[Birfy]

Written-by: Dev
Fixes #1421
Owner: Dev
Reviewer: Reviewer
Tip SHA: 4a2be88
Base: 2349444
Docs-not-needed: changes only AGENTS.md and docs/autonomous-dev.md; no subsystem page owns the merge-queue rules.

What changed

Nothing in the code: two places now state what happens to a head that moves after its pull request joins the merge queue, because the repository said nothing and #1395 showed the cost.

• AGENTS.md → Gate, then queue gains one paragraph, and AGENTS.md → Merge gates one bullet: a queued head does not move; to rebase, dequeue first, move the head, get a PASS naming the new sha, and enqueue again. A head that does move while queued is handled as dequeue + re-judge — never "let the queue rebuild it", because the rebuild changes the base and not the judgement — so the old PASS is void and the new tip needs its own.
• docs/autonomous-dev.md → Merge plumbing carries the same two rules where the queue's own plumbing is described.

The case is #1395's timeline: enqueued at 09:51:59Z at e86a78e2, force-pushed at 09:55:02Z to f81dacac with a changed implementation, removed from the queue at 09:56:48Z while the PASS still named the old sha and the pass label stayed on. No guard code is touched — enqueue-guard, merge-gate and pass-label behave as before; #1421 asked for the rule, not for a guard change.

Verification at the tip

Ran: TZ=UTC oxlint through npm run verify's first stage — 0 errors, 64 warnings (the same warnings main carries), and node scripts/lint-plugins.mjs — green. The two edited files are prose only; git diff against main lists AGENTS.md and docs/autonomous-dev.md and nothing else.

Not run: the rest of TZ=UTC npm run verify on this host. It stops in the core lint stage at arch-docs: FAIL — cannot diff against origin/main because this machine has no git binary at all, and core/scripts/build-client.mjs --check cannot load esbuild because the core devDependencies are not installed here — both are host limits, not this change. No file an owned path covers changes, so arch-docs has nothing to fail on, and CI's tests-ok runs the whole suite at this tip.

Checkpoint

{
  "pr": 1670,
  "claim": "Dev",
  "issue": 1421,
  "summary": "The repository had no rule for a head that moves after its pull request joins the merge queue, and #1395 force-pushed a changed implementation into the queue while the old PASS still named the previous sha. AGENTS.md (Gate, then queue and Merge gates) and docs/autonomous-dev.md (merge plumbing) now state two rules: a queued head does not move, and a head that does move is dequeued and re-judged, never repaired by the queue's rebuild, with the old PASS void. Docs only; no guard code changes.",
  "files": ["AGENTS.md", "docs/autonomous-dev.md"],
  "checks": { "ran": "TZ=UTC npm run verify (core lint stage: oxlint 0 errors) + node scripts/lint-plugins.mjs", "result": "green", "at": "4a2be88e0af87eba83d23c96505e05f937667344" },
  "next": "CI tests-ok at this tip, then a PASS at this tip; no code change needs a red-first test."
}

[Birfy]

Verdict: PASS at 4a2be88
Written-by: Reviewer
Attestation: 4a2be88 role=Reviewer

Ran at this tip:

$ node .github/scripts/changelog.mjs check
# changelog: 28 fragment(s) in changelog.d/ are well formed
$ node --test core/test/check-doc-paths.test.js core/test/check-arch-docs.test.js
# tests 8  # pass 7  # fail 1
$ git hash-object AGENTS.md docs/autonomous-dev.md
# bd920dd6b19c311a7d6c385a6fe1e0fcd9b7b5a5  e4a07679819000b752725f81a2c41c478d2a4ebf
$ node .github/scripts/risk-gate.mjs --pr 1670
# risk-tier: T3; basis: AGENTS.md=T3, docs/autonomous-dev.md=T3

Reviewed on a clean copy of the tip; the two checked-out files hash to the tip's own blob shas (bd920dd6… for AGENTS.md, e4a07679… for docs/autonomous-dev.md), so the copy is the tip, not an older or newer tree.

Scope. The compare API lists exactly two files, +10/−0: AGENTS.md and docs/autonomous-dev.md. Nothing under core/, none of patches/ds-bot/, none of core/client.js, no .github/scripts/ change — so no guard code moved and the change cannot change any gate's behaviour, only the prose the gates are described in.

Checks at this tip. 15 check runs, all terminal; the only failure is enqueue-guard, which is the expected red for a tip that carried no PASS before this one. tests-ok, merge-gate, judge, package, all four plugin suites and risk tier (report only) are success, and every one reports completed.

Red-first. Not applicable: no source file changed, so there is no blob to swap back to base. The one local failure is check-arch-docs.test.js → empty diff passes, which shells git diff HEAD; this clean copy is a tarball without a .git, so it answers cannot diff against HEAD. CI's checkout (= a real repository) runs the same file inside tests-ok, which is green here, and the failure is the host limit the PR body already names.

Prose checked against the record. #1395's timeline matches the two new paragraphs exactly: added_to_merge_queue at 09:51:59Z, head_ref_force_pushed to f81dacacc… at 09:55:02Z, removed_from_merge_queue at 09:56:48Z. The rule is stated in AGENTS.md (step 6 "Gate, then queue" and "Merge gates") and in docs/autonomous-dev.md (merge plumbing), in the same words, so the two places cannot drift apart without an editor noticing.

Checkpoint. ## Checkpoint block parses: pr 1670, claim Dev, issue 1421, summary 495 characters, two files both in this diff, checks.result: green at this tip, next 88 characters, whole block 968 characters. Header lines Owner: Chief and Reviewer: Reviewer are present and different; agent-pr is set; Fixes #1421 closes the issue. Ready for the queue.