Tier: Change-Feed

What this is

The minute-to-hour cadence tier. Used for periodic catch-up reads, polling adapters, cursor-paginated tail-feeds, and recompute-on-event flows. Sits between stream (real-time) and daily-batch (scheduled) — appropriate when consumers can tolerate lag bounded in minutes, not seconds, and not days.

Purpose

The bulk of enterprise integration is change-feed by nature. POS adapters that poll vendor REST APIs, BI tools that ingest periodic snapshots, agent runs that reconcile against actuals every 15 minutes — all change-feed. Stream is wasteful here; daily batch is too slow.

Structure

Property	Value
Cadence	min–hour
Payload size	KB–MB
Protocol fit	REST polling, webhook subscription, paginated cursor
Failure metric	"lag exceeded" / "queue depth above threshold"
Health input	last watermark advance
Recovery primitive	catch up from watermark (idempotency key required)
Alert pattern	lag-exceeded
Cache strategy	short TTL (mins), invalidate on next pull
Required SLA fields	`freshness_budget`, `max_lag`
Forbidden SLA fields	`schedule`, `window_*`, `ttl`
Required recovery	`mode: catch-up-from-watermark`, `watermark_field`, `idempotency_key`
Watcher check interval	1 minute

Health states

green:  now − last_watermark < max_lag
amber:  max_lag ≤ now − last_watermark < 2× max_lag
red:    now − last_watermark ≥ 2× max_lag

Examples

POST /sync/pull (bull polling Counterpoint REST every 60s)
GET /alerts?cursor=&since= — alert tail (Resource axis)
GET /inventory/adjustments?cursor=&since= — adjustment events
POST /l402-otb/reconcile — 15-min OTB reconciliation
ILDWAC recompute jobs triggered by receiving events

Consumers

BI tools and dashboards (polling tail feeds)
Recompute engines (ILDWAC, analytics rollups)
Reconciliation services (l402-otb actuals match)
AI agents that need fresh-but-not-instant context

Anti-pattern

Don't drop a change-feed feed into daily-batch slot to "save infrastructure." If consumers need 15-min freshness, batching daily silently breaks the contract. Either accept change-feed cadence or move to a stream tier — never split the difference.