Vendor-agnostic Layer-1 silent producer wrapping the `engagement_velocity_signal` topic per spec § A.9.1. Subscribes to bus events from BOTH connection.api.hubspot.deal AND connection.api.salesforce.opportunity updates; for each fired record reads any housekeeping-computed row via `enrichment-list` with the dynamic `{{context.event.payload.platform}}` scope and re-emits it through the recipe cycle so the row carries an up-to-date `cursor_at` reflecting the deal touch. The substrate-side housekeeping engagement-aggregates code (D-139 P3 — `backend/server/src/housekeeping/engagement-aggregates/engagement-velocity-signal.ts`) is the canonical compute path with the full Pass-4 evidence-quality fold (authorship + lifecycle + direction filters; 90d window split into recent 30d + baseline 60d; weighted trajectory math). Recipe writes carry `authored_by_recipe_id` distinct from the housekeeping `system.housekeeping.<topic>` author so both rows coexist on the unique `(topic, scope, target_id, authored_by_recipe_id)` index without conflict. Honest-zero `'steady'` default per the trajectory enum invariant when no housekeeping row exists yet.

Vendor-agnostic Layer-1 silent producer wrapping the `engagement_silence_duration` topic per spec § A.9.1. Subscribes to bus events from BOTH connection.api.hubspot.deal AND connection.api.salesforce.opportunity updates; for each fired record reads any housekeeping-computed row via `enrichment-list` with the dynamic `{{context.event.payload.platform}}` scope and re-emits it through the recipe cycle (so the row carries an up-to-date `cursor_at` reflecting the deal touch even when the substrate-side housekeeping cycle hasn't fired yet). The substrate-side housekeeping engagement-aggregates code (D-139 P1a.1 — `backend/server/src/housekeeping/engagement-aggregates/engagement-silence-duration.ts`) remains the canonical compute path; producer recipe writes carry `authored_by_recipe_id` distinct from the housekeeping `system.housekeeping.<topic>` author so both rows coexist on the unique `(topic, scope, target_id, authored_by_recipe_id)` index without conflict. Honest-zero defaults per the value-schema invariant when no housekeeping row exists yet.

Vendor-agnostic Layer-1 silent producer wrapping the `inbound_outbound_ratio` topic per spec § A.9.1. Subscribes to bus events from BOTH connection.api.hubspot.deal AND connection.api.salesforce.opportunity updates; for each fired record reads any housekeeping-computed row via `enrichment-list` with the dynamic `{{context.event.payload.platform}}` scope and re-emits it through the recipe cycle. The substrate-side housekeeping engagement-aggregates code (D-139 P3 — `backend/server/src/housekeeping/engagement-aggregates/inbound-outbound-ratio.ts`) is the canonical compute path with the full Pass-4 evidence-quality fold (inbound = direction='inbound' + authorship excluding automation/system_process; outbound = direction='outbound' + authorship IN user/crm_user; failed sends + no_answer count toward outbound effort but never as prospect engagement). Recipe writes carry `authored_by_recipe_id` distinct from the housekeeping `system.housekeeping.<topic>` author so both rows coexist on the unique `(topic, scope, target_id, authored_by_recipe_id)` index without conflict. Honest-zero `'mutual'` default per the bucket enum invariant when no housekeeping row exists yet.

Vendor-agnostic Layer-1 silent producer wrapping the `last_meaningful_touch` topic per spec § A.9.1. Subscribes to bus events from BOTH connection.api.hubspot.deal AND connection.api.salesforce.opportunity updates; for each fired record reads any housekeeping-computed row via `enrichment-list` with the dynamic `{{context.event.payload.platform}}` scope and re-emits it through the recipe cycle. The substrate-side housekeeping engagement-aggregates code (D-139 P3 — `backend/server/src/housekeeping/engagement-aggregates/last-meaningful-touch.ts`) is the canonical compute path with the full Pass-4 evidence-quality fold (excludes tracking-pixel + workflow auto-logs via authorship NOT IN crm_automation/system_process; lifecycle filter point_in_time + completed only; direction-agnostic — any meaningful inbound or outbound counts). Recipe writes carry `authored_by_recipe_id` distinct from the housekeeping `system.housekeeping.<topic>` author so both rows coexist on the unique `(topic, scope, target_id, authored_by_recipe_id)` index without conflict. Honest-zero defaults per the value-schema invariant (last_touch_at = 0 paired with all-null vendor + entity + authorship + direction) when no housekeeping row exists yet — the value-schema validator enforces the pairing.

Vendor-agnostic Layer-2 visible alert per spec § P6.A. Subscribes to bus events from BOTH connection.api.hubspot.deal AND connection.api.salesforce.opportunity updates; for each fired record reads the cross-vendor `engagement_velocity_signal` enrichment via `enrichment-list` with dynamic `{{context.event.payload.platform}}` scope. Dispatches a notification when velocity trajectory is `decaying` AND the deal/opportunity meta.amount snapshot exceeds the configurable amount floor (default 10,000). The amount is read from the substrate's platform-reference `meta` snapshot per D-128 — populated by the vendor reconciler at ingest time. Pairs with the Layer-1 `engagement-velocity-producer` re-emitter that ticks the topic on each deal touch — substrate-side housekeeping is the canonical compute path, and the alert reads whichever row is freshest (no authored_by filter).

Vendor-agnostic Layer-2 visible alert per spec § P6.A. Subscribes to bus events from BOTH connection.api.hubspot.deal AND connection.api.salesforce.opportunity updates; for each fired record reads the cross-vendor `engagement_silence_duration` enrichment via `enrichment-list` with dynamic `{{context.event.payload.platform}}` scope. Dispatches a notification when silence (days since last meaningful inbound) exceeds the configurable days threshold (default 14) per spec. Pairs with the Layer-1 `engagement-silence-producer` re-emitter that ticks the topic on each deal touch — substrate-side housekeeping is the canonical compute path. Note: by virtue of the event-trigger model, this alert fires when a silent deal IS touched (revealing the silence), not periodically while truly silent — for true daily cadence over silent deals the housekeeping cycle handles topic refresh and a future watcher can fan out without code change here.