2026-09-27 17:06:40 +00:00
1 changed files with 22 additions and 0 deletions
@@ -103,6 +103,28 @@ seat: telegram-sender
 If each consumer could tune it, the mesh's durability would be an emergent property of whichever
 manifest was edited last.
 **Why a module's own events do not carry their own retention, though the same rule would allow
 it.** A seat owns its namespace and gets a stream of its own, so it can say. A module's events
 share one `EVENTS` stream, and three facts about JetStream decide that they must:
 - **Storage is not a property of a subject.** A subject is only an address; a *stream* is a
  separate object that captures subjects matching a filter. So "this topic is durable" is always
  really "some stream covers it", and something has to create that stream.
 - **Overlapping streams are refused, not merged.** Verified against the server: a per-module
  stream beside a shared `mesh.mod.*.event.>` is rejected with *subjects overlap with an existing
  stream*. So "one stream by default, its own for a module that wants different retention" is not
  available — it is all of one or all of the other, and a filter cannot express an exception
  either.
 - **A stream per module breaks cross-module consumption.** An audit logger consuming every
  module's events is one consumer on one stream today; with a stream each it becomes one consumer
  per module, created and destroyed as modules come and go.
 So: one stream, and **per-subject caps** for the fairness that actually matters — a noisy emitter
 cannot evict a quiet one, which is verified (a cap of three, ten messages on one subject and one
 on another, leaves four). What is genuinely unavailable is a different *age* per module, because
 JetStream ages per stream and not per subject. A module that truly needs its own retention has a
 way to say so: declare a seat, which owns its namespace and gets its own stream.
 **Scope gives per-node workers without a new concept.** A module running on three nodes that each
 need their own queue declares a node-scoped seat: one holder per node, three queues, same
 machinery. Mesh-scoped and node-scoped seats already exist; here they do the work of "one shared