A replay consumer now has a 5s idle heartbeat, and the row stream ends at
the first consumer error instead of skipping it. When the server drops the
consumer, as on a restart, two missed heartbeats end the SSE response and
the browser reconnects with Last-Event-ID. Before, the response stayed
open and delivered nothing.
A Last-Event-ID above the stream's newest sequence now replays as a fresh
reader. The server accepts a start past the end and delivers nothing
until the stream reaches it, so a stale id stalled the replay.
swarm-controller's stream tests run against a real nats-server on
loopback (`test_nats`, binary from HIVE_NATS_SERVER, exported by
checks.nix and devshell.nix). They cover: ensuring the stream twice, an
existing stream with other limits being opened as it is, the replay
arriving before live rows, a reconnect getting every later row exactly
once, and a dropped consumer ending the row stream.
The limits test now compares against the subagent stream's own config.
Two comments that described the agent's terminal route as live-only are
corrected.
swarm-controller now creates `term-main-<agent>` for every live agent, in
the same one-minute pass and with the same config style as
`term-sub-<agent>` (#4897): subjects `$SWARM.term.<agent>` only, max_age
24h, max_bytes 64 MiB, discard Old, max_message_size from the queue's
max_payload. An existing stream is opened as it is. The agent keeps its
plain publish on `$SWARM.term.<agent>` and gets no JetStream subject.
`GET /api/agents/{name}/term/stream` creates an ephemeral push consumer on
that stream starting 100 rows back, so a swarm-ui terminal opens with
recent history and then follows new rows, in order, from one
subscription. Each SSE event carries the row's stream sequence as its id,
and a reconnect's Last-Event-ID resumes after it. Without the stream the
route falls back to the live core subscription it used before.
The stream is `term-main-<agent>`, not `term-<agent>`: an agent may be
named `sub-x`, whose `term-<agent>` would be agent `x`'s subagent stream.
Its one literal subject cannot match `$SWARM.term.<agent>.sub.>`, which
needs more tokens, so the two streams never overlap.
The reader gains `$JS.API.CONSUMER.CREATE.*.*.$SWARM.term.*`, the
extended create form whose last tokens are the consumer's filter. Checked
against nats-server 2.14.4, the trailing `*` also admits a literal `*` or
`>` filter, so a consumer under it reaches any terminal row, main or
subagent; those are rows the reader already subscribes to and reads with
`STREAM.MSG.GET.*`.
Closes#4826
