fix(pm): give the clause-② declaration limb a self-solvable exit - #17738

Fixes #17366

The defect: a carrier a seat could write into and not get out of

The clause-② declaration limb had one carrier — the Clause-②: line inside the card's
governing Claim: comment — and repairing a line already written there was not an act every
seat can perform. The MCP GitHub tool set carries no edit-an-issue-comment call; the claim
protocol forbids a second Claim:; and this gate's own refusal forbids the checker filling
the line in ("the declaration IS the judgement"). Three closed doors, and a seat that wrote
the line as prose was left waiting for somebody outside the repository to retype it.

That was measured five times in one shift across two roles, and the fifth instance was still
holding a PR with 38 checks and 0 failures out of the queue when the card was filed.

The fix: one correction comment, read by the same reader

A dedicated comment whose FIRST line is a fixed key naming, in digits, the claim comment it
corrects:

Clause-②-correction: 5642248126
Clause-②: no
Session: `session_01MCLBsUgfykL74aU716rzVK`

The newest correction naming the card's governing claim supersedes that claim's declaration,
in both directions — so a wrong VALUE is repaired by the same act as an unreadable one. The
declaration inside it is read by the SAME CLAUSE2_KEY_LINE through the SAME
readClause2Line, so what moved is WHICH COMMENT may carry the declaration, never what counts
as an answer. That is the move #16304 already made when it asked a sibling CARD.

Attribution is the Session: line the claim protocol already makes mandatory
(SKILL.md 〈模板与表〉, 「session ID 不可省」, and 「mode:subagent 的 dev 与 PM 同会话同 ID」 —
so the session is exactly the granularity of "the claiming seat"). A correction is attributed
when its Session: equals the governing claim's. That is a DECLARED identity, never a verified
one: the value is copyable text and this fleet writes under one GitHub login, so the comparison
is on what the comments SAY — the same ceiling C4 already works at.

⛔ No branch of it may become a new one-way door, which is the defect being removed. A
correction naming another comment, declaring a different session, carrying no Session: line,
or carrying a prose declaration is IGNORED WITH A PRINTED REASON that names an act the claiming
seat can perform. And a governing claim that carries no Session: line at all leaves nothing to
compare: the correction APPLIES, with a note saying attribution could not be verified and why.
Refusing there would have rebuilt the door one room over.

The C2 remedy text was rewritten to name WHO can act and HOW, in three parts: the claim template
in SKILL.md 〈模板与表〉 that already carries the literal Clause-②: yes | no line and should be
copied rather than composed; the fact that an already-posted claim comment is not editable from
every seat; and the one comment that repairs it. It replaces "add the line to that claim comment",
which named an act the claiming seat may have no tool for.

What deliberately did not move

• The accept set. CLAUSE2_KEY_LINE, readValueToken and CLAUSE2_VALUES are untouched. The
  card's five measured prose spellings are pinned as negatives in the self-test.
• The exit register. The correction is a new INPUT to C2, not a new verdict family. 0/1/2/3/4
  keep their meanings and their numbers.
• check-half-states.mjs. CLAIM_COMMENT_MARKER is still imported, not restated, and not
  widened. A correction is not a claim comment and never enters the claim pool.
• SKILL.md. The template already carries the fixed line; this PR points at it and does not
  restate it.
• The writes. This script still writes nothing, hangs no label, and reads no verdict word.

Acceptance, all four from the card

1. A seat writing per the template gets a machine-readable declaration. Pinned by importing
   the reader over the template's own key with each value substituted, plus the new remedy text
   that sends the seat to the template rather than to a regex.
2. The negative control holds. All five measured spellings from the card's table are pinned
   as not-declared, from the line reader and from a claim comment. The #1 spelling is reported
   as a SPELLING near miss; the #2–#5 spelling reaches no pattern at all, because 条款② carries
   no Clause token — pinned as a measured fact.
3. Self-solvability is pinned. A card whose claim declaration is unreadable earns a C2 finding;
   adding ONE correction comment clears it, with the claim comment byte-identical across the two
   threads, no second Claim:, and the governing claim unmoved. Demonstrated end to end through
   the offline --pair-json path: --pair exit 4 with the broken claim, exit 0 with the one
   comment added.
4. Ablation. Deleting the correction reading reds 22 of 465 self-test cases (every criterion-3
   case); deleting the template pointer and the who-can-act remedy reds 7 (criterion 1's new half).
   Both legs were mutated on disk, proved to have landed, then restored to a blob hash equal to
   HEAD's.

Acceptance notes

• ⚠️ Measured and pinned as a CONTROL, not endorsed and not fixed here: the template line copied
  UNFILLED — Clause-②: yes | no — reads as a declared yes, because readValueToken takes the
  first token after the colon and treats the rest as the seat's argument. That is an instance of
  the population [finding] check-clause2-carriers reads a key-INITIAL describing line as a declaration — its own self-test asserts the general property "only DESCRIBES ⇒ MISSING", and the fixture pinning it covers only the other half #17098 is already open against (a key-INITIAL DESCRIBING line read as a
  declaration), so it is ⛔ not filed again here. The case carries a pre-registered FLIP TRIGGER:
  when [finding] check-clause2-carriers reads a key-INITIAL describing line as a declaration — its own self-test asserts the general property "only DESCRIBES ⇒ MISSING", and the fixture pinning it covers only the other half #17098 lands, the expectation becomes kind !== 'declared' and the case flips with it in
  that PR. ⛔ It is not to be deleted and its green today is not an endorsement.
• The PR-body carrier of Clause-②: is read by scripts/check-changeset-no-major.mjs, not by this
  gate: --pair reads the PR side for LABELS (C1) only, and no readClause2Line call here takes a
  PR body. The card-side correction shape therefore has no PR-side counterpart to add, and the
  PR-body carrier is editable by the seat anyway — which is exactly the asymmetry the card names.
• check-scripts-symbol-anchors, check-self-test-wired and check-self-test-workflow-commands
  all pass unchanged: the check:pm-clause2-carriers step in lint.yml already runs the self-test,
  and no second step was added.

Gates, on head dbbfbb596

node scripts/pm/dispatch-gates.mjs --commands derives 35 families for this one-path diff; all 35
ran and all 35 exited 0 (--ran reconciliation: "35 derived famil(ies) accounted for — 35 run, 0
NOT-MEASURED (a DERIVED zero — all 35 recorded an exit code and none of them is 3)"). Lint is the
declared narrowing rather than the repo-wide run CI owns: the receiving population is
eslint.config.mjs's base block (files: ['**/*.{ts,tsx,mts,cts,js,jsx,mjs,cjs}']), --format json reports 1 file linted with 0 errors and 0 warnings, and the config "never enables type-aware
linting (no parserOptions.project, no typed @typescript-eslint rules) for ANY file"
(eslint.config.mjs, its own words) — so this diff cannot move the verdict on any file it does not
touch. node scripts/pm/check-governed-merges.mjs --test scripts/pm/check-clause2-carriers.mjs
prints "✅ NOT governed — ordinary queue landing applies". --pair 17738 exits 0.

Generated by Claude Code

Generated by Claude Code