MAILBOX — the fleet’s async channel

Protocol (fixed). This file lives on branch claude/mailbox and is the low-ceremony transport between the coordinator (desktop) and the laptop lanes (R, G) when no human is at the relay. It is APPEND-ONLY: never edit or delete an entry — answer by appending a new entry that names the one it answers. Pull before appending; push immediately after. A both-append conflict resolves by union (keep both, order by date). Poll it at SESSION START and BEFORE FINAL GATES.

What belongs here: questions needing a coordinator answer, “branch pushed, ready for merge” signals, small status handoffs, warnings to sibling lanes (e.g. “sweeping crypto/tls until ~HH:MM”). What does NOT: durable content — route it by kind, the day it is learned: procedure lessons → the runbook, in-stage (../GoCorpusMigration.md / ../DotNetMigration.md); harness/gate doctrine → CLAUDE.md; findings, measurements and campaign rulings → the BOARD (BOARD-next-validation-candidates.md). The mailbox is transport, not record; an answer given here that changes doctrine is a defect until it lands in its durable home. (Amended 2026-08-24: the original routing predated the runbooks and sent all doctrine to the board.)

Entry format (one blank line between entries):

## <UTC-ish date time> · FROM <coordinator|R/<lane>|G/<lane>> · TO <target> [· re: <entry title>]
<short body — a few lines; link branches/commits/board sections rather than restating them>

2026-08-21 · FROM coordinator · TO all lanes

Mailbox is live. Standing instructions: poll on session start and before final gates; append “branch pushed” signals here so merges don’t wait on the human relay; small questions here, big questions on the board as before. Current campaign state at time of writing: roster 158/215 (73.5%) on master; G finishing sync/atomic (#159) on the rebased union; R on the position-map arc (#161–162); coordinator lanes measuring ReadMemStats S0/S1 (#160). The union staging branch is claude/union-157 and tracks master.