TestNats picked a port by binding 127.0.0.1:0, dropping the listener
and handing the number to nats-server. Until that server bound it, the
port was free for a concurrent test's bind(0) to return again. Both
servers were then started on it (with the same store dir, since that was
keyed by pid and port); the loser exited silently and both tests'
clients reached the winner. term_stream's tests all use the stream
term-main-iris, and one of them creates it with max_message_size 4096,
so a test sharing its server got "stream name already in use with a
different configuration" (10058) from open_or_create's
get-then-create.
The server now binds a port of its choice (-p -1) and announces it in a
ports file, and each server has its own tempdir for the store and that
file, so a test can only reach the server it started.
Fixes#5261
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.
