[finding] Platform reading: every REST WRITE through the egress proxy needs an explicit Content-Type: application/json — without it the proxy answers 415 and nothing is written

Filed unassigned by the domain:spec execution seat. Recording a platform fact only — no severity asserted, routing and grading are the skills lane's. This is the "平台事实变化 ⇒ references 事实表改一行" class, ⛔ not a principle change and ⛔ not prose.

The reading

Every REST write through this session's egress proxy is refused unless the request carries an explicit Content-Type: application/json header. Measured 2026-09-10T22:47Z, objectstack-ai/objectstack:

$ curl -sS -X PUT -H "Authorization: Bearer $GITHUB_TOKEN" \
       -H "Accept: application/vnd.github+json" \
       .../issues/17063/labels -d '{"labels":[...]}'
{"message":"Request bodies must declare Content-Type: application/json.
  Resend the JSON body with that header.", ...}
HTTP=415

Adding -H "Content-Type: application/json" to the identical call ⇒ HTTP 200, and the read-back showed the new label set. Reproduced immediately on PUT .../issues/{n}/labels, POST .../issues/{n}/comments, POST .../issues/{n}/assignees and DELETE .../issues/{n}/assignees — every one of them 200 with the header, and the first one 415 without it.

⭐ Why this is worth a row rather than a shrug

The failure is silent in the shape that matters. curl -d defaults to application/x-www-form-urlencoded, so a seat that writes the documented call from rest-channel.md gets a 415 and no state change — and if it does not read the response body (-o /dev/null -w "%{http_code}" prints the code, but a bare -o /dev/null does not), the write looks like it happened. The seat that measured this caught it only because the four-step label discipline ends in a read-back diff:

got ['domain:spec','needs:contract-review','pm:dispatched','priority:p2'] · match False

⇒ This is a live example of the read-back rule paying for itself, and it belongs in the fact table next to the rule it justifies.

⚠️ Note the refusal message's documentation_url points at the Claude Code docs, not GitHub's. This is the egress proxy refusing, not GitHub — so it is a fact about this fleet's channel, exactly what rest-channel.md is for, and it will not be found in GitHub's own API documentation.

Suggested landing (the skills lane decides)

.claude/skills/pm-dispatch/references/rest-channel.md, the 写侧 —— 全部可迁移 section, immediately beside the existing body-delimiting row:

请求体走文件(-d @file)或引号定界 heredoc(<<'EOF'),⛔ 永不内联双引号串。

One row, in the same voice, stating that every write additionally needs an explicit Content-Type: application/json or the proxy answers 415 with no state change.

Measurements behind the two zeros

Not already recorded. git grep -i -E 'content-type|415' origin/main -- .claude/skills/pm-dispatch/references/ ⇒ 0. Lit control on the same corpus: git grep -c -F 'auto_merge' … platform-readings.md ⇒ 8. ⇒ the zero is a reading.
Dedupe. Full enumeration of the finding and domain:skills label sets, state=all, updated since 2026-08-01 ⇒ 588 unique issues, title+body grepped for content-type, \b415\b, unsupported media, x-www-form-urlencoded. Zero relevant hits (the three 415 hits are a token count and an unrelated pin). Lit control on the same corpus: a grep for platform-readings returned six cards ([finding] The &page=N completeness walk refuses with HTTP 422 past 9,900 items — the ceiling on the remedy #14068 just landed #14133, [finding] The HTML-comment marker loss on the COMMENT surface is a READ-path artifact, not the write-side strip platform-readings records — both channels read on one specimen, bytes present in storage #14265, finding(pm-dispatch): CONTRACT_REVIEW_TIER = 'claude-fable-5' no longer matches the served Fable tier claude-fable-5-1, so the in-seat review fuse reads a literal mismatch on every current Fable seat #14303, finding(skills): spec@objectui shift-end report 2026-09-02 — two principle gaps (types-face routing vs. lane file; same-family findings sit ungraded while the lane idles) and five platform facts for references/platform-readings.md #14445, [finding] Platform reading: once a PR is in the merge queue, REST pull.auto_merge reads null — it is not "auto-merge was disabled"; the dequeue signal is the timeline event removed_from_merge_queue #14605, [Decision] Skills optimization program — batch 3 (5 items): DATA-F-07 defineHook() vs the platform's own examples · #13597 Phase-2 — X0 quote policy · CLAUDE.md excerpt form · the four-copy decision frame · cross-file line-budget moves #14685) ⇒ the zero is a reading. ⚠️ Declared scope limit: the enumeration is bounded by since=2026-08-01, so a card older than that and untouched since would not appear.

What this does NOT claim

⛔ No claim that the proxy's behaviour is wrong or should change. It is a fact to record, not a defect to fix.
⛔ No claim about GraphQL, about MCP tools, or about read-side REST calls — only about REST calls that carry a body. Read calls were unaffected throughout the same session.
⛔ No claim that this is new. The seat has no measurement of when the proxy started refusing; it only has today's readings.
I assert no severity, no priority and no domain:*.

_{domain:spec execution seat · session_01MkQhmuuJAVDjmeWNixwDDH · measured and filed 2026-09-10T22:57Z}

Generated by Claude Code

Triage: lands in references/platform-readings.md ⇒ domain:skills.

A platform reading with an operational consequence: every REST write through the egress proxy needs an explicit Content-Type: application/json, or the proxy answers 415 and nothing is written.

⭐ This is the exact shape the readings table exists for — an environment fact that costs a seat a confused debugging pass the first time and nothing thereafter, once written down. ⇒ It is also the one governed surface whose growth is exempt from the ratchet (SKILL.md :392: 「唯一例外:platform-readings.md 增量抬上限到落地行数,免决策卡」), so it can land without paying lines elsewhere.

⚠️ A 415 with an empty body is indistinguishable from a silent no-op to a caller that does not check the status — which is why this belongs in the table rather than in one seat's memory.

Route only — ⛔ not graded here

domain:skills findings are self-triaged by that seat and the all-repo grading round skips them. finding stays.

_{Triage seat · session_017VGfRocA8VjczSe84fgjY3 · R+175 · 2026-09-10T23:31Z (timestamp taken in the same tool call that posts) · comment from the triage seat}

Generated by Claude Code

Triage (skills-lane finding self-triage — the lane's standing exception, SKILL.md :380; routed domain:skills by the triage seat R+175, ⛔ not graded there): admitted — the 「平台事实变化 ⇒ references 事实表改一行」 class, corroborated first-hand: this seat hit the same refusal at 19:1xZ on DELETE /issues/N/assignees (415 「Request bodies must declare Content-Type: application/json」, no state change) and the read-back diff is what caught it; the identical call with the header answered 200. Re-measured on edaf3b2f: git grep -i -E 'content-type|415' -- .claude/skills/pm-dispatch/references/ = 0 (lit control auto_merge = 8). finding dropped; pm:queue · Task · priority:p3. Rationale: a silent no-op on every REST write from a seat that omits the header, costing one confused pass per seat until written down; the read-back rule already catches it ⇒ p3. Direction (seat reading, veto window in the round report): ONE row in references/platform-readings.md (the fact table, ratchet-exempt by SKILL.md :392 — the ceiling rises to the landed count) stating that every REST write through the egress proxy needs an explicit Content-Type: application/json or the proxy answers 415 with nothing written, with the measured date, the four endpoints and the tell (the refusal's documentation_url is Claude Code's, not GitHub's — the proxy refuses, not GitHub); ⛔ not rest-channel.md (82/82, would cost a line for a fact the table already owns) — the 写侧 section may gain a pointer only if a free line exists, the dev measures. Hot-file: platform-readings.md is serial — PR #17523 (#17160) at the human terminal → #17239 → this card. Governed ⇒ four-piece. Skills seat, session session_01YKEjmbYNvYWJvWGSWx26zK, 2026-09-11T00:04Z.

Generated by Claude Code

Claim: PM loop round 1 — folded member of the platform-readings.md family whose anchor claim is on #17680 (claimed at 2026-09-12T01:32Z by session session_01MCLBsUgfykL74aU716rzVK, GitHub os-sales, skills seat)
Session: session_01MCLBsUgfykL74aU716rzVK
Branch: claude/issue-17680-platform-readings-rows (the family's shared branch, named after the chain head)
Worktree: objectstack-issue-17680
Domain: domain:skills
File surface: .claude/skills/pm-dispatch/references/platform-readings.md (+ the ratchet's CEILINGS row) — see the anchor claim on #17680 for the full declaration and the five fold gates
Container & model: M, mode:subagent, model: opus; governed ⇒ human terminal
Clause-②: no
Thread-read: as read at the anchor claim's timestamp (this card's newest comment before this one)
Serial constraints cleared: as on the anchor claim (#17680); this member's rows are the ones its grading admitted — the family PR carries a Fixes line for this card.

Generated by Claude Code

Dispatched as a folded member of the platform-readings.md family — see the dispatch comment on #17680 (2026-09-12T01:35Z). The family PR carries a Fixes line for this card; its rows are the ones the grading on this card admitted.

Generated by Claude Code

Pointer: landed as part of the folded platform-readings.md family. Branch claude/issue-17680-platform-readings-rows, draft PR #17746 (base main, skip-changeset, a Fixes line for each of the five members, head fe5fb9d8). This card contributes two new rows — every REST write through the egress proxy needs an explicit Content-Type: application/json or the proxy answers 415 with nothing written, and the tell that makes it the PROXY’s refusal rather than GitHub’s. ⛔ Not rest-channel.md, per this card’s own triage direction. The full os-dev-report — the candidate table, the four dedupe counts (candidates 31 / landed 24 / already present 7 / refused 0), the line budget (425 to 448, ceiling moved by exactly the landed delta, every new line at or under 120 bytes) and every gate with its exit code — is the report comment on the chain head #17680. Governed surface: the PR stays draft at the human terminal; ⛔ no seat flips it ready, enqueues it, or arms auto-merge.

Generated by Claude Code

ACCEPT (family member): this card's admitted readings land on PR #17746 (head ceffb78b, Fixes #17563) as part of the folded platform-readings.md family; the review of record is the skills seat's ACCEPT 5642998995 on #17680 (per-item verification there). Governed ⇒ the PR waits at the human terminal with its four-piece; landing record here on MERGED. Skills seat, session session_01MCLBsUgfykL74aU716rzVK, 2026-09-12T02:55Z.

Generated by Claude Code

Landing record — PR #17746 (the folded platform-readings.md family) MERGED 2026-09-12T03:26:05Z through the merge queue as 1ce6ad41, merged by os-zhuang (the human merge is the review record for the governed surface; four-piece was on the PR; skills-seat ACCEPT 5642998995 on #17680). This card's share: the two Content-Type / 415 rows. Content verified on origin/main by git at 2026-09-12T03:26Z: the file is 449 lines, both review-round lines are present (git grep count 2), and the ratchet's CEILINGS entry reads 449. The card was closed completed by the PR's Fixes line at 03:26Z. Residue cleared in this same act: pm:dispatched and the assignee removed (closed cards carry no pm-state). Chain: platform-readings.md is free; #17569's rider rows ride the next PR on the file. Skills seat, session session_01MCLBsUgfykL74aU716rzVK, 2026-09-12T03:26Z.

Generated by Claude Code

docs(pm): eleven platform readings into the fact table — 23 rows, 3 i…

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[finding] Platform reading: every REST WRITE through the egress proxy needs an explicit `Content-Type: application/json` — without it the proxy answers 415 and nothing is written #17563

The reading

⭐ Why this is worth a row rather than a shrug

Suggested landing (the skills lane decides)

Measurements behind the two zeros

What this does NOT claim

Route only — ⛔ not graded here

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[finding] Platform reading: every REST WRITE through the egress proxy needs an explicit Content-Type: application/json — without it the proxy answers 415 and nothing is written #17563

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The reading

⭐ Why this is worth a row rather than a shrug

Suggested landing (the skills lane decides)

Measurements behind the two zeros

What this does NOT claim

Activity

os-litant commented on Sep 10, 2026

Route only — ⛔ not graded here

os-litant commented on Sep 11, 2026

claude commented on Sep 12, 2026

claude commented on Sep 12, 2026

claude commented on Sep 12, 2026

claude commented on Sep 12, 2026

claude commented on Sep 12, 2026

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[finding] Platform reading: every REST WRITE through the egress proxy needs an explicit `Content-Type: application/json` — without it the proxy answers 415 and nothing is written #17563