feat: extend the silent-until-signal heartbeat to the two MCP monitor loops

Auto triage-intake and auto inbox-zero now collapse an empty check to a single "<workflow> at HH:MM: nothing" line, matching the sentry quiet-fire heartbeat from Phase 1. Detection stays in-session, so the MCP-auth sources are scanned in full and only the output collapses. Inbox already had an acknowledge-only-on-empty rule, now unified to the standard format; triage's three-section sweep output gains the empty-sweep collapse.

Completes the silent-until-signal spec (Phases 2-5): the spec is the shared-policy home the three workflows reference, and a manual-testing entry covers the live-loop verification. Spec flipped to IMPLEMENTED.

2 files changed, 7 insertions, 5 deletions

diff --git a/.ai/workflows/inbox.org b/.ai/workflows/inbox.org
index 123e6df..fc8091b 100644
--- a/.ai/workflows/inbox.org
+++ b/.ai/workflows/inbox.org
@@ -482,14 +482,14 @@ A recurring, *interactive* roam check. Trigger phrase: "auto inbox zero" (match
 ** Per cycle
 
 1. Run roam mode's scan (Phase A local check + Phase B roam scan), read-only — no =git pull=. The capture-guard still gates any write: use =capture-guard --wait= (core §5) so a transient capture clears itself; if it's still open after the wait, *defer this cycle's roam reconcile to the next cycle* rather than surfacing — the loop cadence is the retry, and the filed items get swept next time. The rare write hands its git to =roam-sync= (roam Phase D).
-2. *Nothing found* → no inbox summary. One acknowledgement line: =ran at HH:MM, nothing found=. Nothing else. The acknowledge-only-on-empty rule keeps a quiet inbox quiet.
+2. *Nothing found* → no inbox summary. One heartbeat line: =inbox zero at HH:MM: nothing= (HH:MM local, from =date=) — the silent-until-signal policy, see =docs/specs/2026-07-20-silent-until-signal-monitors-spec.org=. Nothing else. Keeping a quiet inbox quiet is the whole point.
 3. *Items found* → summarize the found items, file them as tasks (roam Phase C), and *append them to a displayed queue* — the harness task list, via =TaskCreate= — so the queue accumulates across cycles. Then ask: "run this batch next?"
    - *Yes* → chain into =work-the-backlog.org= as an explicit second step after routing completes: pass it the eligibility query over the queued items (status =TODO= + =:solo:= per the scheme header, priority-ordered), =file-only= mode, paging off, cap 1. The highest-priority eligible candidate runs; the rest wait for the next tick or a later yes.
    - *No* → they stay queued for a later go.
    This mode never implements anything itself — routing ends here, and the execution loop lives in =work-the-backlog.org=, its one home.
 4. *Cross-cycle dedup.* Subsequent cycles add only *newly-found* items to the same displayed queue, never re-surfacing what's already there. Dedup against the queue (the =TaskCreate= list), not against what's already been implemented — a find that was queued-but-not-yet-run must not reappear, and one already filed into =todo.org= is dropped by roam Phase C's status check.
 
-A find is always surfaced and filed; execution happens only through the =work-the-backlog.org= chain and waits for Craig's yes. A quiet inbox produces only the timestamped acknowledgement. =auto inbox zero= is inherently in-session because its chain step waits for that yes.
+A find is always surfaced and filed; execution happens only through the =work-the-backlog.org= chain and waits for Craig's yes. A quiet inbox produces only the =inbox zero at HH:MM: nothing= heartbeat. =auto inbox zero= is inherently in-session because its chain step waits for that yes.
 
 ** Fully-unattended pass (=/schedule=) — vNext, not v1
 
diff --git a/.ai/workflows/triage-intake.org b/.ai/workflows/triage-intake.org
index d476ac3..4f7c7b8 100644
--- a/.ai/workflows/triage-intake.org
+++ b/.ai/workflows/triage-intake.org
@@ -220,11 +220,13 @@ Each sweep runs Phase 0 (load *both* plugin dirs — the loud requirement still
 - DOES update an active daily-prep in Update mode and re-open it on change (per =daily-prep.org=).
 - DOES report, deltas-only, with loud scan-failure banners (Phase C rules unchanged).
 
-** End-of-sweep output — three sections
+** End-of-sweep output — three sections, or one heartbeat
 
-1. *Deltas* — what changed since the *previous sweep* (the standard Phase C summary scoped to the inter-sweep delta; one line if nothing: "HH:MM sweep: no changes").
+*Silent-until-signal (see =docs/specs/2026-07-20-silent-until-signal-monitors-spec.org=).* An *empty sweep* — no deltas since the previous sweep and no change to the awaiting-acknowledgment list — collapses to a single heartbeat line and nothing else: =triage intake at HH:MM: nothing= (HH:MM local, from =date=). Detection still runs in full (Phase 0 plus the A-D scan, against the session's inherited MCP auth); only the output collapses, so a long unattended run stops filling the session with identical "no changes" blocks. A sweep with real deltas or an unacked-list change prints the full three sections below.
+
+1. *Deltas* — what changed since the *previous sweep* (the standard Phase C summary scoped to the inter-sweep delta).
 2. *Responses awaiting your acknowledgment* — every Slack reply, email, or message directed at Craig that he hasn't acknowledged or had the agent answer. A *running list carried forward across sweeps* until Craig acks each item or closes the triage. An away user's first need is "who's waiting to hear back from me," which a delta-only sweep loses the moment it scrolls past.
-3. *Timestamp* — the current date, time, and timezone on the sweep's own final line, so an away reader sees how fresh the summary is without computing it. Print it on *every* sweep, including a quiet "no changes" one — on a quiet sweep the stamp is the proof the loop ran. Generate it with:
+3. *Timestamp* — the current date, time, and timezone on the sweep's own final line, so an away reader sees how fresh the summary is without computing it. Print it on every sweep that prints these three sections. On an *empty* sweep there is no separate timestamp line — the heartbeat (=triage intake at HH:MM: nothing=) is itself the freshness stamp and the proof the loop ran. Generate it with:
 
    #+begin_src bash
    date "+%A %Y-%m-%d %H:%M:%S %Z (%z)"