mini's runners only: the audit compares with the previous one, so it stays on one platform.
+    runs-on: [self-hosted, horizon-game, macOS]
+    timeout-minutes: 240  # every harness (~80 min) plus lan_integration (~40 min an attempt under load, retried)
    steps:
-      - name: 03:00 in Paris
+      - name: 03:07 in Paris
        id: when
+        env:
+          SCHEDULE: ${{ github.event.schedule }}
        run: |
-          hour=$(TZ=Europe/Paris date +%H)
-          if [[ "${{ github.event_name }}" == schedule && "$hour" != 03 ]]; then
-            echo "It is ${hour}:00 in Paris: the other schedule runs the audit."
+          # Which cron is 03:07 in Paris, from Paris's offset today: GitHub can start a schedule hours late, so the
+          # clock at start time can't tell (on 2026-10-26 both started after 04:00 Paris and both skipped).
+          offset=$(TZ=Europe/Paris date +%z)
+          ours=$([ "$offset" = +0200 ] && echo '7 1 * * *' || echo '7 2 * * *')
+          if [[ "${{ github.event_name }}" == schedule && "$SCHEDULE" != "$ours" ]]; then
+            echo "Paris is at UTC${offset} today: the '$ours' schedule runs the audit."
            echo "run=false" >> "$GITHUB_OUTPUT"
          else
            echo "run=true" >> "$GITHUB_OUTPUT"
@@ -65,7 +71,8 @@ jobs:
        run: |
          echo "since=$(date +%Y-%m-%dT%H:%M:%S)" >> "$GITHUB_OUTPUT"
          set +e
-          python3 tools/parity.py --all --timeout 1800 2>&1 | tee "$RUNNER_TEMP/audit.log"
+          # lan_integration (the whole lan_e2e suite) takes ~2,400 s under load, past the usual 1,800.
+          python3 tools/parity.py --all --timeout 3000 2>&1 | tee "$RUNNER_TEMP/audit.log"
          echo "exit=${PIPESTATUS[0]}" >> "$GITHUB_OUTPUT"
          { echo '```'; tail -40 "$RUNNER_TEMP/audit.log"; echo '```'; } >> "$GITHUB_STEP_SUMMARY"
      - name: Issues for the harnesses that regressed
@@ -0,0 +1,77 @@
+name: parity-main
+# The vanilla harnesses on main, a batch of merges at a time (docs/release-flow.md#parity-on-main), on the Mac mini's
+# runner. One run at a time: merges that land while a run goes on wait in one pending run (GitHub keeps only the
+# newest), which checks every merge since main's last green parity-main (tools/parity_main.py base). On a failure it
+# bisects the failing harnesses over those merges and comments on the pull request that broke them. Releases ship
+# only a commit whose parity-main passed (tools/release_train.py), so nothing a harness catches reaches players.
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+permissions:
+  contents: read
+  # The comment on the merge that broke a harness.
+  pull-requests: write
+  # tools/parity_main.py base reads earlier runs.
+  actions: read
+concurrency:
+  group: parity-main
+  cancel-in-progress: false
+env:
+  # Test runs never reach the telemetry server: no live-count ping, no uploads (docs/telemetry.md).
+  HORIZON_TELEMETRY_URL: "off"
+
+jobs:
+  parity-main:
+    # A Mac mini runner of its own (ludovics-mac-mini-2 holds only this label since 2026-10-26): behind PR parity jobs
+    # this run waited 2 h while every merge replaced the pending one, and on the release runner a release then waited
+    # behind the next run. PR parity jobs have ludovics-mac-mini and playhorizon. Not playhorizon: its 4 CPUs
+    # make a core-crate run several times longer, and a failure here bisects and comments on merges.
+    runs-on: [self-hosted, macOS, horizon-parity-main]
+    timeout-minutes: 240  # a core-crate batch reruns ~300 harnesses (~60-90 min), a bisect a few rounds of the failures
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ github.sha }}
+          fetch-depth: 0
+          persist-credentials: false
+          # Keeps .local/ (parity state, probe builds, oracle results) and target/ between runs.
+          clean: false
+      - uses: dtolnay/rust-toolchain@stable
+      - name: Tools from the runner
+        run: bash tools/ci/runner-env.sh
+      - name: Vanilla data, and resources prepared by this preparer
+        run: bash tools/ci/vanilla-data.sh
+      - name: Main's last green parity-main
+        id: base
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: echo "sha=$(python3 tools/parity_main.py base)" >> "$GITHUB_OUTPUT"
+      - name: The harnesses the merges since then can affect
+        id: harnesses
+        # A failure here is judged by the next step: the run passes when every failed harness passes again at HEAD.
+        continue-on-error: true
+        env:
+          PARITY_HOSTS: ''
+          BASE_SHA: ${{ steps.base.outputs.sha }}
+        run: |
+          echo "Merges since ${BASE_SHA}:"
+          git log --first-parent --format='  %h %s' "$BASE_SHA..HEAD"
+          python3 tools/parity.py --changed "$BASE_SHA" --timeout 2400
+      - name: A flake, or the merge that broke them
+        if: steps.harnesses.outcome == 'failure'
+        env:
+          GH_TOKEN: ${{ github.token }}
+          PARITY_HOSTS: ''
+          BASE_SHA: ${{ steps.base.outputs.sha }}
+        run: |
+          rm -rf .local/parity-main-logs && cp -R .local/parity-runner/logs .local/parity-main-logs 2>/dev/null || true
+          python3 tools/parity_main.py bisect "$BASE_SHA" --comment
+      - name: Logs of the failed harnesses
+        if: steps.harnesses.outcome == 'failure'
+        uses: actions/upload-artifact@v4
+        with:
+          name: parity-main-logs
+          path: .local/parity-main-logs/
+          if-no-files-found: ignore
+          retention-days: 7
@@ -1,6 +1,6 @@
 name: parity
-# The vanilla harnesses a pull request's changes can affect, on the Mac mini's runner, which holds the maintainer's
-# own Minecraft files (Horizon never downloads the game). Called by ci.yml for pull requests from this repository
+# The vanilla harnesses a pull request's changes can affect, on the Mac mini's runner or playhorizon's, which hold the
+# maintainer's own Minecraft files (Horizon never downloads the game). Called by ci.yml for pull requests from this repository
 # and by run-parity.yml when a maintainer labels a fork's pull request run-parity. See docs/release-flow.md.
 on:
  workflow_call:
@@ -13,6 +13,13 @@ on:
        description: The commit to check out and test
        type: string
        required: true
+      full:
+        description: >-
+          The pull request carries the full-parity label (a change every harness reaches, such as a crate split): it
+          runs on playhorizon's runner only, so the Mac mini's runners stay free for the others. While that runner is
+          busy the job waits for it.
+        type: boolean
+        default: false
 permissions:
  contents: read
 env:
@@ -21,28 +28,64 @@ env:

 jobs:
  parity:
-    runs-on: [self-hosted, horizon-game]
-    timeout-minutes: 120  # a change to core crates reruns ~300 harnesses: ~60-90 min on the Mac mini
+    runs-on: ${{ inputs.full && fromJSON('["self-hosted", "horizon-game", "playhorizon"]') || fromJSON('["self-hosted", "horizon-game"]') }}
+    # A change to core crates reruns ~350 harnesses: ~60-90 min on the Mac mini; on playhorizon (4 of its 8 vCPUs, 4
+    # harnesses at a time) up to a few hours, and any pull request's job may land there.
+    timeout-minutes: ${{ inputs.full && 360 || 180 }}
    steps:
      - uses: actions/checkout@v4
        with:
-          # The commit the event names: a fork's later pushes need another run-parity label.
+          # The commit the event names: a fork's later pushes need another run-parity label. The next step merges
+          # main into it.
          ref: ${{ inputs.head }}
          fetch-depth: 0
          persist-credentials: false
          # Keeps .local/ (parity state, probe builds, oracle results) and target/ between runs.
          clean: false
+      - name: The head merged into main (what merging it would land)
+        id: merge
+        env:
+          BASE_SHA: ${{ inputs.base }}
+          HEAD_SHA: ${{ inputs.head }}
+        run: |
+          # Harness fixes and game fixes that reached main since the branch was made then apply here too: a head
+          # tested alone failed harnesses already fixed on main (server_knockback before #2114, mob_ai's heap before
+          # #2270, save_roundtrip before #2212). Selection then compares with this main, so it sees only the pull
+          # request's own changes. A head that conflicts with main is tested alone.
+          set -euo pipefail
+          git merge --abort 2>/dev/null || true
+          git fetch -q --no-tags origin +refs/heads/main:refs/remotes/origin/main
+          main=$(git rev-parse origin/main)
+          if git -c user.name=parity -c user.email=parity@localhost merge -q --no-edit --no-ff "$main" >/dev/null 2>&1; then
+            echo "base=$main" >> "$GITHUB_OUTPUT"
+            echo "Tested: head ${HEAD_SHA:0:9} merged into main ${main:0:9}" | tee -a "$GITHUB_STEP_SUMMARY"
+          else
+            git merge --abort
+            echo "base=$BASE_SHA" >> "$GITHUB_OUTPUT"
+            echo "::warning::head ${HEAD_SHA:0:9} conflicts with main ${main:0:9}: tested alone, without main's fixes"
+            echo "Tested: head ${HEAD_SHA:0:9} alone (it conflicts with main ${main:0:9})" | tee -a "$GITHUB_STEP_SUMMARY"
+          fi
      - uses: dtolnay/rust-toolchain@stable
      - name: Tools from the runner
        run: bash tools/ci/runner-env.sh
      - name: Vanilla data, and resources prepared by this preparer
        run: bash tools/ci/vanilla-data.sh
+      - name: The prepared output is the one the preparer's OUTPUT_VERSION says
+        env:
+          BASE_SHA: ${{ steps.merge.outputs.base }}
+        run: |
+          # A head made before OUTPUT_VERSION (#1947) that conflicts with main has neither the tool nor the number.
+          if [ ! -f tools/prepare_output.py ] || ! grep -q OUTPUT_VERSION crates/horizon-prepare/src/lib.rs; then
+            echo "This head's preparer has no OUTPUT_VERSION: nothing to check"
+            exit 0
+          fi
+          python3 tools/prepare_output.py check --cache --base "$BASE_SHA"
      - name: The version constants are the pinned jar's
        run: python3 tools/gen_version_consts.py --check
      - name: The harnesses this change can affect
        env:
          PARITY_HOSTS: ''
-          BASE_SHA: ${{ inputs.base }}
+          BASE_SHA: ${{ steps.merge.outputs.base }}
        run: python3 tools/parity.py --changed "$BASE_SHA" --timeout 2400  # world_spawn takes ~1480 s on a busy runner
      - name: Logs of the failed harnesses
        if: failure()
@@ -1,55 +0,0 @@
-name: promote
-# Beta game releases become stable once a day (docs/release-flow.md, "Channels"): at 20:00 UTC (21:00 in Paris in
-# winter time, 22:00 in summer) tools/release_channels.py promotes the newest beta that had been out 6 hours by then,
-# passed its release smoke test and isn't covered by an issue labelled release-blocker. Launchers on the Alpha
-# channel install every beta when it is published; Stable gets the day's promotion. The later runs of the evening are
-# retries for a run GitHub starts late or skips: they promote the same beta, so stable still moves once.
-# By hand, from GitHub's app too (Actions > promote > Run workflow):
-#   gh workflow run promote -f tag=v0.2.3                 # that beta now, without waiting for 20:00
-#   gh workflow run promote -f tag=v0.2.3 -f force=true   # even blocked or without its smoke test
-#   gh workflow run promote -f dry_run=true               # say what would be promoted
-# Holding betas back: label an issue release-blocker. While it is open it holds every beta; closed as completed it
-# still holds the betas published before it closed. The issue's text is never read (its author could edit it).
-# When the oldest waiting beta is 30 hours old (it missed a promotion it was due for), an issue "Promotion to stable
-# has stalled" says so; it closes itself after the next promotion.
-on:
-  schedule:
-    - cron: '7,37 20-21 * * *'
-  workflow_dispatch:
-    inputs:
-      tag:
-        description: The beta to promote now (empty = the newest beta that is due)
-        type: string
-        default: ''
-      force:
-        description: Promote that tag even if a release-blocker covers it or its smoke test didn't run
-        type: boolean
-        default: false
-      dry_run:
-        description: Say what would be promoted, change nothing
-        type: boolean
-        default: false
-permissions:
-  contents: write
-  issues: write
-concurrency:
-  group: promote
-  cancel-in-progress: false
-jobs:
-  promote:
-    runs-on: ubuntu-latest
-    timeout-minutes: 10
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          # The notes of a promoted release cover every pull request since the last stable one.
-          fetch-depth: 0
-          # gh uses GH_TOKEN below; nothing needs git credentials on disk.
-          persist-credentials: false
-      - name: Promote
-        env:
-          GH_TOKEN: ${{ github.token }}
-          TAG: ${{ inputs.tag }}
-          FORCE: ${{ inputs.force && 'yes' || '' }}
-          DRY_RUN: ${{ (inputs.dry_run || github.ref != 'refs/heads/main') && 'yes' || '' }}
-        run: python3 tools/release_channels.py promote ${TAG:+--tag "$TAG"} ${FORCE:+--force} ${DRY_RUN:+--dry-run}
@@ -1,21 +1,26 @@
 name: release
 # Automatic game releases (docs/release-flow.md). After every green `checks` run on main, every 10 minutes (so a
-# release waiting for merges to settle goes out without another merge) and by hand, tools/release_train.py decides:
-# a release when pull requests merged since the last one changed what players run and the newest merged 5 minutes
-# ago (the oldest 20 minutes ago, if merges never pause), or at once for a pull request labelled release-now.
-# RELEASES_PAUSED=1 (repository variable) stops them.
+# release waiting for merges to settle goes out without another merge) and by hand, tools/release_train.py decides,
+# for a commit whose checks and parity-main (the vanilla harnesses on main) both passed:
+# a release when 5 pull requests merged since the last one changed what players run and the newest merged 5 minutes
+# ago, or when the oldest has waited 6 hours, or at once for a pull request labelled release-now.
+# RELEASES_PAUSED=1 (repository variable) stops them; so does an open issue labelled release-blocker, forced runs too.
 # Builds Linux (an older Ubuntu, so the binary runs on any recent distribution and on NixOS through nix-ld) and
 # Windows on GitHub, macOS on the Mac mini's runner (MAC_RUNNER=macos-latest sends it to GitHub), then
 # publishes vX.Y.Z on the release line in .github/release-line.txt (docs/versioning.md; without it, the dated
-# vYYYY.MM.DD[.N] from before 0.2) with notes from the merged pull requests, as a beta (a pre-release) that promote.yml makes
-# stable in its daily promotion. macOS: with the repository variable MACOS_SIGN_IDENTITY set, the programs are signed with
+# vYYYY.MM.DD[.N] from before 0.2) with notes from the merged pull requests, as the release and GitHub's latest: one
+# channel, which launchers, `horizon-server update` and install.sh follow at once. So it is published only after the
+# checks that used to gate a promotion pass in this run: the Mac mini's smoke test drew a world, and no release-blocker
+# is open (tools/release_train.py gate); otherwise nothing is published. macOS: with the repository variable
+# MACOS_SIGN_IDENTITY set, the programs are signed with
 # Developer ID and the hardened runtime and the zip is notarized, from the runner's signing keychain
 # (packaging/macos/README.md); unset (forks), ad hoc.
 #   gh workflow run release --ref <branch>                       # dry run: builds and notes, publishes nothing
 #   gh workflow run release -f dry_run=false -f force=true       # on main: release now, whatever the rules say
 on:
  workflow_run:
-    workflows: [checks]
+    # A game release ships a commit both passed on (parity-main runs on batches: the newest commit it passed on).
+    workflows: [checks, parity-main]
    types: [completed]
    branches: [main]
  schedule:
@@ -32,6 +37,8 @@ on:
        default: false
 permissions:
  contents: read
+  # The open release-blocker issues (decide).
+  issues: read
 concurrency:
  group: game-release
  cancel-in-progress: false
@@ -59,8 +66,8 @@ jobs:
        env:
          GH_TOKEN: ${{ github.token }}
          RELEASES_PAUSED: ${{ vars.RELEASES_PAUSED }}
-          # The commit whose checks just passed; a dry run builds the branch it was started on; otherwise
-          # main's newest commit with green checks.
+          # The commit whose checks or parity-main just passed; a dry run builds the branch it was started on;
+          # otherwise main's newest commit with green checks and parity-main.
          HEAD_SHA: ${{ github.event.workflow_run.head_sha || (steps.mode.outputs.dry_run == 'true' && github.sha) || '' }}
          FORCE: ${{ inputs.force && 'yes' || '' }}
        run: |
@@ -72,9 +79,50 @@ jobs:
          # A dry run builds whatever the decision, to test the builds.
          if [[ "${{ steps.mode.outputs.dry_run }}" == true ]]; then echo "release=true" >> "$GITHUB_OUTPUT"; fi

-  build:
+  exporters:
    needs: decide
    if: needs.decide.outputs.release == 'true'
+    # This runner holds the maintainer's own pinned Minecraft jars. Only our classes leave it.
+    runs-on: ${{ vars.MAC_RUNNER || 'ludovics-mac-mini' }}
+    # Three full preparations (two isolated, one batched) besides the compile.
+    timeout-minutes: 60
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ needs.decide.outputs.head }}
+          persist-credentials: false
+          clean: true
+      - uses: dtolnay/rust-toolchain@stable
+      - run: bash tools/ci/runner-env.sh
+      - run: bash tools/ci/vanilla-data.sh
+      - name: Compile and validate original exporters against the pinned jars
+        shell: bash
+        run: |
+          set -euo pipefail
+          # target/ is gone after the clean checkout, and vanilla-data.sh builds the preparer only when it
+          # prepares afresh.
+          cargo build --release --locked -p horizon-prepare
+          # Compiled here, never taken from the runner's shared preparations: pull requests' parity jobs
+          # write those (vanilla-data.sh links .local/exporters to them).
+          rm -rf .local/exporters
+          bundle=$(target/release/horizon-prepare compile-exporters --root "$PWD" | tail -1)
+          mkdir -p exporters
+          cp -R "$bundle/server" "$bundle/client" "$bundle/manifest.json" exporters/
+          # Only our classes and their manifest leave this runner.
+          stray=$(find exporters -type f ! -path exporters/manifest.json \
+            ! \( -name '*.class' \( -path 'exporters/server/dev/horizonlab/parity/*' -o -path 'exporters/client/dev/horizonlab/parity/*' \) \))
+          [ -z "$stray" ] || { echo "::error::not one of our classes: $stray"; exit 1; }
+          python3 tools/check_prepare_exporters.py --binary target/release/horizon-prepare
+      - uses: actions/upload-artifact@v4
+        with:
+          name: original-exporters
+          path: exporters/
+          if-no-files-found: error
+          retention-days: 3
+
+  build:
+    needs: [decide, exporters]
+    if: needs.decide.outputs.release == 'true'
    name: build ${{ matrix.name }}
    strategy:
      fail-fast: false
@@ -128,7 +176,8 @@ jobs:
        if: runner.os == 'Linux'
        run: sudo apt-get update && sudo apt-get install -y --no-install-recommends libasound2-dev libudev-dev
      - name: Build the client, horizon-ctl, horizon-prepare and horizon-server
-        run: cargo build --release --locked -p horizon-client --bin horizon-client --bin horizon-ctl -p horizon-prepare --bin horizon-prepare -p horizon-server --bin horizon-server
+        # `horizon-client/mods`: every released game runs code mods (the feature is off in dev builds).
+        run: cargo build --release --locked --features horizon-client/mods -p horizon-client --bin horizon-client --bin horizon-ctl -p horizon-prepare --bin horizon-prepare -p horizon-server --bin horizon-server
      - name: Every program the release folder takes was built
        run: |
          for binary in horizon-client horizon-ctl horizon-prepare horizon-server; do
@@ -203,7 +252,7 @@ jobs:
                  or not report.get("meshed_sections") or not report.get("player"):
              sys.exit("the smoke run did not draw a world")
          EOF
-          # Published with the release: a beta becomes stable only with it (tools/release_channels.py).
+          # Published with the release; the publish job checks it again before it publishes anything.
          cp "$home/smoke.json" "$RUNNER_TEMP/smoke-test.json"
      - uses: actions/upload-artifact@v4
        if: runner.environment == 'self-hosted'
@@ -212,6 +261,10 @@ jobs:
          path: ${{ runner.temp }}/smoke-test.json
          if-no-files-found: error
          retention-days: 3
+      - uses: actions/download-artifact@v4
+        with:
+          name: original-exporters
+          path: exporters
      - name: Package
        run: |
          set -euo pipefail
@@ -250,8 +303,9 @@ jobs:
        run: |
          set -euo pipefail
          # After the client is packaged: target/release/horizon-client is rebuilt without the audio and
-          # controllers features, so it needs neither libasound nor libudev (minimal server images lack them).
-          cargo build --release --locked -p horizon-client --no-default-features --bin horizon-client
+          # controllers features, so it needs neither libasound nor libudev (minimal server images lack them),
+          # and with code mods like the client.
+          cargo build --release --locked -p horizon-client --no-default-features --features mods --bin horizon-client
          cargo run --locked -p xtask -- package-server target/release/horizon-client "dist/${{ matrix.server_dir }}"
          folder="dist/${{ matrix.server_dir }}"
          python3 tools/check_imports.py --server "$folder/horizon-engine" "$folder/horizon-server" "$folder/horizon-prepare"
@@ -319,6 +373,7 @@ jobs:
    timeout-minutes: 15
    permissions:
      contents: write
+      issues: read
    steps:
      - uses: actions/checkout@v4
        with:
@@ -341,6 +396,17 @@ jobs:
        run: |
          key=(); [[ -n "$EPHEMERAL" ]] && key=(--key "$(cat dist/ephemeral.pub)")
          cargo run --locked --quiet -p horizon-release-sign -- verify --tag "$TAG" --publishing "${key[@]}" dist
+      - name: Ready to publish (the smoke test passed, no release-blocker is open)
+        # Right before publishing: an issue labelled while the builds ran still holds this release. A dry run only
+        # reports what a real run would do.
+        env:
+          GH_TOKEN: ${{ github.token }}
+          DRY_RUN: ${{ needs.decide.outputs.dry_run }}
+        run: |
+          if ! python3 tools/release_train.py gate --kind game --smoke dist/smoke-test.json --blockers; then
+            [[ "$DRY_RUN" == true ]] || { echo "::error::Nothing published"; exit 1; }
+            echo "::warning::A real run would publish nothing"
+          fi
      - name: Publish ${{ needs.decide.outputs.tag }}
        if: needs.decide.outputs.dry_run != 'true'
        env:
@@ -348,17 +414,20 @@ jobs:
          TAG: ${{ needs.decide.outputs.tag }}
        run: |
          signature=(); [[ -f dist/SHA256SUMS.sig ]] && signature=(dist/SHA256SUMS.sig)
-          smoke=(); [[ -f dist/smoke-test.json ]] && smoke=(dist/smoke-test.json)
-          # A beta (pre-release), the Alpha channel's: promote.yml makes it stable and latest in its daily promotion
-          # (docs/release-flow.md).
+          # The release and the latest at once: there is one channel (docs/release-flow.md). Each archive gets a
+          # label (file#label), which GitHub's page shows instead of the file name, so nobody takes the game's
+          # files for the download (#1647). Launchers, servers and install.sh match the name, which stays.
          gh release create "$TAG" --target "${{ needs.decide.outputs.head }}" --title "$(cat notes/title.txt)" \
-            --notes-file notes/body.md --prerelease --latest=false dist/horizon-linux-x86_64.tar.gz \
-            dist/horizon-windows-x64.zip dist/horizon-macos-arm64.zip dist/horizon-server-linux-x86_64.tar.gz \
-            dist/SHA256SUMS "${signature[@]}" "${smoke[@]}"
+            --notes-file notes/body.md --latest \
+            "dist/horizon-linux-x86_64.tar.gz#Game files the launcher installs: Linux (horizon-linux-x86_64.tar.gz)" \
+            "dist/horizon-windows-x64.zip#Game files the launcher installs: Windows (horizon-windows-x64.zip)" \
+            "dist/horizon-macos-arm64.zip#Game files the launcher installs: macOS (horizon-macos-arm64.zip)" \
+            "dist/horizon-server-linux-x86_64.tar.gz#Dedicated server for Linux (horizon-server-linux-x86_64.tar.gz)" \
+            dist/SHA256SUMS "${signature[@]}" dist/smoke-test.json
      - name: Dry run, the release that would be published
        if: needs.decide.outputs.dry_run == 'true'
        run: |
-          echo "Would publish ${{ needs.decide.outputs.tag }} at ${{ needs.decide.outputs.head }}: $(cat notes/title.txt)"
+          echo "Would publish ${{ needs.decide.outputs.tag }} at ${{ needs.decide.outputs.head }} as the release and latest: $(cat notes/title.txt)"
          ls -l dist
      - uses: actions/upload-artifact@v4
        with:
@@ -22,3 +22,4 @@ jobs:
    with:
      base: ${{ github.event.pull_request.base.sha }}
      head: ${{ github.event.pull_request.head.sha }}
+      full: ${{ contains(github.event.pull_request.labels.*.name, 'full-parity') }}
@@ -31,3 +31,6 @@
 /.horizon-cache/
 /crash-reports/
 /debug/
+
+# Release-only compiled original exporter bundle.
+/exporters/
@@ -0,0 +1,183 @@
+# Horizon: a map for agents
+
+Minecraft: Java Edition 26.3 rewritten in Rust (wgpu). Vanilla is the specification wherever it has the
+feature. Read [CONTRIBUTING.md](CONTRIBUTING.md) once; this page tells you where things are.
+Feature → files → harness for the most-changed areas: [docs/architecture.md](docs/architecture.md).
+
+## Rules that bite
+
+- **Never commit Mojang's files**: game jars, assets, decompiled source, prepared resources (`.local/`).
+  `tools/check_public_tree.py` rejects them; `git config core.hooksPath .githooks` runs it on commit.
+- **Keep your runs away from real player data.** Any game or launcher you start gets fresh `mktemp -d`
+  folders in `HORIZON_HOME` (the game's data), `HORIZON_LAUNCHER_HOME`, `XDG_DATA_HOME` and
+  `XDG_CONFIG_HOME`, plus `HORIZON_LAUNCHER_NO_SELF_UPDATE=1` and `HORIZON_NO_AUDIO=1`, and, for the
+  launcher, `HORIZON_LAUNCHER_TRASH`, `HORIZON_LAUNCHER_CLIPBOARD` and `HORIZON_LAUNCHER_DESKTOP` pointing into the scratch home. Never write to
+  `~/.local/share/{applications,horizon,horizon-launcher}` or `~/.local/bin`.
+- **Mark what an agent posts.** A PR body starts with a line naming whose agent opened it and with what.
+  Ludovic's agents write `> 🤖 Opened by Ludovic's AI agent (Claude), not by Ludovic himself.`, and a
+  contributor's agent names its own person and tool (issues: "Filed by", reviews: "Review by"). Every
+  comment starts with `🤖 Agent:`. Never write as Ludovic or as anyone else.
+- **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. Ludovic's agents use
+  `Co-Authored-By: Claude <model> <[email protected]>` and
+  `🤖 Generated with [Claude Code](https://claude.com/claude-code)`.
+- Everything players run is Rust. Python/Java only for dev tools and harness drivers in `tools/`.
+- Horizon-only features follow [docs/design-system.md](docs/design-system.md) and are off by default where
+  they would change the vanilla look.
+- Small PRs (< ~500 lines). Labels: `feature` (players get something new), `skip-release` (they see no
+  change), none for a fix. Agents never add `release-now`: the maintainer decides it. Merges ship in batches of 5, or after
+  6 hours ([docs/release-flow.md](docs/release-flow.md)).
+- Contributors first: `gh pr list --state open --search <area>` before you start; never duplicate theirs.
+
+## Crates
+
+Game workspace (root `Cargo.toml`); `launcher/` and `crates/horizon-telemetry-server` are separate workspaces.
+
+| Crate | Owns |
+|---|---|
+| `horizon-client` | The game: a lib (`src/lib.rs`, ~180 flat modules) and the bin (`src/main.rs` → `game.rs` + `game/`), plus `horizon-ctl` (`src/bin/horizon-ctl/`). Also the dedicated server (`--dedicated`) |
+| `horizon-command` | Command parsing (Brigadier): the vanilla tree, argument types, selectors, suggestions, the tree's network form. Re-exported as `horizon_client::command` |
+| `horizon-client-core` | The client lib's bottom layer: `text.rs`, `lang.rs`, `snbt.rs`, `nbt_path.rs`, `component.rs`, `scoreboard.rs`, `bossbar.rs`, `gamerules.rs`, `block_entity_nbt.rs`, registry/particle/sound tables. Re-exported under the old paths (`horizon_client::text`...) |
+| `horizon-world` | Vanilla world data with no gameplay loop: NBT, regions, chunks, `datafix/`, `worldgen/`, `level/` (server-side block behaviour, ticks, redstone), entity physics, items, effects, food, damage |
+| `horizon-core` | Simulation primitives: Java `Random`s, `jmath` (HotSpot-exact `Math`), positions, noise, density, paletted storage, `version.rs` (the pinned version) |
+| `horizon-protocol` | Network protocol 777: codecs, framing, encryption, `packets/{handshake,status,login,configuration,play}.rs`, `entity_data.rs` |
+| `horizon-assets` | Resource decoding: block-state and item models, baking, atlases |
+| `horizon-prepare` | Builds `.local/horizon-client/26.3` from the player's own Minecraft install (runs the Java exporters) |
+| `horizon-server` | `horizon-server`: `server.toml`, CLI, supervisor of the headless game ([docs/hosting.md](docs/hosting.md)) |
+| `horizon-server-files` | `server.properties`, eula, ops/whitelist/bans, usercache |
+| `horizon-friends`, `horizon-relay` | Play with Friends: invite codes, encrypted tunnel, the relay ([docs/play-with-friends.md](docs/play-with-friends.md)) |
+| `horizon-mods`, `horizon-mod-sdk`, `cargo-horizon-mod` | Sandboxed WebAssembly mods: runtime, SDK + WIT, `cargo horizon-mod` ([docs/mods.md](docs/mods.md)) |
+| `horizon-port-pack` | Porting Java modpacks ([docs/modpacks.md](docs/modpacks.md)) |
+| `horizon-shader-api` | Horizon's own WGSL shader packs ([docs/api/shaders.md](docs/api/shaders.md)): `horizon-shaders.toml`, the `.hshader` package; shared by the game, the launcher and the registry |
+| `horizon-shaders` | Shader packs (the `shaders/` folder format), rebuilt clean-room from a written spec of the format; no wgpu |
+| `horizon-theme` | Design tokens and fonts for the launcher, the game's own menus and the website |
+| `horizon-telemetry`, `horizon-telemetry-server`, `horizon-bench` | Opt-in data collection, its ingest server, the benchmark report format |
+| `horizon-dualsense`, `horizon-threads`, `horizon-release-sign`, `horizon-bots`, `xtask` | DualSense output, thread priorities, signed release checksums, load-test bots, repo tasks |
+| `launcher/` | GPUI launcher: `main.rs` (UI), `backend.rs` (installs, updates), `cli.rs`, `mcp.rs`, `*_page.rs` |
+
+Other top-level folders: `tools/` (harnesses and dev scripts), `tests/` (Python unit tests: `python3 -m
+unittest discover -s tests`), `mods/horizon/src/test/java/dev/horizonlab/parity/` (Java oracles),
+`docs/`, `.github/workflows/`. The website (playhorizon.dev) is the private ludovic111/horizon-site: its build
+reads `README.md`, `launcher/links.json`, `docs/api/`, `roadmap/roadmap.json` and `crates/horizon-theme/tokens.css` from main.
+
+## Build and test fast
+
+```sh
+python3 tools/pr_ready.py                  # the self-check: fmt, clippy -D warnings, touched crates' tests, harnesses; paste its block in the PR
+python3 tools/pr_ready.py --quick          # same without harnesses
+cargo test -p horizon-client --lib --bins --tests   # skips the 104 examples (pr_ready does this); `--doc` separately
+cargo test -p horizon-client --features horizon-client/mods --lib mod_content::tests:: -- --ignored   # the 5 slow content-root tests, #[ignore]d; pr_ready runs them when mod content, assets, blocks or items change
+cargo build --profile fast -p horizon-client        # optimized, quick to link: use it to play or run lan_e2e
+python3 tools/parity.py --changed origin/main       # the harnesses your branch can affect (CI's parity job)
+python3 tools/parity.py --changed-files paths.txt --list   # which harnesses cover these files, without running them
+python3 tools/parity.py mob_ai sculk       # named harnesses
+python3 tools/lan_e2e.py --check chest     # two real games over LAN (server-thread host); --in-frame compares the fallback
+python3 tools/agent_control_e2e.py         # horizon-ctl / MCP end to end
+```
+
+- Harnesses and the game need the vanilla data in `.local/` (`minecraft/`, `horizon-client/26.3`, `datagen/`,
+  `tools/`): see [docs/parity-workflow.md](docs/parity-workflow.md). Without it, pr_ready lists the
+  harnesses for CI.
+- A harness = `tools/test_<name>_parity.py` (324 of them) + a Java oracle (`mods/horizon/src/test/java/dev/horizonlab/parity/Vanilla*Oracle.java`)
+  + a Rust probe: `crates/<crate>/examples/<name>_{probe,fixture}.rs` (horizon-world 175, horizon-client 104),
+  or the game binary with a fixture env var (`game/dispense_fixture.rs`, `game/sculk_fixture.rs`,
+  `game/command_harness.rs`, `game/net_harness.rs`). Copy a nearby harness for a new one.
+- Probes build into `.local/parity-target/`; harnesses find binaries via `lab.cargo_target()`, never `target/`.
+- What a change reruns (of 329 harnesses, measured 2026-10-23): a file of the game binary (`game.rs`, `game/`)
+  ~25, a file of the client lib ~103, of `horizon-world` ~103–109, of `horizon-core` ~119. Plan for it.
+- Rust integration tests: `crates/horizon-client/tests/` (`lan_bot.rs`, `generation_saves.rs`, `streaming_meshes.rs`).
+- **macOS:** `cargo build/test --workspace` may fail to link the two wasm guest cdylibs (undefined
+  `horizon:mods/events` symbols) until #1446 lands: add `--exclude coords-hud --exclude predator-missile --exclude horizon-mods-test-guest --exclude horizon-mods-test-ui-guest`.
+  Their real check is `cargo test -p horizon-mods` (builds them for `wasm32-unknown-unknown`).
+- Linux needs `libasound2-dev libudev-dev`; `--no-default-features` drops audio and controllers (the server build).
+- Run and drive the game (starts the `horizon-client` beside `horizon-ctl`; other arguments go to the game):
+  `target/fast/horizon-ctl --socket $PWD/ctl.sock launch --world W --creative --offscreen --wait --resources $PWD/.local/horizon-client/26.3`,
+  then `horizon-ctl --socket … state|keys|turn|command|screenshot|quit`
+  ([docs/horizon-ctl-commands.md](docs/horizon-ctl-commands.md)).
+
+## Vanilla reference
+
+- Decompiled sources: `.local/minecraft/26.3/sources/{client,server}/` (`python3 tools/lab.py decompile`).
+- Bytecode queries (callers through lambdas, every overload):
+  `python3 tools/rea_vanilla.py method net.minecraft.world.level.block.DispenserBlock dispenseFrom`
+  ([docs/decompilation-status.md](docs/decompilation-status.md)).
+- A harness runs the oracle against the real 26.3 jars and the Rust probe on the same inputs, then compares
+  their JSON. Oracle runs are cached by `tools/parity_shim.py`; `--fresh` reruns them.
+- Mirror vanilla's `Math` calls with `horizon_core::jmath`, and vanilla's RNG with `horizon_core::random`:
+  random draws must happen in vanilla's order.
+
+## horizon-client: where things live
+
+`L:` = lib (`crates/horizon-client/src/`), `G:` = bin (`crates/horizon-client/src/game/`). The lib can't see
+`Game`; bin code reaches the lib as `horizon_client::<module>`.
+
+| Subsystem | Files |
+|---|---|
+| Game loop, tick, frame | `game.rs`: `fn run`, `impl ApplicationHandler for Game` (`window_event`, `about_to_wait`), `fn tick`, `fn tick_world`, `fn render`; L: `clock.rs`, `window.rs`, `spans.rs` |
+| Rendering | L: `gfx.rs` (`Renderer::new`, `Renderer::render`), `gfx/` (cull, occlusion, translucency, upload, timing, lod, weather, stars, end_sky), `*.wgsl`, `particles.rs`, `block_entity_render.rs`, `item_render.rs`, `fog.rs`, `clouds.rs`, `camera.rs`, `first_person.rs`; G: `render_tick.rs`, `item_draw.rs` |
+| Chunks, streaming, light | L: `streaming.rs` (worker pool: generate, light, mesh), `world.rs`, `chunk.rs`, `chunk_map.rs`, `light.rs`, `mesher.rs` + `mesher/`, `vanillagen.rs` (binds horizon-world's generator), `lod.rs` + `lod/`, `ticket_levels.rs`; G: `world_loading.rs`, `postprocess.rs`; game.rs `fn update_world` |
+| World generation | `crates/horizon-world/src/worldgen/` (`generator*.rs`, `feature_graph.rs`, `structure/`, `carver/`) |
+| Block behaviour | `crates/horizon-world/src/level/` (`mod.rs`, `tick.rs`, `hooks.rs`, `redstone.rs`, `place.rs`, `interact.rs`); game.rs `fn tick_blocks`, `fn process_level_events` |
+| Mobs | L: `mobs.rs` (types), `mobs/` (`ai.rs`, `goals.rs`, `brain.rs`, `*_brain.rs`, `nav.rs`, `path.rs`, `species.rs`, `spawning.rs`, `render.rs`, `anim.rs`); G: `creatures.rs` (ticking, spawning, mob events), one file per mob family (`dragon.rs`, `wither.rs`, `villagers.rs`, `piglins.rs`, `golems.rs`...), `natural_spawning.rs` |
+| Other entities | L: `entities.rs`, `projectiles.rs`, `arrows.rs`; G: `boats.rs`, `minecarts.rs`, `mounts.rs`, `armor_stands.rs`, `paintings.rs`, `frames.rs`, `fireworks.rs`, `tnt.rs`, `explosion.rs` |
+| Player actions | game.rs (`fn use_hand`, `fn use_item`, `fn attack`, `fn tick_mining`, `fn break_block`); G: `hand.rs`, `combat.rs`, `consume.rs`, `potions.rs`, `shield.rs`, `crossbow.rs`, `trident.rs`, `fishing.rs`; L: `motion.rs` + `motion/` (movement), `collisions.rs`, `items.rs`, `item_data.rs` |
+| Inventory and containers | L: `menu.rs` (`AbstractContainerMenu.clicked`), `container_screen.rs`, `containers.rs`, `creative.rs`, `crafting.rs`, `recipe_book*.rs`, `stations.rs`, `merchant.rs`; game.rs `fn menu_ops`, `fn click_inventory`; G: `stations.rs`, `trading.rs`, `recipe_book.rs`, `machines.rs` |
+| Commands | parse: crate `horizon-command` (`args.rs`, `selector.rs`, `tree_*.rs`, `vanilla.rs`); run: G: `commands.rs` (dispatch) + `commands/*.rs` (`admin`, `execute`, `items`, `players`, `world_cmds`...); L: `scoreboard_cmd.rs`, `data_cmd.rs`; `horizon-client-core`: `nbt_path.rs`, `scoreboard.rs`; G: `functions.rs`, `command_blocks.rs` |
+| UI screens | `Screen` enum in game.rs; L: `title.rs` + `title/`, `options_ui.rs`, `multiplayer.rs`, `pack_screen.rs`, `graphics_ui.rs`, `screen_draw.rs`, `ui.rs` (widgets), `hud.rs`, `hud_layout.rs`, `hud_overlays.rs`, `chat.rs`, `tab_list.rs`; G: `startup_menu.rs`, `screens.rs` (pause, death), `options.rs`, `lan_screen.rs`, `chat.rs`, `sign_edit.rs`, `books.rs` |
+| Multiplayer client | L: `net.rs` (network thread); G: `remote.rs` (`fn handle_packet`, `fn tick_remote`), `remote_*.rs` (mob data, objects, projectiles, vehicles, stations) |
+| LAN host / server side | L: `lan/` (`conn.rs` handshake + login threads, `hub.rs` + `hub/` play state, `chunks.rs`, `entity.rs`, `tracking.rs`, `guest.rs`, `playerdata.rs`); G: `lan.rs` (`LanHost`), `lan_actions.rs` (`fn as_guest`, `fn tick_guests`), `lan_*.rs` per feature, `lan_entities.rs` (tracked entities) |
+| Integrated server | G: `integrated.rs` (the server thread), `levels.rs` (one level per dimension, `fn tick_server`), `server_travel.rs` |
+| Dedicated server | G: `dedicated.rs`, `dedicated/status.rs`; crates `horizon-server-files`, `horizon-server` |
+| Save and load | L: `save.rs` (level.dat, regions, playerdata), `entity_nbt.rs`, `options_file.rs`; `horizon-client-core/src/block_entity_nbt.rs`; G: `saving.rs`, `persist.rs` (entities); `crates/horizon-world/src/{region.rs,nbt.rs,datafix/}` |
+| Input | game.rs `fn window_event`, `fn key_pressed`, `fn play_mouse`; L: `keybinds.rs`, `keymapping.rs`, `key_names.rs`, `mouse.rs`, `input.rs`, `interaction_input.rs`, `gamepad.rs`, `osk.rs`, `clipboard.rs`; G: `pad.rs`, `pad_menu.rs` |
+| Audio | L: `audio.rs` (mixer), `sound_engine.rs`, `sound_events.rs`, `music.rs`, `ambience.rs`; G: `music.rs`, `subtitle_hud.rs` |
+| Resource packs | L: `packs.rs` + `packs/`, `pack_screen.rs`, `atlas_sources.rs`, `sprites.rs`, `mipmap.rs`, `model_library.rs`, `font.rs`; `horizon-client-core/src/lang.rs`; crate `horizon-assets`; G: `packs.rs` |
+| Agent control | L: `control.rs` (socket), `bin/horizon-ctl/`; G: `control.rs`, `agent.rs`, `events.rs`, `ui_control.rs` ([docs/agent-control.md](docs/agent-control.md)) |
+| Mods | crate `horizon-mods`; G: `mods.rs`; L: `mod_content.rs`, `mod_list.rs` |
+| Horizon extras, settings | L: `extras.rs`, `graphics.rs`, `settings.rs`, `minimap.rs`; G: `extras.rs`, `tweaks.rs`, `options.rs` |
+
+## How `Game` is organised
+
+- `struct Game` (game.rs, ~290 fields) holds everything. Its methods are spread over ~180 files: game.rs keeps
+  the core (tick, render, input, inventory, world open/close) and each `game/<feature>.rs` adds an
+  `impl Game<'_>` block for one feature, with its own state types. Fields are private to the bin.
+- Find a feature's code: `grep -rn "fn tick_<thing>\|fn <verb>_<thing>" crates/horizon-client/src/game*`;
+  the file is usually `game/<thing>s.rs`. Who calls it: grep the name in game.rs's `fn tick` / `fn tick_world`.
+- Fields that say which mode runs: `remote` (this window is a client of a server: multiplayer, LAN guest, or
+  single player on its server thread), `lan` (`LanHost`: this world is open to the network), `integrated`
+  (the window's own server thread), `serving` (this `Game` *is* that server thread), `options.dedicated`.
+  `fn tick` returns `tick_remote()` when `remote` is set; nothing else of the local simulation runs.
+- A server's players run through the same gameplay code as the local player: `as_guest` swaps the guest's
+  state (position, inventory, mode, mining, item use) into `Game` for one call (`game/lan_actions.rs`), and
+  `levels.rs` swaps whole dimensions in the same way. Changes reach clients through the block log, level
+  events and the entity tracker (`lan/tracking.rs`, `game/lan_entities.rs`).
+- Shared read-only data: `Resources` (`res`: blocks, items, recipes, mob types, biomes) and `PackResources`
+  (`pack`), both in game.rs.
+
+## The two single-player paths
+
+1. **Server thread (default since #1514):** `game/integrated.rs` runs a second `Game` (`serving`) on a
+   "Server thread" with one level per dimension; the window joins it as a client through memory (`remote`),
+   exactly as a LAN guest or a dedicated server's player does. This is what players run. Open
+   `[server-thread]` issues list the gaps left.
+2. **In-frame (`--in-frame`, `--no-server-thread` or `HORIZON_SERVER_THREAD=0`):** the window's `Game` ticks
+   the world itself, one level that follows the player (`fn enter_dimension`). Deterministic rule fixtures still use this path; player-facing integration uses the default server thread.
+
+LAN guests and dedicated servers always use the server code, so a fix there serves both. Test both paths
+when you touch player-facing gameplay:
+
+```sh
+cargo run --profile fast -p horizon-client -- --resources .local/horizon-client/26.3 --world T               # server thread
+cargo run --profile fast -p horizon-client -- --resources .local/horizon-client/26.3 --world T --in-frame    # in-frame
+python3 tools/lan_e2e.py --check <name>                  # host on its server thread, guest is a server client
+python3 tools/lan_e2e.py --in-frame --check <name>       # comparison (portals, levels, distance, lava need server-thread mode)
+python3 tools/parity.py dedicated_server server_entities server_player_damage
+```
+
+## Docs worth knowing
+
+[docs/parity-workflow.md](docs/parity-workflow.md) (runner, gate, shards, scopes) ·
+[docs/native-client.md](docs/native-client.md) (options, controls, horizon-ctl) ·
+[docs/server-levels.md](docs/server-levels.md) (levels per dimension) ·
+[docs/rust-parity.md](docs/rust-parity.md) (what is ported) · [docs/known-issues.md](docs/known-issues.md) ·
+[docs/release-flow.md](docs/release-flow.md) · [docs/README.md](docs/README.md) (index).
@@ -0,0 +1 @@
+AGENTS.md
@@ -4,8 +4,13 @@ Thanks for helping. Horizon is Minecraft: Java Edition 26.3 rewritten in Rust, a
 everything is that **it plays exactly like vanilla**. This page is the short version of how we work; questions are
 welcome on [Discord](https://discord.gg/HcTeMZxe5E).

-This repository holds the game, the launcher and the website, plus the tools, tests and docs that build, check and
-release them. Anything else (videos, Discord and other community material) lives elsewhere.
+This repository holds the game and the launcher, plus the tools, tests and docs that build, check and release them.
+The website (playhorizon.dev) is built in a separate repository from this one's README, `docs/api/` and roadmap. Anything else (videos, Discord and other community material) lives elsewhere.
+
+**Where to start: [playhorizon.dev/hub](https://playhorizon.dev/hub).** It shows what is being done now and next
+([ROADMAP.md](ROADMAP.md) in the repository), the work board, good first tasks, and the forms to report a bug or
+suggest something. A pull request for a roadmap item carries its `roadmap:<id>` label; ideas go to the suggestion
+queue (the hub, or `/suggest` on Discord) rather than to issues, which are for bugs.

 ## Build it

@@ -39,6 +44,17 @@ probe against Horizon, and compares their outputs. There are about 290 of them.

 Never commit game files, decompiled source or prepared resources (`.local/`): `tools/check_public_tree.py` rejects
 them (`git config core.hooksPath .githooks` runs it before every commit).
+The pre-push hook checks the full history reachable from the branches and tags being pushed. Run
+`python3 tools/check_public_tree.py --history` to audit the history of all local refs.
+
+## Only original code
+
+Horizon's code is written from Minecraft 26.3 itself and from public documentation, never from another mod, loader
+or renderer. Don't read, copy, translate or paraphrase the source of Iris, OptiFine, Sodium or any other project,
+and don't send code an AI tool wrote from it. Their user documentation and file formats are fine to read, and their
+packs and mods are fine to run and observe. Shader packs were removed on 24 October 2026 (#1561) because their code
+had been written from another project's source; they come back only as a clean-room rewrite from a written
+description of the pack format.

 ## Before asking for review

@@ -1,6 +1,46 @@
 [workspace]
-exclude = ["launcher", "crates/horizon-telemetry-server", "third_party/wgpu-hal"]
-members = ["crates/horizon-core", "crates/horizon-dualsense", "crates/horizon-threads", "crates/horizon-world", "crates/voxel-kernels", "crates/horizon-client", "crates/horizon-server-files", "crates/horizon-server", "crates/horizon-bots", "crates/horizon-assets", "crates/horizon-protocol", "crates/horizon-theme", "crates/horizon-shaderpack", "crates/horizon-prepare", "crates/horizon-telemetry", "crates/horizon-bench", "crates/horizon-friends", "crates/horizon-relay", "crates/horizon-mod-sdk", "crates/horizon-mods", "crates/horizon-mods/tests/guest", "crates/cargo-horizon-mod", "crates/horizon-port-pack", "crates/horizon-release-sign", "crates/horizon-mod-sdk/examples/coords-hud", "xtask"]
+exclude = ["launcher", "crates/horizon-telemetry-server", "crates/horizon-mod-registry", "third_party/wgpu-hal"]
+members = [
+    "crates/horizon-core",
+    "crates/horizon-dualsense",
+    "crates/horizon-threads",
+    "crates/horizon-hdr",
+    "crates/horizon-world",
+    "crates/horizon-client",
+    "crates/horizon-client-core",
+    "crates/horizon-command",
+    "crates/horizon-server-files",
+    "crates/horizon-server",
+    "crates/horizon-bots",
+    "crates/horizon-assets",
+    "crates/horizon-protocol",
+    "crates/horizon-theme",
+    "crates/horizon-prepare",
+    "crates/horizon-telemetry",
+    "crates/horizon-bench",
+    "crates/horizon-friends",
+    "crates/horizon-relay",
+    "crates/horizon-mod-sdk",
+    "crates/horizon-mods",
+    "crates/horizon-mods/tests/guest",
+    "crates/horizon-mods/tests/ui_guest",
+    "crates/cargo-horizon-mod",
+    "crates/horizon-port-pack",
+    "crates/horizon-shaders",
+    "crates/horizon-shader-api",
+    "crates/horizon-release-sign",
+    "crates/horizon-mod-sdk/examples/coords-hud",
+    "crates/horizon-mod-sdk/examples/predator-missile",
+    "crates/horizon-mod-sdk/examples/welcome",
+    "crates/horizon-mod-sdk/examples/beacons",
+    "mods/official/fps-overlay",
+    "mods/official/keystrokes",
+    "mods/official/far-view",
+    "mods/official/minimap",
+    "mods/official/zoom",
+    "xtask",
+    "mods/official/recipes",
+]
 resolver = "2"

 [workspace.package]
@@ -16,6 +16,7 @@
  <a href="#download"><b>Download</b></a> ·
  <a href="https://playhorizon.dev/docs/"><b>Documentation</b></a> ·
  <a href="https://github.com/ludovic111/horizon/releases"><b>Release notes</b></a> ·
+  <a href="ROADMAP.md"><b>Roadmap</b></a> ·
  <a href="#project-status"><b>Project status</b></a> ·
  <a href="#contributing"><b>Contributing</b></a>
 </p>
@@ -30,7 +31,7 @@ Horizon is Minecraft: Java Edition 26.3 rewritten in Rust: a native game that re

 Horizon is installed through **the Horizon launcher**. Get it from [playhorizon.dev](https://playhorizon.dev) (the Download button picks your system) or from [the launcher releases](https://github.com/ludovic111/horizon/releases?q=launcher-v&expanded=true), for Linux x86-64, macOS on Apple Silicon or Windows x64. The launcher installs and updates the game, prepares its files from your own copy of Minecraft, and updates itself.

-**You need** Minecraft: Java Edition 26.3, played once (the official launcher, Prism, MultiMC and other launchers all work); a Java 25 JDK, for the one-time preparation; and a GPU with Vulkan on Linux and Windows, or any Apple Silicon Mac. Step by step, with macOS's first-open prompt and the first launch: [Install and first launch](https://playhorizon.dev/docs/install).
+**You need** Minecraft: Java Edition 26.3, played once (the official launcher, Prism, MultiMC and other launchers all work); a Java 25 runtime, for the one-time preparation; and a GPU with Vulkan on Linux and Windows, or any Apple Silicon Mac. Step by step, with macOS's first-open prompt and the first launch: [Install and first launch](https://playhorizon.dev/docs/install).

 <table>
  <tr>
@@ -45,7 +46,7 @@ The [documentation](https://playhorizon.dev/docs/) covers each of these.

 - **The game:** singleplayer with vanilla's world generation, mobs, villagers, raids, redstone, every command, the HUD and the recipe book, on saves in vanilla's format. Worlds from 1.8 to 26.2 are upgraded as vanilla does. [Status table](#project-status).
 - **Horizon's own extras:** new menus (vanilla's are one setting away), graphics presets, distant terrain up to 1024 chunks, controller support, optional zoom, minimap and more, all off by default where they would change the vanilla look. See [Settings](https://playhorizon.dev/docs/settings).
- **Resource packs, shader packs and data packs:** resource packs work, Java shader packs run their full-screen effects (experimental), and data packs load functions, predicates and item modifiers.
+- **Resource packs and data packs:** resource packs work, and data packs load functions, predicates and item modifiers.
 - **Playing with others:** invite friends from the pause menu's Friends button with a code, Open to LAN, and joining offline-mode servers. Horizon cannot sign in to a Microsoft account yet, so it cannot join servers that check accounts. See [Multiplayer](https://playhorizon.dev/docs/multiplayer).
 - **Mods:** Horizon has its own mod system (Rust compiled to WebAssembly). Java mod jars do not run. See [Mods and data packs](https://playhorizon.dev/docs/mods).

@@ -57,7 +58,7 @@ Screenshots, captured in the Rust client itself with vanilla assets and no mods
  </tr>
  <tr>
    <td width="50%"><img src="docs/media/survival.webp" alt="Survival at dusk: a zombie walks up, with the hotbar, health, hunger and experience"></td>
-    <td width="50%"><img src="docs/media/settings.webp" alt="Vanilla's Video Settings screen with Horizon's own buttons at the top: Horizon Graphics, Advanced Graphics and Shader Packs"></td>
+    <td width="50%"><img src="docs/media/settings.webp" alt="Vanilla's Video Settings screen with Horizon's own buttons at the top: Horizon Graphics and Advanced Graphics"></td>
  </tr>
  <tr>
    <td width="50%"><img src="docs/media/village.webp" alt="A plains village among savanna hills, with farms, villagers and an iron golem"></td>
@@ -109,6 +110,10 @@ Everything prepared lands in the gitignored `.local/`. It is derived from the ga

 The client starts on the title screen. Command-line options (`--world`, `--seed`, `--creative`, `--render-distance`, `--dedicated`), controls, scripting through `horizon-ctl` and the architecture are described in [the native client guide](docs/native-client.md). The rest of the developer documentation is indexed in [docs/README.md](docs/README.md), including [the parity workflow](docs/parity-workflow.md).

+## Roadmap
+
+What is being done now, what comes next and where you can help, in plain words and in technical detail: [ROADMAP.md](ROADMAP.md). [playhorizon.dev/hub](https://playhorizon.dev/hub) shows it with the work board, the journal of what shipped and how to help.
+
 ## Contributing

 Issues and pull requests are welcome: see [CONTRIBUTING.md](CONTRIBUTING.md) for how we work (vanilla first, small pull requests, labels), or [the contributing guide](https://playhorizon.dev/docs/contributing) on the site. Questions and ideas: [Discord](https://discord.gg/HcTeMZxe5E). Before opening a pull request, run the self-check and paste the block it prints:
@@ -0,0 +1,980 @@
+# Horizon roadmap
+
+<!-- Generated by tools/roadmap.py from roadmap/roadmap.toml: edit that file, then run `python3 tools/roadmap.py build`. -->
+
+What is being done on Horizon, what comes next and where you can help. There are no dates: things are Now, Next or Later. Each item is said in plain words, with the technical picture folded under it. The same roadmap, with a Simple / Technical switch, the board, the journal and how to help, is on [playhorizon.dev/hub](https://playhorizon.dev/hub). Pull requests carry the `roadmap:<id>` label of their item.
+
+## At a glance
+
+Horizon is Minecraft: Java Edition 26.3 rewritten from scratch in Rust, so it runs faster on the same computer. Single player, LAN, servers, resource packs and Horizon's own mods work today, on your own copy of the game.
+
+**Being done now**
+
+- **Steady frames at long render distances**: Making Horizon faster than vanilla on every computer, with smooth camera movement even at 32 chunks, by spreading the work better over the processor's cores.
+- **Modpacks' world generation, natively**: Making the world-generation mods of popular modpacks (new structures, YUNG's dungeons and mineshafts, packs built on Lithostitched) generate their worlds in Horizon, natively and fast.
+- **Playing on servers: everything shows as it should**: When you play on a server, other players, mobs, items and menus look and behave as in vanilla: skins, poses, item names, inventories and server networks.
+- **Single player as a server: the last differences**: Single player now runs a small server in the background, as vanilla does. We are fixing what still behaves differently there; every fix also works for LAN and server players.
+- **Horizon's mod registry**: One place for mods, modpacks and resource packs made for Horizon: browse them on the website and install them from the launcher in one click.
+
+**Next**: Microsoft sign-in (coming soon); CurseForge in the mod browser (coming soon); Fresh benchmarks against vanilla; Pistons push players and mobs; Horizon on Intel Macs; Faster world creation and entry on small CPUs; Servers that hold 20 TPS with 50 to 100 players; Low-end computers: Steam Deck, old Macs, 8 GB; Native upscaling; A batch of targeted optimisations; A Convert to Rust button for what isn't rewritten yet; Mods with code: machines, magic, mobs; Data packs in the mod browser; Prepare a version without Java; Server console, bans and a full admin API; Hosting polish: Windows service, safe updates; Guided hosting with Tailscale and an invite button; An official Docker image for servers; One single-player path: remove the in-frame world; Villages and combat, exactly as in vanilla; Choose the audio output device; Mods that read and change the world; Machines and blocks with inventories (API 0.4); Lua and other languages for mods; Well-known shader looks, rewritten for Horizon; A visible beta label; Wayland and Hyprland polish; A versioned agent-control protocol; Port mods with your own AI agent; Horizon on X (coming soon); Pipeline protection and a GitHub App for agents; Signed updates everywhere, installers included; A server you install with one command.
+
+**How to help**: Play it and tell us what differs from vanilla (Discord or GitHub), run the benchmark on your computer, vote for what you want next, or pick one of the Help wanted items.
+
+**Developers**: Read CONTRIBUTING.md, pick a Help wanted item or a To do card, check vanilla's code for the behaviour, and paste the block `python3 tools/pr_ready.py` prints in your pull request.
+
+## Now
+
+### Performance
+
+#### Steady frames at long render distances
+
+Making Horizon faster than vanilla on every computer, with smooth camera movement even at 32 chunks, by spreading the work better over the processor's cores.
+
+<details><summary>Technical</summary>
+
+Frame pacing at render distance 32 ([#678](https://github.com/ludovic111/horizon/issues/678)): long frames come from work competing with the render thread. In review: world generation workers build free structure starts instead of queueing them ([#1760](https://github.com/ludovic111/horizon/issues/1760)), the worker pool leaves one core as vanilla does ([#1778](https://github.com/ludovic111/horizon/issues/1778)), and the terrain vertex arena is read as storage where flat draws run ([#1742](https://github.com/ludovic111/horizon/issues/1742)). Still open: far terrain at 48 to 64 chunks ([#718](https://github.com/ludovic111/horizon/issues/718)) and CPU-bound fields of block entities ([#717](https://github.com/ludovic111/horizon/issues/717)). Every change shows before and after numbers from `tools/perf_bench.py` against vanilla 26.3 ([docs/benchmark.md](docs/benchmark.md)).
+
+</details>
+
+#### Faster block lookups
+
+Speeding up the code that reads and writes the blocks of the world, which almost everything in the game goes through: generation, lighting, meshing and ticking.
+
+<details><summary>Technical</summary>
+
+`PalettedContainer` and `PackedStorage` find an entry's word by multiply and shift instead of an integer division ([#1790](https://github.com/ludovic111/horizon/issues/1790), [#1794](https://github.com/ludovic111/horizon/issues/1794)); meshing looks up baked models by index, not by name ([#1747](https://github.com/ludovic111/horizon/issues/1747)). Each change keeps the paletted storage harnesses identical and shows its microbenchmark ([docs/performance/paletted-container-access-results.md](docs/performance/paletted-container-access-results.md)).
+
+</details>
+
+### Modpacks
+
+#### Modpacks' world generation, natively
+
+Making the world-generation mods of popular modpacks (new structures, YUNG's dungeons and mineshafts, packs built on Lithostitched) generate their worlds in Horizon, natively and fast.
+
+<details><summary>Technical</summary>
+
+`horizon-port-pack` carries a pack's data-driven content over; structure mods that need code get a native port: YUNG's worldgen as written ([#1746](https://github.com/ludovic111/horizon/issues/1746)), Lithostitched's limited and guaranteed elements with pool and processor modifiers ([#1777](https://github.com/ludovic111/horizon/issues/1777)), its processors as the game's own types ([#1765](https://github.com/ludovic111/horizon/issues/1765)). Proved by the structure blocks and layout harnesses ([#1753](https://github.com/ludovic111/horizon/issues/1753), [#1757](https://github.com/ludovic111/horizon/issues/1757)). Mods whose Java code does more than world generation don't run ([docs/modpacks.md](docs/modpacks.md)).
+
+</details>
+
+### Servers and multiplayer
+
+#### Playing on servers: everything shows as it should
+
+When you play on a server, other players, mobs, items and menus look and behave as in vanilla: skins, poses, item names, inventories and server networks.
+
+<details><summary>Technical</summary>
+
+Client-of-a-server fixes in `game/remote*.rs` and `horizon-protocol`: mobs' aggressive and item-use flags ([#1802](https://github.com/ludovic111/horizon/issues/1802), [#1798](https://github.com/ludovic111/horizon/issues/1798)), ghost items after a remote menu ([#1795](https://github.com/ludovic111/horizon/issues/1795)), skins ([#1652](https://github.com/ludovic111/horizon/issues/1652)), cookies and transfer packets for proxy networks ([#1650](https://github.com/ludovic111/horizon/issues/1650)), firework boosts ([#1671](https://github.com/ludovic111/horizon/issues/1671)), living-entity attributes and simulation distance ([#1731](https://github.com/ludovic111/horizon/issues/1731)), styled item names ([#1702](https://github.com/ludovic111/horizon/issues/1702)), primed TNT between updates ([#1710](https://github.com/ludovic111/horizon/issues/1710)).
+
+</details>
+
+#### Server dialogs and login screens
+
+Servers that show dialogs, such as the register and login screens of AuthMe, will work in Horizon.
+
+<details><summary>Technical</summary>
+
+26.3's dialog packets and model ([#1720](https://github.com/ludovic111/horizon/issues/1720)), the dialog screen with its buttons and actions ([#1734](https://github.com/ludovic111/horizon/issues/1734)), then text and boolean inputs ([#1735](https://github.com/ludovic111/horizon/issues/1735)).
+
+</details>
+
+#### Pre-generate an area with /pregen
+
+A /pregen command that builds an area of the world ahead of time, so players don't wait for new terrain when they explore.
+
+<details><summary>Technical</summary>
+
+Generates, lights and saves an area before anyone walks there ([#1805](https://github.com/ludovic111/horizon/issues/1805), a contributor's pull request, in review). Useful on servers, and it moves the generation cost away from the first visit; the generation speed-ups are under 'Steady frames at long render distances'.
+
+</details>
+
+### Mods and API
+
+#### Horizon's mod registry
+
+One place for mods, modpacks and resource packs made for Horizon: browse them on the website and install them from the launcher in one click.
+
+<details><summary>Technical</summary>
+
+Merged: the registry index (schema 1, `.hpack`, checks before install, [#1634](https://github.com/ludovic111/horizon/issues/1634)), `cargo horizon-mod check` ([#1642](https://github.com/ludovic111/horizon/issues/1642)) and the submission service (`crates/horizon-mod-registry`, [#1659](https://github.com/ludovic111/horizon/issues/1659)). In review: the website's /mods ([#1596](https://github.com/ludovic111/horizon/issues/1596)) and /mods/submit ([#1635](https://github.com/ludovic111/horizon/issues/1635)), and in the launcher the registry as a source ([#1636](https://github.com/ludovic111/horizon/issues/1636)), install, enable and takedowns ([#1637](https://github.com/ludovic111/horizon/issues/1637)), the Mods page ([#1638](https://github.com/ludovic111/horizon/issues/1638)) and modpacks as their own profiles ([#1640](https://github.com/ludovic111/horizon/issues/1640)).
+
+More: [docs/mods.md](docs/mods.md)
+
+</details>
+
+#### Mods that run on the server
+
+Mods that run on the server side of a world, so a dedicated server or a LAN world can have mods that react to players joining, chat and blocks being broken or placed, and that add commands.
+
+<details><summary>Technical</summary>
+
+API 0.3, experimental first ([#1833](https://github.com/ludovic111/horizon/issues/1833), in review): the same sandboxed component runs on the server thread and the dedicated server, with world events (block broken or placed, entity spawned or killed, player joined or left), game rules and server commands with typed arguments. The world, item and entity interfaces come after (see 'Mods that read and change the world'). [docs/api/mods.md](docs/api/mods.md), [docs/mods.md](docs/mods.md).
+
+</details>
+
+#### Screens, input and drawing for mods
+
+Mods will be able to open their own screens and settings pages and react to keys and item use, so bigger mods, such as the Orbital Laser, can run on the normal game.
+
+<details><summary>Technical</summary>
+
+Capability `ui` is in review ([#1864](https://github.com/ludovic111/horizon/issues/1864)): mod-owned screens and a settings page under Options > Mods, built from vanilla's widgets. Still to design: `input` (an item's use, key binds, the crosshair target), `render` (a budgeted draw list on the native shader API) and `world` (changing blocks). Orbital Laser is the acceptance test: it needs all four today through its author's fork (see 'Orbital Laser on the normal game').
+
+More: [docs/mods.md](docs/mods.md)
+
+</details>
+
+#### Tools for people who make mods
+
+Better tools for mod makers: a test runner that needs no game window, templates for each kind of mod, and clear promises about what keeps working from one version to the next.
+
+<details><summary>Technical</summary>
+
+`cargo horizon-mod test` runs a mod's test scripts against a fake game snapshot ([#1816](https://github.com/ludovic111/horizon/issues/1816)) and, for server mods, scripted server events ([#1837](https://github.com/ludovic111/horizon/issues/1837)); the content template and the guides are merged ([#1859](https://github.com/ludovic111/horizon/issues/1859), [#1810](https://github.com/ludovic111/horizon/issues/1810), [docs/api/stability.md](docs/api/stability.md)). Left: templates for hud, server and machine mods, typed wrappers in the SDK, a frozen 0.1 compatibility mod that every runtime must load, a CI check that fails when a stable reference entry is removed without a new major version, and the SDK on crates.io once the API is stable.
+
+More: [https://playhorizon.dev/docs/test-a-mod](https://playhorizon.dev/docs/test-a-mod)
+
+</details>
+
+### Gameplay parity
+
+#### Single player as a server: the last differences
+
+Single player now runs a small server in the background, as vanilla does. We are fixing what still behaves differently there; every fix also works for LAN and server players.
+
+<details><summary>Technical</summary>
+
+Since [#1514](https://github.com/ludovic111/horizon/issues/1514) single player runs on the server thread (`game/integrated.rs`) and the window joins it as a client; `--in-frame` keeps the old path. The open `[server-thread]` issues list the gaps. In review: a tool that changes a block ends the click ([#1797](https://github.com/ludovic111/horizon/issues/1797)), potions keep their potion over the connection ([#1796](https://github.com/ludovic111/horizon/issues/1796)), mobs' aggression and arm swings ([#1802](https://github.com/ludovic111/horizon/issues/1802)). [docs/server-levels.md](docs/server-levels.md).
+
+</details>
+
+#### Play in your language
+
+Item names, container titles and server messages follow the language you pick, as in vanilla. Today parts of the game stay in English.
+
+<details><summary>Technical</summary>
+
+Translatable components resolved through the selected language for items, containers and server text ([#1806](https://github.com/ludovic111/horizon/issues/1806)), on top of the bundled languages the prepared resources carry ([#1594](https://github.com/ludovic111/horizon/issues/1594)). Left: the client's own screens ([#1672](https://github.com/ludovic111/horizon/issues/1672)) and the main menu with zh_cn ([#1774](https://github.com/ludovic111/horizon/issues/1774)).
+
+</details>
+
+#### Cooldowns drawn on items
+
+After you throw an ender pearl, its slot should show the cooldown sweeping away, as in vanilla.
+
+<details><summary>Technical</summary>
+
+Vanilla draws `ItemCooldowns`' percent as a white overlay over the slot (`GuiGraphicsExtractor.itemDecorations` and `itemCooldown`) in the hotbar and in inventories. Issue [#1763](https://github.com/ludovic111/horizon/issues/1763).
+
+More: [#1933](https://github.com/ludovic111/horizon/issues/1933)
+
+</details>
+
+#### Chat settings and team prefixes
+
+The Hidden and Commands Only chat settings should hide chat, and team prefixes should appear before names in chat.
+
+<details><summary>Technical</summary>
+
+Vanilla checks `ChatVisiblity` before it delivers chat and system messages ([#1376](https://github.com/ludovic111/horizon/issues/1376)), and chat uses the team-formatted display name ([#1378](https://github.com/ludovic111/horizon/issues/1378)). Both issues have exact steps to reproduce.
+
+More: [#1932](https://github.com/ludovic111/horizon/issues/1932) · [#1841](https://github.com/ludovic111/horizon/issues/1841)
+
+</details>
+
+#### A pointing hand over buttons
+
+The mouse pointer should turn into a pointing hand over menu buttons, as in vanilla 26.3.
+
+<details><summary>Technical</summary>
+
+26.3's `AbstractWidget` asks for a cursor from `CursorTypes` when it is hovered; winit's `CursorIcon::Pointer` gives the same shape. Issue [#1347](https://github.com/ludovic111/horizon/issues/1347).
+
+More: [#1897](https://github.com/ludovic111/horizon/issues/1897)
+
+</details>
+
+#### Ctrl+Backspace and scroll bars in menus
+
+Ctrl+Backspace should delete a whole word in the creative search, and every list's scroll bar should be draggable.
+
+<details><summary>Technical</summary>
+
+`EditBox` deletes by word with Ctrl ([#1764](https://github.com/ludovic111/horizon/issues/1764)); the Game Rules and Statistics lists' scroll bars can't be dragged ([#1782](https://github.com/ludovic111/horizon/issues/1782), after [#978](https://github.com/ludovic111/horizon/issues/978)).
+
+More: [#1884](https://github.com/ludovic111/horizon/issues/1884) · [#1931](https://github.com/ludovic111/horizon/issues/1931)
+
+</details>
+
+#### Chickens flap while they fall
+
+Chickens should flap their wings while they fall, not stand still in the air.
+
+<details><summary>Technical</summary>
+
+Vanilla's `Chicken.aiStep` updates `flap` and `flapSpeed` when the chicken isn't on the ground, and the model's wings follow them. Issue [#1706](https://github.com/ludovic111/horizon/issues/1706).
+
+More: [#1892](https://github.com/ludovic111/horizon/issues/1892)
+
+</details>
+
+### Rendering
+
+#### Shader packs, written again from scratch
+
+Shader packs were removed and are being rebuilt from scratch. They come back, off by default, once the best-known packs draw properly.
+
+<details><summary>Technical</summary>
+
+A clean-room rewrite in `horizon-shaderpack`, from the packs' public format documentation only: reading packs, the preprocessor and `.properties` files are merged ([#1584](https://github.com/ludovic111/horizon/issues/1584), [#1585](https://github.com/ludovic111/horizon/issues/1585), [#1586](https://github.com/ludovic111/horizon/issues/1586)); translating programs to WGSL through naga, buffers, uniforms and the terrain, entity, sky, weather and hand stages are in review ([#1698](https://github.com/ludovic111/horizon/issues/1698) to [#1801](https://github.com/ludovic111/horizon/issues/1801)).
+
+More: [#1561](https://github.com/ludovic111/horizon/issues/1561) · [#1771](https://github.com/ludovic111/horizon/issues/1771) · [#1786](https://github.com/ludovic111/horizon/issues/1786)
+
+</details>
+
+#### Horizon's own shader format and kit
+
+Horizon's own way to make shader packs, with tools to write and test them. Every pack is checked before it runs, and the registry will list them.
+
+<details><summary>Technical</summary>
+
+`horizon-shader-api` (API 0.1, experimental): WGSL stages with typed inputs inside the renderer's passes, options as WGSL override constants, and the `horizon-shader new|check|pack` tool with templates and the example pack Golden Hour. Merged: the check every pack passes ([#1820](https://github.com/ludovic111/horizon/issues/1820)) and the tool, templates and guide ([#1822](https://github.com/ludovic111/horizon/issues/1822)). In review: the post stage running in the game with hot reload ([#1861](https://github.com/ludovic111/horizon/issues/1861)), the sky stage ([#1863](https://github.com/ludovic111/horizon/issues/1863)) and registry checks that use the game's own check ([#1855](https://github.com/ludovic111/horizon/issues/1855)). Left: the material, lighting and shadow stages, a last-good fallback on reload, a GPU-time overlay per stage and budgets ([docs/shaders.md](docs/shaders.md), [docs/api/shaders.md](docs/api/shaders.md)). The Iris/OptiFine loader is a separate item, 'Shader packs, written again from scratch'.
+
+</details>
+
+### Horizon extras
+
+#### Discord Rich Presence
+
+Your Discord profile can show that you are playing Horizon, with a switch to turn it off.
+
+<details><summary>Technical</summary>
+
+A Discord IPC client on its own thread ([#1787](https://github.com/ludovic111/horizon/issues/1787)) and the presence with its setting ([#1788](https://github.com/ludovic111/horizon/issues/1788)). Merged: it ships with the next release.
+
+</details>
+
+### Code and tools
+
+#### A leaner codebase that builds faster
+
+Cleaning up Horizon's code: removing what nothing uses and making it quicker to build, so fixes and new features land faster.
+
+<details><summary>Technical</summary>
+
+A review of the whole tree: dead code and stubs removed ([#1432](https://github.com/ludovic111/horizon/issues/1432), [#1658](https://github.com/ludovic111/horizon/issues/1658)), one probe binary per crate ([#1453](https://github.com/ludovic111/horizon/issues/1453), [#1454](https://github.com/ludovic111/horizon/issues/1454)), shared harness helpers ([#1448](https://github.com/ludovic111/horizon/issues/1448)), clippy clean on the whole tree ([#1707](https://github.com/ludovic111/horizon/issues/1707)). [docs/architecture.md](docs/architecture.md) maps each feature to its files and harnesses.
+
+</details>
+
+## Next
+
+### Performance
+
+#### Fresh benchmarks against vanilla
+
+New public numbers comparing Horizon with vanilla on many kinds of computers, measured the same way every time, with a history that shows what each release changed.
+
+<details><summary>Technical</summary>
+
+Redo the comparison after the current performance work ([#1073](https://github.com/ludovic111/horizon/issues/1073)); reliability, coverage and presentation ([#1346](https://github.com/ludovic111/horizon/issues/1346)); a scene must count as loaded only once its first chunk arrives ([#1749](https://github.com/ludovic111/horizon/issues/1749)). Next: a performance history across releases (an automatic comparison of each release with the last, on a timeline), more report fields (server TPS and MSPT, power, battery drain, temperature, throttling) and more hardware (a MacBook on battery, low-end laptops, community reports). Players' reports come in through `--benchmark` and `horizon-launcher data benchmark` ([docs/benchmark.md](docs/benchmark.md)).
+
+</details>
+
+#### Faster world creation and entry on small CPUs
+
+Creating a world and joining it should be quick even on a four-thread laptop, where a fresh world at 32 chunks can make you wait minutes for the first terrain.
+
+<details><summary>Technical</summary>
+
+Cut the per-column generation cost (noise sampling, surface rules, aquifers) and the lock convoy on structure starts, and leave one core free for the rest of the game as vanilla does ([#1760](https://github.com/ludovic111/horizon/issues/1760) and [#1778](https://github.com/ludovic111/horizon/issues/1778), in review, are listed under 'Steady frames at long render distances'). Still to profile on small CPUs: the first seconds of a fresh world deliver no chunk, and fluids remesh for about a minute after loading. Measured with `tools/perf_bench.py` ([docs/benchmark.md](docs/benchmark.md), [docs/profiling.md](docs/profiling.md)).
+
+</details>
+
+#### Servers that hold 20 TPS with 50 to 100 players
+
+Servers that keep 20 ticks per second with 50 to 100 players. Today Horizon holds it up to 50 bots and drops to about 10 at 100.
+
+<details><summary>Technical</summary>
+
+Measured against vanilla on equal work ([docs/server.md](docs/server.md), Scale): Horizon is ahead with few players and when exploring, but vanilla's tick is shorter with 25 to 50 players near spawn. Ideas on the list: send entity changes instead of rebuilding every entity each tick (about 15 percent), fewer memory reads in random ticks and collision scans, cheaper item collision checks, mob AI and natural spawning. The bot benchmark (`horizon-bots`) is the proof.
+
+</details>
+
+#### Low-end computers: Steam Deck, old Macs, 8 GB
+
+Horizon should run well on small machines: integrated graphics, the Steam Deck, older Macs and 8 GB of memory, with a battery mode that saves power on laptops.
+
+<details><summary>Technical</summary>
+
+Partly done: an opt-in 60 FPS cap with fewer workers on battery, Far Detail Reduced for integrated GPUs and animated textures on the GPU (both shipped). Left: measured targets and fixes per class of machine (memory use, worker counts, startup) on a Steam Deck, old Intel and Apple Silicon Macs and 8 GB computers, reported on the Benchmarks page.
+
+More: [docs/benchmark.md](docs/benchmark.md) · [https://playhorizon.dev/docs/performance](https://playhorizon.dev/docs/performance)
+
+</details>
+
+#### Native upscaling
+
+Draw the game at a lower resolution and sharpen it to your screen's size, in the way of FSR or DLSS, to gain frames on weaker graphics cards. An optional graphics setting.
+
+<details><summary>Technical</summary>
+
+A render-scale setting below the window size with an upscaler of our own that runs on every wgpu backend. Proof: frame time against native resolution on integrated GPUs, and screenshots for image quality. Issue [#1403](https://github.com/ludovic111/horizon/issues/1403).
+
+</details>
+
+#### A batch of targeted optimisations
+
+Several smaller speed-ups, each measured: idle block entities that sleep, cheaper particles, faster structure placement, high-rate mice and very large texture packs.
+
+<details><summary>Technical</summary>
+
+Block entities and hoppers that skip work when idle (the hopper item scan is already skipped when no item is near); a particle frustum test first (also a parity gap), then particle quads built on the GPU; jigsaw shortcuts that skip blocked connectors and pool elements known not to fit, with layouts unchanged (trial chambers and ancient cities first); batched raw mouse input on Windows for 8000 Hz mice; a better atlas packer for huge resource packs (a 64x pack builds a 704 MiB atlas for 452 MiB of textures); sign-heavy scenes ([#1461](https://github.com/ludovic111/horizon/issues/1461)). Profile first, keep what pays, show before and after numbers.
+
+More: [docs/profiling.md](docs/profiling.md)
+
+</details>
+
+### Modpacks
+
+#### CurseForge in the mod browser (coming soon)
+
+Coming soon: search and download CurseForge mods and modpacks from the launcher, as you can with Modrinth today.
+
+<details><summary>Technical</summary>
+
+The mod browser lists CurseForge as coming soon ([docs/mod-browser.md](docs/mod-browser.md)): it needs CurseForge API access. Meanwhile packs import from a CurseForge zip or instance folder, and jars only CurseForge hosts come from the player's own instance ([docs/modpacks.md](docs/modpacks.md)).
+
+</details>
+
+#### A Convert to Rust button for what isn't rewritten yet
+
+When a mod, shader pack or modpack hasn't been rewritten for Horizon, one button converts what can be converted, so you don't have to wait for the rewrite.
+
+<details><summary>Technical</summary>
+
+Generalise the mod browser's Port step (`horizon-port-pack`: the data, assets, worldgen and block and item definitions of Java mods, .mrpack and CurseForge zips) to every kind of content: code mods where the API allows it (see 'Mods with code') and shader packs, converting an Iris/OptiFine pack into Horizon's format. The browser says what works before the install. Java code itself does not run ([docs/modpacks.md](docs/modpacks.md), [docs/mod-browser.md](docs/mod-browser.md)).
+
+</details>
+
+#### Mods with code: machines, magic, mobs
+
+Making mods that add machines, magic and mobs work in Horizon, in steps, starting with machines. They are most of what a big modpack is made of.
+
+<details><summary>Technical</summary>
+
+333 of the 496 mods in a big pack (ATM10) contain code. Issue [#1854](https://github.com/ludovic111/horizon/issues/1854) ranks the API gaps (ticking block entities, networking, rendering, menus, inventories) that unlock them in tiers, with machines first as the recommended path and a furnace ported tick for tick as proof. The first API step is a draft ([#1189](https://github.com/ludovic111/horizon/issues/1189), see 'Machines and blocks with inventories'). The path isn't started yet ([docs/modpacks.md](docs/modpacks.md)).
+
+</details>
+
+#### Data packs in the mod browser
+
+Search and install data packs from the launcher's mod browser, for the world you choose, as you do mods and resource packs.
+
+<details><summary>Technical</summary>
+
+A Datapacks tab beside Mods and Resource packs: install into a chosen world's datapacks folder, with the same checks and 'works in Horizon' notes as the other kinds ([docs/mod-browser.md](docs/mod-browser.md)).
+
+</details>
+
+### Servers and multiplayer
+
+#### Prepare a version without Java
+
+Set up Horizon, a server first, without Java on your computer: published tables are combined with your own copy of the game.
+
+<details><summary>Technical</summary>
+
+Today `horizon-prepare` runs Mojang's exporters with Java. Issue [#1750](https://github.com/ludovic111/horizon/issues/1750) proposes publishing the computed version tables once from CI and assembling the rest locally from the player's own jar and assets, provided the tables hold no Mojang content; a contributor offered a pull request, and it would help phones too. A server-only prepare from `server.jar` alone is the first step ([docs/server.md](docs/server.md)).
+
+</details>
+
+#### Server console, bans and a full admin API
+
+Manage a server from a console, ban and pardon players, and drive it from other tools through a full admin API and an MCP server for AI agents.
+
+<details><summary>Technical</summary>
+
+`horizon-server console` (a text interface), `ban`, `pardon`, `ban-ip` and `mcp` over stdio. Admin API additions: the player list, kick, ban, op and whitelist, an SSE stream of logs and events, a text metrics endpoint, config GET and PATCH, backup delete and download. The panel's later features (bans, worlds, server.properties import, logs and crash reports, modpacks) and vanilla's management protocol (the JSON-RPC over WebSocket that the `management-server-*` keys configure), so vanilla's tools can manage a Horizon server. [docs/server.md](docs/server.md), [docs/api/server.md](docs/api/server.md).
+
+</details>
+
+#### Hosting polish: Windows service, safe updates
+
+Smoother hosting: a real Windows service, a backup before every update, backups that keep the world and each player's state, and a changed view distance or message without a restart.
+
+<details><summary>Technical</summary>
+
+A Windows service wrapper instead of the logon scheduled task; `backups.before_update`; hot reload of config for view distance and the message of the day (needs engine support); backups that keep world and player state ([#1808](https://github.com/ludovic111/horizon/issues/1808), a contributor's draft, in review). [docs/hosting.md](docs/hosting.md), docs/server.md.
+
+</details>
+
+#### Guided hosting with Tailscale and an invite button
+
+In the launcher, a guide and a button to host a server and invite friends over Tailscale, so nobody has to open ports on a router.
+
+<details><summary>Technical</summary>
+
+On the Servers page (create, start, back up, update and invite are shipped) add a Tailscale setup that explains and checks each step, and an invite button that hands friends what they need to join over the tailnet. Buttons first, no docs needed, with the details in an Advanced section. Remote access over Tailscale is already described in [docs/server.md](docs/server.md).
+
+More: [docs/hosting.md](docs/hosting.md)
+
+</details>
+
+#### An official Docker image for servers
+
+An official image to run a Horizon dedicated server in Docker with one command, your own copy of the game files mounted in.
+
+<details><summary>Technical</summary>
+
+The repository has the Dockerfile (`packaging/server/Dockerfile`: a multi-stage build on Debian bookworm-slim, user `horizon`, volume `/data`, port 25565, game files mounted read-only, `HORIZON_EULA` and friends answering the first-start questions), and anyone can build it ([docs/hosting.md](docs/hosting.md), section 9). Left: publish the image to a public registry from the release workflow, tagged per release, so it follows the same checks, and update the docs and the launcher. The image never holds Mojang's files.
+
+More: [docs/server.md](docs/server.md)
+
+</details>
+
+#### A server you install with one command
+
+Install and run a Horizon dedicated server from a terminal with a single command, no launcher needed, for VPSes and headless machines.
+
+<details><summary>Technical</summary>
+
+A player's idea (#horizon-ideas). `horizon-server` already runs headless; left: an install script (Linux/macOS shell, Windows PowerShell) that fetches the signed release, checks it, asks for or points at the player's own game files and starts the server, documented in [docs/hosting.md](docs/hosting.md).
+
+</details>
+
+### Mods and API
+
+#### Mods that read and change the world
+
+Mods that can see and change blocks, read inventories and items, and find and affect entities, all through the server so every player sees the same thing.
+
+<details><summary>Technical</summary>
+
+After server mods: read blocks, states and biomes in loaded chunks and change them through the server's block log, so clients and the parity harnesses see vanilla's updates; the player's inventory, held item, open container and item stacks with components; entity queries near a position, a safe subset of entity data and data-driven mod entity types. Snapshots and batched calls per tick, never per-block host calls in hot paths. [docs/api/mods.md](docs/api/mods.md) ('Not there yet').
+
+More: [docs/modpacks.md](docs/modpacks.md)
+
+</details>
+
+#### Machines and blocks with inventories (API 0.4)
+
+Mods that add machines: blocks that tick, hold items and have their own menus. This unlocks the technology mods of big modpacks.
+
+<details><summary>Technical</summary>
+
+Block entities and menus: ticking machines with slots, server menu logic and the menu protocol to clients, energy, item and fluid transfer, data attachments, accessory slots and custom recipe types, with a typed client and server channel and typed config beside them. A draft ([#1189](https://github.com/ludovic111/horizon/issues/1189)) proves a furnace ported tick for tick and holds the ATM10 code-mods plan; the design is redone through the API policy before it merges ([docs/modpacks.md](docs/modpacks.md), docs/api/stability.md).
+
+</details>
+
+#### Lua and other languages for mods
+
+Write mods as Lua scripts, in the style of KubeJS, with no compiler, and later in other languages that pass the tests. Every language runs in the same sandbox.
+
+<details><summary>Technical</summary>
+
+Lua first: Horizon ships a Lua interpreter that is itself a WebAssembly mod, and a script mod's manifest names it and the capabilities it uses, so a script can do exactly what a compiled mod with the same manifest can, with hot reload of `main.lua`. Then C, C++, Zig, Go (TinyGo), AssemblyScript and JavaScript or TypeScript are measured against Rust on the same tick-heavy example, and each is supported only with a template, an example and a CI test. [docs/api/mods.md](docs/api/mods.md) ('Ways in').
+
+</details>
+
+### Gameplay parity
+
+#### Pistons push players and mobs
+
+Pistons and slime blocks will push players, mobs and items as in vanilla. Today moving blocks pass through them.
+
+<details><summary>Technical</summary>
+
+Port `PistonMovingBlockEntity.moveCollidedEntities` and `moveStuckEntities` (honey), the slime bounce and `Entity.limitPistonMovement` for `MoverType.PISTON`, in single player and for a server's players. Issues [#1496](https://github.com/ludovic111/horizon/issues/1496), [#1609](https://github.com/ludovic111/horizon/issues/1609), [#1608](https://github.com/ludovic111/horizon/issues/1608), [#1704](https://github.com/ludovic111/horizon/issues/1704), [#1758](https://github.com/ludovic111/horizon/issues/1758).
+
+</details>
+
+#### One single-player path: remove the in-frame world
+
+Single player will have one way to run, the server thread, so every fix works everywhere and there are fewer bugs. The older in-frame mode goes once everything passes without it.
+
+<details><summary>Technical</summary>
+
+`--in-frame` (also `--no-server-thread` and `HORIZON_SERVER_THREAD=0`) still ticks the world inside the window's `Game`, and most harnesses test that path. Delete it once `lan_e2e --server-thread` and the parity harnesses pass on the server thread, which also halves the bug surface. See also 'Single player as a server' and [docs/server-levels.md](docs/server-levels.md).
+
+</details>
+
+#### Villages and combat, exactly as in vanilla
+
+Villages and fights behaving as in vanilla: iron golems defending villages, villagers remembering their homes, mace smashes and knockback.
+
+<details><summary>Technical</summary>
+
+Villages: iron golem village goals, villager memories across saves, villager age, job-site claiming on dedicated servers, flower offers ([#1639](https://github.com/ludovic111/horizon/issues/1639) is one report). Combat: the mobs' `attack_knockback` attribute, mace smash logic, the hit knockback source on the host, the fire burnout biome tag. Each is checked against vanilla by a harness ([docs/rust-parity.md](docs/rust-parity.md)).
+
+</details>
+
+#### Choose the audio output device
+
+Pick the speakers or headphones Horizon plays through, in Music & Sounds.
+
+<details><summary>Technical</summary>
+
+An output device list in Music & Sounds, falling back to the system default. [#1035](https://github.com/ludovic111/horizon/issues/1035) started it: a player on an older Windows computer had no sound at all, and a device choice is how such cases are found and fixed.
+
+</details>
+
+### Rendering
+
+#### Well-known shader looks, rewritten for Horizon
+
+Popular shader packs rewritten in Horizon's format, so good packs exist from the start. Only packs whose licence is open source and compatible with ours are rewritten, never anything else.
+
+<details><summary>Technical</summary>
+
+The first candidates are Photon, Chocapic13 and MakeUp Ultra Fast, each only after its licence is read and recorded: a pack is rewritten only if it is open source and compatible with Horizon's licence, and the rewrite is written from the shader format's documentation and the look on screen, not from anyone's code. Today only the Golden Hour example exists (`[crates/horizon-shader-api/packs/golden_hour](crates/horizon-shader-api/packs/golden_hour)`).
+
+More: [docs/shaders.md](docs/shaders.md)
+
+</details>
+
+### Launcher
+
+#### Microsoft sign-in (coming soon)
+
+Coming soon: sign in with your Microsoft account to play on online-mode servers. The code is ready; it waits for Microsoft's approval.
+
+<details><summary>Technical</summary>
+
+Device-code sign-in in the launcher and online-mode login in the client ([docs/microsoft-account.md](docs/microsoft-account.md)). It is turned on by setting the app's client id once Minecraft API access is approved; until then the launcher shows "Coming soon".
+
+More: [#1270](https://github.com/ludovic111/horizon/issues/1270)
+
+</details>
+
+#### A visible beta label
+
+A clear 'beta' label in the launcher and the game, so nobody is surprised that Horizon is still being built.
+
+<details><summary>Technical</summary>
+
+Show Beta in the launcher's header and about page, on the game's title screen and on the website, beside the version number ([docs/versioning.md](docs/versioning.md)).
+
+</details>
+
+### Platforms
+
+#### Horizon on Intel Macs
+
+Builds of the game and the launcher for Macs with an Intel processor.
+
+<details><summary>Technical</summary>
+
+x86_64 game and launcher builds, picked per processor ([#1171](https://github.com/ludovic111/horizon/issues/1171)). Before it ships it needs a run on a real Intel Mac: Rosetta on Apple Silicon only proves the CPU code. Requests: [#1161](https://github.com/ludovic111/horizon/issues/1161), [#1792](https://github.com/ludovic111/horizon/issues/1792).
+
+</details>
+
+#### Wayland and Hyprland polish
+
+Fixes for Linux desktops that use Wayland and Hyprland: fullscreen, the clipboard, the GUI scale after a restart and the like.
+
+<details><summary>Technical</summary>
+
+Open: the GUI Scale is clamped to 2 after a restart under Hyprland, while XWayland keeps it ([#1866](https://github.com/ludovic111/horizon/issues/1866)). Earlier reports covered fullscreen dropping on menu clicks, the clipboard and a white overlay ([#1007](https://github.com/ludovic111/horizon/issues/1007), closed). Checked on a real Wayland session.
+
+</details>
+
+### AI and agents
+
+#### A versioned agent-control protocol
+
+A stable, documented way for AI agents and scripts to drive the game and the launcher, with versions and an event stream so tools keep working as Horizon changes.
+
+<details><summary>Technical</summary>
+
+`hello` answers with the API version, the release and the features; `horizon-ctl --api`; MCP serverInfo; reply schemas generated into the reference; a `test.` namespace for hooks; transcript compatibility tests; `subscribe` as a stream of events on one connection; Horizon option files by key and saved-server commands. Agent control itself (`horizon-ctl`, both MCP servers, the No AI switch) is done: [docs/agent-control.md](docs/agent-control.md), [docs/api/agent-control.md](docs/api/agent-control.md).
+
+More: [docs/api/stability.md](docs/api/stability.md)
+
+</details>
+
+#### Port mods with your own AI agent
+
+You can port a mod to Horizon with your own AI agent on your own computer. Horizon documents how and gives you the tools, but provides no hosted agents.
+
+<details><summary>Technical</summary>
+
+A player runs their own agent locally with `horizon-ctl` and the MCP servers ([docs/agent-control.md](docs/agent-control.md)), `cargo horizon-mod`, `horizon-port-pack` and the parity harnesses as the check. Horizon writes the guide (playhorizon.dev/docs/agents, [docs/modpacks.md](docs/modpacks.md)) and runs no agents, accounts or keys for players. The No AI switch turns all of it off.
+
+More: [https://playhorizon.dev/docs/agents](https://playhorizon.dev/docs/agents)
+
+</details>
+
+### Community
+
+#### Horizon on X (coming soon)
+
+Coming soon: an official Horizon account on X, used to announce releases and the weekly summary.
+
+<details><summary>Technical</summary>
+
+Kira already posts the roadmap items marked `announce = true` when they ship, and the weekly summary, as soon as the account's credentials exist ([roadmap/README.md](roadmap/README.md), 'The journal'). Waiting for the account itself.
+
+</details>
+
+### Code and tools
+
+#### Pipeline protection and a GitHub App for agents
+
+Safer releases: changes to the release machinery need the owner's review, and AI agents use a smaller identity of their own instead of a personal account.
+
+<details><summary>Technical</summary>
+
+`.github/CODEOWNERS` lists the workflows, the release and signing tools, the update-checking code and the installers ([#1015](https://github.com/ludovic111/horizon/issues/1015)); the branch protection that makes it count waits for the `horizon-agent` GitHub App, which reads and writes code, pull requests and issues but can't change settings, workflows, secrets or members, and whose tokens last an hour. It needs the owner to create the App and switch the protection on ([docs/security.md](docs/security.md)).
+
+</details>
+
+#### Signed updates everywhere, installers included
+
+Every download Horizon makes is checked against the project's signature, including the first install with install.sh and install.ps1.
+
+<details><summary>Technical</summary>
+
+Releases carry signed checksums, and the launcher and `horizon-server update` refuse anything unsigned ([#1011](https://github.com/ludovic111/horizon/issues/1011), [#1014](https://github.com/ludovic111/horizon/issues/1014)). Left: the first install through `install.sh` and `install.ps1` still trusts only the checksum GitHub publishes, because verifying Ed25519 signatures needs OpenSSL 3, which macOS doesn't ship ([docs/security.md](docs/security.md)).
+
+</details>
+
+## Later
+
+### Performance
+
+#### Exact far terrain from real chunks
+
+Far terrain drawn from the world you really built and explored, caves and builds included, not only a preview from the seed.
+
+<details><summary>Technical</summary>
+
+Keep a 3D mip store on disk built from real chunks, drawn by the GPU beside the seed preview for areas nobody has visited. Written from scratch and measured before it is kept. Builds on Far Detail and the far-terrain levels of detail already shipped; the open work on them is [#718](https://github.com/ludovic111/horizon/issues/718).
+
+</details>
+
+### Modpacks
+
+#### Older Fabric and Forge mods
+
+Recognise mods built for versions before 26.1 in the mod browser, so they can be checked and carried over like newer ones.
+
+<details><summary>Technical</summary>
+
+A mapping table from intermediary and SRG names so pre-26.1 jars can be classified, and a rename for mod ids with dashes (`fabric-api`); the port step then treats them like newer jars ([docs/mod-browser.md](docs/mod-browser.md)).
+
+</details>
+
+#### A modpack's own resource and shader packs
+
+Importing a modpack also brings the resource packs and shader packs it ships with, where Horizon can use them.
+
+<details><summary>Technical</summary>
+
+Porting a pack carries data, assets and worldgen today; the resource packs and shader packs bundled with it are left out. Resource packs can be carried as they are; shader packs go through the converter ([docs/modpacks.md](docs/modpacks.md)).
+
+</details>
+
+#### Whole modpacks, such as ATM10, rewritten
+
+Rewriting a complete big modpack for Horizon so it runs far better than the original. Not a priority now: the work above comes first.
+
+<details><summary>Technical</summary>
+
+The project's first goal for modpacks: support them ten times better than vanilla and port any of them. It was set aside in favour of compatibility through the browser. What exists: ATM10's world generates and 42 of its 496 mods are carried at least in part ([docs/modpacks.md](docs/modpacks.md)). It depends on 'Mods with code' and the native mod API.
+
+</details>
+
+#### Running Java mods that aren't rewritten
+
+Run Java mods that nobody has rewritten for Horizon yet, through a bridge or a converter. Hard and not started: the Convert button and native rewrites come first.
+
+<details><summary>Technical</summary>
+
+Earlier research ([#527](https://github.com/ludovic111/horizon/issues/527), closed) found that Java mods can't simply run, because they call Minecraft's own classes. Options to look at again: a jar-to-WebAssembly backend, or a bridge for simple Fabric mods. Whatever is chosen has to run inside the same sandbox and capability checks as native mods.
+
+</details>
+
+### Servers and multiplayer
+
+#### Ely.by and other sign-in providers
+
+Sign in with other account providers, such as Ely.by or any Yggdrasil-compatible one, beside Microsoft.
+
+<details><summary>Technical</summary>
+
+Issue [#1270](https://github.com/ludovic111/horizon/issues/1270) asks for Ely.by and Yggdrasil-compatible servers with an account selector in the launcher. It builds on the Microsoft sign-in ([docs/microsoft-account.md](docs/microsoft-account.md)).
+
+</details>
+
+#### Online-mode checks for Play with Friends
+
+Friends who join through an invite code could prove who they are with their Microsoft account, as on online-mode servers.
+
+<details><summary>Technical</summary>
+
+Play with Friends joins over an encrypted tunnel with an invite code ([docs/play-with-friends.md](docs/play-with-friends.md), 'Identity'). Online-mode checks against Mojang's session servers can be added on top of the same tunnel; they need Microsoft sign-in first, which is coming soon. Play with Friends stays self-hosted between players, with no relay run by the project.
+
+</details>
+
+### Mods and API
+
+#### Orbital Laser on the normal game
+
+The community mod Orbital Laser, made for a fork of Horizon, running on the normal game and listed in the registry as the showcase of the mod API.
+
+<details><summary>Technical</summary>
+
+A pull request on [https://github.com/Stink-O/orbital-laser](https://github.com/Stink-O/orbital-laser) (MIT) once the input, ui, render and world capabilities exist (see 'Screens, input and drawing for mods'): today the mod needs them through its author's fork. Tested in the game, and listed in the registry.
+
+</details>
+
+#### Native versions of popular client mods
+
+Built-in versions of the client mods players ask for: block info on hover, a recipe viewer like JEI, a world map and schematic overlays.
+
+<details><summary>Technical</summary>
+
+Done as extras: a mod list and menu, a minimap and a zoom ([docs/extras.md](docs/extras.md)). Left: block info tooltips, a recipe viewer (a contributor offered to port JEI if it becomes a native feature), a world map and a schematic overlay. They need the read-only interfaces `inventory-read`, `recipes`, `world-read` and `render` in the mod API, or they go into the game directly.
+
+More: [docs/mods.md](docs/mods.md)
+
+</details>
+
+#### Create-style physics as a native mod
+
+Contraptions and physics like the Create and Aeronautics mods, as a mod for Horizon rather than part of the base game.
+
+<details><summary>Technical</summary>
+
+Issue [#805](https://github.com/ludovic111/horizon/issues/805) (porting QOL mods) closed with this answer: it would come as a native Horizon mod on the mod API. It needs server mods, entities and rendering first.
+
+</details>
+
+#### Proximity voice chat as a native mod
+
+Hear nearby players talk, as with the voice chat mods of other Minecraft versions, as a Horizon mod.
+
+<details><summary>Technical</summary>
+
+Needs server mods, mod networking and an audio interface in the mod API before anything can be built ([docs/api/mods.md](docs/api/mods.md)).
+
+</details>
+
+### Gameplay parity
+
+#### Every Minecraft version, prepared automatically
+
+Every past and future Minecraft version prepared for Horizon automatically. When Mojang releases one, Horizon follows it, and every system is checked against it again.
+
+<details><summary>Technical</summary>
+
+The port pipeline ([docs/version-ports.md](docs/version-ports.md), `tools/version_port.py`) detects a release, prepares it, diffs its classes against the pinned 26.3, regenerates the data-driven tables, runs every parity harness on it and writes a port report that becomes issues. The goal is as little human work as possible for any version, past or future. Detection and the first slices are merged; the scheduled agent that runs it every day isn't installed yet. Two versions in one build are out of scope.
+
+</details>
+
+#### Controllers: tested on real pads, and in the launcher
+
+Make controller support solid: tested with real PlayStation and Xbox pads and a Steam Deck, and usable in the launcher too.
+
+<details><summary>Technical</summary>
+
+The game side is merged ([docs/controllers.md](docs/controllers.md)): pads read with gilrs, menus, rumble, glyphs, remapping and DualSense adaptive triggers, lightbar and haptics, but not yet confirmed on real pads or a Steam Deck (DualSense haptics stay behind a switch until then). Left: a test pass on real hardware, and the same focus navigation in the GPUI launcher.
+
+</details>
+
+#### The full debug screen
+
+Vanilla's complete F3 screen: debug options, a profiler chart, ten-second captures and an atlas dump.
+
+<details><summary>Technical</summary>
+
+Today F3 shows position, chunk, light, biome and FPS ([docs/native-client.md](docs/native-client.md)). Vanilla also has F3+F6 debug options with profiles, F3+1 the profiler pie, F3+L a ten-second capture and F3+S the atlas dump ([#562](https://github.com/ludovic111/horizon/issues/562) asked for the F3 editor).
+
+</details>
+
+### Rendering
+
+#### A light default shader pack
+
+A small built-in look (tone mapping, colour grade, a cheap vignette) that costs almost nothing, for players who want a nicer picture without a heavy pack.
+
+<details><summary>Technical</summary>
+
+An opt-in, composite-only pack on the native shader API, under about 0.3 ms at 1080p, shown on the Shader Packs page. Pack option sliders and profiles, and a Failed row with the full error, belong with it.
+
+More: [docs/shaders.md](docs/shaders.md)
+
+</details>
+
+#### Optional ray tracing
+
+An optional ray-tracing mode for graphics cards that support it (RTX and recent AMD): shadows, water reflections and global lighting on top of the vanilla look.
+
+<details><summary>Technical</summary>
+
+A spike with ray-traced sun shadows, off by default, is a draft ([#1180](https://github.com/ludovic111/horizon/issues/1180)). Reflections, global illumination, Apple M3 and newer if it is cheap, and a performance report per card come after.
+
+</details>
+
+#### HDR monitors
+
+Output for HDR monitors: brighter highlights and richer colour where your screen supports it.
+
+<details><summary>Technical</summary>
+
+Issue [#1441](https://github.com/ludovic111/horizon/issues/1441). Needs a surface format and a tone-mapping path per backend, and tests on real HDR screens on Windows, macOS and Linux.
+
+</details>
+
+#### MSAA, anisotropic filtering, exclusive fullscreen
+
+More graphics options: multisample anti-aliasing, anisotropic filtering and an exclusive fullscreen mode. Today Horizon has FXAA and borderless fullscreen.
+
+<details><summary>Technical</summary>
+
+Not implemented ([docs/graphics.md](docs/graphics.md)). Anisotropic filtering needs linear magnification in wgpu, which blurs close blocks, so close-up sharpness has to be kept first; MSAA would sit beside FXAA; exclusive fullscreen where the backend supports it.
+
+</details>
+
+### Launcher
+
+#### Lean installs that use less disk
+
+Smaller installs: Horizon keeps one shared copy of the prepared game files and removes what only the preparation needed.
+
+<details><summary>Technical</summary>
+
+A shared resource store keyed by the preparer's digest, no prepare intermediates left behind, the current and the previous version kept, and an automatic clean-up. Not started.
+
+</details>
+
+### Platforms
+
+#### Horizon on Linux ARM64
+
+Game and launcher builds for 64-bit ARM Linux computers.
+
+<details><summary>Technical</summary>
+
+Issue [#1709](https://github.com/ludovic111/horizon/issues/1709): aarch64 builds of the game and the launcher in the release workflow, tested on a real ARM machine with its Vulkan driver. The server build already drops audio and controllers (`--no-default-features`).
+
+</details>
+
+#### Android, iOS and the browser
+
+Versions of Horizon for Android, iOS and web browsers. Nothing official yet; contributors have started the first pieces.
+
+<details><summary>Technical</summary>
+
+No official build. Android was first closed as not planned, with touch controls, a mobile interface, packaging and loading the player's own assets all missing; the roadmap now includes it, iOS and a WebAssembly build for the browser as long-term goals. First pieces from contributors: `horizon-dualsense` compiling on iOS ([#1813](https://github.com/ludovic111/horizon/issues/1813)) and helper-thread limits on Android ([#1751](https://github.com/ludovic111/horizon/issues/1751)). Preparing without Java ([#1750](https://github.com/ludovic111/horizon/issues/1750)) matters here too. Horizon ships none of Mojang's files on any platform.
+
+</details>
+
+#### AppImage and a Nix flake
+
+Install Horizon on any Linux distribution as an AppImage, and on NixOS through a Nix flake.
+
+<details><summary>Technical</summary>
+
+A player's idea (#horizon-ideas). An AppImage of the launcher and game from the release workflow, and a flake.nix packaging the release binaries with their runtime libraries (Vulkan loader, X11/Wayland, ALSA), the way horizon-parity's NixOS setup runs them today.
+
+</details>
+
+### Horizon extras
+
+#### A complete video studio inside the game
+
+Record, replay and edit videos without leaving the game: record in a keypress, replay a session, cut and finish the video. One of Horizon's original goals.
+
+<details><summary>Technical</summary>
+
+Three stages. Recording: capture gameplay in a keypress with an encoder thread and little frame-time cost. Replay: a replay mode for recorded sessions. Editing: cuts, camera paths, titles and export. None of it exists yet; the agent-control socket ([docs/agent-control.md](docs/agent-control.md)) already lets tools drive the game for scripted shots.
+
+</details>
+
+#### Game menus in the launcher's style
+
+An optional look for the game's own menus and options that matches the Horizon launcher. Off by default: the vanilla menus stay as they are.
+
+<details><summary>Technical</summary>
+
+A player's idea (#horizon-ideas). A built-in resource pack or a Horizon setting that restyles the title, pause and options screens with the launcher's design tokens (crates/horizon-theme), following [docs/design-system.md](docs/design-system.md); off by default because it changes the vanilla look.
+
+</details>
+
+### AI and agents
+
+#### An optional AI teammate
+
+An optional AI teammate you can talk to by voice. It plays beside you, helps or finishes the game with you, runs on your computer first, and exists only if you turn it on. The No AI switch hides it.
+
+<details><summary>Technical</summary>
+
+Draft pull requests: the companion ([#1068](https://github.com/ludovic111/horizon/issues/1068)), its safety modes and their evaluation ([#1069](https://github.com/ludovic111/horizon/issues/1069)) and a route that finishes the game ([#1070](https://github.com/ludovic111/horizon/issues/1070)). In the drafts: a companion that follows, fights, mines, crafts, sleeps and respawns; chat and push-to-talk voice, with speech recognition and a choice of voices; presets (very strong, helper, beat the game); a guard model with Clean, Kid and Salty modes; perception levels from Fair to All-knowing; hardware detection with a simple mode and an Advanced tab; local models first, cloud keys optional. The No AI switch is already in the game. Left: the speedrun route doesn't finish the game reliably yet, voices for more languages, and the safety evaluation, which must pass before it ships.
+
+</details>
+
+### Community
+
+#### A video series about Horizon
+
+A series of videos about how Horizon is made and what is new, with each upload announced on Discord.
+
+<details><summary>Technical</summary>
+
+Kira already shows new uploads in a read-only Discord channel (done). The series follows each stage of the project: a script, edits, titles and a thumbnail per video.
+
+</details>
+
+## Help wanted
+
+### Performance
+
+#### Benchmark your computer
+
+Run Horizon's built-in benchmark and share the report: every new computer makes the performance work more accurate. No coding needed.
+
+<details><summary>Technical</summary>
+
+`horizon-launcher play --arg=--benchmark --arg=standard` writes a JSON report; `horizon-launcher data benchmark <report>` shows what would be sent and uploads it (playhorizon.dev/docs/performance). Results from three installs with the same hardware appear on the Benchmarks page. Example: [#1711](https://github.com/ludovic111/horizon/issues/1711).
+
+More: [https://playhorizon.dev/docs/performance](https://playhorizon.dev/docs/performance)
+
+</details>
+
+### Gameplay parity
+
+#### End city banners keep their pattern
+
+Banners in End cities show as plain magenta instead of with their pattern.
+
+<details><summary>Technical</summary>
+
+Compare the banner block entities the End city templates place with vanilla's (`EndCityPieces`, the templates' block entity NBT, `BannerBlockEntity`'s patterns), in `crates/horizon-world/src/worldgen/structure/`. Issue [#1438](https://github.com/ludovic111/horizon/issues/1438); possibly related: [#526](https://github.com/ludovic111/horizon/issues/526).
+
+</details>
+
+#### Enchanted loot in End cities
+
+Armour and tools in End city chests should come enchanted, as in vanilla.
+
+<details><summary>Technical</summary>
+
+`loot.rs` implements `enchant_with_levels`: find why the End city chest table's rolls come out bare, and compare them with vanilla's for a few seeds. Issues [#1437](https://github.com/ludovic111/horizon/issues/1437), [#1660](https://github.com/ludovic111/horizon/issues/1660).
+
+</details>
+
+## Recently shipped
+
+- **OpenGL for old computers** (v0.2.63): Horizon now starts on old PCs whose graphics card has no Vulkan or DirectX 12 driver: it switches to OpenGL by itself, and Options > Graphics can pick OpenGL by hand. [#1917](https://github.com/ludovic111/horizon/issues/1917) · [#1920](https://github.com/ludovic111/horizon/issues/1920) · [#1936](https://github.com/ludovic111/horizon/issues/1936)
+- **Server resource packs** (v0.2.48): Servers can send you their resource pack: Horizon asks, downloads it and applies it, like vanilla. [#1562](https://github.com/ludovic111/horizon/issues/1562) · [#1569](https://github.com/ludovic111/horizon/issues/1569) · [#1570](https://github.com/ludovic111/horizon/issues/1570)
+- **Single player on its own server thread** (v0.2.39): Single player runs on a server thread, as vanilla does, so the world keeps ticking smoothly while the window draws. [#1514](https://github.com/ludovic111/horizon/issues/1514) · [docs/server-levels.md](docs/server-levels.md)
+- **GPU occlusion culling on Macs** (v0.2.17): On Macs the GPU now skips terrain hidden behind hills and caves: 8 to 48% more frames per second at 32 chunks on an M4 Pro. [#1434](https://github.com/ludovic111/horizon/issues/1434)
+- **Animated textures on the GPU** (v0.2.5): Water, lava and other animated blocks are now animated by the graphics card: 1.7 to 2.4 times better 1% lows on Intel graphics. [#1239](https://github.com/ludovic111/horizon/issues/1239)
+- **Far Detail for integrated graphics** (v0.2.5): An optional Reduced setting for far terrain, suggested on integrated graphics, that saves 2 to 4 ms of GPU time per frame. [#1199](https://github.com/ludovic111/horizon/issues/1199) · [#1029](https://github.com/ludovic111/horizon/issues/1029)
+- **The launcher's mod browser** (launcher@0.2.0): Search Modrinth for mods, modpacks and resource packs from the launcher; it says before installing what works in Horizon. [#1154](https://github.com/ludovic111/horizon/issues/1154) · [#1242](https://github.com/ludovic111/horizon/issues/1242) · [#1243](https://github.com/ludovic111/horizon/issues/1243) · [#1246](https://github.com/ludovic111/horizon/issues/1246) · [docs/mod-browser.md](docs/mod-browser.md)
+- **A blocky, Minecraft-like launcher** (launcher@0.2.0): The launcher got a new blocky look in Horizon's purple, in dark and light. [#1269](https://github.com/ludovic111/horizon/issues/1269) · [docs/design-system.md](docs/design-system.md)
+- **Dynamic lights** (v2026.10.22): An optional extra: torches you hold, drop or set on fire light up what is around them. [#1162](https://github.com/ludovic111/horizon/issues/1162)
+- **Host a server from the launcher** (launcher-v0.15.0): The launcher's Servers page creates, starts, backs up and updates a Horizon server with buttons, and invites friends. [#1026](https://github.com/ludovic111/horizon/issues/1026) · [docs/hosting.md](docs/hosting.md)
@@ -1,35 +1,5 @@
 # Third-party notices

-## CullLeaves
-
-The optional leaf and mangrove-root face-culling behavior is adapted from
-[CullLeaves](https://github.com/TeamMidnightDust/CullLeaves) by MidnightDust.
-Its MIT license is reproduced below.
-
-```text
-MIT License
-
-Copyright (c) 2020 MidnightDust
-
-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.
-```
-
 ## wgpu-hal

 `third_party/wgpu-hal` is [wgpu-hal](https://github.com/gfx-rs/wgpu) 30.0.1 by the gfx-rs
@@ -47,4 +17,5 @@ by The Pixelify Sans Project Authors, licensed under the SIL Open Font License 1

 `crates/horizon-theme/icons/pixel/*.svg` are icons from
 [Pixelarticons](https://github.com/halfmage/pixelarticons) by Gerrit Halfmann, under the MIT
-license (`crates/horizon-theme/icons/pixel/LICENSE-pixelarticons.txt`).
+license (`crates/horizon-theme/icons/pixel/LICENSE-pixelarticons.txt`). `star.svg` is Horizon's own, drawn on
+the same grid.
@@ -131,8 +131,8 @@ average) and reached the ThinkPad over the tailnet.
  It ran with Paper's defaults except `connection-throttle: -1` in `bukkit.yml`. Every bot connects from one
  address, and the default throttle (4 s) refused all but the first. Paperclip patched the pinned server jar
  from its cache. Same Java and heap.
- Fabric + Lithium: the pinned server jar on Fabric loader 0.19.5 (`packs/fabric.lock.json`) with Lithium
-  `mc26.3-0.26.2-fabric` (`packs/mods.lock.json`, checked against its SHA-512). Lithium needs no Fabric API.
+- Fabric + Lithium: the pinned server jar on Fabric loader 0.19.5 (`tools/benchmark-deps/fabric.lock.json`) with Lithium
+  `mc26.3-0.26.2-fabric` (`tools/benchmark-deps/mods.lock.json`, checked against its SHA-512). Lithium needs no Fabric API.
  Same Java and heap.

 The Paper and Fabric jars are dev-only downloads into `.local/server-bench/jars` and are never committed or
@@ -4,10 +4,10 @@ version = "0.1.0"
 edition.workspace = true
 license.workspace = true
 rust-version = "1.86"
-description = "cargo horizon-mod new/build/run: make Horizon mods in Rust (docs/mods.md)"
+description = "cargo horizon-mod new/build/run/check: make Horizon mods in Rust (docs/mods.md)"

 [dependencies]
-horizon-mods = { path = "../horizon-mods", default-features = false, features = ["pack"] }
+horizon-mods = { path = "../horizon-mods", default-features = false, features = ["pack", "runtime", "index"] }
 serde_json = "1.0.151"

 [lints]
@@ -0,0 +1,337 @@
+//! `cargo horizon-mod check <file>`: what the registry checks of a submission,
+//! run anywhere: its kind's own checks (docs/api/mod-index.md), its signature
+//! when given a key, and for a mod a trial run in the sandbox: it must start,
+//! survive ticks, frames, a chat line and each of its commands (a server mod:
+//! a player joining, chatting, typing them and leaving), and import no more
+//! than its capabilities.
+use horizon_mods::{
+    Clock, GameMode, Mods, Output, Package, Player, ServerPlayer, Snapshot, Status,
+    index::{self, Facts, Kind},
+    manifest::component_imports,
+};
+use serde_json::{Value, json};
+use std::path::Path;
+
+/// How long the trial run plays: two seconds of game.
+const TICKS: u64 = 40;
+const FRAMES_PER_TICK: u64 = 3;
+
+pub struct Report {
+    pub kind: Kind,
+    pub facts: Facts,
+    pub sha256: String,
+    pub size: u64,
+    pub signed: bool,
+    /// A mod has code to run (a content mod may have none).
+    pub code: bool,
+    /// A mod's component imports.
+    pub imports: Vec<String>,
+    /// A mod's commands, each run once.
+    pub commands: Vec<String>,
+    /// What the mod showed during the trial run.
+    pub output: Vec<String>,
+}
+
+impl Report {
+    pub fn json(&self) -> Value {
+        let requires: Vec<Value> = self
+            .facts
+            .requires
+            .iter()
+            .map(|r| json!({"id": r.id, "version": r.version, "sha256": r.sha256}))
+            .collect();
+        json!({
+            "kind": self.kind.name(),
+            "id": self.facts.id,
+            "version": self.facts.version,
+            "api": self.facts.api,
+            "side": self.facts.side,
+            "capabilities": self.facts.capabilities,
+            "api_level": self.facts.api_level,
+            "game": self.facts.game,
+            "requires": requires,
+            "sha256": self.sha256,
+            "size": self.size,
+            "signed": self.signed,
+            "code": self.code,
+            "imports": self.imports,
+            "commands": self.commands,
+            "output": self.output,
+        })
+    }
+
+    pub fn text(&self) -> String {
+        let f = &self.facts;
+        let mut out = format!(
+            "{} {} ({}",
+            f.id.as_deref().unwrap_or("resource pack"),
+            f.version.as_deref().unwrap_or(""),
+            self.kind.name()
+        );
+        if let Some(side) = f.side {
+            let side = serde_json::to_value(side).unwrap_or_default();
+            out += &format!(", API {}, {}", f.api, side.as_str().unwrap_or("?"));
+        } else if self.kind == Kind::Shader {
+            out += &format!(", shader API {}", f.api);
+        } else if !f.api.is_empty() {
+            out += &format!(", format {}", f.api);
+        }
+        if let Some(game) = &f.game {
+            out += &format!(", for {game}");
+        }
+        let signed = if self.signed {
+            "signature verified"
+        } else {
+            "unsigned"
+        };
+        out += &format!(
+            ")\n  {} bytes, SHA-256 {}, {signed}\n",
+            self.size, self.sha256
+        );
+        if let Some(level) = f.api_level {
+            out += &format!("  needs mod API level {level} or newer\n");
+        }
+        for c in &f.capabilities {
+            out += &format!("  may {}\n", c.describe());
+        }
+        for r in &f.requires {
+            out += &format!("  needs {} {} ({})\n", r.id, r.version, &r.sha256[..12]);
+        }
+        if self.kind == Kind::Mod && !self.code {
+            out += "  no code: content only, nothing to run\n";
+        } else if self.kind == Kind::Mod {
+            let commands = if self.commands.is_empty() {
+                String::new()
+            } else {
+                format!(", /{}", self.commands.join(", /"))
+            };
+            out += &format!(
+                "  trial run: started, {TICKS} ticks, {} frames, a chat line{commands}: ok\n",
+                TICKS * FRAMES_PER_TICK
+            );
+        }
+        out
+    }
+}
+
+/// The kind a file's extension says.
+pub fn kind_of(path: &Path) -> Option<Kind> {
+    match path.extension()?.to_str()? {
+        "hmod" => Some(Kind::Mod),
+        "hpack" => Some(Kind::Modpack),
+        "zip" => Some(Kind::ResourcePack),
+        "hshader" => Some(Kind::Shader),
+        _ => None,
+    }
+}
+
+/// Checks the file at `path` as `kind`; `key` and `signature` (the
+/// `.minisig` text) check its signature.
+pub fn check(
+    path: &Path,
+    kind: Kind,
+    key: Option<&str>,
+    signature: Option<&str>,
+) -> Result<Report, String> {
+    let size = std::fs::metadata(path)
+        .map_err(|e| format!("{}: {e}", path.display()))?
+        .len();
+    if size > index::MAX_FILE {
+        return Err(format!("over {} MiB", index::MAX_FILE >> 20));
+    }
+    index::open(&kind)?;
+    let facts = index::inspect(&kind, path)?;
+    let signed = match (key, signature) {
+        (Some(key), Some(sig)) => {
+            index::verify_signature(key, sig, path)?;
+            true
+        }
+        (None, None) => false,
+        _ => return Err("--key and --signature go together".into()),
+    };
+    let mut report = Report {
+        kind,
+        facts,
+        sha256: index::sha256_file(path)?,
+        size,
+        signed,
+        code: false,
+        imports: Vec::new(),
+        commands: Vec::new(),
+        output: Vec::new(),
+    };
+    if report.kind == Kind::Mod {
+        trial_run(path, &mut report)?;
+    }
+    Ok(report)
+}
+
+/// Runs a mod in the sandbox, as the game does, from a scratch copy so its
+/// storage lands in a folder removed afterwards. A content mod has no code to
+/// run: `inspect` already read its content as the game does.
+fn trial_run(path: &Path, report: &mut Report) -> Result<(), String> {
+    let package = Package::read(path)?;
+    let Some(wasm) = package.wasm.as_deref() else {
+        return Ok(());
+    };
+    report.code = true;
+    report.imports = component_imports(wasm)?;
+    package
+        .manifest
+        .check_imports(report.imports.iter().map(String::as_str))?;
+    let dir = std::env::temp_dir().join(format!("horizon-mod-check-{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&dir);
+    std::fs::create_dir_all(&dir).map_err(|e| e.to_string())?;
+    let copy = dir.join("mod.hmod");
+    let result = std::fs::copy(path, &copy)
+        .map_err(|e| e.to_string())
+        .and_then(|_| play(&copy, report));
+    let _ = std::fs::remove_dir_all(&dir);
+    result
+}
+
+fn play(path: &Path, report: &mut Report) -> Result<(), String> {
+    let mut mods = Mods::load(&[path.to_path_buf()], |_| true, |_| false);
+    let failed = |mods: &Mods| match &mods.entries()[0].status {
+        Status::Failed(reason) => Some(reason.clone()),
+        _ => None,
+    };
+    if let Some(reason) = failed(&mods) {
+        return Err(format!("it didn't start: {reason}"));
+    }
+    let client: Vec<String> = mods.commands().map(str::to_owned).collect();
+    let server: Vec<String> = mods.server_commands().map(|c| c.name.clone()).collect();
+    report.commands = [client.clone(), server.clone()].concat();
+    // A server mod plays with one player on, who joins, chats and leaves.
+    let steve = ServerPlayer {
+        id: "00000000-0000-4000-8000-000000000001".into(),
+        name: "Steve".into(),
+        x: 0.5,
+        y: 64.0,
+        z: 0.5,
+        dimension: "minecraft:overworld".into(),
+        game_mode: GameMode::Survival,
+        health: 20.0,
+    };
+    let snapshot = |t: u64| Snapshot {
+        player: Some(Player {
+            x: 0.5 + t as f64 * 0.1,
+            y: 64.0,
+            z: 0.5,
+            yaw: 90.0,
+            pitch: 0.0,
+            health: 20.0,
+            food: 20,
+            dimension: "minecraft:overworld".into(),
+        }),
+        clock: Some(Clock {
+            game_time: t,
+            day_time: 1000 + t,
+        }),
+        players: vec![steve.clone()],
+        // The GUI of a 1280 x 720 window at scale 3.
+        gui_size: (427.0, 240.0),
+        ..Snapshot::default()
+    };
+    mods.set_snapshot(snapshot(0));
+    mods.player_joined(&steve);
+    for t in 0..TICKS {
+        mods.set_snapshot(snapshot(t));
+        mods.tick(t);
+        mods.server_tick(t);
+        for _ in 0..FRAMES_PER_TICK {
+            mods.frame(1.0 / 60.0);
+        }
+    }
+    mods.chat("<Steve> hello");
+    mods.player_chat(&steve, "hello");
+    for name in &client {
+        mods.command(name);
+    }
+    for name in &server {
+        mods.server_command(&steve, name);
+    }
+    mods.set_snapshot(Snapshot::default());
+    mods.player_left(&steve);
+    for out in mods.drain() {
+        report.output.push(match out {
+            Output::Chat { text, .. } => format!("chat: {text}"),
+            Output::Tell { text, .. } => format!("tell: {text}"),
+            Output::Broadcast { text, .. } => format!("broadcast: {text}"),
+            Output::Feedback { text, error } | Output::Reply { text, error, .. } => {
+                format!("{}: {text}", if error { "error" } else { "feedback" })
+            }
+            Output::Command { line } => format!("command: /{line}"),
+            Output::QuietCommands { lines, .. } => {
+                format!("{} quiet command(s)", lines.len())
+            }
+            Output::Stopped { reason, .. } => return Err(format!("it stopped: {reason}")),
+            Output::SetBlocks {
+                dimension, blocks, ..
+            } => {
+                format!("set {} block(s) in {dimension}", blocks.len())
+            }
+            Output::OpenScreen { .. } => "opened a screen".to_string(),
+            Output::CloseScreen { .. } => "closed its screen".to_string(),
+            Output::PlaceRecipe { book_id, all } => {
+                format!("placed recipe {book_id}{}", if all { " (all)" } else { "" })
+            }
+            Output::Give { item, count, .. } => format!("gave {count} {item}"),
+            Output::Shake { strength, seconds } => {
+                format!("shook the camera: {strength:.2} for {seconds:.1} s")
+            }
+        });
+    }
+    let shapes = mods.hud_shapes().count();
+    if shapes > 0 {
+        report.output.push(format!("drew {shapes} HUD shape(s)"));
+    }
+    match failed(&mods) {
+        Some(reason) => Err(format!("it stopped: {reason}")),
+        None => Ok(()),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn fixture(name: &str) -> std::path::PathBuf {
+        Path::new(env!("CARGO_MANIFEST_DIR"))
+            .join("../horizon-mods/tests/index")
+            .join(name)
+    }
+
+    #[test]
+    fn checks_each_kind_its_own_way() {
+        let pack = fixture("cozy-1.0.0.hpack");
+        let report = check(&pack, kind_of(&pack).unwrap(), None, None).unwrap();
+        assert_eq!(report.facts.requires[0].id, "coords_hud");
+        assert!(
+            report
+                .text()
+                .contains("cozy 1.0.0 (modpack, format 1, for 26.3)")
+        );
+        // The fixture mod's code is a stand-in: its manifest reads, its run fails.
+        let hmod = fixture("coords_hud-0.1.0.hmod");
+        let key = std::fs::read_to_string(fixture("test.pub")).unwrap();
+        let sig = std::fs::read_to_string(fixture("coords_hud-0.1.0.hmod.minisig")).unwrap();
+        let key = key.lines().last().unwrap();
+        let e = check(&hmod, Kind::Mod, Some(key), Some(&sig))
+            .err()
+            .unwrap();
+        assert!(e.contains("didn't start"), "{e}");
+        let e = check(
+            &hmod,
+            Kind::Mod,
+            Some(key),
+            Some("untrusted comment: x\nRUQ=\n"),
+        )
+        .err()
+        .unwrap();
+        assert!(e.contains("signature"), "{e}");
+        let e = check(&pack, Kind::Shader, None, None).err().unwrap();
+        assert!(e.contains("horizon-shaders.toml"), "{e}");
+        assert!(check(&pack, Kind::Mod, None, None).is_err());
+    }
+}
@@ -1,13 +1,24 @@
 //! `cargo horizon-mod`: make Horizon mods in Rust (`docs/mods.md`).
 //!
-//! - `new <path> [--name "Name"] [--sdk-path <dir>]`: a mod crate from the template.
-//! - `build [--debug]`: the `.hmod` in `target/horizon-mod/`.
+//! - `new <path> [--template code|content] [--name "Name"] [--sdk-path <dir>]`:
+//!   a mod from a template: a Rust crate, or a content mod (no code).
+//! - `build [--debug]`: the `.hmod` in `target/horizon-mod/`, with the mod's
+//!   `assets/` and `data/`; a folder without `Cargo.toml` is content only.
 //! - `run [--game <horizon-client>] [-- <game args>]`: build, then play with
 //!   the mod; run `build` again and the game reloads it.
+//! - `test [--debug] [--hmod <file>] [<name>]`: build, then run the mod's
+//!   `tests/*.toml` scripts in the sandbox, with no game.
+//! - `check <file> [--json]`: what the registry checks of a submission
+//!   (`.hmod`, `.hpack`, resource pack `.zip`), with a trial run for a mod.
+//! - `registry build|review|check|list`: the registry repository's CI.
 use horizon_mods::{
-    Manifest, Package,
+    Capability, Content, Manifest, Package,
    manifest::{MANIFEST, component_imports, componentize},
+    testing::{Script, TestGame},
 };
+mod check;
+mod registry;
+
 use std::{
    path::{Path, PathBuf},
    process::{Command, ExitCode, Stdio},
@@ -28,7 +39,10 @@ fn main() -> ExitCode {
            println!("Built {}", p.display());
        }),
        Some("run") => run(&args[1..]),
-        _ => Err("usage: cargo horizon-mod new <path> | build [--debug] | run [--game <horizon-client>] [-- <game args>]".into()),
+        Some("test") => test(&args[1..]),
+        Some("check") => check(&args[1..]),
+        Some("registry") => registry::main(&args[1..]),
+        _ => Err("usage: cargo horizon-mod new <path> [--template code|content] | build [--debug] | run [--game <horizon-client>] [-- <game args>] | test [--debug] [--hmod <file>] [<name>] | check <file> [--kind <kind>] [--key <public key> --signature <file.minisig>] [--json] | registry build|review|check|list".into()),
    };
    match result {
        Ok(()) => ExitCode::SUCCESS,
@@ -82,19 +96,72 @@ fn new(args: &[String]) -> Result<(), String> {
            .replace("{name}", &name)
            .replace("{sdk}", &sdk)
    };
-    let files = [
+    let code = [
        ("Cargo.toml", include_str!("../template/Cargo.toml.in")),
        (MANIFEST, include_str!("../template/horizon-mod.toml")),
        ("src/lib.rs", include_str!("../template/src/lib.rs")),
        (".gitignore", include_str!("../template/gitignore")),
+        (
+            "tests/hello.toml",
+            include_str!("../template/tests/hello.toml"),
+        ),
    ];
-    for (file, text) in files {
+    // A block copying a vanilla one, with its model, name, loot, recipe and tag.
+    let content = [
+        (
+            MANIFEST,
+            include_str!("../template/content/horizon-mod.toml"),
+        ),
+        (
+            "data/{id}/horizon/block/glowing_amethyst.json",
+            include_str!("../template/content/block.json"),
+        ),
+        (
+            "assets/{id}/blockstates/glowing_amethyst.json",
+            include_str!("../template/content/blockstate.json"),
+        ),
+        (
+            "assets/{id}/models/block/glowing_amethyst.json",
+            include_str!("../template/content/model.json"),
+        ),
+        (
+            "assets/{id}/items/glowing_amethyst.json",
+            include_str!("../template/content/item.json"),
+        ),
+        (
+            "assets/{id}/lang/en_us.json",
+            include_str!("../template/content/lang.json"),
+        ),
+        (
+            "data/{id}/loot_table/blocks/glowing_amethyst.json",
+            include_str!("../template/content/loot.json"),
+        ),
+        (
+            "data/{id}/recipe/glowing_amethyst.json",
+            include_str!("../template/content/recipe.json"),
+        ),
+        (
+            "data/minecraft/tags/block/mineable/pickaxe.json",
+            include_str!("../template/content/pickaxe.json"),
+        ),
+        (".gitignore", include_str!("../template/gitignore")),
+    ];
+    let files: &[(&str, &str)] = match flag(args, "--template").unwrap_or("code") {
+        "code" => &code,
+        "content" => &content,
+        other => return Err(format!("no template {other}: code or content")),
+    };
+    for &(file, text) in files {
+        let file = fill(file);
+        let file = file.as_str();
        let to = dir.join(file);
        std::fs::create_dir_all(to.parent().expect("a file in the mod"))
            .map_err(|e| e.to_string())?;
        std::fs::write(&to, fill(text)).map_err(|e| format!("{}: {e}", to.display()))?;
    }
-    Manifest::parse(&std::fs::read_to_string(dir.join(MANIFEST)).map_err(|e| e.to_string())?)?;
+    let manifest =
+        Manifest::parse(&std::fs::read_to_string(dir.join(MANIFEST)).map_err(|e| e.to_string())?)?;
+    Content::read(dir, &manifest)?;
    println!(
        "Created {} (mod id {id}). Next: cd {path} && cargo horizon-mod run",
        dir.display()
@@ -102,14 +169,53 @@ fn new(args: &[String]) -> Result<(), String> {
    Ok(())
 }

-/// Builds the crate in the current folder and packs `target/horizon-mod/<id>.hmod`.
+/// Builds the mod in the current folder and packs `target/horizon-mod/<id>.hmod`:
+/// the manifest, the crate's component (none without a `Cargo.toml`: a
+/// content mod) and the files in `assets/` and `data/`.
 fn build(release: bool) -> Result<PathBuf, String> {
-    let manifest_text = std::fs::read_to_string(MANIFEST)
+    build_in(Path::new("."), release)
+}
+
+fn build_in(root: &Path, release: bool) -> Result<PathBuf, String> {
+    let manifest_text = std::fs::read_to_string(root.join(MANIFEST))
        .map_err(|e| format!("{MANIFEST}: {e} (run this in a mod's folder)"))?;
    let manifest = Manifest::parse(&manifest_text)?;
+    let (wasm, target_dir) = if root.join("Cargo.toml").exists() {
+        let (wasm, target) = compile(root, release)?;
+        // The game refuses a component importing capabilities the manifest lacks.
+        manifest.check_imports(component_imports(&wasm)?.iter().map(String::as_str))?;
+        (Some(wasm), target)
+    } else if manifest.capabilities.contains(&Capability::Registries) {
+        (None, root.join("target"))
+    } else {
+        return Err(format!(
+            "no Cargo.toml: only a content mod (capability registries in {MANIFEST}) has no code"
+        ));
+    };
+    // The same checks as the game's, and the files in the order it lists them.
+    let content = Content::read(root, &manifest)?;
+    let mut reader = content.reader()?;
+    let mut files = Vec::with_capacity(content.files.len());
+    for name in &content.files {
+        files.push((name.as_str(), reader.read(name)?));
+    }
+    let files: Vec<(&str, &[u8])> = files.iter().map(|(n, b)| (*n, b.as_slice())).collect();
+    let dir = target_dir.join("horizon-mod");
+    std::fs::create_dir_all(&dir).map_err(|e| e.to_string())?;
+    let path = dir.join(format!("{}.hmod", manifest.id));
+    // Write then rename, so a running game never reads half a file.
+    let partial = path.with_extension("hmod.partial");
+    let bytes = Package::write_files(&manifest_text, wasm.as_deref(), &files)?;
+    std::fs::write(&partial, bytes).map_err(|e| e.to_string())?;
+    std::fs::rename(&partial, &path).map_err(|e| e.to_string())?;
+    Ok(path)
+}
+
+/// Builds the crate for WebAssembly: its component, and Cargo's target folder.
+fn compile(root: &Path, release: bool) -> Result<(Vec<u8>, PathBuf), String> {
    let cargo = std::env::var("CARGO").unwrap_or_else(|_| "cargo".into());
    let mut cmd = Command::new(cargo);
-    cmd.args([
+    cmd.current_dir(root).args([
        "build",
        "--lib",
        "--target",
@@ -137,17 +243,96 @@ fn build(release: bool) -> Result<PathBuf, String> {
        .rfind(|f| f.extension().is_some_and(|e| e == "wasm"))
        .ok_or("the build made no .wasm: is the crate a cdylib?")?;
    let wasm = componentize(&std::fs::read(&core).map_err(|e| e.to_string())?)?;
-    // The game refuses a component importing capabilities the manifest lacks.
-    manifest.check_imports(component_imports(&wasm)?.iter().map(String::as_str))?;
-    let target_dir = core.ancestors().nth(3).ok_or("unexpected target folder")?;
-    let dir = target_dir.join("horizon-mod");
-    std::fs::create_dir_all(&dir).map_err(|e| e.to_string())?;
-    let path = dir.join(format!("{}.hmod", manifest.id));
-    // Write then rename, so a running game never reads half a file.
-    let partial = path.with_extension("hmod.partial");
-    std::fs::write(&partial, Package::write(&manifest_text, &wasm)?).map_err(|e| e.to_string())?;
-    std::fs::rename(&partial, &path).map_err(|e| e.to_string())?;
-    Ok(path)
+    let target = core.ancestors().nth(3).ok_or("unexpected target folder")?;
+    Ok((wasm, target.to_path_buf()))
+}
+
+/// `check <file>`: the registry's checks of a submission, printed; fails
+/// when one does.
+fn check(args: &[String]) -> Result<(), String> {
+    let file = args
+        .first()
+        .filter(|a| !a.starts_with("--"))
+        .ok_or("cargo horizon-mod check <file>")?;
+    let path = Path::new(file);
+    let kind = match flag(args, "--kind") {
+        Some(k) => horizon_mods::index::Kind::from(k.to_string()),
+        None => check::kind_of(path)
+            .ok_or("pass --kind mod|modpack|resourcepack: the extension doesn't say")?,
+    };
+    let signature = flag(args, "--signature")
+        .map(|p| std::fs::read_to_string(p).map_err(|e| format!("{p}: {e}")))
+        .transpose()?;
+    let report = check::check(path, kind, flag(args, "--key"), signature.as_deref());
+    if args.iter().any(|a| a == "--json") {
+        let json = match &report {
+            Ok(r) => serde_json::json!({"ok": true, "report": r.json()}),
+            Err(e) => serde_json::json!({"ok": false, "error": e}),
+        };
+        println!("{json}");
+    }
+    let report = report?;
+    if !args.iter().any(|a| a == "--json") {
+        print!("{}", report.text());
+    }
+    Ok(())
+}
+
+/// `test`: every `tests/*.toml` script (those whose name holds `<name>`)
+/// against the built mod, or the `.hmod` given with `--hmod`.
+fn test(args: &[String]) -> Result<(), String> {
+    let hmod = match flag(args, "--hmod") {
+        Some(p) => PathBuf::from(p),
+        None => build(!args.iter().any(|a| a == "--debug"))?,
+    };
+    let filter = args
+        .iter()
+        .enumerate()
+        .find(|(i, a)| !a.starts_with("--") && (*i == 0 || args[i - 1] != "--hmod"))
+        .map(|(_, a)| a.as_str());
+    let mut scripts: Vec<PathBuf> = std::fs::read_dir("tests")
+        .map_err(|e| {
+            format!(
+                "tests/: {e} (a mod's tests are tests/<name>.toml: docs/mods.md, \"Testing a mod\")"
+            )
+        })?
+        .filter_map(|e| Some(e.ok()?.path()))
+        .filter(|p| p.extension().is_some_and(|e| e == "toml"))
+        .filter(|p| filter.is_none_or(|f| p.to_string_lossy().contains(f)))
+        .collect();
+    scripts.sort();
+    if scripts.is_empty() {
+        return Err("no tests/*.toml to run".into());
+    }
+    println!(
+        "running {} scripts against {}",
+        scripts.len(),
+        hmod.display()
+    );
+    let mut failed = 0;
+    for path in &scripts {
+        let result = std::fs::read_to_string(path)
+            .map_err(|e| e.to_string())
+            .and_then(|text| Script::parse(&text))
+            .and_then(|script| {
+                let mut game = TestGame::load(&hmod)?;
+                script.run(&mut game)?;
+                Ok(script.steps.len())
+            });
+        match result {
+            Ok(steps) => println!("test {} ... ok ({steps} steps)", path.display()),
+            Err(e) => {
+                failed += 1;
+                println!("test {} ... FAILED\n  {e}", path.display());
+            }
+        }
+    }
+    let passed = scripts.len() - failed;
+    if failed > 0 {
+        return Err(format!("{failed} failed, {passed} passed"));
+    }
+    println!("test result: ok. {passed} passed");
+    Ok(())
 }

 fn run(args: &[String]) -> Result<(), String> {
@@ -192,10 +377,57 @@ mod tests {
        );
        let cargo = std::fs::read_to_string(path.join("Cargo.toml")).unwrap();
        assert!(cargo.contains("name = \"my-mod\"") && cargo.contains(SDK_GIT));
+        let script = std::fs::read_to_string(path.join("tests/hello.toml")).unwrap();
+        assert_eq!(Script::parse(&script).unwrap().steps.len(), 3);
        assert!(
            new(&[path.display().to_string()]).is_err(),
            "never overwrites"
        );
        std::fs::remove_dir_all(&dir).unwrap();
    }
+
+    #[test]
+    fn the_content_template_builds_and_checks_with_no_code() {
+        let dir = std::env::temp_dir().join(format!("horizon-mod-content-{}", std::process::id()));
+        let path = dir.join("gems");
+        let new_args = [
+            path.display().to_string(),
+            "--template".into(),
+            "content".into(),
+        ];
+        new(&new_args).unwrap();
+        assert!(!path.join("Cargo.toml").exists());
+        let hmod = build_in(&path, true).unwrap();
+        assert_eq!(hmod, path.join("target/horizon-mod/gems.hmod"));
+        let package = Package::read(&hmod).unwrap();
+        assert!(package.wasm.is_none());
+        let content = Content::read(&hmod, &package.manifest).unwrap();
+        assert!(
+            content
+                .files
+                .contains(&"data/gems/horizon/block/glowing_amethyst.json".into())
+        );
+        assert_eq!(content.files.len(), 8, "{:?}", content.files);
+        let report = check::check(&hmod, check::kind_of(&hmod).unwrap(), None, None).unwrap();
+        assert!(!report.code);
+        assert!(
+            report.text().contains("no code: content only"),
+            "{}",
+            report.text()
+        );
+        // Without registries, a mod needs code.
+        let manifest = std::fs::read_to_string(path.join(MANIFEST)).unwrap();
+        let manifest = manifest.replace("[\"registries\"]", "[]");
+        std::fs::write(path.join(MANIFEST), manifest).unwrap();
+        assert!(build_in(&path, true).unwrap_err().contains("no Cargo.toml"));
+        assert!(
+            new(&[
+                dir.join("x").display().to_string(),
+                "--template".into(),
+                "lua".into()
+            ])
+            .is_err()
+        );
+        std::fs::remove_dir_all(&dir).unwrap();
+    }
 }
@@ -0,0 +1,159 @@
+//! `cargo horizon-mod registry build|review|check|list`: the registry repository's CI
+//! (`ludovic111/horizon-mods`, docs/api/mod-index.md). Network-free: the
+//! workflow downloads the files and publishes what this writes.
+use horizon_mods::index::{
+    FILE_HOST,
+    registry::{self, Sources},
+};
+use std::path::Path;
+
+/// Where the registry's site is published (its icons).
+const SITE: &str = "https://ludovic111.github.io/horizon-mods/";
+
+const USAGE: &str = "usage: cargo horizon-mod registry build <checkout> --files <dir> --out <index.json> [--release <url>] [--site <url>] [--generated <time>]
+       cargo horizon-mod registry review <base checkout> <head checkout> --author <login> [--json]
+       cargo horizon-mod registry check <base checkout> <head checkout> --files <dir>
+       cargo horizon-mod registry list <checkout>";
+
+fn flag<'a>(args: &'a [String], name: &str) -> Option<&'a str> {
+    super::flag(args, name)
+}
+
+fn positional(args: &[String]) -> Vec<&str> {
+    let mut out = Vec::new();
+    let mut skip = false;
+    for a in args {
+        if skip {
+            skip = false;
+        } else if a == "--json" {
+        } else if a.starts_with("--") {
+            skip = true;
+        } else {
+            out.push(a.as_str());
+        }
+    }
+    out
+}
+
+fn lines(errors: Vec<String>) -> String {
+    format!("{} problem(s):\n  {}", errors.len(), errors.join("\n  "))
+}
+
+pub fn main(args: &[String]) -> Result<(), String> {
+    let rest = args.get(1..).unwrap_or_default();
+    let pos = positional(rest);
+    match args.first().map(String::as_str) {
+        Some("build") => {
+            let [checkout] = pos[..] else {
+                return Err(USAGE.into());
+            };
+            let (files, out) = (flag(rest, "--files"), flag(rest, "--out"));
+            let (Some(files), Some(out)) = (files, out) else {
+                return Err(USAGE.into());
+            };
+            let generated = flag(rest, "--generated")
+                .map(str::to_owned)
+                .or_else(|| std::env::var("REGISTRY_GENERATED").ok())
+                .unwrap_or_default();
+            let index = registry::build(&Sources {
+                registry: Path::new(checkout),
+                files: Path::new(files),
+                release: flag(rest, "--release").unwrap_or(FILE_HOST),
+                site: flag(rest, "--site").unwrap_or(SITE),
+                generated,
+            })
+            .map_err(lines)?;
+            let text = serde_json::to_string_pretty(&index).map_err(|e| e.to_string())?;
+            std::fs::write(out, text + "\n").map_err(|e| format!("{out}: {e}"))?;
+            println!(
+                "Wrote {out}: {} project(s), {} taken down",
+                index.projects.len(),
+                index.revoked.len()
+            );
+            Ok(())
+        }
+        Some("review") => {
+            let [base, head] = pos[..] else {
+                return Err(USAGE.into());
+            };
+            let author = flag(rest, "--author").ok_or(USAGE)?;
+            let (base, _) = registry::load(Path::new(base)).map_err(lines)?;
+            let (head, _) = registry::load(Path::new(head)).map_err(lines)?;
+            let review = registry::review(&base, &head, author);
+            if rest.iter().any(|a| a == "--json") {
+                let json = serde_json::json!({"errors": review.errors, "notes": review.notes});
+                println!("{json}");
+            } else {
+                for n in &review.notes {
+                    println!("note: {n}");
+                }
+                for e in &review.errors {
+                    println!("error: {e}");
+                }
+            }
+            if review.errors.is_empty() {
+                Ok(())
+            } else {
+                Err(format!(
+                    "{} change(s) the registry refuses",
+                    review.errors.len()
+                ))
+            }
+        }
+        // `check` (and its trial run) on each file `head` lists and `base`
+        // doesn't: a pull request's new files.
+        Some("check") => {
+            let [base, head] = pos[..] else {
+                return Err(USAGE.into());
+            };
+            let files = Path::new(flag(rest, "--files").ok_or(USAGE)?);
+            let old: Vec<String> = match registry::load(Path::new(base)) {
+                Ok((entries, _)) => entries
+                    .iter()
+                    .flat_map(|e| e.versions.iter().map(|v| v.sha256.clone()))
+                    .collect(),
+                // The first pull request has no entries to compare with.
+                Err(_) => Vec::new(),
+            };
+            let (entries, _) = registry::load(Path::new(head)).map_err(lines)?;
+            let mut failed = 0;
+            for e in &entries {
+                for v in e.versions.iter().filter(|v| !old.contains(&v.sha256)) {
+                    println!("{} {} ({}):", e.id, v.version, v.file);
+                    let report = crate::check::check(
+                        &files.join(&v.sha256),
+                        e.kind.clone(),
+                        e.key.as_deref(),
+                        v.signature.as_deref(),
+                    );
+                    match report {
+                        Ok(r) => print!("{}", r.text()),
+                        Err(err) => {
+                            failed += 1;
+                            println!("  error: {err}");
+                        }
+                    }
+                }
+            }
+            if failed == 0 {
+                Ok(())
+            } else {
+                Err(format!("{failed} file(s) failed their check"))
+            }
+        }
+        // The files CI must download for `build`: `<sha256> <id> <version> <file>`.
+        Some("list") => {
+            let [checkout] = pos[..] else {
+                return Err(USAGE.into());
+            };
+            let (entries, _) = registry::load(Path::new(checkout)).map_err(lines)?;
+            for e in &entries {
+                for v in &e.versions {
+                    println!("{} {} {} {}", v.sha256, e.id, v.version, v.file);
+                }
+            }
+            Ok(())
+        }
+        _ => Err(USAGE.into()),
+    }
+}
@@ -0,0 +1,4 @@
+{
+  "template": "minecraft:amethyst_block",
+  "properties": { "hardness": 2.0, "light": 7 }
+}
@@ -0,0 +1,5 @@
+{
+  "variants": {
+    "": { "model": "{id}:block/glowing_amethyst" }
+  }
+}
@@ -0,0 +1,10 @@
+id = "{id}"
+name = "{name}"
+version = "0.1.0"
+description = ""
+authors = []
+# A content mod: blocks and items from data/ and assets/, no code (API 0.2).
+api = "0.2"
+side = "both"
+# registries: "May add blocks and items to your worlds".
+capabilities = ["registries"]
@@ -0,0 +1,3 @@
+{
+  "model": { "type": "minecraft:model", "model": "{id}:block/glowing_amethyst" }
+}
@@ -0,0 +1,3 @@
+{
+  "block.{id}.glowing_amethyst": "Glowing Amethyst"
+}
@@ -0,0 +1,11 @@
+{
+  "type": "minecraft:block",
+  "pools": [
+    {
+      "condition": { "type": "minecraft:survives_explosion" },
+      "entries": [{ "type": "minecraft:item", "name": "{id}:glowing_amethyst" }],
+      "rolls": 1
+    }
+  ],
+  "random_sequence": "{id}:blocks/glowing_amethyst"
+}
@@ -0,0 +1,4 @@
+{
+  "parent": "minecraft:block/cube_all",
+  "textures": { "all": "minecraft:block/amethyst_block" }
+}
@@ -0,0 +1,3 @@
+{
+  "values": ["{id}:glowing_amethyst"]
+}
@@ -0,0 +1,6 @@
+{
+  "type": "minecraft:crafting_shapeless",
+  "category": "building",
+  "ingredients": ["minecraft:amethyst_block", "minecraft:glowstone_dust"],
+  "result": { "id": "{id}:glowing_amethyst" }
+}
@@ -0,0 +1,14 @@
+# `cargo horizon-mod test` runs every tests/*.toml against the built mod, with no game:
+# steps happen in order, and `expect` checks what the mod showed during the step.
+# Every key: docs/mods.md, "Testing a mod".
+
+[[step]]
+expect.commands = ["hello"]
+
+[[step]]
+command = "hello world"
+expect.chat = ["Hello world! (1 so far)"]
+
+[[step]]
+command = "hello again"
+expect.chat = ["Hello again! (2 so far)"]
@@ -4,15 +4,15 @@ use crate::json::{Result, error};
 use horizon_core::random::RandomSource;

 #[derive(Clone, Debug)]
-enum Choice {
-    Single(Variant),
+enum Choice<T> {
+    Single(T),
    Weighted {
-        variants: Vec<Variant>,
+        variants: Vec<T>,
        ends: Vec<i32>,
        total: i32,
    },
 }
-impl Choice {
+impl Choice<Variant> {
    fn new(value: &VariantSet) -> Result<Self> {
        match value {
            VariantSet::Single(value) => Ok(Self::Single(value.clone())),
@@ -41,7 +41,23 @@ impl Choice {
            }
        }
    }
-    fn select(&self, random: &mut impl RandomSource) -> &Variant {
+}
+impl<T> Choice<T> {
+    fn map<U>(&self, f: &mut impl FnMut(&T) -> U) -> Choice<U> {
+        match self {
+            Self::Single(value) => Choice::Single(f(value)),
+            Self::Weighted {
+                variants,
+                ends,
+                total,
+            } => Choice::Weighted {
+                variants: variants.iter().map(&mut *f).collect(),
+                ends: ends.clone(),
+                total: *total,
+            },
+        }
+    }
+    fn select(&self, random: &mut impl RandomSource) -> &T {
        match self {
            Self::Single(value) => value,
            Self::Weighted {
@@ -60,10 +76,11 @@ impl Choice {
 }
 /// Compile once per definition and share across its bound block states. Prefix
 /// sums avoid rebuilding weight totals or scanning all entries during selection.
+/// `map` swaps each variant for what it stands for (its baked model).
 #[derive(Clone, Debug)]
-pub struct CompiledChoices {
-    variants: Vec<Choice>,
-    multipart: Vec<Choice>,
+pub struct CompiledChoices<T = Variant> {
+    variants: Vec<Choice<T>>,
+    multipart: Vec<Choice<T>>,
 }
 impl CompiledChoices {
    pub fn new(definition: &BlockStateDefinition) -> Result<Self> {
@@ -82,10 +99,19 @@ impl CompiledChoices {
                .collect::<Result<_>>()?,
        })
    }
+}
+impl<T> CompiledChoices<T> {
+    /// The same choices, with `f` of each variant in its place.
+    pub fn map<U>(&self, mut f: impl FnMut(&T) -> U) -> CompiledChoices<U> {
+        CompiledChoices {
+            variants: self.variants.iter().map(|c| c.map(&mut f)).collect(),
+            multipart: self.multipart.iter().map(|c| c.map(&mut f)).collect(),
+        }
+    }
    /// The variant `particleMaterial` comes from: the first entry of a weighted
    /// list (`WeightedVariants`) and, for a multipart root, of its first
    /// selector whether or not that selector applies (`MultiPartModel`).
-    pub fn particle_variant(&self, selected: &SelectedModels) -> Option<&Variant> {
+    pub fn particle_variant(&self, selected: &SelectedModels) -> Option<&T> {
        let choice = match selected {
            SelectedModels::Variant(index) => self.variants.get(*index)?,
            SelectedModels::Multipart(_) => self.multipart.first()?,
@@ -95,14 +121,23 @@ impl CompiledChoices {
            Choice::Weighted { variants, .. } => variants.first()?,
        })
    }
-    /// Append selected variants without allocating intermediate part lists. A
-    /// multipart root consumes nextLong even for an empty selected subset, then
-    /// resets the same random source to that seed before each selected part.
+    /// Append selected variants without allocating intermediate part lists.
    pub fn collect<'a>(
        &'a self,
        selected: &SelectedModels,
        random: &mut impl RandomSource,
-        output: &mut Vec<&'a Variant>,
+        output: &mut Vec<&'a T>,
+    ) -> Result<()> {
+        self.for_each(selected, random, |v| output.push(v))
+    }
+    /// Each selected variant, in order. A multipart root consumes nextLong
+    /// even for an empty selected subset, then resets the same random source
+    /// to that seed before each selected part.
+    pub fn for_each<'a>(
+        &'a self,
+        selected: &SelectedModels,
+        random: &mut impl RandomSource,
+        mut f: impl FnMut(&'a T),
    ) -> Result<()> {
        match selected {
            SelectedModels::Variant(index) => {
@@ -110,7 +145,7 @@ impl CompiledChoices {
                    .variants
                    .get(*index)
                    .ok_or_else(|| error("invalid variant selection"))?;
-                output.push(choice.select(random));
+                f(choice.select(random));
            }
            SelectedModels::Multipart(indices) => {
                if indices.iter().any(|index| *index >= self.multipart.len()) {
@@ -119,7 +154,7 @@ impl CompiledChoices {
                let seed = random.next_long();
                for index in indices {
                    random.set_seed(seed);
-                    output.push(self.multipart[*index].select(random));
+                    f(self.multipart[*index].select(random));
                }
            }
        }
@@ -1031,19 +1031,22 @@ pub struct ItemModels {
 }

 impl ItemModels {
-    pub fn components(&self, stack: &StackView) -> Components {
-        let mut out = self
-            .prototypes
-            .get(&stack.item)
-            .cloned()
-            .unwrap_or_default();
+    /// The stack's components: its item's defaults with the stack's patch on top. A stack
+    /// with no patch (most stacks a screen draws) borrows the defaults instead of copying them.
+    pub fn components(&self, stack: &StackView) -> std::borrow::Cow<'_, Components> {
+        static NONE: Components = BTreeMap::new();
+        let prototype = self.prototypes.get(&stack.item).unwrap_or(&NONE);
+        if stack.patch.is_empty() {
+            return std::borrow::Cow::Borrowed(prototype);
+        }
+        let mut out = prototype.clone();
        for (key, value) in &stack.patch {
            match value {
                Some(v) => out.insert(key.clone(), v.clone()),
                None => out.remove(key),
            };
        }
-        out
+        std::borrow::Cow::Owned(out)
    }
    /// `ItemModelResolver.updateForTopItem`.
    pub fn resolve(&self, stack: &StackView, ctx: &Context, env: &dyn ItemEnv) -> ResolvedItem {
@@ -1,8 +1,7 @@
 //! The machine a report was measured on. CPU, RAM and OS are detected here; the GPU and the display
 //! come from the program that rendered (the game knows its adapter, the launcher its window).

-use std::process::Command;
-
+use horizon_telemetry::system::command_output as output;
 use serde::{Deserialize, Serialize};

 #[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
@@ -173,12 +172,6 @@ pub fn cpu_seconds(pid: u32) -> Option<f64> {
    Some(ticks / 100.0)
 }

-fn output(program: &str, args: &[&str]) -> Option<String> {
-    let out = Command::new(program).args(args).output().ok()?;
-    let text = String::from_utf8(out.stdout).ok()?.trim().to_owned();
-    (out.status.success() && !text.is_empty()).then_some(text)
-}
-
 #[cfg(target_os = "macos")]
 fn os_version() -> Option<String> {
    output("sw_vers", &["-productVersion"])
@@ -245,13 +245,19 @@ pub struct Report {
 impl Report {
    /// An empty report for this machine, created now.
    pub fn new(kind: Kind, app: App) -> Report {
+        Self::with_hardware(kind, app, Hardware::detect())
+    }
+
+    /// Starts a report using supplied hardware, without running system probes.
+    /// Interactive apps can collect the remaining machine details after their first frame.
+    pub fn with_hardware(kind: Kind, app: App, hardware: Hardware) -> Report {
        Report {
            format: FORMAT.to_owned(),
            version: VERSION,
            kind,
            created: utc_now(),
            app,
-            hardware: Hardware::detect(),
+            hardware,
            conditions: Conditions::default(),
            metrics: BTreeMap::new(),
            frames: Vec::new(),
@@ -173,6 +173,11 @@ impl Random {
    }
 }

+/// One bot thread that panics poisons the locks it held; the others and the report go on.
+fn lock<T>(m: &Mutex<T>) -> std::sync::MutexGuard<'_, T> {
+    m.lock().unwrap_or_else(std::sync::PoisonError::into_inner)
+}
+
 fn raw(id: i32, write: impl FnOnce(&mut Writer)) -> Vec<u8> {
    let mut w = Writer::new();
    w.varint(id);
@@ -329,7 +334,7 @@ fn read(
 ) {
    use ids::play::clientbound as cb;
    use ids::play::serverbound as sb;
-    let send = |body: Vec<u8>| writer.lock().unwrap().send(&body);
+    let send = |body: Vec<u8>| lock(&writer).send(&body);
    let mut seen = HashSet::new();
    let mut batch = BatchSize::new();
    let mut teleports = 0u64;
@@ -338,7 +343,7 @@ fn read(
            Ok(packet) => packet,
            Err(e) => {
                if bot.online.swap(false, Ordering::SeqCst) {
-                    *bot.error.lock().unwrap() = Some(e.to_string());
+                    *lock(&bot.error) = Some(e.to_string());
                }
                return;
            }
@@ -356,7 +361,7 @@ fn read(
            cb::LEVEL_CHUNK_WITH_LIGHT => {
                bot.chunks.fetch_add(1, Ordering::Relaxed);
                if let (Ok(x), Ok(z)) = (r.i32(), r.i32()) {
-                    if !bot.held.lock().unwrap().insert((x, z)) {
+                    if !lock(&bot.held).insert((x, z)) {
                        bot.resent.fetch_add(1, Ordering::Relaxed);
                    }
                    if seen.insert((x, z)) {
@@ -368,7 +373,7 @@ fn read(
            cb::FORGET_LEVEL_CHUNK => {
                if let Ok(play::Clientbound::ForgetLevelChunk(p)) =
                    play::Clientbound::decode(id, &body)
-                    && bot.held.lock().unwrap().remove(&(p.pos[0], p.pos[1]))
+                    && lock(&bot.held).remove(&(p.pos[0], p.pos[1]))
                {
                    bot.forgotten.fetch_add(1, Ordering::Relaxed);
                }
@@ -389,7 +394,7 @@ fn read(
            }
            cb::PLAYER_POSITION => match play::Clientbound::decode(id, &body) {
                Ok(play::Clientbound::PlayerPosition(p)) => {
-                    let mut at = bot.teleport.lock().unwrap();
+                    let mut at = lock(&bot.teleport);
                    let previous = at.unwrap_or([0.0; 3]);
                    // Relative flags: X 1, Y 2, Z 4.
                    let pos: [f64; 3] = std::array::from_fn(|i| {
@@ -420,7 +425,7 @@ fn read(
            },
            cb::DISCONNECT | cb::START_CONFIGURATION => {
                bot.online.store(false, Ordering::SeqCst);
-                *bot.error.lock().unwrap() = Some(if id == cb::DISCONNECT {
+                *lock(&bot.error) = Some(if id == cb::DISCONNECT {
                    format!(
                        "disconnected: {}",
                        String::from_utf8_lossy(&body)
@@ -455,7 +460,7 @@ fn run_bot(
    let connection = match join(&o, &name) {
        Ok(c) => c,
        Err(e) => {
-            *bot.error.lock().unwrap() = Some(e);
+            *lock(&bot.error) = Some(e);
            return;
        }
    };
@@ -469,12 +474,12 @@ fn run_bot(
    use ids::play::serverbound as sb;
    // Wait for the spawn position.
    let spawn = loop {
-        if let Some(at) = *bot.teleport.lock().unwrap() {
+        if let Some(at) = *lock(&bot.teleport) {
            break at;
        }
        if !bot.online.load(Ordering::SeqCst) || asked.elapsed() > Duration::from_secs(60) {
-            if bot.error.lock().unwrap().is_none() {
-                *bot.error.lock().unwrap() = Some("no spawn position within 60 s".into());
+            if lock(&bot.error).is_none() {
+                *lock(&bot.error) = Some("no spawn position within 60 s".into());
            }
            return;
        }
@@ -482,7 +487,7 @@ fn run_bot(
    };
    bot.joined_after_ms
        .store(asked.elapsed().as_millis() as u64, Ordering::SeqCst);
-    let send = |body: Vec<u8>| writer.lock().unwrap().send(&body).is_ok();
+    let send = |body: Vec<u8>| lock(&writer).send(&body).is_ok();
    send(raw(sb::PLAYER_LOADED, |_| {}));
    let mut random = Random(o.seed ^ (index as u64).wrapping_mul(0x2545_F491_4F6C_DD1D));
    let mut pos = spawn;
@@ -491,17 +496,15 @@ fn run_bot(
    let mut target = pos;
    let mut next = Instant::now();
    loop {
-        if until.lock().unwrap().is_some_and(|u| Instant::now() >= u)
-            || !bot.online.load(Ordering::SeqCst)
-        {
+        if lock(&until).is_some_and(|u| Instant::now() >= u) || !bot.online.load(Ordering::SeqCst) {
            break;
        }
        // A teleport from the server wins over where the bot thought it was.
-        if let Some(at) = bot.teleport.lock().unwrap().take() {
+        if let Some(at) = lock(&bot.teleport).take() {
            pos = at;
        }
        let here = ((pos[0].floor() as i32) >> 4, (pos[2].floor() as i32) >> 4);
-        if !bot.held.lock().unwrap().contains(&here) {
+        if !lock(&bot.held).contains(&here) {
            bot.waited.fetch_add(1, Ordering::Relaxed);
        } else if pos[1] < cruise {
            pos[1] = (pos[1] + 0.5).min(cruise);
@@ -558,7 +561,7 @@ fn run_bot(
    }
    // Offline first, so the reader doesn't count the closed connection as a failure.
    bot.online.store(false, Ordering::SeqCst);
-    writer.lock().unwrap().shutdown();
+    lock(&writer).shutdown();
 }

 fn behaviour_of(mode: &str, index: usize) -> Behaviour {
@@ -612,13 +615,10 @@ fn main() {
        let total = |f: fn(&Bot) -> &AtomicU64| -> u64 {
            bots.iter().map(|b| f(b).load(Ordering::Relaxed)).sum()
        };
-        let failed = bots
-            .iter()
-            .filter(|b| b.error.lock().unwrap().is_some())
-            .count();
+        let failed = bots.iter().filter(|b| lock(&b.error).is_some()).count();
        if first.is_none() && online > 0 {
            first = Some(Instant::now());
-            *until.lock().unwrap() = Some(Instant::now() + Duration::from_secs(o.seconds));
+            *lock(&until) = Some(Instant::now() + Duration::from_secs(o.seconds));
        }
        println!(
            "{}",
@@ -636,10 +636,10 @@ fn main() {
            })
        );
        previous_chunks = chunks;
-        let over = until.lock().unwrap().is_some_and(|u| Instant::now() >= u);
+        let over = lock(&until).is_some_and(|u| Instant::now() >= u);
        let all_failed = failed == o.bots;
        if over || all_failed || (first.is_none() && start.elapsed() > Duration::from_secs(120)) {
-            *until.lock().unwrap() = Some(Instant::now());
+            *lock(&until) = Some(Instant::now());
            break;
        }
    }
@@ -669,7 +669,7 @@ fn main() {
            "forgotten": b.forgotten.load(Ordering::Relaxed),
            "pulled_back": b.pulled_back.load(Ordering::Relaxed),
            "waited_ticks": b.waited.load(Ordering::Relaxed),
-            "error": *b.error.lock().unwrap(),
+            "error": *lock(&b.error),
        })).collect::<Vec<_>>(),
    });
    if o.report.as_deref() == Some("-") {
@@ -0,0 +1,14 @@
+[package]
+name = "horizon-client-core"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+rust-version = "1.90"
+description = "The client's lowest layer: chat text and translations, SNBT and NBT paths, the scoreboard, boss bars, game rules and the registry and particle tables commands name"
+
+[dependencies]
+horizon-world = { path = "../horizon-world" }
+serde_json = { version = "1.0.151", features = ["raw_value"] }
+
+[lints]
+workspace = true
@@ -61,6 +61,16 @@ fn f32_tag(v: f32) -> Tag {
    Tag::Float(v.to_bits())
 }

+/// `TheEndGatewayBlockEntity.loadAdditional`: BlockPos.CODEC and Level.isInSpawnableBounds.
+pub fn gateway_exit(tag: &Tag) -> Option<[i32; 3]> {
+    let Tag::IntArray(v) = tag else { return None };
+    let p: [i32; 3] = v.as_slice().try_into().ok()?;
+    ((-30_000_000..30_000_000).contains(&p[0])
+        && (-20_000_000..20_000_000).contains(&p[1])
+        && (-30_000_000..30_000_000).contains(&p[2]))
+    .then_some(p)
+}
+
 /// What a block entity reads and writes, in `saveAdditional` order.
 struct Fields<'a> {
    input: &'a Tag,
@@ -259,7 +269,7 @@ fn is_pos(tag: &Tag) -> bool {
    matches!(tag, Tag::IntArray(v) if v.len() == 3)
 }
 /// The loaded `SignText` of one side, or the empty text.
-pub(crate) fn sign_side(tag: Option<&Tag>) -> Tag {
+pub fn sign_side(tag: Option<&Tag>) -> Tag {
    let empty = || string("");
    let mut messages: Vec<Tag> = match tag.and_then(|t| t.get("messages")) {
        Some(Tag::List(list)) => list.iter().filter_map(component).collect(),
@@ -424,10 +434,7 @@ pub fn canonical(tag: &Tag) -> Option<Tag> {
        }
        "minecraft:end_gateway" => {
            f.long("Age", 0);
-            f.keep("exit_portal", |t| {
-                is_pos(t)
-                    && matches!(t, Tag::IntArray(v) if v[1].abs() <= 30_000_000 && v[0].abs() <= 30_000_000 && v[2].abs() <= 30_000_000)
-            });
+            f.keep("exit_portal", |t| gateway_exit(t).is_some());
            if flag(tag.get("ExactTeleport")) == Some(true) {
                f.put("ExactTeleport", boolean(true));
            }
@@ -664,7 +671,9 @@ pub fn canonical(tag: &Tag) -> Option<Tag> {
        }
        "minecraft:trial_spawner" => {
            // `TrialSpawnerStateData.Packed` and `FullConfig`: every key is optional
-            // and defaulted by vanilla; they are kept as loaded.
+            // and defaulted by vanilla; they are kept as loaded. No `spawn_data` is
+            // added: an absent one loads as Optional.empty and is not stored, and
+            // an empty entity would keep the spawner from ever picking a mob.
            if let Tag::Compound(c) = tag {
                for (k, v) in c {
                    let key = k.to_string_lossy();
@@ -676,12 +685,6 @@ pub fn canonical(tag: &Tag) -> Option<Tag> {
                    }
                }
            }
-            if !f.out.contains_key(&"spawn_data".into()) {
-                f.put(
-                    "spawn_data",
-                    Tag::compound([("entity", Tag::Compound(Compound::new()))]),
-                );
-            }
        }
        "minecraft:vault" => {
            // `VaultConfig.DEFAULT` (when the config is absent): the trial key and the
@@ -827,6 +830,21 @@ mod tests {
        canonical(&snbt(s)).expect("known type")
    }

+    #[test]
+    fn a_trial_spawner_without_spawn_data_saves_none() {
+        let fresh = canon(
+            r#"{id:"minecraft:trial_spawner",x:1,y:2,z:3,normal_config:"minecraft:trial_chamber/ranged/skeleton/normal"}"#,
+        );
+        assert_eq!(fresh.get("spawn_data"), None);
+        let picked = canon(
+            r#"{id:"minecraft:trial_spawner",x:1,y:2,z:3,spawn_data:{entity:{id:"minecraft:skeleton"}}}"#,
+        );
+        assert_eq!(
+            picked.get("spawn_data"),
+            Some(&snbt(r#"{entity:{id:"minecraft:skeleton"}}"#))
+        );
+    }
+
    #[test]
    fn every_type_has_defaults() {
        for id in TYPES.iter().chain(NEWEST.iter()) {
@@ -14,40 +14,64 @@ pub const STYLES: [&str; 5] = [
    "notched_12",
    "notched_20",
 ];
-/// `BossBarColor.getFormatting`.
+/// `BossBarColor.getFormatting`. Purple is dark blue in 26.3.
 pub fn color_rgb(color: &str) -> u32 {
    let name = match color {
        "pink" => "red",
        "red" => "dark_red",
-        "purple" => "dark_purple",
+        "purple" => "dark_blue",
        other => other,
    };
    text::named_color(name).unwrap_or(text::WHITE)
 }

+/// A version-4 shaped id from a resource id. Saved boss events do not keep
+/// their UUID (`CustomBossEvents` mints a new one on load).
+pub fn stable_uuid(id: &str) -> u128 {
+    let mut h = 0xcbf29ce484222325u64;
+    for b in id.as_bytes() {
+        h ^= u64::from(*b);
+        h = h.wrapping_mul(0x100000001b3);
+    }
+    let most = (h as i64) & -61441 | 16384;
+    let least = (h.rotate_left(17) as i64) & 4_611_686_018_427_387_903 | i64::MIN;
+    ((most as u64 as u128) << 64) | (least as u64 as u128)
+}
+
 #[derive(Clone, Debug, PartialEq)]
 pub struct BossBar {
    pub id: String,
+    /// The `ServerBossEvent` UUID. Not saved.
+    pub uuid: u128,
    pub name: Comp,
    pub color: String,
    pub style: String,
    pub value: i32,
    pub max: i32,
+    /// `ServerBossEvent.visible`. A new bar is visible; nobody sees it until
+    /// a player is added.
    pub visible: bool,
-    /// Whether the (single) local player is in the bar's player set.
-    pub player: bool,
+    pub darken: bool,
+    pub music: bool,
+    pub fog: bool,
+    /// `CustomBossEvent.players`, the UUIDs told about the bar.
+    pub players: Vec<[i32; 4]>,
 }
 impl BossBar {
    pub fn new(id: &str, name: Comp) -> Self {
        Self {
            id: id.to_owned(),
+            uuid: stable_uuid(id),
            name,
            color: "white".into(),
            style: "progress".into(),
            value: 0,
            max: 100,
-            visible: false,
-            player: false,
+            visible: true,
+            darken: false,
+            music: false,
+            fog: false,
+            players: Vec::new(),
        }
    }
    /// `CustomBossEvent.getDisplayName`.
@@ -91,31 +115,34 @@ impl BossBars {
    pub fn ids(&self) -> Vec<String> {
        self.bars.iter().map(|b| b.id.clone()).collect()
    }
-    /// The saved compound; the player's UUID stands for "the local player".
-    pub fn pack(&self, player: Option<[i32; 4]>) -> Tag {
+    /// The saved compound (`CustomBossEvent.Packed`).
+    pub fn pack(&self) -> Tag {
        let mut c = Compound::new();
        for b in &self.bars {
-            let mut e = vec![
-                ("Name", json_to_tag(&b.name)),
-                ("Visible", Tag::Byte(i8::from(b.visible))),
-                ("Value", Tag::Int(b.value)),
-                ("Max", Tag::Int(b.max)),
-                ("Color", Tag::String(b.color.as_str().into())),
-                ("Overlay", Tag::String(b.style.as_str().into())),
-                ("DarkenScreen", Tag::Byte(0)),
-                ("PlayBossMusic", Tag::Byte(0)),
-                ("CreateWorldFog", Tag::Byte(0)),
-            ];
-            let players = match (b.player, player) {
-                (true, Some(u)) => vec![Tag::IntArray(u.to_vec())],
-                _ => Vec::new(),
-            };
-            e.push(("Players", Tag::List(players)));
-            c.insert(b.id.as_str().into(), Tag::compound(e));
+            let players = b
+                .players
+                .iter()
+                .map(|u| Tag::IntArray(u.to_vec()))
+                .collect();
+            c.insert(
+                b.id.as_str().into(),
+                Tag::compound([
+                    ("Name", json_to_tag(&b.name)),
+                    ("Visible", Tag::Byte(i8::from(b.visible))),
+                    ("Value", Tag::Int(b.value)),
+                    ("Max", Tag::Int(b.max)),
+                    ("Color", Tag::String(b.color.as_str().into())),
+                    ("Overlay", Tag::String(b.style.as_str().into())),
+                    ("DarkenScreen", Tag::Byte(i8::from(b.darken))),
+                    ("PlayBossMusic", Tag::Byte(i8::from(b.music))),
+                    ("CreateWorldFog", Tag::Byte(i8::from(b.fog))),
+                    ("Players", Tag::List(players)),
+                ]),
+            );
        }
        Tag::Compound(c)
    }
-    pub fn unpack(data: &Tag, player: Option<[i32; 4]>) -> Self {
+    pub fn unpack(data: &Tag) -> Self {
        let mut bars = Vec::new();
        if let Tag::Compound(c) = data {
            for (id, e) in c {
@@ -130,21 +157,30 @@ impl BossBars {
                    Some(Tag::Byte(v)) => i32::from(*v),
                    _ => d,
                };
-                let in_players = match (get("Players"), player) {
-                    (Some(Tag::List(l)), Some(u)) => l
+                let players = match get("Players") {
+                    Some(Tag::List(l)) => l
                        .iter()
-                        .any(|t| matches!(t, Tag::IntArray(a) if a.as_slice() == u)),
-                    _ => false,
+                        .filter_map(|t| match t {
+                            Tag::IntArray(a) if a.len() == 4 => Some([a[0], a[1], a[2], a[3]]),
+                            _ => None,
+                        })
+                        .collect(),
+                    _ => Vec::new(),
                };
+                let id = id.to_string_lossy();
                bars.push(BossBar {
-                    id: id.to_string_lossy(),
+                    uuid: stable_uuid(&id),
+                    id,
                    name: get("Name").map_or_else(|| literal(""), tag_to_json),
                    color: text("Color", "white"),
                    style: text("Overlay", "progress"),
                    value: num("Value", 0),
                    max: num("Max", 100),
                    visible: num("Visible", 0) != 0,
-                    player: in_players,
+                    darken: num("DarkenScreen", 0) != 0,
+                    music: num("PlayBossMusic", 0) != 0,
+                    fog: num("CreateWorldFog", 0) != 0,
+                    players,
                });
            }
        }
@@ -167,17 +203,15 @@ mod tests {
        bar.value = 25;
        bar.max = 50;
        bar.visible = true;
-        bar.player = true;
-        let uuid = Some([1, 2, 3, 4]);
-        let back = BossBars::unpack(&b.pack(uuid), uuid);
+        bar.darken = true;
+        bar.players = vec![[1, 2, 3, 4]];
+        let back = BossBars::unpack(&b.pack());
        assert_eq!(back, b);
-        // Another player's UUID does not include the local player.
-        assert!(!BossBars::unpack(&b.pack(uuid), Some([9, 9, 9, 9])).bars[0].player);
        let bar = b.get("test:x").unwrap();
        assert_eq!(bar.progress(), 0.5);
        assert_eq!(bar.display_name().plain(), "chat.square_brackets");
        assert_eq!(color_rgb("pink"), text::RED);
-        assert_eq!(color_rgb("purple"), 0xAA00AA);
+        assert_eq!(color_rgb("purple"), text::named_color("dark_blue").unwrap());
        b.remove("test:x");
        assert!(b.bars.is_empty());
    }
@@ -167,6 +167,26 @@ fn object_style(o: &serde_json::Map<String, Value>) -> Style {
    style.underlined = flag("underlined");
    style.strikethrough = flag("strikethrough");
    style.obfuscated = flag("obfuscated");
+    style.font = o.get("font").and_then(crate::text::font_id);
+    // ClickEvent.CODEC: the actions a chat line acts on here. A component
+    // from a server never opens a file.
+    if let Some(e) = o.get("click_event").and_then(Value::as_object) {
+        let text = |k: &str| e.get(k).and_then(Value::as_str).map(str::to_owned);
+        style.click = match e.get("action").and_then(Value::as_str) {
+            Some("suggest_command") => text("command").map(crate::text::ClickEvent::SuggestCommand),
+            Some("copy_to_clipboard") => {
+                text("value").map(crate::text::ClickEvent::CopyToClipboard)
+            }
+            _ => None,
+        };
+    }
+    // HoverEvent.ShowText.
+    if let Some(e) = o.get("hover_event").and_then(Value::as_object)
+        && e.get("action").and_then(Value::as_str) == Some("show_text")
+        && let Some(value) = e.get("value")
+    {
+        style.hover = Some(Box::new(to_text(value, &mut |s| Text::literal(s))));
+    }
    style
 }
 /// `ComponentSerialization.CODEC` decoding into text. `selector` components
@@ -232,7 +252,7 @@ pub fn to_text_with(
            } else if let Some(sel) = o.get("selector").and_then(Value::as_str) {
                resolve(sel)
            } else if let Some(key) = o.get("keybind").and_then(Value::as_str) {
-                crate::keybinds::display_name(key)
+                crate::key_display::display_name(key)
            } else {
                Text::empty()
            };
@@ -266,4 +286,26 @@ mod tests {
        let (v, _) = parse_snbt("[\"a\",{\"text\":\"b\"}]").unwrap();
        assert_eq!(to_text(&v, &mut |_| Text::empty()).plain(), "ab");
    }
+
+    #[test]
+    fn the_font_is_inherited_and_kept() {
+        let (v, _) =
+            parse_snbt(r#"{text:"a",font:"alt",extra:["b",{text:"c",font:"minecraft:uniform"}]}"#)
+                .unwrap();
+        let t = to_text(&v, &mut |_| Text::empty());
+        let fonts: Vec<_> = t.chars().map(|(_, s)| s.font.clone()).collect();
+        let (alt, uniform) = (
+            Some("minecraft:alt".into()),
+            Some("minecraft:uniform".into()),
+        );
+        assert_eq!(fonts, [alt.clone(), alt, uniform]);
+        // Back to JSON with the field, which a re-read keeps.
+        let again = to_text(&t.component(), &mut |_| Text::empty());
+        let kept: Vec<_> = again.chars().map(|(_, s)| s.font.clone()).collect();
+        assert_eq!(kept, fonts);
+        // Not an identifier: no font.
+        let (v, _) = parse_snbt(r#"{text:"a",font:"Bad Font"}"#).unwrap();
+        let t = to_text(&v, &mut |_| Text::empty());
+        assert_eq!(t.spans[0].style.font, None);
+    }
 }
@@ -292,27 +292,4 @@ mod tests {
        assert_eq!(GameRules::load(&dir), rules);
        let _ = fs::remove_dir_all(dir);
    }
-    /// The world's save (Level.write) writes the rules as they are now, and a
-    /// world opened again reads them back (#74).
-    #[test]
-    fn level_save_keeps_changed_rules() {
-        let dir =
-            std::env::temp_dir().join(format!("horizon-gamerules-level-{}", std::process::id()));
-        let _ = fs::remove_dir_all(&dir);
-        let mut level = crate::save::Level::default();
-        level.write(&dir).unwrap();
-        // Rules changed while playing, then saved and loaded again.
-        let mut rules = GameRules::load(&dir);
-        assert_eq!(rules, GameRules::default());
-        assert!(rules.set("advance_time", Value::Bool(false)));
-        assert!(rules.set("advance_weather", Value::Bool(false)));
-        assert!(rules.set("random_tick_speed", Value::Int(0)));
-        level.game_rules = rules.by_name();
-        level.write(&dir).unwrap();
-        assert_eq!(GameRules::load(&dir), rules);
-        let read = crate::save::Level::read(&dir).unwrap();
-        assert_eq!(read.game_rules, rules.by_name());
-        assert_eq!(read.game_rule("advance_time"), 0);
-        let _ = fs::remove_dir_all(dir);
-    }
 }
@@ -0,0 +1,18 @@
+//! Resource identifiers (`Identifier`).
+
+/// Identifier.parse: `ns:path` or `path`, validated.
+pub fn parse_identifier(raw: &str) -> Option<String> {
+    let (ns, path) = match raw.split_once(':') {
+        Some(("", path)) => ("minecraft", path),
+        Some((ns, path)) => (ns, path),
+        None => ("minecraft", raw),
+    };
+    let ns_ok = ns != ".."
+        && ns
+            .chars()
+            .all(|c| c.is_ascii_lowercase() || c.is_ascii_digit() || matches!(c, '_' | '.' | '-'));
+    let path_ok = path.chars().all(|c| {
+        c.is_ascii_lowercase() || c.is_ascii_digit() || matches!(c, '_' | '.' | '-' | '/')
+    });
+    (ns_ok && path_ok).then(|| format!("{ns}:{path}"))
+}
@@ -0,0 +1,38 @@
+//! Key display names (`InputConstants.Key.getDisplayName`), shared by key
+//! mappings and `keybind` text components.
+use crate::text::Text;
+
+/// InputConstants.Key.getDisplayName: one-character keys as the upper-case
+/// character, others by translation.
+pub fn display_name(key: &str) -> Text {
+    if let Some(rest) = key.strip_prefix("key.keyboard.")
+        && rest.chars().count() == 1
+    {
+        let c = rest.to_uppercase();
+        return Text::literal(c);
+    }
+    let symbol = match key {
+        "key.keyboard.minus" => Some("-"),
+        "key.keyboard.equal" => Some("="),
+        "key.keyboard.left.bracket" => Some("["),
+        "key.keyboard.right.bracket" => Some("]"),
+        "key.keyboard.backslash" => Some("\\"),
+        "key.keyboard.semicolon" => Some(";"),
+        "key.keyboard.apostrophe" => Some("'"),
+        "key.keyboard.grave.accent" => Some("`"),
+        "key.keyboard.comma" => Some(","),
+        "key.keyboard.period" => Some("."),
+        "key.keyboard.slash" => Some("/"),
+        _ => None,
+    };
+    if let Some(s) = symbol {
+        return Text::literal(s);
+    }
+    if let Some(n) = key.strip_prefix("key.mouse.")
+        && n.parse::<u32>().is_ok()
+        && !crate::lang::has(key)
+    {
+        return Text::translate("key.mouse", &[Text::literal(n)]);
+    }
+    Text::translate(key, &[])
+}
@@ -4,7 +4,10 @@
 //! language used by every screen.
 use std::{
    collections::{BTreeMap, HashMap},
-    sync::{Arc, RwLock},
+    sync::{
+        Arc, RwLock,
+        atomic::{AtomicBool, Ordering},
+    },
 };

 #[derive(Clone, Debug, PartialEq, Eq)]
@@ -23,11 +26,16 @@ impl LanguageInfo {
 #[derive(Default)]
 pub struct Language {
    pub code: String,
+    /// `LanguageInfo.bidirectional`: text without a strong character reads
+    /// right to left (`ClientLanguage.defaultRightToLeft`).
+    bidirectional: bool,
    map: HashMap<String, String>,
 }
 pub const DEFAULT: &str = "en_us";

 static CURRENT: RwLock<Option<Arc<Language>>> = RwLock::new(None);
+/// The current language's `bidirectional`, read for every drawn string.
+static BIDIRECTIONAL: AtomicBool = AtomicBool::new(false);

 /// A source of resource files: the prepared root plus packs, highest priority last.
 pub trait ResourceSource {
@@ -37,6 +45,25 @@ pub trait ResourceSource {
        vec!["minecraft".into()]
    }
 }
+/// Horizon's own strings, compiled in so they need no prepared resources.
+struct Bundled;
+impl ResourceSource for Bundled {
+    fn read(&self, path: &str) -> Option<Vec<u8>> {
+        let body = match path {
+            "assets/horizon/lang/en_us.json" => {
+                include_str!("../../horizon-client/assets/horizon/lang/en_us.json")
+            }
+            "assets/horizon/lang/ru_ru.json" => {
+                include_str!("../../horizon-client/assets/horizon/lang/ru_ru.json")
+            }
+            _ => return None,
+        };
+        Some(body.as_bytes().to_vec())
+    }
+    fn namespaces(&self) -> Vec<String> {
+        vec!["horizon".into()]
+    }
+}
 impl ResourceSource for std::path::PathBuf {
    fn read(&self, path: &str) -> Option<Vec<u8>> {
        std::fs::read(self.join(path)).ok()
@@ -77,12 +104,6 @@ pub fn apply_deprecated(map: &mut HashMap<String, String>, json: &[u8]) {
 }

 impl Language {
-    pub fn from_map(code: &str, map: HashMap<String, String>) -> Self {
-        Self {
-            code: code.to_owned(),
-            map,
-        }
-    }
    /// ClientLanguage.loadFrom: en_us first, then the selected language, each
    /// from every namespace and every source in priority order (later sources
    /// override).
@@ -92,6 +113,12 @@ impl Language {
        if code != DEFAULT {
            codes.push(code);
        }
+        // Horizon's own strings first, so a pack or the prepared root can still
+        // override them. Vanilla has no key for "Controller vibration".
+        let bundled = Bundled;
+        let mut all: Vec<&dyn ResourceSource> = vec![&bundled];
+        all.extend_from_slice(sources);
+        let sources = all.as_slice();
        let namespaces: std::collections::BTreeSet<String> =
            sources.iter().flat_map(|s| s.namespaces()).collect();
        for c in codes {
@@ -115,14 +142,23 @@ impl Language {
        {
            apply_deprecated(&mut map, &bytes);
        }
+        let bidirectional = available(sources)
+            .iter()
+            .any(|info| info.code == code && info.bidirectional);
        Self {
            code: code.to_owned(),
+            bidirectional,
            map,
        }
    }
    pub fn get(&self, key: &str) -> Option<&str> {
        self.map.get(key).map(String::as_str)
    }
+    /// The resolved map, for `horizon_protocol::text::plain`: a server's
+    /// components carry keys, and the network layer resolves them with this.
+    pub fn map(&self) -> &HashMap<String, String> {
+        &self.map
+    }
    pub fn len(&self) -> usize {
        self.map.len()
    }
@@ -173,11 +209,16 @@ pub fn available(sources: &[&dyn ResourceSource]) -> Vec<LanguageInfo> {
 }

 pub fn set(language: Language) {
+    BIDIRECTIONAL.store(language.bidirectional, Ordering::Relaxed);
    *CURRENT.write().unwrap_or_else(|e| e.into_inner()) = Some(Arc::new(language));
 }
 pub fn current() -> Option<Arc<Language>> {
    CURRENT.read().unwrap_or_else(|e| e.into_inner()).clone()
 }
+/// `ClientLanguage.defaultRightToLeft` of the current language.
+pub fn bidirectional() -> bool {
+    BIDIRECTIONAL.load(Ordering::Relaxed)
+}
 pub fn code() -> String {
    current().map_or_else(|| DEFAULT.to_owned(), |l| l.code.clone())
 }
@@ -210,6 +251,16 @@ mod tests {
            self.0.get(path).cloned()
        }
    }
+    #[test]
+    fn bundled_horizon_strings_follow_the_language() {
+        // No prepared resources at all: the namespace is compiled in.
+        let empty = Mem(HashMap::new());
+        let en = Language::load(&[&empty], "en_us");
+        assert_eq!(en.get("horizon.options.controller"), Some("Controller"));
+        let ru = Language::load(&[&empty], "ru_ru");
+        assert_eq!(ru.get("horizon.options.controller"), Some("Геймпад"));
+    }
+
    #[test]
    fn layers_selected_language_over_english() {
        let base = Mem(HashMap::from([
@@ -0,0 +1,25 @@
+//! The client's lowest layer, below commands and gameplay: chat text and
+//! translations, SNBT and NBT paths, text components, the scoreboard, boss
+//! bars, game rules, block entity NBT tables, and the registry, particle and
+//! sound source tables commands name, and the `pack.mcmeta` filter regex.
+//! horizon-client re-exports each module under its old path
+//! (`horizon_client::text`, ...).
+#![forbid(unsafe_code)]
+pub mod block_entity_nbt;
+pub mod bossbar;
+pub mod component;
+pub mod fastutil_order;
+pub mod gamerules;
+pub mod identifier;
+pub mod key_display;
+pub mod lang;
+pub mod nbt_path;
+pub mod particle_type;
+pub mod pattern;
+pub mod registries;
+pub mod scoreboard;
+pub mod snbt;
+pub mod sound_source;
+pub mod text;
+pub mod uuid;
+pub type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
@@ -0,0 +1,209 @@
+//! Particle types (`ParticleTypes`): the vanilla particle types with a client
+//! implementation, by registry name, and their per-type flags.
+
+macro_rules! particle_types {
+    ($($variant:ident = $name:literal),* $(,)?) => {
+        /// Vanilla particle types with a client implementation here.
+        #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+        pub enum ParticleType { $($variant),* }
+        impl ParticleType {
+            pub const ALL: &'static [ParticleType] = &[$(ParticleType::$variant),*];
+            /// Registry path (`minecraft:<name>`), also the sprite-set file name.
+            pub fn name(self) -> &'static str {
+                match self { $(ParticleType::$variant => $name),* }
+            }
+            pub fn from_name(name: &str) -> Option<Self> {
+                let name = name.strip_prefix("minecraft:").unwrap_or(name);
+                match name { $($name => Some(ParticleType::$variant),)* _ => None }
+            }
+        }
+    };
+}
+particle_types! {
+    Block = "block",
+    BlockCrumble = "block_crumble",
+    Trail = "trail",
+    DustPillar = "dust_pillar",
+    FallingDust = "falling_dust",
+    Smoke = "smoke",
+    LargeSmoke = "large_smoke",
+    WhiteSmoke = "white_smoke",
+    Flame = "flame",
+    SoulFireFlame = "soul_fire_flame",
+    CopperFireFlame = "copper_fire_flame",
+    SmallFlame = "small_flame",
+    Lava = "lava",
+    DrippingWater = "dripping_water",
+    FallingWater = "falling_water",
+    DrippingLava = "dripping_lava",
+    FallingLava = "falling_lava",
+    LandingLava = "landing_lava",
+    DrippingHoney = "dripping_honey",
+    FallingHoney = "falling_honey",
+    LandingHoney = "landing_honey",
+    FallingNectar = "falling_nectar",
+    FallingSporeBlossom = "falling_spore_blossom",
+    SporeBlossomAir = "spore_blossom_air",
+    DrippingObsidianTear = "dripping_obsidian_tear",
+    FallingObsidianTear = "falling_obsidian_tear",
+    LandingObsidianTear = "landing_obsidian_tear",
+    DrippingDripstoneWater = "dripping_dripstone_water",
+    FallingDripstoneWater = "falling_dripstone_water",
+    DrippingDripstoneLava = "dripping_dripstone_lava",
+    FallingDripstoneLava = "falling_dripstone_lava",
+    Splash = "splash",
+    Rain = "rain",
+    Bubble = "bubble",
+    SulfurBubbles = "sulfur_bubbles",
+    BubblePop = "bubble_pop",
+    BubbleColumnUp = "bubble_column_up",
+    CurrentDown = "current_down",
+    Underwater = "underwater",
+    Portal = "portal",
+    ReversePortal = "reverse_portal",
+    Enchant = "enchant",
+    Nautilus = "nautilus",
+    VaultConnection = "vault_connection",
+    Crit = "crit",
+    EnchantedHit = "enchanted_hit",
+    DamageIndicator = "damage_indicator",
+    Heart = "heart",
+    AngryVillager = "angry_villager",
+    HappyVillager = "happy_villager",
+    Composter = "composter",
+    Mycelium = "mycelium",
+    Dolphin = "dolphin",
+    EggCrack = "egg_crack",
+    Poof = "poof",
+    Explosion = "explosion",
+    ExplosionEmitter = "explosion_emitter",
+    CampfireCosySmoke = "campfire_cosy_smoke",
+    CampfireSignalSmoke = "campfire_signal_smoke",
+    Note = "note",
+    Dust = "dust",
+    TotemOfUndying = "totem_of_undying",
+    Firework = "firework",
+    EndRod = "end_rod",
+    Ash = "ash",
+    WhiteAsh = "white_ash",
+    CrimsonSpore = "crimson_spore",
+    WarpedSpore = "warped_spore",
+    CherryLeaves = "cherry_leaves",
+    PaleOakLeaves = "pale_oak_leaves",
+    TintedLeaves = "tinted_leaves",
+    Effect = "effect",
+    InstantEffect = "instant_effect",
+    EntityEffect = "entity_effect",
+    Witch = "witch",
+    Infested = "infested",
+    Cloud = "cloud",
+    Sneeze = "sneeze",
+    Snowflake = "snowflake",
+    Soul = "soul",
+    SculkSoul = "sculk_soul",
+    DragonBreath = "dragon_breath",
+    Gust = "gust",
+    SmallGust = "small_gust",
+    GustEmitterLarge = "gust_emitter_large",
+    GustEmitterSmall = "gust_emitter_small",
+    DustColorTransition = "dust_color_transition",
+    SculkCharge = "sculk_charge",
+    SculkChargePop = "sculk_charge_pop",
+    Shriek = "shriek",
+    SonicBoom = "sonic_boom",
+    Vibration = "vibration",
+    SweepAttack = "sweep_attack",
+    Glow = "glow",
+    WaxOn = "wax_on",
+    WaxOff = "wax_off",
+    ElectricSpark = "electric_spark",
+    Scrape = "scrape",
+    SquidInk = "squid_ink",
+    GlowSquidInk = "glow_squid_ink",
+    Item = "item",
+    ItemSlime = "item_slime",
+    ItemSnowball = "item_snowball",
+    ItemCobweb = "item_cobweb",
+    SulfurCubeGoo = "sulfur_cube_goo",
+    Flash = "flash",
+    Firefly = "firefly",
+    TrialSpawnerDetection = "trial_spawner_detection",
+    TrialSpawnerDetectionOminous = "trial_spawner_detection_ominous",
+    TrialOmen = "trial_omen",
+    RaidOmen = "raid_omen",
+    OminousSpawning = "ominous_spawning",
+    Spit = "spit",
+    Fishing = "fishing",
+    DustPlume = "dust_plume",
+    RedPoplarLeaves = "red_poplar_leaves",
+    OrangePoplarLeaves = "orange_poplar_leaves",
+    YellowPoplarLeaves = "yellow_poplar_leaves",
+    PauseMobGrowth = "pause_mob_growth",
+    ResetMobGrowth = "reset_mob_growth",
+    BlockMarker = "block_marker",
+}
+impl ParticleType {
+    /// `ParticleType.getOverrideLimiter` (`ParticleTypes.register(name, true)`):
+    /// spawned regardless of distance.
+    pub fn override_limiter(self) -> bool {
+        matches!(
+            self,
+            Self::BlockMarker
+                | Self::DamageIndicator
+                | Self::ExplosionEmitter
+                | Self::Explosion
+                | Self::Gust
+                | Self::GustEmitterLarge
+                | Self::GustEmitterSmall
+                | Self::SonicBoom
+                | Self::SculkCharge
+                | Self::SculkChargePop
+                | Self::Vibration
+                | Self::Poof
+                | Self::Spit
+                | Self::SquidInk
+                | Self::SweepAttack
+                | Self::CampfireCosySmoke
+                | Self::CampfireSignalSmoke
+                | Self::GlowSquidInk
+                | Self::Glow
+                | Self::WaxOn
+                | Self::WaxOff
+                | Self::ElectricSpark
+                | Self::Scrape
+                | Self::TrialSpawnerDetection
+                | Self::TrialSpawnerDetectionOminous
+                | Self::VaultConnection
+                | Self::OminousSpawning
+        )
+    }
+    /// `SingleQuadParticle.Layer.translucent`: types whose vanilla particle class
+    /// hardcodes the translucent layer, drawn after translucent terrain.
+    /// `TerrainParticle`, `BreakingItemParticle` and `BlockMarker` resolve their
+    /// layer from the sprite instead (`Layer.bySprite`); see the `translucent`
+    /// sprite set on the engine.
+    pub fn translucent_layer(self) -> bool {
+        match self {
+            // CampfireSmokeParticle.
+            Self::CampfireCosySmoke | Self::CampfireSignalSmoke
+            // PlayerCloudParticle.
+            | Self::Cloud | Self::Sneeze
+            // SpellParticle.
+            | Self::Effect | Self::InstantEffect | Self::EntityEffect
+            | Self::Witch | Self::Infested | Self::TrialOmen | Self::RaidOmen
+            // EmissiveRisingParticle.
+            | Self::Soul | Self::SculkSoul
+            // SculkChargeParticle, SculkChargePopParticle, ShriekParticle,
+            // VibrationSignalParticle, FireflyParticle, OverlayParticle.
+            | Self::SculkCharge | Self::SculkChargePop | Self::Shriek
+            | Self::Vibration | Self::Firefly | Self::Flash
+            // SimpleAnimatedParticle and its subclasses: EndRodParticle,
+            // SparkParticle (firework), SquidInkParticle, TotemParticle.
+            | Self::EndRod | Self::Firework | Self::SquidInk | Self::GlowSquidInk
+            | Self::TotemOfUndying
+            // FlyTowardsPositionParticle: its LifetimeAlpha(0, 0.6, 0.25, 1) is not opaque.
+            | Self::VaultConnection => true,
+            _ => false,
+        }
+    }
+}
@@ -0,0 +1,188 @@
+//! Registry contents and source state that commands validate and complete
+//! arguments against (what the server's registry access holds).
+use std::collections::BTreeMap;
+
+/// Registry contents and source state used to validate and complete arguments.
+#[derive(Clone, Debug, Default)]
+pub struct Registries {
+    /// Permission level of the command source.
+    pub permission: u8,
+    pub items: Vec<String>,
+    pub item_tags: Vec<String>,
+    /// Block id -> (property, allowed values).
+    pub blocks: BTreeMap<String, Vec<(String, Vec<String>)>>,
+    pub block_tags: Vec<String>,
+    /// Entity types that `summon` can create.
+    pub summonable: Vec<String>,
+    /// Every entity type (selector `type=`).
+    pub entity_types: Vec<String>,
+    pub effects: Vec<String>,
+    pub enchantments: Vec<String>,
+    pub structures: Vec<String>,
+    pub biomes: Vec<String>,
+    pub dimensions: Vec<String>,
+    pub clocks: Vec<String>,
+    pub timelines: Vec<String>,
+    pub time_markers: Vec<String>,
+    pub advancements: Vec<String>,
+    /// Game rule name -> integer-valued.
+    pub game_rules: Vec<(String, bool)>,
+    pub players: Vec<String>,
+    /// Scoreboard objective names, team names and tracked score holders.
+    pub objectives: Vec<String>,
+    pub teams: Vec<String>,
+    pub tracked: Vec<String>,
+    /// Loaded datapack functions (`ns:path`) and function tags (`ns:path`).
+    pub functions: Vec<String>,
+    /// `/data ... storage` ids.
+    pub storages: Vec<String>,
+    /// Boss bar ids and datapack predicate ids.
+    pub bossbars: Vec<String>,
+    pub predicates: Vec<String>,
+    pub item_modifiers: Vec<String>,
+    pub schedules: Vec<String>,
+    pub stopwatches: Vec<String>,
+    pub recipes: Vec<String>,
+    pub sounds: Vec<String>,
+    pub damage_types: Vec<String>,
+    pub attributes: Vec<String>,
+    pub loot_tables: Vec<String>,
+    pub templates: Vec<String>,
+    pub random_sequences: Vec<String>,
+    pub datapacks_enabled: Vec<String>,
+    pub datapacks_disabled: Vec<String>,
+    pub function_tags: Vec<String>,
+    /// The block the source is looking at (relevant coordinates).
+    pub target_block: Option<[i32; 3]>,
+    /// Every registry's element and tag ids (`minecraft:item` -> ...), as
+    /// the server's registry access and reloadable registries hold them.
+    pub by_registry: BTreeMap<String, RegistryIds>,
+    /// Blocks whose default state has a block entity.
+    pub block_entities: std::collections::BTreeSet<String>,
+    /// Block tag -> member blocks.
+    pub block_tag_members: BTreeMap<String, Vec<String>>,
+    /// Data component types with a codec (not transient).
+    pub persistent_components: Vec<String>,
+    /// Recipes `/recipe` can give (not special).
+    pub learnable_recipes: Vec<String>,
+    /// Advancement id -> criterion names.
+    pub advancement_criteria: BTreeMap<String, Vec<String>>,
+    /// World clock -> time markers shown in commands.
+    pub clock_time_markers: BTreeMap<String, Vec<String>>,
+    /// Trigger objectives the source may use (`/trigger` suggestions).
+    pub trigger_objectives: Vec<String>,
+    /// Objectives with the `trigger` criterion -> holder -> whether its score is locked.
+    pub trigger_scores: BTreeMap<String, BTreeMap<String, bool>>,
+}
+/// The ids and tag ids of one registry.
+#[derive(Clone, Debug, Default)]
+pub struct RegistryIds {
+    pub ids: Vec<String>,
+    pub tags: Vec<String>,
+}
+const EMPTY: &[String] = &[];
+impl Registries {
+    /// Fill what the game did not build itself from vanilla's exported
+    /// registries (`command-registries.json`, written by
+    /// `VanillaCommandParseOracle registries`): built-in registries such as
+    /// mob effects, data component types and dialogs, block entities and tag
+    /// members. Registries that data packs reload stay with the game.
+    pub fn fill_from_export(&mut self, r: &serde_json::Value) {
+        fn strings(v: &serde_json::Value) -> Vec<String> {
+            v.as_array()
+                .map(|a| {
+                    a.iter()
+                        .filter_map(|x| x.as_str().map(str::to_owned))
+                        .collect()
+                })
+                .unwrap_or_default()
+        }
+        let fill = |field: &mut Vec<String>, key: &str| {
+            if field.is_empty() {
+                *field = strings(&r[key]);
+            }
+        };
+        fill(&mut self.effects, "effects");
+        fill(&mut self.enchantments, "enchantments");
+        fill(&mut self.attributes, "attributes");
+        fill(&mut self.damage_types, "damage_types");
+        fill(&mut self.templates, "templates");
+        fill(&mut self.persistent_components, "persistent_components");
+        fill(&mut self.learnable_recipes, "learnable_recipes");
+        const RELOADED: [&str; 5] = [
+            "minecraft:advancement",
+            "minecraft:recipe",
+            "minecraft:loot_table",
+            "minecraft:predicate",
+            "minecraft:item_modifier",
+        ];
+        for (name, entry) in r["by_registry"].as_object().into_iter().flatten() {
+            if RELOADED.contains(&name.as_str()) || self.by_registry.contains_key(name) {
+                continue;
+            }
+            self.by_registry.insert(
+                name.clone(),
+                RegistryIds {
+                    ids: strings(&entry["ids"]),
+                    tags: strings(&entry["tags"]),
+                },
+            );
+        }
+        if self.block_entities.is_empty() {
+            self.block_entities = strings(&r["block_entities"]).into_iter().collect();
+        }
+        if self.block_tag_members.is_empty() {
+            for (tag, members) in r["block_tag_members"].as_object().into_iter().flatten() {
+                self.block_tag_members.insert(tag.clone(), strings(members));
+            }
+        }
+        if self.clock_time_markers.is_empty() {
+            for (clock, markers) in r["clock_time_markers"].as_object().into_iter().flatten() {
+                self.clock_time_markers
+                    .insert(clock.clone(), strings(markers));
+            }
+        }
+        if self.advancement_criteria.is_empty() {
+            for (id, criteria) in r["advancement_criteria"].as_object().into_iter().flatten() {
+                self.advancement_criteria
+                    .insert(id.clone(), strings(criteria));
+            }
+        }
+    }
+    /// The element ids of a registry (sorted).
+    pub fn ids(&self, registry: &str) -> &[String] {
+        if let Some(r) = self.by_registry.get(registry) {
+            return &r.ids;
+        }
+        match registry {
+            "minecraft:item" => &self.items,
+            "minecraft:entity_type" => &self.entity_types,
+            "minecraft:mob_effect" => &self.effects,
+            "minecraft:enchantment" => &self.enchantments,
+            "minecraft:worldgen/structure" => &self.structures,
+            "minecraft:worldgen/biome" => &self.biomes,
+            "minecraft:world_clock" => &self.clocks,
+            "minecraft:timeline" => &self.timelines,
+            "minecraft:attribute" => &self.attributes,
+            "minecraft:damage_type" => &self.damage_types,
+            "minecraft:sound_event" => &self.sounds,
+            "minecraft:predicate" => &self.predicates,
+            "minecraft:item_modifier" => &self.item_modifiers,
+            "minecraft:loot_table" => &self.loot_tables,
+            "minecraft:recipe" => &self.recipes,
+            "minecraft:advancement" => &self.advancements,
+            _ => EMPTY,
+        }
+    }
+    /// The tag ids of a registry (sorted).
+    pub fn tags(&self, registry: &str) -> &[String] {
+        if let Some(r) = self.by_registry.get(registry) {
+            return &r.tags;
+        }
+        match registry {
+            "minecraft:item" => &self.item_tags,
+            "minecraft:block" => &self.block_tags,
+            _ => EMPTY,
+        }
+    }
+}
@@ -2,9 +2,9 @@
 //! `ObjectiveCriteria`, `NumberFormat`) and its saved data
 //! (`data/minecraft/scoreboard.dat`, `ScoreboardSaveData.Packed`).
 use crate::{
-    command::Registries,
    component,
    fastutil_order::{HashSetOrder, OpenOrder},
+    registries::Registries,
    text::{self, Style, Text},
 };
 use horizon_world::nbt::Tag;
@@ -118,6 +118,7 @@ pub fn style_from_json(v: &Value) -> Style {
    s.underlined = flag("underlined");
    s.strikethrough = flag("strikethrough");
    s.obfuscated = flag("obfuscated");
+    s.font = o.get("font").and_then(text::font_id);
    s
 }
 impl NumberFormat {
@@ -1265,7 +1266,7 @@ fn entity_uuids(tag: &mut Tag) {
                            })
                            .collect::<Option<Vec<i32>>>(),
                        Tag::String(s) => {
-                            crate::save::uuid_from_text(&s.to_string_lossy()).map(Vec::from)
+                            crate::uuid::uuid_from_text(&s.to_string_lossy()).map(Vec::from)
                        }
                        _ => None,
                    };
@@ -0,0 +1,7 @@
+//! Sound sources (`SoundSource`), by name.
+
+/// SoundSource names in vanilla order.
+pub const SOUND_SOURCES: [&str; 11] = [
+    "master", "music", "record", "weather", "block", "hostile", "neutral", "player", "ambient",
+    "voice", "ui",
+];
@@ -61,6 +61,13 @@ pub struct Style {
    pub click: Option<ClickEvent>,
    /// Hover text.
    pub hover: Option<Box<Text>>,
+    /// The font (`FontDescription.Resource`), a full id like
+    /// `minecraft:alt`; the default font when unset.
+    pub font: Option<String>,
+}
+/// A style's `font` field: an identifier (`alt` is `minecraft:alt`).
+pub fn font_id(v: &Value) -> Option<String> {
+    crate::identifier::parse_identifier(v.as_str()?)
 }
 impl Style {
    pub fn color(c: u32) -> Self {
@@ -83,6 +90,9 @@ impl Style {
        if self.hover.is_none() {
            self.hover.clone_from(&base.hover);
        }
+        if self.font.is_none() {
+            self.font.clone_from(&base.font);
+        }
    }
    pub fn is_bold(&self) -> bool {
        self.bold == Some(true)
@@ -418,6 +428,43 @@ impl Text {
        }
        out
    }
+    /// `resolve_legacy` borrowing `self` when no span holds a `§` code (the
+    /// common case).
+    pub fn resolved(&self) -> std::borrow::Cow<'_, Text> {
+        if self.spans.iter().any(|s| s.text.contains('§')) {
+            std::borrow::Cow::Owned(self.resolve_legacy())
+        } else {
+            std::borrow::Cow::Borrowed(self)
+        }
+    }
+    /// The text without its legacy `§` codes (ChatFormatting.stripFormatting:
+    /// a `§` and a code character, `0`-`9`, `a`-`f`, `k`-`o` or `r`).
+    pub fn strip_legacy(&self) -> Text {
+        if !self.spans.iter().any(|s| s.text.contains('§')) {
+            return self.clone();
+        }
+        let code =
+            |c: char| matches!(c.to_ascii_lowercase(), '0'..='9' | 'a'..='f' | 'k'..='o' | 'r');
+        let mut out = Text::default();
+        for span in &self.spans {
+            let mut text = String::with_capacity(span.text.len());
+            let mut chars = span.text.chars().peekable();
+            while let Some(c) = chars.next() {
+                if c == '§' && chars.peek().is_some_and(|&n| code(n)) {
+                    chars.next();
+                } else {
+                    text.push(c);
+                }
+            }
+            if !text.is_empty() {
+                out.spans.push(Span {
+                    text,
+                    style: span.style.clone(),
+                });
+            }
+        }
+        out
+    }
    /// Characters with their effective styles.
    pub fn chars(&self) -> impl Iterator<Item = (char, &Style)> {
        self.spans
@@ -445,13 +492,10 @@ impl Text {
        }
        out
    }
-    pub fn char_count(&self) -> usize {
-        self.spans.iter().map(|s| s.text.chars().count()).sum()
-    }
 }

 /// The style fields of a component's JSON.
-const STYLE_KEYS: [&str; 8] = [
+const STYLE_KEYS: [&str; 9] = [
    "color",
    "bold",
    "italic",
@@ -460,6 +504,7 @@ const STYLE_KEYS: [&str; 8] = [
    "obfuscated",
    "click_event",
    "hover_event",
+    "font",
 ];
 /// Style.Serializer: the fields a style sets.
 fn style_json(style: &Style) -> Vec<(String, Value)> {
@@ -500,6 +545,9 @@ fn style_json(style: &Style) -> Vec<(String, Value)> {
            json!({ "action": "show_text", "value": hover.component() }),
        ));
    }
+    if let Some(font) = &style.font {
+        out.push(("font".to_owned(), font.clone().into()));
+    }
    out
 }

@@ -656,4 +704,20 @@ mod tests {
        assert_eq!(t.spans[1].style.color, Some(GOLD));
        assert_eq!(t.slice(1, 2).plain(), "y");
    }
+    #[test]
+    fn resolved_borrows_clean_text_and_restyles_codes() {
+        let clean = Text::colored("Steve", GOLD);
+        assert!(matches!(clean.resolved(), std::borrow::Cow::Borrowed(_)));
+        // A colour code inside a span clears its decorations (a bold
+        // "§cSteve" draws "Steve" red, not bold).
+        let styled = Style {
+            bold: Some(true),
+            ..Style::default()
+        };
+        let styled = Text::styled("§cSteve", styled);
+        let resolved = styled.resolved();
+        assert_eq!(resolved.plain(), "Steve");
+        assert_eq!(resolved.spans[0].style.color, Some(RED));
+        assert_eq!(resolved.spans[0].style.bold, Some(false));
+    }
 }
@@ -0,0 +1,24 @@
+//! UUIDs as vanilla's four-int form, to and from their text form.
+
+pub fn uuid_text(u: [i32; 4]) -> String {
+    let hex: String = u.iter().map(|v| format!("{:08x}", *v as u32)).collect();
+    format!(
+        "{}-{}-{}-{}-{}",
+        &hex[0..8],
+        &hex[8..12],
+        &hex[12..16],
+        &hex[16..20],
+        &hex[20..32]
+    )
+}
+pub fn uuid_from_text(s: &str) -> Option<[i32; 4]> {
+    let hex: String = s.chars().filter(|c| *c != '-').collect();
+    if hex.len() != 32 {
+        return None;
+    }
+    let mut out = [0i32; 4];
+    for (i, v) in out.iter_mut().enumerate() {
+        *v = u32::from_str_radix(&hex[i * 8..i * 8 + 8], 16).ok()? as i32;
+    }
+    Some(out)
+}
@@ -9,30 +9,38 @@ description = "Horizon native development client"

 [dependencies]
 horizon-assets = { path = "../horizon-assets" }
+horizon-client-core = { path = "../horizon-client-core" }
+horizon-command = { path = "../horizon-command" }
 horizon-core = { path = "../horizon-core" }
 # The server thread ahead of the workers (MinecraftServer.spin's Thread.setPriority).
 horizon-threads = { path = "../horizon-threads" }
+horizon-hdr = { path = "../horizon-hdr" }
 horizon-world = { path = "../horizon-world" }
 horizon-protocol = { path = "../horizon-protocol" }
 # server.properties, eula.txt and the user lists, shared with horizon-server.
 horizon-server-files = { path = "../horizon-server-files" }
+# Shader packs: reading them and turning their GLSL into naga modules.
+horizon-shaders = { path = "../horizon-shaders" }
+# Horizon's own shader packs: the format, the stages and the check (docs/shaders.md).
+horizon-shader-api = { path = "../horizon-shader-api" }
 horizon-friends = { path = "../horizon-friends" }
 # Horizon mods: sandboxed WebAssembly components, off unless installed and turned on (docs/mods.md).
-horizon-mods = { path = "../horizon-mods" }
-wgpu = { version = "30.0.1", default-features = false, features = ["std", "parking_lot", "vulkan", "metal", "wgsl"] }
+# Their runtime is the `mods` feature.
+horizon-mods = { path = "../horizon-mods", default-features = false, features = ["index"] }
+wgpu = { version = "30.0.1", default-features = false, features = ["std", "parking_lot", "vulkan", "metal", "wgsl", "naga-ir"] }
 winit = "0.30.13"
 pollster = "0.4"
 bytemuck = { version = "1.24", features = ["derive"] }
 glam = "0.30"
 png = "0.18"
 sha2 = "0.10.9"
+# Server resource packs are checked and cached by their SHA-1, as vanilla does.
+sha1 = "0.10"
 serde = { version = "1", features = ["derive"] }
 serde_json = { version = "1.0.151", features = ["raw_value"] }
-# Shader packs: pack.toml, and WGSL checked before it reaches wgpu.
-toml = "1.1"
-naga = { version = "30.0.1", features = ["wgsl-in"] }
-# Java (OptiFine/Iris) shader packs, translated to WGSL.
-horizon-shaderpack = { path = "../horizon-shaderpack" }
+# hlsl-out: the gfx.rs tests translate every shader as wgpu's DirectX 12 backend does. A normal feature,
+# not a dev-dependency's, so builds, tests and examples share one build of naga, wgpu and this crate.
+naga = { version = "30.0.1", features = ["wgsl-in", "hlsl-out"] }
 # Sound (ALSA on Linux); the `audio` feature.
 cpal = { version = "0.16", optional = true }
 symphonia = { version = "0.5", default-features = false, features = ["ogg", "vorbis"] }
@@ -54,6 +62,7 @@ gilrs = { version = "0.11", optional = true }
 horizon-dualsense = { path = "../horizon-dualsense", optional = true }
 # HTTPS to the Minecraft services (online-mode session join).
 ureq = { version = "2", default-features = false, features = ["tls"] }
+unicode-bidi = "0.3.18"

 [target.'cfg(unix)'.dependencies]
 # The server thread's CPU time per tick (`HORIZON_SPIKES`, spans.rs).
@@ -65,6 +74,11 @@ rustix = { version = "1", default-features = false, features = ["std", "time"] }
 # on the PATH.
 wgpu = { version = "30.0.1", default-features = false, features = ["dx12"] }

+[target.'cfg(not(target_os = "macos"))'.dependencies]
+# OpenGL (WGL on Windows, EGL on Linux), the last fallback, for GPUs with no Vulkan or
+# DirectX 12 driver (`graphicsApi`, graphics.rs).
+wgpu = { version = "30.0.1", default-features = false, features = ["gles"] }
+
 [target.'cfg(windows)'.build-dependencies]
 # The icon resource in the .exe (build.rs).
 winresource = "0.1"
@@ -76,12 +90,20 @@ default = ["audio", "controllers"]
 audio = ["dep:cpal"]
 # Controllers: gilrs, and the DualSense's own output. Without it only `horizon-ctl pad`'s virtual pad.
 controllers = ["dep:gilrs", "dep:horizon-dualsense"]
+# Runs code mods (wasmtime and cranelift: a quarter of a clean build). On in every release build
+# (release.yml); the tests and probes don't need it. Content mods load without it.
+mods = ["horizon-mods/runtime"]
 # Records the call sites of mob random draws (`mob_ai_probe` traces).
 rng-trace = ["horizon-core/rng-trace"]

+# Its own name, not `probe`: Cargo copies every crate's examples into one target/<profile>/examples.
+[[example]]
+name = "client_probe"
+path = "examples/probe/main.rs"
+
 [lints]
 workspace = true

 [dev-dependencies]
 # Every WGSL shader translated as wgpu's DirectX 12 backend does (gfx.rs tests).
-naga = { version = "30.0.1", features = ["wgsl-in", "hlsl-out"] }
+naga = { version = "30.0.1", features = ["wgsl-in", "hlsl-out", "msl-out", "spv-out"] }
@@ -0,0 +1,15 @@
+{
+  "horizon.options.controller": "Controller",
+  "horizon.options.vibration": "Vibration",
+  "horizon.options.adaptive_triggers": "Adaptive Triggers",
+  "horizon.options.lightbar": "Lightbar",
+  "horizon.options.look_sensitivity": "Look Sensitivity",
+  "horizon.options.invert_x": "Invert Look X",
+  "horizon.options.invert_y": "Invert Look Y",
+  "horizon.options.sneak_button": "Sneak Button",
+  "horizon.options.move_deadzone": "Move Deadzone",
+  "horizon.options.look_deadzone": "Look Deadzone",
+  "horizon.options.button_glyphs": "Button Glyphs",
+  "horizon.options.menu_navigation": "Menu Navigation",
+  "horizon.options.on_screen_keyboard": "On-Screen Keyboard"
+}
@@ -0,0 +1,15 @@
+{
+  "horizon.options.controller": "Геймпад",
+  "horizon.options.vibration": "Вибрация",
+  "horizon.options.adaptive_triggers": "Адаптивные триггеры",
+  "horizon.options.lightbar": "Подсветка",
+  "horizon.options.look_sensitivity": "Чувствительность обзора",
+  "horizon.options.invert_x": "Инверсия обзора по X",
+  "horizon.options.invert_y": "Инверсия обзора по Y",
+  "horizon.options.sneak_button": "Кнопка приседания",
+  "horizon.options.move_deadzone": "Мёртвая зона движения",
+  "horizon.options.look_deadzone": "Мёртвая зона обзора",
+  "horizon.options.button_glyphs": "Символы кнопок",
+  "horizon.options.menu_navigation": "Навигация по меню",
+  "horizon.options.on_screen_keyboard": "Экранная клавиатура"
+}
@@ -1,104 +0,0 @@
-//! Full production fact loading, including file reads, interning and temporary destruction.
-//! cargo run --profile fast -p horizon-client --example block_facts_bench -- ROOT [SAMPLES]
-//! Use SAMPLES=1 with an OS peak-RSS wrapper; `digest` checks all facts
-//! and the shape sharing partition (including sharing between outlines and edges).
-use horizon_client::blocks::BlockFacts;
-use horizon_world::{DATA_VERSION, nbt::Tag, registry::BlockRegistry};
-use serde_json::Value;
-use std::{
-    collections::{HashMap, hash_map::DefaultHasher},
-    fs,
-    hash::{Hash, Hasher},
-    hint::black_box,
-    path::Path,
-    time::Instant,
-};
-type Result<T> = horizon_client::Result<T>;
-
-fn tag(value: &Value) -> Result<Tag> {
-    Ok(match value {
-        Value::String(s) => Tag::String(s.as_str().into()),
-        Value::Number(n) => Tag::Int(i32::try_from(n.as_i64().ok_or("registry number")?)?),
-        Value::Array(a) => Tag::List(a.iter().map(tag).collect::<Result<_>>()?),
-        Value::Object(o) => Tag::Compound(
-            o.iter()
-                .map(|(k, v)| Ok((k.as_str().into(), tag(v)?)))
-                .collect::<Result<_>>()?,
-        ),
-        _ => return Err("registry value".into()),
-    })
-}
-fn registry(root: &Path) -> Result<BlockRegistry> {
-    let facts: Value = serde_json::from_slice(&fs::read(root.join("facts.json"))?)?;
-    Ok(BlockRegistry::from_nbt(&Tag::compound([
-        ("DataVersion", Tag::Int(DATA_VERSION)),
-        (
-            "states",
-            Tag::List(
-                facts["states"]
-                    .as_array()
-                    .ok_or("registry states")?
-                    .iter()
-                    .map(|s| tag(&s[4]))
-                    .collect::<Result<_>>()?,
-            ),
-        ),
-        ("defaults", tag(&facts["defaults"])?),
-    ]))?)
-}
-fn main() -> Result<()> {
-    let args: Vec<_> = std::env::args().skip(1).collect();
-    let root = Path::new(
-        args.first()
-            .ok_or("usage: block_facts_bench ROOT [SAMPLES|digest]")?,
-    );
-    let setup = Instant::now();
-    let registry = registry(root)?;
-    println!(
-        "registry_setup_ms={:.3}",
-        setup.elapsed().as_secs_f64() * 1000.0
-    );
-    if args.get(1).is_some_and(|s| s == "digest") {
-        let facts = BlockFacts::load(root, &registry)?;
-        let mut hash = DefaultHasher::new();
-        let mut shapes = HashMap::new();
-        facts.air.hash(&mut hash);
-        for state in &facts.states {
-            format!("{state:?}").hash(&mut hash);
-            for shape in [&state.outline, &state.outline_edges] {
-                let next = shapes.len();
-                shapes
-                    .entry((shape.as_ptr(), shape.len()))
-                    .or_insert(next)
-                    .hash(&mut hash);
-            }
-        }
-        println!(
-            "states={} shared_shapes={} digest={:016x}",
-            facts.states.len(),
-            shapes.len(),
-            hash.finish()
-        );
-        return Ok(());
-    }
-    let samples: usize = args.get(1).map(|s| s.parse()).transpose()?.unwrap_or(9);
-    assert!(samples > 0);
-    // First load is reported separately; OS file caches are not forcibly evicted.
-    let load = || -> Result<f64> {
-        let start = Instant::now();
-        let facts = black_box(BlockFacts::load(black_box(root), black_box(&registry))?);
-        let ms = start.elapsed().as_secs_f64() * 1000.0;
-        drop(facts);
-        Ok(ms)
-    };
-    println!("first_load_ms={:.3}", load()?);
-    if samples > 1 {
-        load()?;
-        load()?;
-        let mut times = (0..samples).map(|_| load()).collect::<Result<Vec<_>>>()?;
-        println!("samples_ms={times:.3?}");
-        times.sort_by(f64::total_cmp);
-        println!("median_ms={:.3}", times[times.len() / 2]);
-    }
-    Ok(())
-}
@@ -1,216 +0,0 @@
-//! Resident chunk storage benchmark: generates a block of vanilla terrain, then
-//! reports the resident block/biome memory, the cost of lookups, meshing and
-//! lighting on it.
-//!
-//! chunk_bench <client resource dir> [--seed S] [--size N]
-#![forbid(unsafe_code)]
-use horizon_client::{
-    assets::Assets,
-    biome::Biomes,
-    blocks::BlockFacts,
-    chunk::{Chunk, MIN_Y, SECTIONS},
-    light::{LightTables, apply_lighting, light_chunk},
-    mesher::{MeshTables, Mesher},
-    models,
-    streaming::{ChunkGenerator, Proto},
-    vanillagen::VanillaTerrain,
-};
-use horizon_core::biome::BiomeZoom;
-use std::{path::PathBuf, sync::Arc, time::Instant};
-type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
-
-fn main() -> Result<()> {
-    let args: Vec<String> = std::env::args().skip(1).collect();
-    let root = PathBuf::from(args.first().ok_or("usage: chunk_bench RESOURCES")?);
-    let flag = |name: &str, default: i64| -> i64 {
-        args.iter()
-            .position(|a| a == name)
-            .and_then(|i| args.get(i + 1))
-            .and_then(|v| v.parse().ok())
-            .unwrap_or(default)
-    };
-    let (seed, size) = (flag("--seed", 12345), flag("--size", 8) as i32);
-    let assets = Assets::load(&root)?;
-    let render = assets.reload(&root)?;
-    let facts = BlockFacts::load(&root, assets.registry)?;
-    let biomes = Biomes::load(&root)?;
-    let tables = MeshTables::new(
-        &assets,
-        &render,
-        &facts,
-        models::load_visibility(&root, assets.registry)?,
-    )?;
-    let light = LightTables::load(&root, assets.registry, &facts)?;
-    let terrain = VanillaTerrain::new(&root.join("worldgen"), assets.registry, &biomes, seed)?;
-    let mut worker = terrain.worker();
-
-    // Protos for size+4 columns, decorated for the inner size+2, finished as size+2.
-    let started = Instant::now();
-    let outer = size + 4;
-    let mut protos: Vec<Option<Proto>> = (0..outer * outer)
-        .map(|i| Some(terrain.proto(&mut worker, i % outer, i / outer)))
-        .collect();
-    eprintln!("proto: {:.2}s", started.elapsed().as_secs_f64());
-    let started = Instant::now();
-    let inner = size + 2;
-    for z in 1..=inner {
-        for x in 1..=inner {
-            let mut region: [Proto; 9] = std::array::from_fn(|k| {
-                let (dx, dz) = (k as i32 % 3 - 1, k as i32 / 3 - 1);
-                protos[((z + dz) * outer + x + dx) as usize]
-                    .take()
-                    .expect("proto")
-            });
-            terrain.decorate(&mut worker, &mut region);
-            for (k, p) in region.into_iter().enumerate() {
-                let (dx, dz) = (k as i32 % 3 - 1, k as i32 / 3 - 1);
-                protos[((z + dz) * outer + x + dx) as usize] = Some(p);
-            }
-        }
-    }
-    eprintln!("decorate: {:.2}s", started.elapsed().as_secs_f64());
-    let started = Instant::now();
-    let mut chunks: Vec<Chunk> = Vec::new();
-    for z in 1..=inner {
-        for x in 1..=inner {
-            let proto = protos[(z * outer + x) as usize].take().expect("proto");
-            let mut chunk = terrain.finish(proto);
-            chunk.x = x;
-            chunk.z = z;
-            chunks.push(chunk);
-        }
-    }
-    let finish = started.elapsed().as_secs_f64();
-    println!(
-        "finish (proto -> resident chunk): {:.1} ms per chunk",
-        finish * 1e3 / chunks.len() as f64
-    );
-
-    let chunks: Vec<Arc<Chunk>> = chunks.into_iter().map(Arc::new).collect();
-    let at = |x: i32, z: i32| chunks[((z - 1) * inner + x - 1) as usize].clone();
-
-    // Light all inner-inner columns.
-    let started = Instant::now();
-    let mut lit = Vec::new();
-    for z in 2..inner {
-        for x in 2..inner {
-            let region: [[Option<Arc<Chunk>>; 3]; 3] = std::array::from_fn(|dz| {
-                std::array::from_fn(|dx| Some(at(x + dx as i32 - 1, z + dz as i32 - 1)))
-            });
-            let borrowed = horizon_client::mesher::borrow(&region);
-            lit.push(((x, z), light_chunk(&borrowed, &light, true)));
-        }
-    }
-    println!(
-        "light: {:.2} ms per column",
-        started.elapsed().as_secs_f64() * 1e3 / lit.len() as f64
-    );
-    let mut chunks: Vec<Chunk> = chunks.iter().map(|c| (**c).clone()).collect();
-    for ((x, z), sections) in lit {
-        apply_lighting(&mut chunks[((z - 1) * inner + x - 1) as usize], sections);
-    }
-    let chunks: Vec<Arc<Chunk>> = chunks.into_iter().map(Arc::new).collect();
-    let at = |x: i32, z: i32| chunks[((z - 1) * inner + x - 1) as usize].clone();
-
-    // Memory.
-    let (mut bytes, mut sections, mut uniform) = (0usize, 0usize, 0usize);
-    for chunk in &chunks {
-        bytes += chunk.heap_bytes();
-        for s in &chunk.sections {
-            sections += 1;
-            uniform += usize::from(s.is_uniform(s.get(0)));
-        }
-    }
-    println!(
-        "resident: {} chunks, {} sections ({} uniform), {:.1} KiB per chunk ({:.2} MiB total)",
-        chunks.len(),
-        sections,
-        uniform,
-        bytes as f64 / 1024.0 / chunks.len() as f64,
-        bytes as f64 / 1048576.0
-    );
-
-    // Meshing.
-    let mut mesher = Mesher {
-        nether_shading: false,
-        assets: &assets,
-        render: &render,
-        tables: &tables,
-        biomes: &biomes,
-        visibility: tables.visibility.clone(),
-        zoom: BiomeZoom::new(7),
-        blend_radius: 2,
-        smooth_lighting: true,
-        cutout_leaves: true,
-        cull_leaves: false,
-    };
-    let mut best = f64::MAX;
-    let mut quads = 0usize;
-    for _ in 0..3 {
-        let started = Instant::now();
-        let mut jobs = 0;
-        quads = 0;
-        for z in 2..inner {
-            for x in 2..inner {
-                let region: [[Option<Arc<Chunk>>; 3]; 3] = std::array::from_fn(|dz| {
-                    std::array::from_fn(|dx| Some(at(x + dx as i32 - 1, z + dz as i32 - 1)))
-                });
-                let borrowed = horizon_client::mesher::borrow(&region);
-                for sy in 0..SECTIONS as i32 {
-                    let mesh = mesher.mesh(&borrowed, sy);
-                    quads += (mesh.solid.len() + mesh.translucent.len()) / 4;
-                    jobs += 1;
-                }
-            }
-        }
-        best = best.min(started.elapsed().as_secs_f64() / f64::from(jobs));
-    }
-    println!(
-        "mesh: {:.1} us per section ({} quads total)",
-        best * 1e6,
-        quads
-    );
-
-    // Random lookups, as collision and entity queries do.
-    let mut state = 0x9E37_79B9_7F4A_7C15u64;
-    let started = Instant::now();
-    let mut sum = 0u64;
-    let lookups = 20_000_000u64;
-    for _ in 0..lookups {
-        state ^= state << 13;
-        state ^= state >> 7;
-        state ^= state << 17;
-        let cx = 2 + (state % u64::from((inner - 2) as u32)) as i32;
-        let cz = 2 + ((state >> 8) % u64::from((inner - 2) as u32)) as i32;
-        let chunk = &chunks[((cz - 1) * inner + cx - 1) as usize];
-        let (x, y, z) = (
-            (state >> 16) as i32 & 15,
-            MIN_Y + ((state >> 24) % 384) as i32,
-            (state >> 40) as i32 & 15,
-        );
-        sum += u64::from(chunk.get(x, y, z));
-    }
-    println!(
-        "random get: {:.2} ns per lookup (checksum {sum})",
-        started.elapsed().as_secs_f64() * 1e9 / lookups as f64
-    );
-    // Coherent scan, as a column or area query does.
-    let started = Instant::now();
-    let mut sum = 0u64;
-    for _ in 0..4 {
-        for chunk in &chunks {
-            for y in MIN_Y..MIN_Y + 384 {
-                for z in 0..16 {
-                    for x in 0..16 {
-                        sum += u64::from(chunk.get(x, y, z));
-                    }
-                }
-            }
-        }
-    }
-    println!(
-        "scan get: {:.2} ns per lookup (checksum {sum})",
-        started.elapsed().as_secs_f64() * 1e9 / (4.0 * chunks.len() as f64 * 98304.0)
-    );
-    Ok(())
-}
@@ -0,0 +1,168 @@
+//! What a column costs to load, on real terrain: generates and lights the
+//! columns around a point with the vanilla generator, as a world being explored
+//! does, then meshes every section of the inner columns on this one thread, so a
+//! change to generation or meshing shows as time per column and per section.
+//!
+//!     cargo run --release -p horizon-client --example chunk_load_bench -- \
+//!         .local/horizon-client/26.3 [--seed 1234] [--center CX CZ] [--radius 8]
+//!         [--threads N] [--rounds 3]
+//!
+//! The default centre is the village of `tools/perf_bench.py`. The generation
+//! figure is wall time with N workers (the game's own pool); the mesh figure is
+//! this thread's CPU time in `Mesher::mesh`, the best of `--rounds`, so other
+//! work on the machine changes it less. The checksum of the meshes shows that an
+//! A/B pair of builds made the same ones.
+use horizon_client::{
+    assets::Assets,
+    biome::Biomes,
+    blocks::BlockFacts,
+    chunk::HEIGHT,
+    light::LightTables,
+    mesher::{MeshTables, Mesher, Region, borrow},
+    models,
+    spans::thread_cpu,
+    streaming::{Streaming, WorkerContext},
+    vanillagen::VanillaTerrain,
+    world::World,
+};
+use horizon_core::biome::{BiomeZoom, obfuscate_seed};
+use horizon_world::registry::BlockStateId;
+use std::{
+    hash::{DefaultHasher, Hash, Hasher},
+    path::PathBuf,
+    sync::Arc,
+    thread,
+    time::{Duration, Instant},
+};
+
+type Error = Box<dyn std::error::Error>;
+
+fn flag<T: std::str::FromStr>(args: &[String], name: &str, default: T) -> T {
+    args.iter()
+        .position(|a| a == name)
+        .and_then(|i| args.get(i + 1)?.parse().ok())
+        .unwrap_or(default)
+}
+
+fn main() -> Result<(), Error> {
+    let args: Vec<String> = std::env::args().collect();
+    let root = PathBuf::from(args.get(1).ok_or("usage: chunk_load_bench <resources>")?);
+    let seed: i64 = flag(&args, "--seed", 1234);
+    let radius: i32 = flag(&args, "--radius", 8);
+    let rounds: usize = flag(&args, "--rounds", 3);
+    let threads: usize = flag(
+        &args,
+        "--threads",
+        thread::available_parallelism().map_or(2, |n| n.get()),
+    );
+    let center = args
+        .iter()
+        .position(|a| a == "--center")
+        .map(|i| -> Result<(i32, i32), Error> {
+            Ok((
+                args.get(i + 1).ok_or("--center CX CZ")?.parse()?,
+                args.get(i + 2).ok_or("--center CX CZ")?.parse()?,
+            ))
+        })
+        .transpose()?
+        .unwrap_or((-60, 10));
+
+    let assets = Arc::new(Assets::load(&root)?);
+    let render = Arc::new(assets.reload(&root)?);
+    let facts = BlockFacts::load(&root, assets.registry)?;
+    let visibility = models::load_visibility(&root, assets.registry)?;
+    let biomes = Arc::new(Biomes::load(&root)?);
+    let context = Arc::new(WorkerContext {
+        tables: Arc::new(MeshTables::new(&assets, &render, &facts, visibility)?),
+        light: Arc::new(LightTables::load(&root, assets.registry, &facts)?),
+        biomes: biomes.clone(),
+        assets: assets.clone(),
+        render,
+    });
+    let terrain = VanillaTerrain::new(&root.join("worldgen"), assets.registry, &biomes, seed)?;
+
+    // Generation and light, on the game's worker pool. Meshing is left out
+    // here and measured on its own below.
+    let mut streaming = Streaming::new(Arc::new(terrain), context.clone(), threads);
+    streaming.mesh = false;
+    streaming.center = center;
+    streaming.radius = radius;
+    let mut world = World::new(BlockStateId(0), 0);
+    let started = Instant::now();
+    let mut quiet = 0;
+    while quiet < 100 {
+        let before = world.chunks.len();
+        let _ = streaming.update(&mut world);
+        thread::sleep(Duration::from_millis(2));
+        quiet = if streaming.pending() == 0 && before == world.chunks.len() {
+            quiet + 1
+        } else {
+            0
+        };
+    }
+    let generated = started.elapsed() - Duration::from_millis(2 * 100);
+    let columns = world.chunks.len();
+    println!(
+        "generated and lit {columns} columns in {:.0} ms with {threads} workers ({:.2} ms per column)",
+        generated.as_secs_f64() * 1e3,
+        generated.as_secs_f64() * 1e3 / columns.max(1) as f64
+    );
+
+    // Meshing every section of the columns whose neighbours are all loaded.
+    let inner = radius - 1;
+    let regions: Vec<(Region, i32)> = (center.0 - inner..=center.0 + inner)
+        .flat_map(|x| (center.1 - inner..=center.1 + inner).map(move |z| (x, z)))
+        .filter_map(|(x, z)| {
+            let region: Region = std::array::from_fn(|dz| {
+                std::array::from_fn(|dx| {
+                    world
+                        .chunks
+                        .get(&(x + dx as i32 - 1, z + dz as i32 - 1))
+                        .cloned()
+                })
+            });
+            region
+                .iter()
+                .flatten()
+                .all(Option::is_some)
+                .then_some(region)
+        })
+        .flat_map(|region| (0..HEIGHT / 16).map(move |sy| (region.clone(), sy)))
+        .collect();
+    let mut best = Duration::MAX;
+    let (mut vertices, mut checksum) = (0, 0);
+    for _ in 0..rounds.max(1) {
+        let mut mesher = Mesher {
+            nether_shading: false,
+            zoom: BiomeZoom::new(obfuscate_seed(seed)),
+            blend_radius: 2,
+            smooth_lighting: true,
+            cutout_leaves: true,
+            assets: &context.assets,
+            render: &context.render,
+            tables: &context.tables,
+            biomes: &context.biomes,
+            visibility: context.tables.visibility.clone(),
+        };
+        vertices = 0;
+        let mut hash = DefaultHasher::new();
+        let mut spent = Duration::ZERO;
+        for (region, sy) in &regions {
+            let started = thread_cpu().ok_or("no thread CPU clock here")?;
+            let mesh = mesher.mesh(&borrow(region), *sy);
+            spent += thread_cpu().ok_or("no thread CPU clock here")? - started;
+            vertices += mesh.solid.len() + mesh.translucent.len();
+            bytemuck::cast_slice::<_, u8>(&mesh.solid).hash(&mut hash);
+            bytemuck::cast_slice::<_, u8>(&mesh.translucent).hash(&mut hash);
+        }
+        checksum = hash.finish();
+        best = best.min(spent);
+    }
+    println!(
+        "meshed {} sections ({vertices} vertices, checksum {checksum:016x}) in {:.1} ms of CPU ({:.1} us per section)",
+        regions.len(),
+        best.as_secs_f64() * 1e3,
+        best.as_secs_f64() * 1e6 / regions.len().max(1) as f64
+    );
+    Ok(())
+}
@@ -1,140 +0,0 @@
-//! Isolated production mob-model builder benchmark; no assets, Game, GPU or full-frame work.
-//! CARGO_TARGET_DIR=/home/bob/Documents/horizon/target CARGO_INCREMENTAL=0 \
-//! cargo run --profile fast -p horizon-client --example entity_geometry_bench
-use horizon_client::{
-    mesher::Vertex,
-    mobs::{Part, Polygon, anim::Poses, render},
-};
-use std::{hint::black_box, time::Instant};
-
-fn cube(name: String, position: f32) -> Part {
-    let polygons = (0..6)
-        .map(|face| {
-            let axis = face / 2;
-            let side = (face % 2) as f32;
-            let mut normal = [0.0; 3];
-            normal[axis] = side * 2.0 - 1.0;
-            Polygon {
-                normal,
-                vertices: [[0.0, 0.0], [1.0, 0.0], [1.0, 1.0], [0.0, 1.0]].map(|uv| {
-                    let mut vertex = [0.0; 5];
-                    vertex[axis] = side * 8.0;
-                    vertex[(axis + 1) % 3] = uv[0] * 8.0;
-                    vertex[(axis + 2) % 3] = uv[1] * 8.0;
-                    vertex[3] = uv[0];
-                    vertex[4] = uv[1];
-                    vertex
-                }),
-            }
-        })
-        .collect();
-    Part {
-        name,
-        pose: [position, 0.0, 0.0, 0.1, 0.2, 0.0, 1.0, 1.0, 1.0],
-        polygons,
-        children: Vec::new(),
-    }
-}
-
-fn build(model: &Part, poses: &Poses, count: usize, out: &mut Vec<Vertex>) {
-    for i in 0..count {
-        render::draw(
-            black_box(model),
-            glam::Mat4::from_translation(glam::Vec3::new((i % 32) as f32, 0.0, (i / 32) as f32)),
-            black_box(poses),
-            [0.125, 0.25, 0.5, 0.75],
-            0xffc0_d0e0,
-            0xf0f0,
-            0,
-            out,
-        );
-    }
-    black_box(out.as_slice());
-}
-
-fn measure(model: &Part, poses: &Poses, count: usize, iterations: usize, reuse: bool) -> f64 {
-    let mut retained = Vec::new();
-    build(model, poses, count, &mut retained); // Untimed warmup.
-    let start = Instant::now();
-    for _ in 0..iterations {
-        let mut out = if reuse {
-            std::mem::take(&mut retained)
-        } else {
-            Vec::new()
-        };
-        out.clear();
-        build(model, poses, count, &mut out);
-        if reuse {
-            retained = out;
-        }
-    }
-    start.elapsed().as_secs_f64() * 1e6 / iterations as f64
-}
-
-fn main() {
-    let mut model = cube("body".into(), 0.0);
-    model.children = (1..6).map(|i| cube(format!("part{i}"), i as f32)).collect();
-    let poses = Poses::new(&model);
-    for count in [32, 256, 1024, 4096, 8192] {
-        let mut expected = Vec::new();
-        build(&model, &poses, count, &mut expected);
-        let mut retained = Vec::new();
-        build(&model, &poses, count, &mut retained);
-        let (pointer, capacity) = (retained.as_ptr(), retained.capacity());
-        // Populated -> empty/reset -> smaller -> populated must never leave stale vertices.
-        for n in [0, count / 2, count, count] {
-            retained.clear();
-            build(&model, &poses, n, &mut retained);
-            let mut fresh = Vec::new();
-            build(&model, &poses, n, &mut fresh);
-            assert_eq!(
-                bytemuck::cast_slice::<Vertex, u8>(&retained),
-                bytemuck::cast_slice::<Vertex, u8>(&fresh)
-            );
-            assert_eq!(
-                (retained.as_ptr(), retained.capacity()),
-                (pointer, capacity)
-            );
-        }
-        assert_eq!(
-            bytemuck::cast_slice::<Vertex, u8>(&retained),
-            bytemuck::cast_slice::<Vertex, u8>(&expected)
-        );
-        let iterations = (100_000 / count).clamp(40, 1000);
-        let mut fresh = Vec::new();
-        let mut reused = Vec::new();
-        let mut paired_speedups = Vec::new();
-        // Alternate order, reporting medians over eleven warmed batches.
-        for batch in 0..11 {
-            let mut pair = [0.0; 2];
-            for reuse in if batch % 2 == 0 {
-                [false, true]
-            } else {
-                [true, false]
-            } {
-                let time = measure(&model, &poses, count, iterations, reuse);
-                pair[usize::from(reuse)] = time;
-                if reuse {
-                    reused.push(time);
-                } else {
-                    fresh.push(time);
-                }
-            }
-            paired_speedups.push(pair[0] / pair[1]);
-        }
-        paired_speedups.sort_by(f64::total_cmp);
-        fresh.sort_by(f64::total_cmp);
-        reused.sort_by(f64::total_cmp);
-        println!(
-            "entities={count} vertices={} capacity={capacity} retained_bytes={} fresh_us={:.3} reused_us={:.3} speedup={:.3}x paired_speedup_median={:.3}x paired_speedup_range={:.3}..{:.3}x iterations={iterations} batches=11 byte_equivalence=pass pointer_capacity_reuse=pass",
-            retained.len(),
-            capacity * size_of::<Vertex>(),
-            fresh[5],
-            reused[5],
-            fresh[5] / reused[5],
-            paired_speedups[5],
-            paired_speedups[0],
-            paired_speedups[10]
-        );
-    }
-}
@@ -1,205 +0,0 @@
-//! Compare the exact read/deserialize sequences used by the model loaders.
-//! Run with `cargo run -p horizon-client --profile fast --example json_readers_bench`.
-//! Optional arguments: resource directory, repetitions (default 9).
-use serde_json::{Map, Value, json};
-use std::{
-    collections::BTreeMap,
-    fmt::Debug,
-    fs::{self, File},
-    hint::black_box,
-    io::BufReader,
-    path::{Path, PathBuf},
-    time::Instant,
-};
-
-type Result<T> = horizon_client::Result<T>;
-
-#[derive(Clone, Copy)]
-enum Reader {
-    File,
-    Buffered,
-    Slice,
-}
-const READERS: [Reader; 3] = [Reader::File, Reader::Buffered, Reader::Slice];
-
-// These match the map types and reader expressions at all three production sites.
-macro_rules! reader {
-    ($name:ident, $map:ty) => {
-        fn $name(path: &Path, reader: Reader) -> Result<$map> {
-            Ok(match reader {
-                Reader::File => serde_json::from_reader(File::open(path)?)?,
-                Reader::Buffered => serde_json::from_reader(BufReader::new(File::open(path)?))?,
-                Reader::Slice => serde_json::from_slice(&fs::read(path)?)?,
-            })
-        }
-    };
-}
-reader!(prepare_facts, Map<String, Value>);
-reader!(catalog_facts, BTreeMap<String, Value>);
-
-struct Fixture(PathBuf);
-impl Fixture {
-    fn new() -> Result<Self> {
-        let root =
-            std::env::temp_dir().join(format!("horizon-json-readers-{}", std::process::id()));
-        fs::create_dir(&root)?;
-        Ok(Self(root))
-    }
-}
-impl Drop for Fixture {
-    fn drop(&mut self) {
-        let _ = fs::remove_dir_all(&self.0);
-    }
-}
-
-fn fixtures(root: &Path) -> Result<()> {
-    let states: Vec<_> = (0..56)
-        .map(|i| {
-            json!({"facing": (["north", "east", "south", "west"][i % 4]),
-                "powered": if i / 4 % 2 == 0 { "false" } else { "true" },
-                "age": (i / 8).to_string()})
-        })
-        .collect();
-    let mut models = Map::new();
-    let mut render = Map::new();
-    for i in 0..1024 {
-        let name = format!("minecraft:fixture_block_{i:04}");
-        models.insert(
-            name.clone(),
-            json!({
-                "schema": {"facing": {"named": ["north", "east", "south", "west"]},
-                    "powered": {"named": ["false", "true"]}, "age": {"integer": [0, 6]}},
-                "states": states
-            }),
-        );
-        render.insert(
-            name,
-            json!({"rule": "never", "can_occlude": true, "bars_tag": false}),
-        );
-    }
-    fs::write(root.join("model-states.json"), serde_json::to_vec(&models)?)?;
-    fs::write(
-        root.join("render-definitions.json"),
-        serde_json::to_vec(&render)?,
-    )?;
-    Ok(())
-}
-
-fn benchmark<T: PartialEq + Debug>(
-    label: &str,
-    path: &Path,
-    repetitions: usize,
-    read: impl Fn(&Path, Reader) -> Result<T>,
-) -> Result<()> {
-    let expected = read(path, Reader::File)?;
-    for reader in READERS {
-        assert_eq!(expected, read(path, reader)?);
-        for _ in 0..2 {
-            black_box(read(black_box(path), reader)?);
-        }
-    }
-    drop(expected);
-    let mut samples: [Vec<f64>; 3] = std::array::from_fn(|_| Vec::new());
-    for repetition in 0..repetitions {
-        // Rotate reader order to distribute drift across implementations.
-        for offset in 0..3 {
-            let index = (repetition + offset) % 3;
-            let start = Instant::now();
-            let value = black_box(read(black_box(path), READERS[index])?);
-            samples[index].push(start.elapsed().as_secs_f64() * 1000.0);
-            drop(value); // Match the loaders: retain the parsed tree after loading.
-        }
-    }
-    let median: Vec<_> = samples
-        .iter_mut()
-        .map(|s| {
-            s.sort_by(f64::total_cmp);
-            s[s.len() / 2]
-        })
-        .collect();
-    println!(
-        "{label}: {} bytes, {repetitions} samples/reader, median ms: File={:.3}, BufReader={:.3}, read+slice={:.3}; slice speedup={:.2}x",
-        fs::metadata(path)?.len(),
-        median[0],
-        median[1],
-        median[2],
-        median[0] / median[2]
-    );
-    Ok(())
-}
-
-fn main() -> Result<()> {
-    let args: Vec<_> = std::env::args().skip(1).collect();
-    let fixture = if args.is_empty() {
-        Some(Fixture::new()?)
-    } else {
-        None
-    };
-    let root = fixture
-        .as_ref()
-        .map(|f| f.0.clone())
-        .unwrap_or_else(|| PathBuf::from(&args[0]));
-    if fixture.is_some() {
-        fixtures(&root)?;
-        println!(
-            "Generated representative fixtures: 1024 blocks, 57344 model states; warm filesystem cache."
-        );
-    }
-    let repetitions = args.get(1).map(|s| s.parse()).transpose()?.unwrap_or(9);
-    assert!(repetitions > 0, "repetitions must be positive");
-    benchmark(
-        "prepare model states",
-        &root.join("model-states.json"),
-        repetitions,
-        prepare_facts,
-    )?;
-    benchmark(
-        "catalog model states",
-        &root.join("model-states.json"),
-        repetitions,
-        catalog_facts,
-    )?;
-    benchmark(
-        "render definitions",
-        &root.join("render-definitions.json"),
-        repetitions,
-        catalog_facts,
-    )
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn reader_equivalence_and_errors() -> Result<()> {
-        let fixture = Fixture::new()?;
-        let path = fixture.0.join("test.json");
-        fs::write(&path, br#"{"minecraft:stone":{"schema":{},"states":[{}]},"unicode":"\u2603","duplicate":1,"duplicate":2}"#)?;
-        let expected = prepare_facts(&path, Reader::File)?;
-        for reader in READERS {
-            assert_eq!(expected, prepare_facts(&path, reader)?);
-            assert_eq!(
-                expected.iter().collect::<BTreeMap<_, _>>(),
-                catalog_facts(&path, reader)?.iter().collect()
-            );
-        }
-        for invalid in [b"{\"a\": ".as_slice(), b"{} trailing", b"{\"a\":\"\xff\"}"] {
-            fs::write(&path, invalid)?;
-            for reader in READERS {
-                let error = prepare_facts(&path, reader).unwrap_err();
-                assert!(error.downcast_ref::<serde_json::Error>().is_some());
-                assert!(catalog_facts(&path, reader).is_err());
-            }
-        }
-        fs::remove_file(&path)?;
-        for reader in READERS {
-            let error = prepare_facts(&path, reader).unwrap_err();
-            assert_eq!(
-                error.downcast_ref::<std::io::Error>().unwrap().kind(),
-                std::io::ErrorKind::NotFound
-            );
-        }
-        Ok(())
-    }
-}
@@ -1,143 +0,0 @@
-//! Serve a small flat world on the LAN server without the game, for joining
-//! with a real client while developing the protocol:
-//! `cargo run --release --example lan_flat -- RESOURCES PORT`.
-use horizon_client::{
-    assets::Assets,
-    blocks::BlockFacts,
-    chunk::{Chunk, MIN_Y},
-    lan::{
-        Lan,
-        chunks::ChunkEncoder,
-        data::SyncData,
-        hub::{HostEvent, HostState, Hub, HubConfig, TickCtx},
-    },
-    world::World,
-};
-use horizon_protocol::packets::play::Serverbound as S;
-use std::{path::PathBuf, sync::Arc, time::Duration};
-
-fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let mut args = std::env::args().skip(1);
-    let root = PathBuf::from(args.next().ok_or("RESOURCES PORT")?);
-    let port: u16 = args.next().ok_or("port")?.parse()?;
-    let assets = Assets::load(&root)?;
-    let facts = BlockFacts::load(&root, assets.registry)?;
-    let state = |name: &str| assets.registry.default_state(name).map_or(0, |s| s.0);
-    let sync = Arc::new(SyncData::load(&root)?);
-    let biomes: Vec<String> = sync
-        .dynamic
-        .registries
-        .get("minecraft:worldgen/biome")
-        .map(|v| v.iter().map(|(n, _)| n.clone()).collect())
-        .unwrap_or_default();
-    let encoder = ChunkEncoder::new(
-        facts
-            .states
-            .iter()
-            .map(|s| (s.name.clone(), s.fluid_level > 0 || s.waterlogged)),
-        &sync.builtin,
-        &biomes,
-        &biomes,
-    );
-    let (stone, dirt, grass) = (
-        state("minecraft:stone"),
-        state("minecraft:dirt"),
-        state("minecraft:grass_block"),
-    );
-    let mut world = World::new(facts.air, 0);
-    for cz in -8..=8 {
-        for cx in -8..=8 {
-            let mut chunk = Chunk::empty(cx, cz);
-            for z in 0..16 {
-                for x in 0..16 {
-                    for y in MIN_Y..60 {
-                        let v = if y == 59 {
-                            grass
-                        } else if y > 55 {
-                            dirt
-                        } else {
-                            stone
-                        };
-                        chunk.set(x, y, z, v);
-                    }
-                }
-            }
-            chunk.lit = true;
-            world.chunks.insert((cx, cz), Arc::new(chunk));
-        }
-    }
-    let lan = Lan::start(sync.clone(), port, "Flat - Example".into(), 8)?;
-    println!("listening on {}", lan.port);
-    let mut hub = Hub::new(
-        lan,
-        sync,
-        encoder,
-        HubConfig {
-            default_game_mode: 1,
-            guest_commands: true,
-            force_game_mode: false,
-            hardcore: false,
-            view_distance: 8,
-            simulation_distance: 8,
-            dimension: "minecraft:overworld".into(),
-            seed: 0,
-            max_players: 8,
-            dedicated: false,
-            integrated: false,
-        },
-    );
-    let mut next_entity = 100u32;
-    let host = HostState {
-        uuid: 42,
-        name: "Host".into(),
-        entity_id: 1,
-        position: [0.5, 60.0, 0.5],
-        yaw: 0.0,
-        pitch: 0.0,
-        head_yaw: 0.0,
-        on_ground: true,
-        game_mode: 1,
-        sneaking: false,
-        sprinting: false,
-        equipment: Default::default(),
-        health: 20.0,
-        attributes: Vec::new(),
-        bed: None,
-        living_flags: 0,
-    };
-    loop {
-        world.game_time += 1;
-        world.day_time += 1;
-        let mut ctx = TickCtx {
-            world: &mut world,
-            host: Some(&host),
-            entities: &[],
-            next_entity: &mut next_entity,
-            spawn: [8.5, 60.0, 8.5],
-            difficulty: 2,
-            difficulty_locked: false,
-            clock_rate: 1.0,
-            tick_rate: 20.0,
-            tick_frozen: false,
-            tick_steps: (0, 0),
-            collision: None,
-        };
-        for event in hub.tick(&mut ctx) {
-            match event {
-                HostEvent::Joined(conn) => hub.place_new_player(conn, &mut ctx),
-                HostEvent::Packet(_, packet) => {
-                    if std::env::var_os("HORIZON_NET_DEBUG").is_some()
-                        && !matches!(*packet, S::ClientTickEnd(_))
-                    {
-                        eprintln!("[lan] {packet:?}");
-                    }
-                }
-                HostEvent::Chat { line, .. } | HostEvent::Warn(line) | HostEvent::Error(line) => {
-                    println!("{line}")
-                }
-                HostEvent::Left(_) => {}
-            }
-        }
-        std::thread::sleep(Duration::from_millis(50));
-    }
-}
@@ -1,153 +0,0 @@
-//! Read-only saved chunk benchmark. All timings exclude resource/corpus setup.
-//!
-//! load_bench RESOURCES DIMENSION_DIR [--rounds N] [--limit N] [--checksum]
-//! Add --profile-worker when a sampling collector cannot sample the main thread.
-//! Reports warm filesystem SaveDir::load (read, inflate, NBT, decode and light),
-//! plus isolated inflate/NBT and native decode. No files in the save are changed.
-use horizon_client::{
-    assets::Assets,
-    biome::Biomes,
-    blocks::BlockFacts,
-    save::{SaveDir, SaveTables, decode_with},
-};
-use horizon_world::{nbt::Limits, region::RegionFile};
-use sha2::{Digest, Sha256};
-use std::{hint::black_box, path::PathBuf, sync::Arc, time::Instant};
-
-type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
-
-fn main() -> Result<()> {
-    if std::env::args().any(|a| a == "--profile-worker") {
-        std::thread::spawn(|| run().map_err(|e| e.to_string()))
-            .join()
-            .expect("benchmark worker")
-            .map_err(Into::into)
-    } else {
-        run()
-    }
-}
-
-fn run() -> Result<()> {
-    let args: Vec<String> = std::env::args().skip(1).collect();
-    let usage = "load_bench RESOURCES DIMENSION_DIR [--rounds N] [--limit N] [--checksum]";
-    let root = PathBuf::from(args.first().ok_or(usage)?);
-    let dimension = PathBuf::from(args.get(1).ok_or(usage)?);
-    let flag = |name: &str, default: usize| -> Result<usize> {
-        Ok(match args.iter().position(|a| a == name) {
-            Some(i) => args.get(i + 1).ok_or(usage)?.parse()?,
-            None => default,
-        })
-    };
-    let rounds = flag("--rounds", 5)?;
-    let limit = flag("--limit", 256)?;
-    if rounds == 0 || limit == 0 {
-        return Err("rounds and limit must be positive".into());
-    }
-    let assets = Assets::load(&root)?;
-    let facts = BlockFacts::load(&root, assets.registry)?;
-    let biomes = Biomes::load(&root)?;
-    let tables = Arc::new(SaveTables::new(&assets).with_block_entities(&facts));
-    let source = SaveDir::new(dimension.clone());
-    let _ = source.tables.set(tables.clone());
-    let mut paths: Vec<_> = std::fs::read_dir(dimension.join("region"))?
-        .map(|e| e.map(|e| e.path()))
-        .collect::<std::io::Result<_>>()?;
-    paths.retain(|p| p.extension().is_some_and(|e| e == "mca"));
-    paths.sort();
-    let mut corpus = Vec::new();
-    'regions: for path in paths {
-        let mut region = RegionFile::open(path)?;
-        let mut positions: Vec<_> = region.chunks().map(|(pos, _)| pos).collect();
-        positions.sort_by_key(|p| (p.x, p.z));
-        for pos in positions {
-            let record = region.read(pos)?.ok_or("missing record")?;
-            let tag = record.nbt(Limits::default())?;
-            if decode_with(&tag, assets.registry, &biomes, Some(&tables)).is_none() {
-                continue;
-            }
-            corpus.push((pos, record, tag));
-            if corpus.len() == limit {
-                break 'regions;
-            }
-        }
-    }
-    if corpus.is_empty() {
-        return Err("no full chunks in corpus".into());
-    }
-    let mut records_hash = Sha256::new();
-    for (pos, record, _) in &corpus {
-        records_hash.update(pos.x.to_le_bytes());
-        records_hash.update(pos.z.to_le_bytes());
-        records_hash.update((record.compressed.len() as u64).to_le_bytes());
-        records_hash.update(&record.compressed);
-    }
-    println!(
-        "{}",
-        serde_json::json!({"corpus": dimension, "chunks": corpus.len(), "rounds": rounds,
-            "compressed_records_sha256": format!("{:x}", records_hash.finalize()),
-            "compressed_bytes": corpus.iter().map(|(_, r, _)| r.compressed.len()).sum::<usize>()})
-    );
-    // Prime SaveDir's region handles and the filesystem cache before measurement.
-    for (pos, _, _) in &corpus {
-        black_box(
-            source
-                .load(pos.x, pos.z, assets.registry, &biomes)
-                .ok_or("load failed")?,
-        );
-    }
-    for round in 0..rounds {
-        let started = Instant::now();
-        for (pos, _, _) in &corpus {
-            black_box(
-                source
-                    .load(pos.x, pos.z, assets.registry, &biomes)
-                    .ok_or("load failed")?,
-            );
-        }
-        let load_s = started.elapsed().as_secs_f64();
-        let started = Instant::now();
-        for (_, record, _) in &corpus {
-            black_box(record.nbt(Limits::default())?);
-        }
-        let nbt_s = started.elapsed().as_secs_f64();
-        let started = Instant::now();
-        for (_, _, tag) in &corpus {
-            black_box(
-                decode_with(tag, assets.registry, &biomes, Some(&tables)).ok_or("decode failed")?,
-            );
-        }
-        let decode_s = started.elapsed().as_secs_f64();
-        println!(
-            "{}",
-            serde_json::json!({"round": round, "load_s": load_s,
-            "inflate_nbt_s": nbt_s, "decode_s": decode_s})
-        );
-    }
-    if args.iter().any(|a| a == "--checksum") {
-        let mut hash = Sha256::new();
-        let mut light_loaded = 0;
-        for (pos, _, _) in &corpus {
-            let chunk = source
-                .load(pos.x, pos.z, assets.registry, &biomes)
-                .ok_or("load failed")?;
-            hash.update(pos.x.to_le_bytes());
-            hash.update(pos.z.to_le_bytes());
-            light_loaded += usize::from(chunk.light_loaded);
-            for section in &chunk.sections {
-                for i in 0..4096 {
-                    hash.update(section.get(i).to_le_bytes());
-                    hash.update([section.light(i)]);
-                }
-                for i in 0..64 {
-                    hash.update(section.biomes.get(i).to_le_bytes());
-                }
-            }
-        }
-        println!(
-            "{}",
-            serde_json::json!({"blocks_biomes_light_sha256": format!("{:x}", hash.finalize()),
-            "light_loaded": light_loaded})
-        );
-    }
-    Ok(())
-}
@@ -1,8 +1,7 @@
 //! Replays `tools/test_ambient_sound_parity.py` scripts through Horizon's
 //! ambient sound handlers over its `SoundEngine`:
 //! `ambient_fixture ROOT INPUT OUTPUT`.
-#[path = "audio_common/mod.rs"]
-mod common;
+use crate::audio_common as common;
 use common::{Fake, d, f, flush};
 use horizon_client::ambience::{Ambience, AmbientContext, AmbientSounds, Mood, bubble_column_in};
 use horizon_client::sound_engine::{Bound, SoundEngine, TickContext, Ticking};
@@ -47,8 +46,8 @@ fn sounds(a: &[&str]) -> AmbientSounds {
    }
 }

-fn main() {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() {
+    let args: Vec<String> = crate::args().collect();
    let mut engine = SoundEngine::new(SoundRegistry::load(std::path::Path::new(&args[1])));
    engine.listening = true;
    let mut backend = Fake::default();
@@ -50,8 +50,8 @@ fn particle(k: ArrowParticle) -> &'static str {
        ArrowParticle::Splash => "splash",
    }
 }
-fn main() -> Result<()> {
-    let args: Vec<_> = std::env::args().skip(1).collect();
+pub fn main() -> Result<()> {
+    let args: Vec<_> = crate::args().skip(1).collect();
    if args.len() != 3 {
        return Err("usage: arrow_probe RESOURCES FIXTURE_DIRECTORY --describe|REFERENCE".into());
    }
@@ -163,6 +163,8 @@ fn main() -> Result<()> {
                                    ArrowSound::HitGround => "hit",
                                    ArrowSound::Splash => "splash",
                                    ArrowSound::Extinguish => "extinguish",
+                                    ArrowSound::TridentHitGround => "trident_hit_ground",
+                                    ArrowSound::TridentHit => "trident_hit",
                                },
                                volume.to_bits(),
                                pitch.to_bits()
@@ -18,8 +18,8 @@ fn music(m: Option<&Music>) -> String {
    })
 }

-fn main() {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() {
+    let args: Vec<String> = crate::args().collect();
    let root = std::path::Path::new(&args[1]);
    let tables = MusicTables::load(root);
    let ambient = AmbientTables::load(root);
@@ -24,8 +24,8 @@ fn db(v: &Value) -> f64 {
    f64::from_bits(u64::from_str_radix(v.as_str().unwrap(), 16).unwrap())
 }

-fn main() -> Result<()> {
-    let args: Vec<_> = std::env::args().skip(1).collect();
+pub fn main() -> Result<()> {
+    let args: Vec<_> = crate::args().skip(1).collect();
    let [root, input, output, scene_json] = &args[..] else {
        return Err("usage: auto_jump_probe RESOURCES INPUT OUTPUT SCENE_JSON".into());
    };
@@ -118,8 +118,8 @@ fn status(s: ShulkerStatus) -> &'static str {
    }
 }

-fn main() -> Result<()> {
-    let args: Vec<PathBuf> = std::env::args_os().skip(1).map(PathBuf::from).collect();
+pub fn main() -> Result<()> {
+    let args: Vec<PathBuf> = crate::args_os().skip(1).map(PathBuf::from).collect();
    let [root, inputs, output] = args.as_slice() else {
        return Err("usage: block_entity_anim_fixture RESOURCES INPUTS OUTPUT".into());
    };
@@ -110,8 +110,8 @@ fn intern(s: &str) -> &'static str {
    }
 }

-fn main() -> Result<()> {
-    let args: Vec<PathBuf> = std::env::args_os().skip(1).map(PathBuf::from).collect();
+pub fn main() -> Result<()> {
+    let args: Vec<PathBuf> = crate::args_os().skip(1).map(PathBuf::from).collect();
    let [root, inputs, textures, output] = args.as_slice() else {
        return Err("usage: block_entity_render_fixture RESOURCES INPUTS TEXTURES OUTPUT".into());
    };
@@ -367,6 +367,7 @@ fn main() -> Result<()> {
            lid: &|_| open,
            sign: &|_| sign.as_ref(),
            banner: &|_| layers.clone(),
+            skull: &|_| None,
            glyph: &|c| atlas.glyph_cell(c),
        };
        let mut verts = Vec::new();
@@ -26,8 +26,8 @@ fn entity(name: &str) -> BlockEntity {
        .unwrap_or_else(|| panic!("no block entity for {name}"))
 }

-fn main() {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() {
+    let args: Vec<String> = crate::args().collect();
    let input = std::fs::read_to_string(&args[1]).expect("input");
    let mut out = String::new();
    let mut entities = BlockEntities::default();
@@ -8,8 +8,8 @@ use std::{
    io::{BufRead, BufReader, BufWriter, Write},
    path::Path,
 };
-fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let args: Vec<_> = std::env::args().collect();
+pub fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let args: Vec<_> = crate::args().collect();
    let root = Path::new(&args[1]);
    let assets = Assets::load(root)?;
    let render = assets.reload(root)?;
@@ -51,8 +51,8 @@ impl Around for Column {
    }
 }

-fn main() -> horizon_client::Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> horizon_client::Result<()> {
+    let args: Vec<String> = crate::args().collect();
    let root = Path::new(
        args.get(1)
            .ok_or("usage: block_transform_fixture RESOURCES INPUT OUTPUT")?,
@@ -16,8 +16,8 @@ use std::{
 };
 /// The stage sprite origin the cracks carry (the oracle compares the geometry and UVs only).
 const STAGE: [f32; 2] = [0.25, 0.5];
-fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let args: Vec<_> = std::env::args().collect();
+pub fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let args: Vec<_> = crate::args().collect();
    let root = Path::new(&args[1]);
    let assets = Assets::load(root)?;
    let render = assets.reload(root)?;
@@ -323,8 +323,8 @@ fn avatar(c: &Value, out: &mut impl Write) -> Result<()> {
    Ok(())
 }

-fn main() -> Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> Result<()> {
+    let args: Vec<String> = crate::args().collect();
    let input = BufReader::new(File::open(&args[1])?);
    let mut out = BufWriter::new(File::create(&args[2])?);
    for (n, line) in input.lines().enumerate() {
@@ -70,8 +70,8 @@ fn describe(state: &BlockState) -> String {
    format!("{}|{}", state.name, props.join(","))
 }

-fn main() -> horizon_client::Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> horizon_client::Result<()> {
+    let args: Vec<String> = crate::args().collect();
    let root = Path::new(
        args.get(1)
            .ok_or("usage: cauldron_fixture RESOURCES INPUT OUTPUT")?,
@@ -5,8 +5,9 @@
 //! the oracle's JSON form.
 //!
 //! usage: chat_screen_fixture RESOURCES REGISTRIES CASES OUTPUT
+use crate::pack_screen_fixture;
 use horizon_client::{
-    chat::{ChatAction, ChatScreen, Commands},
+    chat::{ChatAbilities, ChatAction, ChatScreen, ChatVisibility, Commands},
    command::vanilla,
    hud::HudAtlas,
    lang,
@@ -15,14 +16,11 @@ use horizon_client::{
 use serde_json::{Value, json};
 use std::{fmt::Write as _, fs, path::PathBuf};
 use winit::keyboard::KeyCode as K;
-#[path = "pack_screen_fixture.rs"]
-#[allow(dead_code)]
-mod pack_screen_fixture;
 #[path = "chat_screen_fixture/registries.rs"]
 mod registries;

-fn main() -> horizon_client::Result<()> {
-    let args: Vec<PathBuf> = std::env::args_os().skip(1).map(PathBuf::from).collect();
+pub fn main() -> horizon_client::Result<()> {
+    let args: Vec<PathBuf> = crate::args_os().skip(1).map(PathBuf::from).collect();
    let [root, registries, inputs, output] = args.as_slice() else {
        return Err("usage: chat_screen_fixture RESOURCES REGISTRIES CASES OUTPUT".into());
    };
@@ -55,6 +53,7 @@ fn main() -> horizon_client::Result<()> {
            history.len(),
            w,
            h,
+            ChatAbilities::new(ChatVisibility::Full),
        );
        screen.auto_suggestions = case["autoSuggest"] == true;
        let mut closed = false;
@@ -1,8 +1,8 @@
 //! CloudRenderer face selection and mesh traversal, without a GPU.
 use horizon_client::clouds;
 use std::{fmt::Write, fs};
-fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let args: Vec<_> = std::env::args().collect();
+pub fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let args: Vec<_> = crate::args().collect();
    let mut output = String::new();
    for (case, line) in fs::read_to_string(&args[1])?.lines().enumerate() {
        let values: Vec<i32> = line
@@ -132,8 +132,8 @@ fn tree(d: &Dispatcher, node: usize) -> Value {
    v
 }

-fn main() -> horizon_client::Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> horizon_client::Result<()> {
+    let args: Vec<String> = crate::args().collect();
    if args.get(1).map(String::as_str) == Some("tree") {
        let d = &vanilla::registered(false);
        let mut v = tree(d, 0);
@@ -24,8 +24,8 @@ fn input_name(input: Input) -> &'static str {
    }
 }

-fn main() -> Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> Result<()> {
+    let args: Vec<String> = crate::args().collect();
    let input = BufReader::new(File::open(&args[1])?);
    let mut out = BufWriter::new(File::create(&args[2])?);
    for (n, line) in input.lines().enumerate() {
@@ -0,0 +1,48 @@
+use horizon_client::{
+    Result,
+    item_data::StackData,
+    items::{ItemStack, Items},
+};
+use horizon_world::nbt::Tag;
+use serde_json::Value;
+use std::{
+    fs::File,
+    io::{BufRead, BufReader, BufWriter, Write},
+    path::Path,
+};
+
+pub fn main() -> Result<()> {
+    let args: Vec<_> = crate::args().collect();
+    let root = Path::new(env!("CARGO_MANIFEST_DIR")).join("../../.local/horizon-client/26.3");
+    let items = Items::catalog(&root)?;
+    let mut out = BufWriter::new(File::create(&args[2])?);
+    for line in BufReader::new(File::open(&args[1])?).lines() {
+        let row: Value = serde_json::from_str(&line?)?;
+        let mut stack = ItemStack::new(
+            row["item"].as_str().unwrap(),
+            row["count"].as_u64().unwrap() as u32,
+        );
+        match row["tool"].as_str().unwrap() {
+            "default" => {}
+            mode => {
+                let mut data = StackData::default();
+                let tool = if mode == "implicit" {
+                    Tag::compound([] as [(&str, Tag); 0])
+                } else {
+                    Tag::compound([(
+                        "can_destroy_blocks_in_creative",
+                        Tag::Byte(i8::from(mode == "allow")),
+                    )])
+                };
+                data.set_other("minecraft:tool", Some(tool));
+                stack.extra = Some(Box::new(data));
+            }
+        }
+        writeln!(
+            out,
+            "{}",
+            items.can_destroy_block(Some(&stack), row["creative"].as_bool().unwrap())
+        )?;
+    }
+    Ok(())
+}
@@ -11,8 +11,8 @@ use horizon_client::{
 use serde_json::{Value, json};
 use std::{fs, path::Path};

-fn main() -> horizon_client::Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> horizon_client::Result<()> {
+    let args: Vec<String> = crate::args().collect();
    let usage = "usage: creative_search_fixture RESOURCES CREATIVE_JSON VANILLA_JSON OUTPUT";
    let names = Names::load(Path::new(args.get(1).ok_or(usage)?));
    let creative = Creative::from_json(&serde_json::from_slice(&fs::read(
@@ -0,0 +1,89 @@
+use horizon_client::{
+    Result,
+    cushion::{self, World},
+};
+use horizon_core::geometry::{Aabb, ShapeOp, Vec3, VoxelShape};
+use serde_json::Value;
+use std::{
+    collections::HashMap,
+    fs::File,
+    io::{BufRead, BufReader, BufWriter, Write},
+};
+
+struct Cell {
+    outline: VoxelShape,
+    collision: VoxelShape,
+    suffocating: bool,
+}
+struct Fixture(HashMap<[i32; 3], Cell>);
+impl World for Fixture {
+    fn outline_bounds(&self, p: [i32; 3]) -> Option<Aabb> {
+        self.0
+            .get(&p)?
+            .outline
+            .bounds()
+            .map(|b| b.move_by(Vec3::new(p[0] as f64, p[1] as f64, p[2] as f64)))
+    }
+    fn collision_shapes(&self, _: Aabb) -> Vec<VoxelShape> {
+        self.0
+            .iter()
+            .map(|(p, c)| {
+                c.collision
+                    .moved(Vec3::new(p[0] as f64, p[1] as f64, p[2] as f64))
+            })
+            .collect()
+    }
+    fn suffocating(&self, p: [i32; 3]) -> bool {
+        self.0.get(&p).is_some_and(|c| c.suffocating)
+    }
+}
+fn shape(value: &Value) -> Result<VoxelShape> {
+    let mut shape = VoxelShape::empty();
+    for b in value.as_array().unwrap() {
+        let f = |i: usize| b[i].as_f64().unwrap();
+        shape = shape.join(
+            &VoxelShape::from_box(Aabb::new(
+                Vec3::new(f(0), f(1), f(2)),
+                Vec3::new(f(3), f(4), f(5)),
+            ))?,
+            ShapeOp::OR,
+        )?;
+    }
+    Ok(shape)
+}
+pub fn main() -> Result<()> {
+    let args: Vec<_> = crate::args().collect();
+    let mut out = BufWriter::new(File::create(&args[2])?);
+    for line in BufReader::new(File::open(&args[1])?).lines() {
+        let row: Value = serde_json::from_str(&line?)?;
+        let mut world = Fixture(HashMap::new());
+        for c in row["cells"].as_array().unwrap() {
+            let p = std::array::from_fn(|i| c[i].as_i64().unwrap() as i32);
+            world.0.insert(
+                p,
+                Cell {
+                    outline: shape(&c[3])?,
+                    collision: shape(&c[4])?,
+                    suffocating: c[5].as_bool().unwrap(),
+                },
+            );
+        }
+        let p = &row["pos"];
+        let (x, y, z) = (
+            p[0].as_f64().unwrap(),
+            p[1].as_f64().unwrap(),
+            p[2].as_f64().unwrap(),
+        );
+        let bounds = Aabb::new(
+            Vec3::new(x - 0.5, y, z - 0.5),
+            Vec3::new(x + 0.5, y + 0.25, z + 0.5),
+        );
+        writeln!(
+            out,
+            "{} {}",
+            cushion::can_place(&world, bounds),
+            cushion::survives(&world, bounds)
+        )?;
+    }
+    Ok(())
+}
@@ -0,0 +1,49 @@
+//! How the probe binary runs a probe. main.rs lists the probes and nothing else (tools/parity.py leaves it out of
+//! the harnesses' dependencies); code every probe relies on goes here.
+use std::process::ExitCode;
+
+/// `probes! { a, b, }` declares the binary's `main`, which runs the probe module named by its first argument.
+macro_rules! probes {
+    ($($name:ident,)*) => {
+        fn run(name: &str) -> Option<std::process::ExitCode> {
+            use std::process::Termination;
+            Some(match name {
+                $(stringify!($name) => $name::main().report(),)*
+                _ => return None,
+            })
+        }
+
+        fn main() -> std::process::ExitCode {
+            dispatch::main(&[$(stringify!($name)),*], run)
+        }
+    };
+}
+
+/// The probe's command line as its own example saw it: the program, then the arguments after the probe's name.
+pub fn args() -> std::vec::IntoIter<String> {
+    let mut args: Vec<String> = std::env::args().collect();
+    if args.len() > 1 {
+        args.remove(1);
+    }
+    args.into_iter()
+}
+
+/// args(), as OsStrings.
+pub fn args_os() -> std::vec::IntoIter<std::ffi::OsString> {
+    let mut args: Vec<_> = std::env::args_os().collect();
+    if args.len() > 1 {
+        args.remove(1);
+    }
+    args.into_iter()
+}
+
+pub fn main(names: &[&str], run: fn(&str) -> Option<ExitCode>) -> ExitCode {
+    let name = std::env::args().nth(1).unwrap_or_default();
+    run(&name).unwrap_or_else(|| {
+        eprintln!(
+            "usage: client_probe <name> [arguments...]\nprobes: {}",
+            names.join(" ")
+        );
+        ExitCode::from(2)
+    })
+}
@@ -14,8 +14,8 @@ fn d(v: f64) -> String {
    format!("{:016x}", v.to_bits())
 }

-fn main() -> Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> Result<()> {
+    let args: Vec<String> = crate::args().collect();
    let mut out = BufWriter::new(File::create(&args[2])?);
    for (n, line) in BufReader::new(File::open(&args[1])?).lines().enumerate() {
        let c: Value = serde_json::from_str(&line?)?;
@@ -10,8 +10,8 @@ use horizon_client::{
 };
 use std::{fmt::Write as _, fs, path::Path};

-fn main() -> horizon_client::Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> horizon_client::Result<()> {
+    let args: Vec<String> = crate::args().collect();
    let root = Path::new(
        args.get(1)
            .ok_or("usage: enchanting_fixture RESOURCES INPUT OUTPUT")?,
@@ -3,13 +3,13 @@
 //! posed model with `mobs::render::draw` under the case's living-entity root
 //! transform and writes each drawn part's packed vertex normals.
 //!
-//! cargo run --profile fast -p horizon-client --example entity_anim_fixture -- \
+//! cargo run --profile fast -p horizon-client --example probe -- entity_anim_fixture \
 //!     RESOURCES VANILLA.jsonl OUT.jsonl
 use horizon_client::mesher::Vertex;
 use horizon_client::mobs::{
    Mob, MobData, MobTypes, Part, Species, allay,
    anim::{self, Poses, State},
-    aquatic, body_anim as b_anim, equine, guardian,
+    aquatic, bat, body_anim as b_anim, equine, guardian,
    keyframes::AnimationState,
    render, shulker, sniffer, species, tame,
 };
@@ -108,6 +108,22 @@ fn entity_state(mob: &mut Mob, species: Species, case: &Value) {
    let flag = |k: &str| case[k].as_bool().unwrap_or(false);
    let num = |k: &str| case[k].as_f64().unwrap_or(0.0) as f32;
    match species {
+        Species::Bat => {
+            mob.extra.flag = flag("isResting");
+            mob.anim.states[0].started = case["flyAnimationState"].as_f64().map(|v| v as f32);
+            mob.anim.states[1].started = case["restAnimationState"].as_f64().map(|v| v as f32);
+            if let Some(ticks) = case["@batTicks"].as_array() {
+                for (i, flags) in ticks.iter().enumerate() {
+                    mob.age = i as u32 + 1;
+                    bat::set_resting(mob, flags.as_i64().unwrap_or(0) & 1 != 0);
+                    if flag("@batInFrame") {
+                        bat::tick(mob);
+                    } else {
+                        bat::setup_animation_states(mob);
+                    }
+                }
+            }
+        }
        Species::Sheep => mob.extra.anim_ticks = num("eatTick") as i32,
        Species::Guardian | Species::ElderGuardian => {
            mob.anim.v[guardian::TAIL] = num("tailAnimation");
@@ -288,8 +304,8 @@ fn entity_state(mob: &mut Mob, species: Species, case: &Value) {
    }
 }

-fn main() -> horizon_client::Result<()> {
-    let args: Vec<String> = std::env::args().skip(1).collect();
+pub fn main() -> horizon_client::Result<()> {
+    let args: Vec<String> = crate::args().skip(1).collect();
    let root = PathBuf::from(&args[0]);
    let types = MobTypes::load(&root)?;
    let animations = MobData::load_animations(&root);
@@ -377,7 +393,7 @@ fn main() -> horizon_client::Result<()> {
            mob.extra.age = -24000;
        }
        mob.age = f("ageInTicks") as u32;
-        let state = State {
+        let mut state = State {
            pos: f("walkAnimationPos"),
            speed: f("walkAnimationSpeed"),
            age: f("ageInTicks"),
@@ -389,6 +405,20 @@ fn main() -> horizon_client::Result<()> {
        };
        let mut poses = Poses::new(&model);
        entity_state(&mut mob, def.species, case);
+        if let Some(ticks) = case["@walkTicks"].as_array() {
+            for speed in ticks {
+                mob.previous_limb_speed = mob.limb_speed;
+                mob.limb_speed += (speed.as_f64().unwrap() as f32 - mob.limb_speed) * 0.4;
+                mob.limb_position += mob.limb_speed;
+            }
+            if !case["@alive"].as_bool().unwrap() {
+                mob.health = 0.0;
+            }
+            let extracted = anim::state(&mob, f("@partial"));
+            state.pos = extracted.pos;
+            state.speed = extracted.speed;
+        }
+
        let flag = |k: &str| case[k].as_bool().unwrap_or(false);
        let num = |k: &str| case[k].as_f64().unwrap_or(0.0) as f32;
        let started = |k: &str| AnimationState {
@@ -456,14 +486,6 @@ fn main() -> horizon_client::Result<()> {
                    roll_amount: num("rollAmount"),
                },
            ),
-            Species::Bat => b_anim::bat(
-                p,
-                s,
-                flag("isResting"),
-                &started("flyAnimationState"),
-                &started("restAnimationState"),
-                &animations,
-            ),
            Species::Armadillo => b_anim::armadillo(
                p,
                s,
@@ -570,6 +592,7 @@ fn main() -> horizon_client::Result<()> {
                    pose,
                    num("maxCrossbowChageDuration"),
                    num("ticksUsingItem"),
+                    false,
                );
            }
            Species::Evoker | Species::Illusioner | Species::Pillager | Species::Vindicator => {
@@ -590,7 +613,11 @@ fn main() -> horizon_client::Result<()> {
            }
            _ => anim::setup(&mob, s, p, &animations),
        }
-        out.push_str(&format!("{}\n", emit(&model, &mut poses, case, layer)));
+        let mut result = emit(&model, &mut poses, case, layer);
+        if case["@walkTicks"].is_array() {
+            result["walk"] = json!([state.pos, state.speed]);
+        }
+        out.push_str(&format!("{result}\n"));
    }
    fs::write(&args[2], out)?;
    Ok(())
@@ -61,8 +61,8 @@ fn species(id: &str) -> Species {
    }
 }

-fn main() -> Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> Result<()> {
+    let args: Vec<String> = crate::args().collect();
    let input = BufReader::new(File::open(&args[1])?);
    let mut out = BufWriter::new(File::create(&args[2])?);
    for (n, line) in input.lines().enumerate() {
@@ -23,6 +23,7 @@ fn stack(spec: &str) -> LootStack {
        map: false,
        exploration: None,
        ominous_amplifier: None,
+        stew_effects: Vec::new(),
    };
    for e in parts {
        let (name, level) = e.rsplit_once(':').unwrap_or((e, "1"));
@@ -53,8 +54,8 @@ fn line(s: &LootStack) -> String {
    out
 }

-fn main() -> horizon_client::Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> horizon_client::Result<()> {
+    let args: Vec<String> = crate::args().collect();
    let root = Path::new(
        args.get(1)
            .ok_or("usage: entity_death_loot_fixture RESOURCES INPUT OUTPUT")?,
@@ -13,8 +13,8 @@ fn d(v: f64) -> String {
    format!("{:016x}", v.to_bits())
 }

-fn main() -> Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> Result<()> {
+    let args: Vec<String> = crate::args().collect();
    let mut out = BufWriter::new(File::create(&args[2])?);
    for (n, line) in BufReader::new(File::open(&args[1])?).lines().enumerate() {
        let c: Value = serde_json::from_str(&line?)?;
@@ -9,8 +9,8 @@ use horizon_client::{
 };
 use std::{collections::HashMap, fmt::Write as _, fs, path::Path};

-fn main() -> horizon_client::Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> horizon_client::Result<()> {
+    let args: Vec<String> = crate::args().collect();
    let root = Path::new(
        args.get(1)
            .ok_or("usage: environment_fixture RESOURCES INPUT OUTPUT")?,
@@ -154,11 +154,11 @@ const MEMORIES: [&str; 7] = [
 fn variant(m: &Mob, regs: &SpawnRegistries, v: &mut Vec<String>) {
    use Species as S;
    let s = m.species();
-    let named = |reg: &finalize::VariantRegistry, i: u8| {
-        format!(
-            "minecraft:{}",
+    let named = |reg: &finalize::VariantRegistry, i: Option<u8>| {
+        let name = i.map_or("classic", |i| {
            reg.names.get(i as usize).map_or("?", |n| n.as_str())
-        )
+        });
+        format!("minecraft:{name}")
    };
    let var = format!("minecraft:{}", finalize::variant_name(s, m.extra.variant));
    match s {
@@ -388,8 +388,8 @@ fn describe(m: &Mob, all: &[Mob], regs: &SpawnRegistries) -> String {
    t.join(" ")
 }

-fn main() -> horizon_client::Result<()> {
-    let args: Vec<String> = std::env::args().collect();
+pub fn main() -> horizon_client::Result<()> {
+    let args: Vec<String> = crate::args().collect();
    let root = Path::new(
        args.get(1)
            .ok_or("usage: finalize_spawn_fixture RESOURCES INPUT OUTPUT HALLOWEEN")?,