Reconcile os-dev contract and pm-dispatch channel references with measured seat reality (#12440)

* docs(agents): reconcile os-dev contract with measured seat reality

os-dev.md half of the channel-reality fold: label-step gated-seat fallback
(MCP read-union-write-readback) and objectui phantom-label mechanism
statement; zero-quota payload read tier + mcp_calls report field; slot
parking on the verify-lock queue; mechanical stall self-check; pre-installed
Chromium fact; commit-before-ablation companion clause; tail/PR-body
read-back and placeholder-word spelling for GitHub-bound text.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JANH3y7qe3MD8aLaLXci8N

* docs(pm-dispatch): per-session-class channel matrix in platform-readings

Repo-scoped probe replaces the rate-limit dual-duty claim; rate-limit
becomes the one-call credential discriminator; 2026-08-25 seat matrix
(subagent seats gated on reads AND writes, gh absent, MCP + git push fine);
payload tier added to the default read order and degradation ladder;
augment-5 queue procedure (queue-ref decisive read, update-branch conflict
surfacing, 405 retry positive) supersedes the churn heuristic; blocked
download recorded as not-proof-of-absence. Adds paid by same-file cuts.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JANH3y7qe3MD8aLaLXci8N

* docs(pm-dispatch): qualify rest-channel check marks by session class

The channel-boundary header now states the marks were measured in a
session-gate-open seat and that gated seats (os-dev subagents and some
top-level seats, 2026-08-25) get 403 on the whole repo-scoped class, reads
and writes; probe-first with the rate-limit credential discriminator; the
additive-label row names the measured MCP read-union-write-readback
fallback; semantic-search fallback qualified for gated seats. Adds paid by
same-file cuts.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JANH3y7qe3MD8aLaLXci8N

* docs(pm-dispatch): record per-container gate variance in the seat matrix

PM review amend: the matrix row overclaimed (subagent seats uniformly
gated) with a same-day counterexample from the seat that wrote it. Now
records both readings — 2026-08-25 five-plus dev seats all gated, and the
2026-08-26 open-gate os-dev seat (additive POST 200, rate-limit 15000/hr)
— concluding gate state varies per container and the repo-scoped probe is
the only safe read. Net add paid by tightening the silent-downgrade row.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JANH3y7qe3MD8aLaLXci8N

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Co-authored-by: Claude <noreply@anthropic.com>

Author: os-steve