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.
A seat's protocol lives in the store (migration 0047; seeded additively), a served verb carries its
description and schema, holding a mesh seat requires serving its verbs, a node-scoped seat's tool
carries the node, and the control plane serves status, nodes, node, modules, seats, builds, plan,
assign, unassign, push, build and tools on its seat by running the same commands (novox/hq ADR 0132,
ADR 0154, design 33). A grant of * reaches a role's tools; seat:<seat>.<verb> grants one.
jschoubben