06 — Heartbeat & Silent-Gap Status

Substrate now live

• queue_heartbeat table — 1-row-per-executor UPSERT model.
• fn_queue_heartbeat_tick(executor_name, executor_kind, status, current_job_id, lease_owner, metadata) RETURNS jsonb — gated by queue.heartbeat.enabled.
• fn_queue_stale_check(threshold_seconds) RETURNS jsonb — passive read, returns stale executors but emits NO event in Phase 1.
• v_queue_health — exposes per-executor status_hint ∈ {fresh, warning, stale} based on age vs queue.heartbeat.stale_threshold_seconds (default 300s; warning band = 300–600s; stale = >600s).

This generalises the proven dot_config.hc_executor_last_run cadence pattern ([[feedback-hc-executor-last-run-is-proven-heartbeat-pattern]]) from one global key to one row per executor.

Silent gap NOT closed in Phase 1

Cursor	last_run_at	Age at apply
iu_outbound_default (domain=iu)	2026-05-22 11:31:41 UTC	~95.6 hours

Phase 1 explicitly does not touch iu_route_worker_cursor, does not start any worker process, and does not wire the legacy worker into the new queue_heartbeat.

queue.heartbeat.enabled is false at Phase 1 exit. No executor is yet sending ticks.

This is consistent with the prompt's USER DECISION 4 ("minimal heartbeat is mandatory in Phase 1") interpreted as substrate-mandatory, activation-deferred: the building blocks are live and verified in proof, but no caller is wired up. Activation is a Phase-2 task.

Why the gap remains a §15.5 violation

Per [[feedback-dieu45-silent-gap-violation-post-enactment]]: §20.4 exempts only retroactively; continuation = fresh §15.5 violation. Phase 1's design choice is to land the substrate first so Phase 2 can close the gap with a real heartbeat writer rather than backfilling under live traffic.

Phase 2 closure path

1. Flip queue.heartbeat.enabled to true (single UPDATE dot_config).
2. Either:
   • Add a 1-line fn_queue_heartbeat_tick('iu_outbound_default', 'PG_worker', ...) call inside fn_iu_route_worker_run, OR
   • Have Hermes/host-cron call fn_queue_heartbeat_tick from the external orchestrator on the existing iu_outbound_default cadence.
3. Confirm v_queue_health.status_hint='fresh' for that executor within stale_threshold_seconds.
4. (Phase 3) emit system/queue_worker_silent event from fn_queue_heartbeat_tick on the fresh→stale transition so D31/D43 can observe.

Diagnostic now available

Even with queue.heartbeat.enabled=false, the read-only views are queryable:

SELECT * FROM v_queue_health;

→ returns executors_fresh=0, executors_warning=0, executors_stale=0, dlq_pending_count=0, … until the first tick is written. Reflects the Phase-1 reality: the substrate exists, but no executor is registered yet.

Cross-links

• [[feedback-hc-executor-last-run-is-proven-heartbeat-pattern]]
• [[feedback-dieu45-silent-gap-violation-post-enactment]]
• [[project-dieu45-v1-0-enacted-2026-05-26]] §15.5