docs(agents): pre-authorise expbkmain merges, and own them until deployed

[tusharbhardwaj-bk]

Records a standing instruction from the reviewer: merging a green PR to expbkmain needs no further ask, but the work is not finished at merge — follow it through the build and the systemd install timer, and report only once expbkt3 is actually serving the merge SHA.

The reasoning is in the diff: "merged" is not a delivery. The reviewer cannot verify anything until the new build is live, and a build or install can still fail after a green PR. Ground truth is /home/ubuntu/.t3/expbkt3-dev/deployed-sha matching the merge commit plus t3-expbkt3.service active — not the PR state.

bkmain is deliberately unchanged and still needs a human, because deploying it restarts the service hosting the team's live sessions.

Docs only. AGENTS.md and every .md path are exempt from check-fork-markers.ts, so no fork markers are needed.

🤖 Generated with Claude Code

---

^{Need help on this PR? Tag @codesmith-bot with what you need. Autofix is disabled.}

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ No successful main baseline artifact is available yet. This run establishes the initial measurement.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	—	11.4 KiB	—	15.1 KiB	✅
Codex	Thread snapshot wire	—	5.7 KiB	—	7.3 KiB	✅
Codex	Live turn WebSocket wire	—	5.7 KiB	—	7.8 KiB	✅
Codex	Live turn WebSocket decoded	—	50.3 KiB	—	66.4 KiB	✅
Codex	Live turn messages	—	10	—	21	✅
Claude	Total thread wire	—	11.4 KiB	—	15.1 KiB	✅
Claude	Thread snapshot wire	—	5.7 KiB	—	7.3 KiB	✅
Claude	Live turn WebSocket wire	—	5.6 KiB	—	7.8 KiB	✅
Claude	Live turn WebSocket decoded	—	51.2 KiB	—	66.4 KiB	✅
Claude	Live turn messages	—	9	—	21	✅

Baseline: unavailable · PR result: 6030bad · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 95.6 KiB
• Claude decoded thread snapshot: 96.3 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.