A build says what it does on the bus, as it happens (novox/hq ADR 0157)

The build-machine seat emits `started` and `log.<build id>` beside `built`. Every line the builder
speaks — each step, each command with its duration, and on failure the command's own output — goes
to stderr as before and onto the bus under the build's id, one subject per build, kept a week in
EVENTS with every other event. `builds --log <id>` reads it back from the stream with a consumer
that is gone when the reading is done, on the command line and as the controller's seat verb;
`builds` lists each build's id and `build` says the id it asked with.

Lines are core publishes with a sequence number, so a build is not slowed by an ack per line and a
gap is visible; `started` and `built` are awaited into the stream. The seat protocol widens
additively at the controller's next start; the holder's grant follows on the broker node's next
composition.

internal/broker/streams.go

@@ -79,7 +79,7 @@ func MeshStreams() []Stream {
 				"n-1 by construction (issue 107)",
 		},
 		{
-			Name: "EVENTS",
+			Name: EventsStream,
 			// A seat's own events ride here too: they are 1:many like any event, and the
 			// `event` token keeps them clear of both the seat's work queue (`accept`) and its
 			// tools (`tool`), which must not be persisted.
@@ -220,6 +220,9 @@ func seatEventSubject(seat, verb string) string {
 	return "mesh.seat." + seat + ".event." + verb
 }
 
+// EventsStream holds every module's and every role's events, a build's log among them.
+const EventsStream = "EVENTS"
+
 // MeshConsumers is what the controller consumes, in the order a person reads it.
 //
 // **Unlimited redelivery on CONTROL, deliberately.** The store window's bound is the controller's,