Fix the lobby layout test and queue merges

.claude/skills/codetrial-contribute/collaboration.md

@@ -138,11 +138,11 @@ triage's outdated ones.
 ## Make CI green before asking for review
 
 "Before asking someone to review, you MUST resolve any regressions flagged by
-GitHub Actions." (#256, #260). Open the failing `gates (<lane>)` job, not
-`check` (`.claude/skills/codetrial-verify/ci-failure.sh <pr>` names the failed
-gates and whether `main` fails them too), and rerun that lane with
-`./scripts/test.sh <lane>`
-([codetrial-verify](../codetrial-verify/SKILL.md) describes the lanes). A bad
+GitHub Actions." (#256, #260). Open the failing job, not `check`
+([codetrial-verify](../codetrial-verify/SKILL.md) says which one, and
+`.claude/skills/codetrial-verify/ci-failure.sh <pr>` names the failed gates and
+whether `main` fails them too), and rerun a failing lane with
+`./scripts/test.sh <lane>`. A bad
 commit message skips the rest of the portable lane, so fix the messages
 first.
 

.claude/skills/codetrial-triage/pulls.md

@@ -225,9 +225,9 @@ last; a stale base is a rebase request; one `main` shares, or an environment
 limit, is the maintainer's. The sweep's `status` lists them (`failing:` in
 `why`), and `ci-failure.sh` in
 [codetrial-verify](../codetrial-verify/SKILL.md#failed-github-actions-checks)
-tells those cases apart for one PR in one call. Read the failing
-`gates (<lane>)` job, not `check` or `mutation`, which only collect results ([codetrial-verify](../codetrial-verify/SKILL.md)
-describes the lanes). A failing commit-message check skips the rest of the
+tells those cases apart for one PR in one call. Read the failing job that
+[codetrial-verify](../codetrial-verify/SKILL.md) names, not `check`, which only
+collects results. A failing commit-message check skips the rest of the
 portable lane, so name it first. A second PR
 from the same author for the same change supersedes the first or is superseded
 by it; report which in the sweep output and leave the

.claude/skills/codetrial-verify/SKILL.md

@@ -15,12 +15,12 @@ make check                # every gate, plus a live Gemini credential check
 
 CI runs one `gates (<lane>)` job per lane in parallel: `gates (rust)`,
 `gates (portable)` and `gates (browser)`. The `check` job only collects their
-results and `mutation` does the same for the mutant shards, so neither log
-says what failed: open the failing lane, or the failing `mutants` shard when
-`mutation` is the red one. On a pull request the portable lane
-checks the commit messages first, and a bad message skips the rest of that
-lane only. A gate names its lane where it is declared, one naming none is
-portable, and a test proves the three lanes together cover the full run.
+results and the mutation jobs', so its log does not say what failed: open the
+failing lane, or, when every lane is green, the failing `plan-mutants` job or
+`mutants` shard. On a pull request the portable lane checks the commit
+messages first, and a bad message skips the rest of that lane only. A gate
+names its lane where it is declared, one naming none is portable, and a test
+proves the three lanes together cover the full run.
 Reproduce a failure with the same lane locally.
 
 `scripts/test.sh` is a list of named gates that all run before it reports, so
@@ -130,7 +130,7 @@ regression check in the existing lane.
 
 ## Failed GitHub Actions checks
 
-The lanes and the aggregate `check` and `mutation` jobs are described above;
+The lanes and the aggregate `check` job are described above;
 telling a stale base, a regression, a race and an environment limit apart is in
 [collaboration.md](../codetrial-contribute/collaboration.md#make-ci-green-before-asking-for-review);
 reading the job log, and why it is `--log`, is the recipe in
@@ -152,9 +152,9 @@ locally with the same head. A `cargo-audit` failure on a PR whose base predates
 the advisory fix is a stale base, answered by a rebase (#334), not a code
 change; `stale_base` (defined in the script's header) says exactly that, and
 the PR sweep lists such a PR in `rebase` on its own. The aggregate `check` job
-only collects the lanes, so its entry points at the failing `gates (<lane>)`
-one. A check outside Actions has only its link, and `held` checks have no log
-until a maintainer approves the run.
+only collects results, so its entry points at the failing job it collected,
+as in the lanes section above. A check outside Actions has only its link, and
+`held` checks have no log until a maintainer approves the run.
 
 The raw calls behind it, when one answer needs checking:
 

.claude/skills/codetrial-verify/ci-failure.sh

@@ -151,11 +151,11 @@ failing=$(printf '%s\n' "$checks" | jq -r "$defs"'.[] | select(failed)
           | if $read then . else .gates = null | .errors = null | .excerpt = null end'
     done | jq -s .)
 
-# The check job only collects the lanes, so it says nothing of its own. A
-# failing check outside Actions (cubic) has no gates to read, so a rebase is not
-# known to clear it, and it rules a stale base out. Each gate that reads data
-# from outside the tree maps to the files whose change would make the failure
-# the PR's own; a gate added here needs nothing else.
+# The check job only collects the lanes and the mutation jobs, so it says
+# nothing of its own. A failing check outside Actions (cubic) has no gates to
+# read, so a rebase is not known to clear it, and it rules a stale base out.
+# Each gate that reads data from outside the tree maps to the files whose change
+# would make the failure the PR's own; a gate added here needs nothing else.
 printf '%s\n' "$checks" | jq --argjson failing "$failing" --arg head "$head" \
     --argjson pr "$pr" --argjson meta "$meta" --argjson jobs "$main_jobs" \
     "$defs"'

.claude/skills/codetrial-verify/review.md

@@ -101,7 +101,7 @@ report what it reports. For each area, look for:
 - Ordering. A resume racing the message it replays, a check then an act across
   an await, a message handled before the state it assumes.
 - Tests. A new branch no test reaches; a surviving mutant in code the diff adds
-  (CI's mutation job names them, as on #262; it is skipped when the diff
+  (CI's `mutants` shards name them, as on #262; it is skipped when the diff
   changes no Rust, so `web/` code has no mutation evidence and each new branch
   needs a test that reaches it); a browser test of the shapes
   [SKILL.md](SKILL.md) says reviewers reject (Writing a test).
@@ -200,7 +200,7 @@ Past about 500 changed lines, or when several reviewers are run, split them
 by lens rather than by file, each reading the whole diff for one thing: the
 specification checklist; the owners in step 2; trust boundaries, workflows and
 what reaches a log or a public thread; failure paths and boundaries; tests,
-including what CI's mutation job says survived; and comments and messages
+including what CI's `mutants` shards say survived; and comments and messages
 against the register in
 [codetrial-conventions](../codetrial-conventions/SKILL.md). A reviewer handed a
 lens reports only that lens, so silence on the others is not a pass.

.github/actions/chromium/action.yml

@@ -0,0 +1,27 @@
+name: Install Chromium
+description: Restore Playwright's Chromium and install its system libraries.
+
+# The browser binary, not the npm package. package-lock.json pins the
+# playwright version, and the version is what decides which build of Chromium
+# lands in this directory. Needs `npm ci` first, since it runs that playwright.
+#
+# The install is one command on a cache hit too: it then only installs the
+# system libraries, which are not in the cached directory. Without it the
+# browser suites skip themselves and the gate passes while testing nothing.
+outputs:
+  key:
+    description: The exact key, for the step that saves the browser.
+    value: ${{ steps.restore.outputs.cache-primary-key }}
+  cache-hit:
+    description: Whether the exact key was restored.
+    value: ${{ steps.restore.outputs.cache-hit }}
+runs:
+  using: composite
+  steps:
+    - id: restore
+      uses: actions/cache/restore@v6
+      with:
+        path: ~/.cache/ms-playwright
+        key: playwright-${{ runner.os }}-${{ hashFiles('package-lock.json') }}
+    - shell: sh
+      run: npx playwright install --with-deps chromium

.github/actions/restore-vendor/action.yml

@@ -0,0 +1,31 @@
+name: Restore vendored bytes
+description: Restore the web/vendor tree the portable lane saves.
+
+# One definition of the key for every job that reads this cache: the gate
+# lanes, the mutation shards, the release legs and the avatar check.
+#
+# Keyed on the whole tree, not on SHA256SUMS alone. The cached path holds the
+# committed vendor files as well as the fetched ones, so a key that only reads
+# the pins is unchanged when a committed file is edited: the restore then puts
+# the old bytes back over the edit and verify-vendor passes on content the pull
+# request does not contain. Hashing the tree costs a re-fetch when a README
+# under web/vendor changes, which is the cheaper side of that trade.
+#
+# At restore time the directory holds only checked-out files, so the key is a
+# function of the commit. No restore-keys: a stale entry here is 24 MB of bytes
+# that fail their hash.
+outputs:
+  key:
+    description: The exact key, for the step that saves the tree.
+    value: ${{ steps.restore.outputs.cache-primary-key }}
+  cache-hit:
+    description: Whether the exact key was restored.
+    value: ${{ steps.restore.outputs.cache-hit }}
+runs:
+  using: composite
+  steps:
+    - id: restore
+      uses: actions/cache/restore@v6
+      with:
+        path: web/vendor
+        key: vendor-${{ hashFiles('web/vendor/**') }}