Trimming Chain-of-Thought Leakage

Chain-of-thought leakage is prose whose vantage is the authoring session rather than the repository: it cites artifacts only that session could see, narrates the change instead of the state, or argues with a reviewer who has left. The fix is never deletion alone when a passage carries factual clauses — restate each so it stands at HEAD, then delete the transcript around it; a passage carrying none (an audit code, control-flow narration) is deleted outright. REQUIRED BACKGROUND: dev-prose-standard owns the complete-proposition rule this skill applies. It is guidance, not a script.

The one test

For every suspect passage ask: could a reader at HEAD, with no access to any session transcript, PR thread, or uncommitted draft, resolve every reference and verify every claim? If no, restate the surviving facts from the repository's vantage and delete the rest. If yes, it is not leakage, however historical it sounds — but resolvability only clears this skill's bar: on current-state surfaces (READMEs, docs, JSDoc) a resolvable change story is still change narration, and class 3 routes it to its sanctioned home.

Taxonomy

1. Dead design-session citations — (decision 7), (audit C2), design §4.7, plan §1.4, phase labels (T4, W3, P-I), "the design ledger", "(B ruling)". If the decision has a committed owner, cite it by name and path; otherwise delete the citation and restate its factual clause to stand alone.
2. Stack and PR vantage — "a later PR in this stack", "this PR adds", "the previous commit". State the shipped mechanism or the extension point; deferred work moves to a TODO marker or an issue reference.
3. Change narration and version stamps — "used to", "no longer", "the old X", and indexical stamps ("v1", "this cut", "today", "now" contrasting with a past state). State the present behavior; a fixed regression becomes a present-tense counterfactual ("without X, Y happens"), never repo history ("used to Y").
4. Review choreography — "Rejected in review:", "the reviewer confirmed", draft ordinals ("v5 of this note"), round attributions. Keep the surviving decision and rationale as plain fact; delete who said it when.
5. Reviewer-addressed justification — "the cast is safe — it simply…", "this is correct because…". A comment arguing its own correctness addresses a reviewer, not a maintainer. State the invariant that makes the code safe, or delete the comment if the code shows it.
6. Restatement and derivation transcripts — control-flow narration ("first we X, then we Y"), test walkthroughs, proofs of obvious branches. Delete; keep only a non-obvious contract or invariant.
7. Hedges and planning residue — "probably fine for now", "should be enough", deferrals with no marker. Promote to TODO/FIXME or restate as the actual bound; delete the hedge.
8. Authoring-language slips — untranslated working-language fragments (端, 设计稿, ---- 私有 ---- separators) in prose whose language is otherwise English, or the reverse in a zh counterpart. Translate or delete.

What is not leakage

Unaided citation passes fail in both directions by deleting durable references and keeping dead ones. Apply these keep rules as written:

• Issue references — #1470, TODO(name):, "issue #N owns the follow-up" resolve at HEAD; keep them on any surface, including READMEs.
• Merged-PR and issue citations inside design notes and postmortems — sanctioned evidence where the project's own documentation standard routes change stories.
• Suppression justifications — oxlint-disable … -- reason, coverage-ignore reasons, empty-catch explanations are required prose; fix a false reason, never delete it.
• Counterfactual-present regression pins — "without X, Y happens", "a naive X would…".
• Measured bounds — "(measured: 512 nests ≈ 0.15s)" calibrating a constant; the provenance word "measured" is load-bearing.
• Runtime old/new states — "the old connection drains before the new one accepts" is runtime lifecycle, not change history.
• Historical stage names inside a note's change-story sections — "the first cut shipped X" is current-state-safe there; indexical stamps ("this cut") stay banned everywhere.
• External references that resolve outside the repo by design — standards sections (RFC 9110 §10.1.5), Figma frame names; the §-ban covers uncommitted internal drafts, not external standards or committed docs that own their §-numbering.
• Project voice and genre forms — "we" as project voice; a note's Alternatives-considered section.

Workflow

1. Scope and exclusions per dev-prose-standard: require an explicit scope; never touch vendored/generated directories, archived snapshots, or recorded fixtures — recorded model output and sealed history keep their original voice.
2. Audit read-only first: search for the taxonomy signals (ordinal citations, "used to"/"no longer", "this PR/cut", "rejected in review", control-flow narration, stray working-language fragments) with ripgrep, then judge every hit semantically. Patterns are probes, not the definition — also read the densest prose in scope (module JSDoc, READMEs, design notes) without a pattern in hand.
3. Fix owner-first per surface: generated catalogs → fix the source JSDoc or generator template, then regenerate; model-visible strings → wording is behavior, so flag for a snapshot-backed change instead of silently rewording.
4. Before deleting anything, enumerate the passage's propositions (prose-standard) and check the overcorrection traps: trims that flip an obligation into an endorsement, promote a hypothetical to a shipped feature, delete a true fact, or drop provenance.
5. Verify: re-run the searches expecting only sanctioned keeps; confirm every remaining citation resolves at HEAD; run the project's relevant gates (git diff --check, lint, doc checks where defined).