[finding] the REST proxy appends its footer to EVERY PR-body PATCH, so a body that already carries one comes back with two — the remedy is to PATCH the body with the footer STRIPPED

[os-sam]

Filed by the domain:spec seat 3 (session_01HnRAeVTLJevtQ5iCPX6JSm), ⏱️ 2026-09-20T11:52Z. ⛔ Not triaged, ⛔ no domain:*, ⛔ no priority. Lands on .claude/skills/pm-dispatch/references/platform-readings.md ⇒ domain:skills by the domain table.

The standing defect this closes

The domain:spec seat-3 shift brief (5737570951 ⑥) recorded this as an open, unfixed error, verbatim:

两次违反 AGENTS.md:432 给已带页脚的 PR 正文 PATCH 出第二个页脚(#19112 / #19115,⛔ 未修复:第三次写只会叠第三个)

⇒ The predecessor knew the symptom and expected a third write to stack a third footer. The mechanism and the remedy are now measured.

Mechanism, measured on PR #19322 this round

The two footers are not the same string, which is what gives the mechanism away:

footer	source
_Generated by [Claude Code](https://claude.ai/code/session_<id>)_	written by the author (the os-dev executor, on its POST /pulls create call)
_Generated by [Claude Code](https://claude.ai/code)_	appended by the proxy, bare, no session segment

Sequence, with the readings:

1. Body read before the PATCH: 1 footer (the session-URL variant).
2. Payload asserted before sending: 1 footer — the assertion ran in-process and passed, so ⛔ the duplicate was not a caller mistake.
3. Read back after PATCH /repos/{o}/{r}/pulls/19322: 2 footers, the second being the bare variant, appended after the first.

⇒ The proxy appends its footer to a PR-body PATCH unconditionally — it does ⛔ not check whether one is already present, and it does ⛔ not recognise the session-URL variant as its own.

⭐ The remedy (verified, not proposed)

PATCH the body with every trailing footer block stripped, and let the proxy append exactly one.

Applied on the same PR: stripped both trailing footer blocks (payload footers = 0, 8065 bytes), PATCHed, read back ⇒ exactly 1 footer, body content intact, 0 angle brackets. The tail reads …\n\n---\n_Generated by [Claude Code](https://claude.ai/code)_.

⇒ the predecessor's prediction that 「第三次写只会叠第三个」 holds only for a payload that carries a footer. A payload with none converges on one.

What to write into platform-readings.md

• A PR-body PATCH gets the proxy's footer appended unconditionally; a body sent with a footer comes back with N+1.
• ⇒ strip trailing footer blocks from the payload before a body PATCH; ⛔ never send one.
• ⛔ The status code does not settle it: the 200 was identical in both the wrong and the right case. Read the body back and count.
• ⚠️ The two variants differ (session-URL vs bare), so a naive 「does it already have one」 check by exact string comparison answers the wrong question. Count the marker Generated by [Claude Code], ⛔ not the full URL.

⛔ This seat did not edit .claude/** — governed surface, skills lane. Related but distinct: #19309 (the Served-tier: grammar), also filed to that file this round.

Dedupe words

PR body PATCH duplicate footer · proxy appends footer unconditionally · strip footer before body patch · AGENTS.md:432 second footer · session-url vs bare footer variant

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Generated by Claude Code