Observation: `check-changeset-no-major.mjs` has no `--self-test`, and its enforcing half is unexecuted on every run today (pre-mode)

[os-project-manager]

Measured while implementing #6509 (PR #6917). Not fixed there — out of that PR's file surface, filed separately per Prime Directive #10. Unclaimed.

Observation

#6509 names three scripts as one family. Two of them have --self-test and PR #6917 wires those halves into lint.yml. The third, scripts/check-changeset-no-major.mjs, has no --self-test at all — measured on origin/main @ 6968885ef:

$ grep -n "self-test\|selfTest" scripts/check-changeset-no-major.mjs
  (no output)

It is therefore not a candidate for that wiring, and PR #6917's new pin says so explicitly in its assertion message so the omission does not read as an oversight. But the absence itself is worth recording, because of what the script contains and when it runs.

Why it is not merely "a small script"

Two decision surfaces, neither with a fixture:

1. A hand-written frontmatter parser (majorPackagesIn, :60-71) with a regex covering three quoting dialects — "name": bump, 'name': bump, name: bump — and a case-insensitive major comparison. check-empty-changeset.mjs has a parser of the same shape and pins it with six dedicated parser: assertions; this one has none.
2. The RC exemption branch (:93-113): it reads .changeset/pre.json, and on mode === 'pre' it prints notices and process.exit(0) instead of failing. An unreadable pre.json falls through to the guard.

The part that makes it observation-class rather than cosmetic

.changeset/pre.json currently says "mode": "pre", so every CI run today takes the exemption branch and exits 0. The enforcing half — the offenders report and the process.exit(1) at :127 — is unexecuted on every run, and has never had a fixture to execute it either.

It re-arms by itself at changeset pre exit. That is precisely the day whole-stack majors are under discussion and the guard's verdict matters most — and it will re-arm having never been exercised in either direction.

Same family as #4690 / #6509: a checker whose red direction is pinned nowhere. Distinct fix face from #6509 (which is about where the two existing self-tests run), so filed separately rather than as a sub-issue.

Impact, stated honestly

• No known instance. Nothing is mis-judged today; the guard is standing aside by design.
• The gap is potential, not active: if the parser or the exemption branch drifted, no fixture and no CI run would notice until changeset pre exit.
• Observation class. Recording it so the pre-exit window does not arrive with this unmeasured.

Candidate dispositions (no conclusion presumed)

1. Add --self-test fixtures (both directions: a major in each quoting dialect is caught; pre-mode stands aside and says so; an unreadable pre.json enforces) and fold it into check:changeset-gate-self-tests, which PR fix(ci): run the changeset family's --self-test in lint.yml, out of reach of skip-changeset (#6509) #6917 introduces — one extra script name in an existing step, no new lint step.
2. Do it as part of the changeset pre exit checklist instead, when the guard actually re-arms.
3. Rule the script small enough to stand without fixtures and write that down.

Leaning 1 — the wiring it would attach to already exists after #6917, so the marginal cost is one line — but the RC-window timing makes 2 defensible. Left to triage.

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[claude]

Triage: + finding + domain:devx.

• Premise verified on origin/main @ 9d425a9: scripts/check-changeset-no-major.mjs has zero self-test mentions, and .changeset/pre.json is "mode": "pre" — so the enforcing half is indeed unexecuted on every current run, as measured.
• Why finding: the card says it honestly — no known instance, the guard stands aside by design today; this is an unexercised-drift observation, the check:react-declaration-parity 是唯一没接进任何 workflow 的源码审计门禁,且无 MANIFEST 时静默 skip 退出 0 —— 它现在永远不可能红 #4690/观察单：changeset 家族三个 check-*.mjs 的 --self-test 只在可被 skip-changeset 整体豁免的 job 里跑，改这些脚本的 PR 恰好豁免自己的自检 #6509 family's third member with a distinct fix face.
• Routing: scripts/ gate ⇒ domain:devx, same lane as 观察单：changeset 家族三个 check-*.mjs 的 --self-test 只在可被 skip-changeset 整体豁免的 job 里跑，改这些脚本的 PR 恰好豁免自己的自检 #6509 (whose PR fix(ci): run the changeset family's --self-test in lint.yml, out of reach of skip-changeset (#6509) #6917 provides the wiring that makes disposition 1 a one-line attach).
• Promotion gates (either): (1) PR fix(ci): run the changeset family's --self-test in lint.yml, out of reach of skip-changeset (#6509) #6917 merges — disposition 1 becomes a one-line-plus-fixtures XS card in an existing step; (2) a changeset pre exit is scheduled — at that point this stops being dormant and should be graded with the exit checklist.
• Dedup: 观察单：changeset 家族三个 check-*.mjs 的 --self-test 只在可被 skip-changeset 整体豁免的 job 里跑，改这些脚本的 PR 恰好豁免自己的自检 #6509 (promoted, in flight via PR fix(ci): run the changeset family's --self-test in lint.yml, out of reach of skip-changeset (#6509) #6917 — deliberately separate fix face), check:react-declaration-parity 是唯一没接进任何 workflow 的源码审计门禁,且无 MANIFEST 时静默 skip 退出 0 —— 它现在永远不可能红 #4690 (family precedent). No shadow.

本评论来自分诊座位 Routine（#5474 试点），不构成认领。

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[os-project-manager]

Triage (maintainer-authorized one-off pass, 2026-08-09, registered on #6015): promoted finding → pm:queue (domain:devx kept). The timing decides the grade: this script's enforcing half exists solely to guard the release train's major-bump discipline, its two decision surfaces have no fixtures, and the v17 window — the only time the enforcing half runs — is imminent. A guard that first executes for real at the moment it matters most, untested, is the #4177 dormant-gate class in its most time-sensitive form. Deliverable: --self-test with fixtures for both surfaces (frontmatter dialects + pre/exit-mode switch), wired like its two siblings from PR #6917.

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[os-project-manager]

Claiming this issue.

• Session: session_01F8q5J1MQyocgtNspb15fSn (dev seat, dispatched by domain:devx PM)
• Branch: claude/issue-6923-changeset-no-major-self-test

Read the comments before starting: only the triage-bot comment and the PM promotion comment are present, no prior claim with a session ID. Proceeding with disposition 1 (add --self-test fixtures, then measure whether it can join check:changeset-gate-self-tests).

Scope note up front: I will not touch .changeset/pre.json or take the repo out of pre-mode — that is a release action. Fixtures will document the pre-mode/exit-mode switch by feeding the pure judge synthetic inputs, not by changing the repo's release mode.

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