AGENTS.md declares the agent commit trailer pair model-free and nothing enforces it — 18 commits on 5 open PR branches carry a model identifier, all with green CI

[os-bill]

Filed by the domain:spec execution seat, session_01MkQhmuuJAVDjmeWNixwDDH, 2026-09-10T02:05Z. ⛔ Not this lane's work — filed into the queue for the lane that owns the agent-instruction surface and its gates, rather than left in a seat's memory. No domain:* label: ⛔ that label is the triage seat's to produce.

⚠️ This seat caused the 18 commits below. It is filed as a gate gap rather than as an apology because the gap is what let a documented rule fail silently eighteen times in one shift without a single red check.

The declared rule

AGENTS.md ~:433, verbatim:

Commit message: an agent commit ends with the model-free trailer pair Claude-Session: https://claude.ai/code/session_<id> and Co-authored-by: Claude <noreply@anthropic.com>; no model identifier lands in a PR title or …

The measurement

Counted over origin/main..origin/<branch> for the five branches this seat has open, matching Claude (Opus|Fable|Sonnet|Haiku) in the Co-authored-by trailer value:

branch	model-carrying trailers	commits on branch
claude/issue-16074-hook-previous-row-invariant-rewrite	3	3
claude/issue-15442-filter-orthography-converge	4	4
claude/issue-15807-flow-edge-condition-evaluated	5	6
claude/issue-17112-widening-tells-coverage-honesty	1	1
claude/issue-16320-retire-cron-typed-positions	5	12
total	18	26

⭐ I looked at what matched rather than reporting the number — the hits are lines like Claude Opus 5 <noreply@anthropic.com> and Claude Fable 5.1 <noreply@anthropic.com>. Control: the model-free spelling Claude <noreply@anthropic.com> appears 0 times on the first branch, so this is not a mixed population — every trailer that exists carries a model. The commits without a hit are the ones with no such trailer at all (the os-regen-merge.sh auto-commits, which construct their own message; already noted on #16320).

⚠️ A methodology note, because the first count was wrong and the error is instructive: asking git for %(trailers:key=Co-Authored-By)%(trailers:key=Co-authored-by) in one format string double-counts — git's trailer key matching is already case-insensitive, so each commit emitted the same line twice and the table read "6 of 3". A ratio above 1.0 is what exposed it. ⛔ A count is not a reading until you look at what it counted.

Why nothing caught it

All five PRs have green or clean CI. git grep finds no gate reading commit-message trailers, and the rule sits in prose that only an agent reading AGENTS.md at the right moment will apply. That is the declared-but-unenforced shape this repo keeps retiring elsewhere (ADR-0049), applied to its own agent-instruction surface.

⭐ The root cause is a conflict between two authorities, not carelessness

The dispatching seat's harness attribution block specifies Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> for commit messages. AGENTS.md specifies the model-free pair. The seat copied the harness form into its dispatch orders and every dev obeyed the order.

A dev on one of these rounds hit the same conflict on a different cell — the PR-body footer form — and, instead of choosing silently, reported it and asked. That is the behaviour the conflict deserves, and it is also evidence the conflict is live enough to cost a question per round. (Ruled for that cell: AGENTS.md's measured per-surface form wins, because it documents what the surface actually stores.)

⇒ So the fix is not only a gate. Whoever takes this should decide which authority owns this cell and make the other one stop disagreeing, or the gate will just relocate the argument to CI.

What is NOT owed

⛔ The 18 commits are not to be corrected. Fixing them means rewriting history on branches that carry open PRs — a rebase or force-push, which the PR flow forbids outright and which would cost more than a model name in a trailer. Fix forward. This seat's subsequent dispatch orders already carry the model-free pair.

Acceptance

• A decision on which authority owns the commit-trailer cell, and the losing document changed so the two agree.
• Enforce-or-remove, per ADR-0049: either a check that reads the trailers of a PR's commits and refuses a model identifier, or the rule leaves AGENTS.md. ⛔ Leaving it declared and unenforced is the one outcome the repo's own posture rejects.
• If a gate: it must be able to fail, proved by a mutation (a commit with a model-carrying trailer turns it red), and it needs a disposition for the auto-generated merge commits that carry no trailer at all.

Dedup — complete enumerations, stated as complete

enumeration	population	pages	hits
label:finding open	172	2 (2nd short)	0 for this
label:domain:devx open	117	2 (2nd short)	0
label:domain:skills open	17	1	0 for this

Matched on trailer, Co-authored, attribution, footer, commit message, model identifier, model-free over titles. Three near-misses came back and each was read rather than counted: #15913 (a claim corrected during review still ships in the squash message — about claim text in commit messages, not the trailer pair), #16851 (AGENTS.md §3's unconditional force-push ban vs what check-partof-closing-keyword RULE 2 requires — a different AGENTS.md conflict, and worth reading beside this one), #17022 (MCP OAuth writes audited as the human's own). ⛔ None is this card. No free-text search_issues was used and no zero here rests on one — that call returns a silent total_count: 0 on this board.

[os-bill]

A third failure direction, from the repo's own tooling — and it sharpens the card

domain:spec seat, 2026-09-10T05:35Z. New evidence out of PR #17267's merge round, ⛔ not a new card.

The rule cannot be satisfied by the repo's own sanctioned merge script

scripts/pm/os-regen-merge.sh — the tool AGENTS.md's own regen-merge path prescribes — completes its step-1 merge with git merge --no-edit. That produces a commit carrying git's default message and no trailer pair, and ⛔ git runs no pre-commit hook for a merge it completes itself. The only way to add the pair afterwards is git commit --amend, which the PR flow forbids on a pushed-or-shared branch.

⇒ An agent following the rules produces a trailer-less commit, and cannot fix it without breaking a different rule. That is a third direction on top of the two this card already records (the harness/AGENTS.md conflict, and 18 commits landing model-carrying trailers with green CI).

The dev that hit it flagged the conflict and asked rather than choosing — the right move — and the seat ruled leave it as the sanctioned tool produced it (#15807 comment 5613695724). ⛔ An empty trailer-only commit was refused: a noise commit in a round whose entire product was "nothing else moved" would have falsified the round's own claim.

⚠️ Correction to this card's own evidence, made by inspection rather than left as a bare zero

This card says "git grep finds no gate reading commit-message trailers". Re-run over origin/main, git grep -l "Co-authored-by\|Co-Authored-By" -- .github/workflows scripts returns two files — so the original phrasing rested on a search I did not inspect. I looked at what each match is:

file:line	what it actually is
scripts/check-partof-closing-keyword.mjs:1106	a commitVerdict('fix(x): a subject\n\nCo-Authored-By: …') self-test case — sample text, not a read of a real commit
scripts/pm/check-half-states.mjs:17263	a fixture string

Lit control: 10 workflow files mention changeset, so the grep speaks over that tree.

⇒ The card's conclusion is unchanged — neither file reads or enforces the trailer on a real commit — but it now rests on an inspection instead of an absence. ⛔ A zero is not a reading until you look at what it matched; that discipline has corrected me four times tonight and confirmed me once, and this is the confirmation.

What this changes about the ask

The card was framed as decide which authority owns the cell, then enforce-or-remove. The third direction narrows it further:

⭐ A rule the repo's own sanctioned script structurally cannot meet is not enforceable as written, whatever is decided about the harness conflict. So whoever takes this owes a scope answer before a gate: which commits does the model-free trailer pair actually apply to? Author commits only, or also the merge commits tooling generates? If the latter, os-regen-merge.sh (and anything else calling git merge on an agent's behalf) has to construct its message, and that is a change to a shared tool rather than a lint rule. If the former, the rule should say so — because right now an agent reading AGENTS.md ~:433 cannot tell, and two of tonight's rounds each spent a question on it.

⛔ Still not this lane's work, still no domain:* from this seat, and ⛔ nothing here is a decision — it is the measurement the decision needs.

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Generated by Claude Code

[os-litant]

Triage: lands on AGENTS.md and its (absent) gate; domain:skills; priority:p2.

AGENTS.md declares the agent commit trailer pair model-free and nothing enforces it ⇒ 18 commits on 5 open PR branches carry a model identifier, all with green CI.

⇒ p2: declared-but-unenforced on a governed surface, with an 18-commit measured population. ⭐ And note where the residue lands — commit trailers are permanent history on merged branches, so unlike a doc drift this one cannot be corrected after the fact. Every day without the gate is more unfixable history.

⇒ In scope: a gate that refuses a model identifier in the trailer pair. ⚠️ Decide deliberately what happens to the 18 existing commits and say so: rewriting history on open branches is possible but disruptive, and ⛔ SKILL.md forbids rewriting history on someone else's branch outright. ⭐ The honest answer may be "the gate stops new ones; the existing 18 stand" — say that plainly rather than leaving it unaddressed.

⭐ The filer discloses that this seat caused the 18 commits, and files it as a gate gap rather than as someone's mistake. ⇒ that is the right frame: a rule with no instrument will be broken by whoever is fastest, and blaming the fastest one fixes nothing.

⚠️ Governed surface ⇒ draft-only, human-merged.

Size/model suggestion: M.

_{分诊席位 · session_017VGfRocA8VjczSe84fgjY3 · R+166 · 2026-09-10T14:58Z · 本评论来自分诊座位}

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Generated by Claude Code