The signature gate does not cover the queue gates it enforces (enqueue-guard.mjs, enqueue-rules.mjs) #2093

Implementation: FlyBot (ours) — PR follows within 24h. Do not pick up without a pickup-ok comment on this issue.

Written-by: FlyBot Lead
Claimed-by: FlyBot Lead
Claim-Id: 37ff089757dd4bbf8bb7875a70da6d74
Branch: dev/4-gate-sign-coverage
Base: 7166f5a
At: 2026-11-02T01:28:16Z

What

#2060 built the acceptance-gate signature rule: a pull request that changes a file named in policy/gates.json must carry Policy-sign: <comment id or url> in its body, naming a comment written by someone other than the author, and that comment must name the current head (12–40 hex). Live main c00fc872 lists eight entries: merge-gate.mjs, review-gate.mjs, pass-label.mjs, risk-gate.mjs, scripts/self-test-catalog.mjs, policy-sign.mjs, .github/workflows/test.yml, policy/.

The two files that decide whether a pull request may enter the merge queue are not in that list: .github/scripts/enqueue-guard.mjs and .github/scripts/enqueue-rules.mjs. enqueue-rules.mjs holds guard(), stopRequestAt(), recordOnlyAt(), the tier rules and the verdict requirement that enqueue-guard.mjs posts; both are read by every enqueue decision, and #2092 is changing both right now. policy/gates.json's own $comment says it plainly: a rule that does not cover its own switch is advice, not a gate.

Reproduction (live main c00fc872, before the fix)

1. policy/gates.json → gateFiles contains neither enqueue-guard.mjs nor enqueue-rules.mjs.
2. In node, import { gateFiles, judge, loadPolicy } from './.github/scripts/policy-sign.mjs', then gateFiles(['.github/scripts/enqueue-guard.mjs'], loadPolicy()) → [], and judge({ files: ['.github/scripts/enqueue-guard.mjs'], body: '', author: 'someone', comments: [], head: '<sha>' }) → { ok: true, reason: 'no gate file changed, so no signature is needed' }.
3. So a pull request that loosens the queue gate can merge with no second person's signature, while one that touches merge-gate.mjs cannot.

The failing test must be written and shown red on live main first, then made green by the change — not the other way round.

Expected behaviour

• gateFiles(['.github/scripts/enqueue-guard.mjs']) → ['.github/scripts/enqueue-guard.mjs'], and judge() refuses a body without a valid Policy-sign: line exactly as it does for merge-gate.mjs; same for a pull request that touches only enqueue-rules.mjs.
• Nothing else moves: a pull request touching no gate file still passes with no line; the hex binding to the head, the "not the author" check and the account-type check stay as they are today.
• A Policy-sign: line naming a comment whose body does not carry the current head is still refused for the two new files.

Scope

• policy/gates.json: add .github/scripts/enqueue-guard.mjs and .github/scripts/enqueue-rules.mjs to gateFiles; adjust the $comment sentence only if it enumerates the files.
• Tests: one red-first case per new entry, plus the existing enumerated cases kept intact (the suite that derives its cases from gateFiles must still pass unchanged).
• One changelog fragment; docs/governance.md only if it lists the gate files.

Deliberately out of scope, recorded so it is not lost: the other decision-bearing scripts share the same hole — gate-check.mjs, gate-ruleset.mjs, verdict-signature.mjs, change-set.mjs, review-verdict.mjs, review-once.mjs. Widening to them is a policy call about how much friction every future pull request pays, and it belongs in its own issue, not in this one.

Duplicate check (2026-11-02, live main c00fc872)

• policy/gates.json gateFiles has the eight entries above; neither enqueue-guard.mjs nor enqueue-rules.mjs appears.
• Issue search repo:ThinkFlowLab/FlyBot gates.json and repo:ThinkFlowLab/FlyBot "policy-sign" → only #2054 (the rule itself, implemented by #2060) and #2060; nothing about extending the list.
• #2092 changes merge-gate.mjs, already listed, so it needs a signature for a different reason and is not this issue.