The EchoMQ bus.

For a single reader, a stream is three verbs: XADD to append, XREAD to consume, XDEL to remove when done. The edge appears the moment two independent consumers need the same entries. You can no longer delete on completion — a fast group would pull entries out from under a slow one. The coordination primitive is the consumer group: an entry read through a group (XREADGROUP GROUP g c >) is placed on that group’s Pending Entries List, a consumer drains its own PEL first on rejoin, and XACK guarantees an entry will not be re-delivered within that group. The trap the field account names precisely: an acknowledged entry is not deleted — it stays in the stream until something trims it, and left alone it fills the box. EchoMQ keeps these verbs exactly — XADD, XRANGE, XREADGROUP, XACK, XAUTOCLAIM — as additive registrations on the existing EchoMQ.Connector, a protocol minor on the same RESP3 wire and house port as the jobs, the bus, and the cache. No second system to run: that was the whole objection to Kafka.

EchoMQ claims the small end explicitly — event streams, bounded retention, a handful of groups per stream — and keeps its databases (Tables, the journal, Postgres) beside the log, which is what makes keyed compaction someone else’s problem. Its contribution is to turn each edge the field account discovered into something named. First, an order theorem: stream order equals branded-id sort order equals mint order, because every record’s id is minted so its byte order is its time order. But a consumer group adds a second axis — a re-claimed PEL entry returns to a consumer out of real-time order, the honest cost of at-least-once — and the spec names exactly where the theorem holds (the stream) and where it cannot (a re-claim), so a spec asserting “order preserved” can never be a false green. Second, retention is policy, not a bespoke process: a declared per-stream window (MAXLEN ~ approx, MINID by mint instant) rather than a Janitor trimming by estimate. Third, the archive: a fold consumer commits each trimmed slice into the native EchoStore.Graft engine before it trims (fold-before-trim), and the engine streams those pages to Tigris — so the field account’s “acked entries are never deleted” fear is answered by folding them to durable object storage, not by hoarding RAM. The three dives walk the verbs, the retention problem, and the full six-rung tier.