Crash-log stack trace (tui_gateway_crash.log) from the user's session
pinned the regression: SIGPIPE arrived while main thread was blocked on
for-raw-in-sys.stdin — i.e., a background thread (debug print to stderr,
most likely from HERMES_VOICE_DEBUG=1) wrote to a pipe whose buffer the
TUI hadn't drained yet, and SIG_DFL promptly killed the process.
Two fixes that together restore CLI parity:
- entry.py: SIGPIPE → SIG_IGN instead of the _log_signal handler that
then exited. With SIG_IGN, Python raises BrokenPipeError on the
offending write, which write_json already handles with a clean exit
via _log_exit. SIGTERM / SIGHUP still route through _log_signal so
real termination signals remain diagnosable.
- hermes_cli/voice.py:_debug: wrap the stderr print in a BrokenPipeError
/ OSError try/except. This runs from daemon threads (silence callback,
TTS playback, beep), so a broken stderr must not escape and ride up
into the main event loop.
Verified by spawning the gateway subprocess locally:
voice.toggle status → 200 OK, process stays alive, clean exit on
stdin close logs "reason=stdin EOF" instead of a silent reap.
SIG_DFL for SIGPIPE means the kernel reaps the gateway subprocess the
instant a background thread (TTS playback, silence callback, voice
status emitter) writes to a stdout the TUI stopped reading — before
the Python interpreter can run excepthook, threading.excepthook,
atexit, or the entry.py post-loop _log_exit.
Replace the three SIG_DFL / SIG_IGN bindings with a _log_signal
handler that:
- records which signal (SIGPIPE / SIGTERM / SIGHUP) fired and when;
- dumps the main-thread stack at signal delivery AND every live
thread's stack via sys._current_frames — the background-thread
write that provoked SIGPIPE is almost always visible here;
- writes everything to ~/.hermes/logs/tui_gateway_crash.log and prints
a [gateway-signal] breadcrumb to stderr so the TUI Activity surfaces
it as well.
SIGINT stays ignored (TUI handles Ctrl+C for the user).
Gateway exits weren't reaching the panic hook because entry.py calls
sys.exit(0) on broken stdout — clean termination, no exception. That
left "gateway exited" in the TUI with zero forensic trail when pipe
breaks happened mid-turn.
Entry.py now tags each exit path — startup-write failure, parse-error-
response write failure, per-method response write failure, stdin EOF —
with a one-line entry in ~/.hermes/logs/tui_gateway_crash.log and a
gateway.stderr breadcrumb. Includes the JSON-RPC method name on the
dispatch path, which is the only way to tell "died right after handling
voice.toggle on" from "died emitting the second message.complete".
The stdin-read loop in entry.py calls handle_request() inline, so the
five handlers that can block for seconds to minutes
(slash.exec, cli.exec, shell.exec, session.resume, session.branch)
freeze the dispatcher. While one is running, any inbound RPC —
notably approval.respond and session.interrupt — sits unread in the
pipe buffer and lands only after the slow handler returns.
Route only those five onto a small ThreadPoolExecutor; every other
handler stays on the main thread so the fast-path ordering is
unchanged and the audit surface stays small. write_json is already
_stdout_lock-guarded, so concurrent response writes are safe. Pool
size defaults to 4 (overridable via HERMES_TUI_RPC_POOL_WORKERS).
- add _LONG_HANDLERS set + ThreadPoolExecutor + atexit shutdown
- new dispatch(req) function: pool for long handlers, inline for rest
- _run_and_emit wraps pool work in a try/except so a misbehaving
handler still surfaces as a JSON-RPC error instead of silently
dying in a worker
- entry.py swaps handle_request → dispatch
- 5 new tests: sync path still inline, long handlers emit via stdout,
fast handler not blocked behind slow one, handler exceptions map to
error responses, non-long methods always take the sync path
Manual repro confirms the fix: shell.exec(sleep 3) + terminal.resize
sent back-to-back now returns the resize response at t=0s while the
sleep finishes independently at t=3s. Before, both landed together
at t=3s.
Fixes#12546.
