docs(skills): cw-land lands on main, with the pre-push drift checks

The engine's cw-land still offered worktrees and integration branches as
landing shapes, and said not to push without explicit authorization.
That contradicts AGENTS.md since 2026-10-08: one canonical checkout on
main, no maintainer branches or worktrees, and verified slices are pushed
directly. codewhale-ops/skills/cw-land defers to this file for Engine
specifics, so the stale copy was the one agents read.

- Landing shape: the canonical checkout's main, stage only your paths,
  push verified main.
- The four cheap checks that have turned main red most often (fmt,
  sync-changelog --check, release/check-versions.sh, runtime-contract
  budget), plus the path-specific ones. New CHANGELOG entries go at the
  top of [Unreleased]: our appends at the end conflicted with open
  contributor PRs (#7013 went DIRTY twice that way).
- A contributor branch that conflicts only because main moved is
  resolved on their branch with merge-tree, commit-tree and a refspec
  push, which needs no local branch. This replaces the integration-branch
  fallback, with the zsh `${sha}:refs` pitfall noted.
- Before a merge, list PRs based on the source branch (root AGENTS.md).
- The worktree cleanup step is dropped. The red flag now limits only
  tag, release, publish and deploy.

Docs only; every script path named was checked to exist.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01NBKbhx19BRbZtvWK8rVKjz

docs/skills/cw-land/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: cw-land
-description: "Use when turning verified Codewhale work into commits, branches, or a merge: choosing direct-main vs. worktree vs. integration branch, preserving contributor credit, and honoring the gate artifact before merging."
+description: "Use when turning verified Codewhale work into commits on main and pushing them, or merging a contributor PR: staging only your paths, the pre-push drift checks, preserving contributor credit, and honoring the gate artifact before merging."
 ---
 
 # cw-land
@@ -24,26 +24,35 @@ Stage 5 of the loop: [cw-orient](../cw-orient/SKILL.md) →
 
 ## Workflow
 
-1. **Choose the landing shape.**
-   - **The checkout that already exists** is the default. Direct to `main` is
-     permitted for a small coherent change when that checkout is current and
-     owns the affected files; when several agents share it, partition by file,
-     stage only your paths, and retry a commit that fails on `index.lock`.
-     Local commit permission never implies push, merge, tag, release, or
-     deploy permission.
-   - **No maintainer PR branches** (`AGENTS.md`): verified slices land on
-     `main` directly and hosted CI runs there. PRs are for contributors.
-   - **A worktree** is for a lane that genuinely conflicts with the dirt you
-     found in [cw-orient](../cw-orient/SKILL.md), or an experiment you may
-     throw away — not for parallel agents on the same lane.
-   - **An integration branch** (`integration/<topic>-<pr>-<date>`) is for
-     resolving a contributor PR that conflicts with a moving `main` when you
-     cannot push to their fork. It leaves their branch untouched.
+1. **Land on the canonical checkout's `main`.** `AGENTS.md` owns this: no
+   maintainer PR branches, worktrees, nested clones or integration lanes.
+   Several agents share the checkout, so partition by file, check
+   `git status` before staging, stage only your paths (never `git add -A`),
+   and retry a commit that fails on `index.lock`. Push verified `main`
+   directly; hosted CI runs there. PRs are for contributors.
 
 2. **Commit narrow and build-green.** One coherent change per commit; the tree
    builds at every commit. Put the real verification in the message — actual
    pass/fail counts, not "tests pass".
 
+   Before every push, run the cheap drift checks that have turned a green
+   `main` red most often. They take seconds:
+   ```bash
+   cargo fmt --all -- --check
+   sh scripts/sync-changelog.sh --check        # after any CHANGELOG.md edit
+   bash scripts/release/check-versions.sh
+   python3 scripts/check-runtime-contract-budget.py
+   ```
+   Add the one that matches what you touched: `check-tui-locale-parity.py`
+   and `check-tui-product-vocabulary.sh` (locale strings),
+   `check-dead-code-budget.py` (`#[allow(dead_code)]`),
+   `check-blocking-calls-budget.py` (async code),
+   `check-readme-translations.py` and `check-readme-locales.sh` (READMEs),
+   `node web/scripts/derive-facts.mjs && node web/scripts/check-facts.mjs`
+   (public facts). Put a new CHANGELOG entry at the **top** of
+   `[Unreleased]`. Open contributor PRs append at its end, and an entry of
+   ours there conflicts with every one of them.
+
 3. **Preserve credit mechanically, not just politely.** Commit authorship and
    `Co-authored-by:` trailers must use the contributor's own GitHub-linked
    address — GitHub reads neither `.github/AUTHOR_MAP` nor `.mailmap` for the
@@ -77,8 +86,13 @@ Stage 5 of the loop: [cw-orient](../cw-orient/SKILL.md) →
      one side whole, then re-insert the other side's additions at their
      original anchor; when the conflict doesn't fit that pattern, resolve it
      however is correct and let the compiler judge.
-   - `maintainerCanModify` does not guarantee push access to the fork. When the
-     push is refused, land the resolved merge on an integration branch here.
+   - Resolve on their branch without creating a local branch. Build the merge
+     commit with `git merge-tree --write-tree origin/main <pr-head>` and
+     `git commit-tree <tree> -p <pr-head> -p origin/main`, then push it with
+     `git push <fork-url> "${sha}:refs/heads/<their-branch>"`. In zsh, write
+     `${sha}`, not `$sha:refs`, because `:r` is a history modifier.
+     `maintainerCanModify` does not guarantee that the push is accepted. When
+     the fork refuses it, ask on the PR. Harvesting is the last resort.
    - **Check the contribution gate before assuming a PR is stalled.** An
      unlisted author's workflow runs sit at `action_required` and never start,
      so the PR looks abandoned when nobody has actually looked at it. Approve
@@ -93,17 +107,15 @@ Stage 5 of the loop: [cw-orient](../cw-orient/SKILL.md) →
 
 6. **Merging under a gate.** `AGENTS.md` ("Merging under a gate") owns this:
    the artifact must literally say PASS, the review thread outranks the check
-   rollup, and ambiguity blocks the merge — never the reverse.
-
-7. **Clean up your own lane.** When a worktree you created lands on `main`,
-   remove it (`git worktree remove <path>`) and delete its merged branch.
-   Leave other writers' worktrees alone; `git worktree list` shows them.
-   Worktree sprawl was a 560 GB problem here once.
+   rollup, and ambiguity blocks the merge — never the reverse. Before you
+   merge, list the open PRs whose base is the PR's source branch
+   (`gh pr list --base <branch>`) and retarget them first. Otherwise they
+   close when that branch goes away.
 
 ## Red flags / don't
 
-- Don't push, merge, tag, create a release, or deploy without explicit
-  authorization. A local commit is not permission for any of those.
+- Don't tag, create a release, publish, or deploy without explicit
+  authorization. Pushing verified `main` is allowed; it is none of those.
 - Don't rewrite published history, retag a release, or force-push a shared ref.
 - Don't commit `AGENTS.md` / `CLAUDE.md` operator controls that live outside the
   product repository into a public repo.
@@ -117,8 +129,8 @@ Stage 5 of the loop: [cw-orient](../cw-orient/SKILL.md) →
 
 ## Output
 
-- The landing shape you chose and why (direct main / worktree / integration).
-- Commit SHAs, branch name, and whether the branch is local-only or pushed.
+- Commit SHAs, the paths committed, the drift checks run, and the resulting
+  `origin/main` SHA.
 - The credit trailers applied and to whom.
 - The gate artifact's literal verdict at merge time, if a gate applies.
 - Exactly which public actions you took, and which you deliberately did not.