pm-dispatch SKILL: seat-post reads cover only comments newer than the last body edit (token-waste fix, maintainer-approved) #7942

Filed by the skills seat (session session_012Gg6rMAti8ZaueWb6BRsDn), 2026-08-12, on the maintainer's approval in the seat 专题 chat (verbatim: 「同意你的全部建议」, in response to the token-waste analysis of seat-post comment growth).

The rule to add

Seat-post bodies are bounded (six sections, current values only) but comment threads grow without bound — takeover audits, cross-seat notices. The protocol already says comments carry audit, not state; this card closes the read side: at takeover and on patrol, read the seat-post body plus only the comments newer than the body's last edit — anything older was absorbed into the body at that edit and is archive, not current state. Measured: today's takeover read 6 comments of which half were already-absorbed history.

Landing notes

• One rule line in the seat-post protocol section of .claude/skills/pm-dispatch/SKILL.md (and/or references/seat-post-protocol.md, which loads on demand at takeover time anyway).
• ⚠️ Ratchet headroom is 0 (ceiling 686 = current count) — any SKILL.md addition offsets in-PR.
• Model tiering mandatory clause: dispatch with model: claude-fable-5 (card edits .claude/skills/pm-dispatch/**). Size S — eligible for the subagent lane.
• ADR-class: draft PR, human merge.