A separate $SWARM.control.<agent> subject carries commands, apart from
the text subject. swarm-controller exposes POST /api/agents/{name}/cancel
as a NATS request; the harness answers whether a turn was actually
stopped, through the same cancel path as the dashboard button. The agent
credential gets subscribe on its control subject and allow_responses to
answer; only the controller may publish there.
Refs #3803
The agent view in the swarm UI gets a message box. The text reaches the
agent's harness straight from swarm-controller over the swarm queue and
becomes an inbox turn from the operator's authelia username. hive-c0re is
not in the path.
- gateway: `/api/` forwards authelia's `Remote-User`, replacing any the
client sent.
- swarm-controller: `POST /api/agents/{name}/input` takes that header as
the sender (401 without it) and sends `{from, body}` as a NATS request
on `$SWARM.input.<agent>`. No subscriber is a 503.
- swarm-nats-auth: the controller is granted publish on `$SWARM.input.*`;
no hive or agent grant names the family, so the harness can trust
`from`.
- hive-agent: a task subscribes to the agent's own input subject and
pushes each message into the serve loop's existing reminder channel,
renamed `local_msg_*` since it now carries both.
The harness does not reply to the request: no agent grant covers a reply
subject. The controller therefore answers 202 once the request times out
(2s) and 503 on the server's no-responders status.
Closes#4828
