This is the bug that was actually closing Firefox. `_kill_port_process`, run on
every bridge (re)start to free the port, used `lsof -ti :PORT` / `fuser PORT/tcp`
— both of which match a process whose socket merely *involves* that port number
in ANY state, including ESTABLISHED client connections. It then SIGTERMed every
match.
The bridge defaults to port 3000 — a ubiquitous local dev-server port. With a
browser tab open on localhost:3000, `lsof -ti :3000` returned Firefox's PID, so
each restart of the (crash-looping) WhatsApp bridge SIGTERMed Firefox, closing
the whole browser at irregular intervals with no crash and no coredump.
Proven live with the kernel `signal:signal_generate` tracepoint:
hermes-gateway(3396516) -> sig=15 (code=0/SI_USER) -> comm=firefox pid=3371585
captured immediately after a gateway start, while Firefox held a socket on the
bridge port. Demonstrated over-match: `lsof -ti :8080` returns the listener AND
the gateway's own client connection; `lsof -ti tcp:8080 -sTCP:LISTEN` returns
only the listener.
Fix: `_listener_pids_on_port` resolves only LISTEN-state sockets
(`lsof -ti tcp:PORT -sTCP:LISTEN`, with an `ss -ltnp` fallback) and
`_kill_port_process` signals just those. A client whose connection happens to
involve the port number is never touched — which is also more correct, since a
client never blocks the new bridge from binding. Windows already filtered
LISTENING; the broad `fuser -k` path is removed.
Adds TestKillPortProcess: real-socket tests proving a separate client process
is excluded from the listener lookup and survives port cleanup. 9 tests green.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
069ab40c5f