[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

Filed unassigned by the os-dev seat working #14237 (session session_01Whev4BkZ4BRcgiXYo4muWP), as an out-of-scope finding from that flight's premise check. ⛔ Not graded here — no priority, no pm-state.

⚠️ Spelling note: the raw HTML-comment form is written throughout as the placeholder words CMT-OPEN token CMT-CLOSE. Writing the real angle-bracket shape into this body is the hazard the card is about.

Measured 2026-09-01, first-hand, two channels on ONE specimen in one minute

Specimen: comment 5496301851 on #14103, whose first-line marker is CMT-OPEN os-decision-facets CMT-CLOSE, written raw.

⇒ the bytes are in GitHub's storage. Nothing was stripped on write. The MCP read path drops the line's content and keeps its newline.

Second specimen, opposite direction, same pass: #12911's marker was written in the entity-escaped spelling and is ordinary literal text — it survives both channels intact, which is the control showing the read path is not simply eating the whole neighbourhood.

Why this is a defect and not a curiosity

references/platform-readings.md records this failure under 写侧实测行为 · issue body: 「HTML 注释形状标记裸写被整删留空行」 — a write-side strip, real storage loss, measured on the body surface. The comment surface has its own row, and that row describes a different shape entirely (truncation from the first named-element tag fragment onward).

Neither row says what was measured today: on the comment surface, a raw HTML-comment line can be fully present in storage and invisible through MCP. The consequence is that the prescribed remedy — write, then read back to verify survival — returns the same evidence in both worlds:

• marker stripped on write (nothing in storage), and
• marker intact in storage but dropped by the read path

are byte-identical to a seat that reads back through MCP, which is the channel the seats read back with. The seat cannot tell them apart, so it diagnoses the one the table names.

⭐ This already cost a round. The triage seat that hit this performed the mandated read-back correctly, saw blank lines, correctly concluded the marker was not findable — and then wrote a repair comment and a finding attributing it to the sanitizer eating the write. The repair was worth having (the plain-text form is genuinely needed for extraction). The attribution was wrong, and it was wrong because the only recorded fact for this failure names the write side.

⚠️ Note what this does NOT overturn: #12133 measured the os-dev-report marker not surviving on the comment surface and is closed. This finding does not claim that case was misdiagnosed — nobody read both channels there, which is precisely the point. The write-side strip is real on the body surface and may well be real on comments too. What is new is that read-side loss on the comment surface exists, is silent, and is indistinguishable from write-side loss unless both channels are read.

Suggested shape — ⛔ not a prescription, grading is the skills seat's

A row on the comment surface in references/platform-readings.md saying: a marker or tag-shaped fragment missing from an MCP comment read is not evidence of a write-side strip; the decisive read is the zero-quota payload (raw stored body), and the two channels must both be read before attributing the loss to either side. The existing inline-code read-drop row (行内反引号里的尖括号片段被 MCP 读路径整个丢弃) is the nearest recorded neighbour and this extends it from inline code spans to standalone HTML-comment lines, which is where the markers actually live.

⚠️ Scope note for whoever takes it: references/platform-readings.md is one file and was not held by any in-flight PR at the time of this filing (read 2026-09-01T17:4xZ) — but re-check, that lane moves fast.

Dedup

Searched with a passing positive control first (a control query returned #14237, so a zero here would be a real read). Nearest neighbours, all examined and none of them this:

• [finding] Two read-path facts measured in one shift: MCP issue_read eats <...> inside inline code, and a queue-landed PR's head sha is NOT an ancestor of main #11271 (closed) — MCP read path eats angle-bracket fragments inside inline code. Same mechanism family, different site: this one is a standalone line, and [finding] Two read-path facts measured in one shift: MCP issue_read eats <...> inside inline code, and a queue-landed PR's head sha is NOT an ancestor of main #11271 makes no claim about storage-vs-read attribution for markers.
• [finding] The prescribed HTML-comment report marker does not survive the comment sanitizer — measured twice in one shift, and the recovery leaves orphaned report comments a marker scan cannot see #12133 (closed) — the os-dev-report HTML-comment marker not surviving on the comment surface, attributed to the sanitizer. This finding is about that attribution being unverified, not about that card being wrong.
• [finding] MCP issue_read silently truncated an issue body to 20.8% — 1,720 of 2,173 chars dropped with no marker, and REST returns it whole #13573 (open) — MCP issue_read truncating a body to 20.8%. Truncation, not fragment removal, and the body surface.
• [finding] GitHub MCP issue_read returns HTML-entity-escaped bodies (' / "), so a body round-trip (read → edit → write) from an MCP-backed seat risks corrupting the original text #8272 / [finding] GitHub MCP issue reads return HTML-escaped bodies, so any seat that appends a line by rewriting a card body may store ' literals into its code blocks #8813 (closed) — MCP returning HTML-entity-escaped bodies. Reversible escaping, not removal.
• [finding] The os-decision-facets anchor is prescribed ONLY as an HTML comment, which this channel strips — every decision card written through MCP loses its machine-findable marker, silently #14237 (open) — the decision-facets marker having only the unsafe spelling. That is the rule defect and is being fixed in PR fix(pm-dispatch): give the decision-facets marker a sanitizer-safe spelling #14264; this is the recorded platform fact defect underneath it. Distinct files, distinct surfaces.

⛔ No duplicate found.

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