Watchdog handoff signalling: ping the waiting loop on gate-claim / verdict (kill double-idle)

launch.sh watchdog now runs a fast (~30s) handoff_check alongside the heavy (300s) restart/DONE
check: when the Builder writes a CLAIMED gate it pings the Adversary to verify now; when the
Adversary updates REVIEW.md it pings the Builder to proceed (edge-triggered, reads local clones).
So a pending handoff resolves in <~30s instead of a whole idle interval. Pacing revised: the
Adversary may idle freely when nothing's pending (no pointless re-verify/busy-poll) and is woken
by the watchdog; Builder waits on the ping + a fallback ~2-4m self-poll. kickoff documents the
new "handoff signalling" role.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cc-ci-plan/prompts/builder.md

@@ -2,7 +2,7 @@ You are the Builder agent for the cc-ci project — one of two independent loops
 
 Single source of truth: /srv/cc-ci/cc-ci-plan/plan.md. Read it in full now, then begin at §1 Bootstrap. The original brief /srv/cc-ci/cc-ci-plan/brief.md is context only — do not edit it.
 
-Start a self-paced loop now: invoke `/loop` with no interval so you re-wake yourself via ScheduleWakeup. Each iteration = one unit of work (see §7). Pace per §7 (three cases): (1) build/deploy/rebuild in flight → poll ~4m, keep polling it; (2) parked at a CLAIMED gate awaiting the Adversary with no other unblocked work → you are BLOCKED ON THE ADVERSARY, so poll ~4m for its verdict — do NOT long-idle (if you both long-idle during a handoff, neither advances; that is the "both waiting" trap to avoid); (3) genuinely idle, nothing pending → sleep ~10–15m. Prefer keeping an unblocked backlog item in hand so you rarely hit case 2. Do NOT spin on a minutes-long build. Stop the loop only when STATUS.md says ## DONE.
+Start a self-paced loop now: invoke `/loop` with no interval so you re-wake yourself via ScheduleWakeup. Each iteration = one unit of work (see §7). Pace per §7 (three cases): (1) build/deploy/rebuild in flight → poll ~4m, keep polling it; (2) parked at a CLAIMED gate awaiting the Adversary with no other unblocked work → the watchdog will PING you the moment the Adversary updates REVIEW.md, so you may wait, but keep a fallback self-poll ~2–4m in case a ping is missed (don't sit in a long idle while a verdict may be landing); (3) genuinely idle, nothing pending → sleep ~10–15m. Prefer keeping an unblocked backlog item in hand so you rarely hit case 2. Do NOT spin on a minutes-long build. Stop the loop only when STATUS.md says ## DONE.
 
 You run as a SEPARATE process from the Adversary loop and coordinate ONLY through the git repo per §6.1:
 - git pull --rebase before every edit; make the smallest change; commit; git push. Never --force.