hermes-agent/tests/tui_gateway
brooklyn! 1e326c686d
fix(tui-gateway): harden stdio transport against half-closed pipes + SIGTERM races (#17118)
* fix(tui-gateway): harden stdio transport against half-closed pipes + SIGTERM races

`tui_gateway` reports `tui_gateway_crash.log` traces where the main
thread sits in `sys.stdin` while a worker holds `_stdout_lock` mid-
flush, and SIGTERM then calls `sys.exit(0)` while the lock is still
held — the interpreter shutdown stalls behind the wedged write.

Two narrowly scoped hardenings:

**`tui_gateway/transport.py`**

* Move JSON serialisation outside the lock — long messages no longer
  block sibling writers while we serialise.
* Treat `BrokenPipeError`, `ValueError` ("I/O on closed file") and
  generic `OSError` from both `write` and `flush` as "peer is gone":
  return `False` instead of bubbling, matching what `write_json`'s
  callers in `entry.py` already expect.
* Split `flush` into its own try block so a stuck flush never strands
  a partial write or holds the lock indefinitely on its way out.
* Optional `HERMES_TUI_GATEWAY_NO_FLUSH=1` env knob to skip explicit
  `flush()` entirely on environments where a half-closed read pipe
  produces an indefinite kernel-level block.  Default unchanged.

**`tui_gateway/entry.py`**

* `_log_signal` now spawns a 1-second daemon timer that calls
  `os._exit(0)` if the orderly `sys.exit(0)` path is itself stuck
  behind a wedged worker.  Atexit handlers run inside the grace
  window when they can; the timer is the safety net so a deadlocked
  flush no longer strands the gateway process.

Tests:

* `test_write_json_closed_stream_returns_false` — ValueError path.
* `test_write_json_oserror_on_flush_returns_false` — OSError on flush
  must not strand the lock; the write portion still landed before the
  flush failure.
* `test_write_json_no_flush_env_skips_flush` — env knob bypass.

Validation: `scripts/run_tests.sh tests/tui_gateway/test_protocol.py`
(42/42 pass; one pre-existing failure on
`test_session_resume_returns_hydrated_messages` is unrelated to this
change — same `include_ancestors` mock kwarg issue tracked elsewhere).
`scripts/run_tests.sh tests/test_tui_gateway_server.py` 90/90 pass.

* review(copilot): tighten transport hardening comments + test cleanup

* review(copilot): narrow exception capture, configurable grace, simpler no-flush test

* fix(tui-gateway): narrow ValueError to closed-stream; surface UnicodeEncodeError

Copilot review on PR #17118: `UnicodeEncodeError` is a ValueError
subclass, so a non-UTF-8 stdout (mismatched PYTHONIOENCODING / locale)
would have been silently swallowed as 'peer gone' under
`except ValueError`.  That hides a real environment bug.

Now:
- UnicodeEncodeError → log with exc_info (warning) and drop the frame
- ValueError where str(e) contains 'closed file' → peer gone, return False
- Any other ValueError → log loudly, drop frame (defensive, but visible)

Same shape applied to flush.  Adds two regression tests.

* fix(tui-gateway): reserve write() False for peer-gone; re-raise programming errors

Round 2 Copilot review on PR #17118: `Transport.write()` returning
`False` is documented as 'peer is gone', and `entry.py` reacts by
calling `sys.exit(0)`.  But the implementation also returned False
for non-IO conditions (non-JSON-safe payloads, UnicodeEncodeError,
unrelated ValueErrors), so a programming error or local env bug would
present as a clean disconnect — exactly the diagnosis pain we wanted
to eliminate.

Now:
- `json.dumps` failure → re-raises (TypeError/ValueError surfaces in crash log)
- `BrokenPipeError` → False (peer gone)
- `ValueError('...closed file...')` → False (peer gone)
- `UnicodeEncodeError` and any other ValueError → re-raise
- `OSError` → False (existing IO-failure semantics, debug-logged)

Tests updated to assert the re-raise behaviour and added a
non-serializable-payload regression test.

* fix(tui-gateway): narrow OSError to peer-gone errnos; honest test naming

Round 3 Copilot review on PR #17118:

- Docstring claimed False = peer gone, but generic OSError on write/flush
  also returned False — meaning ENOSPC/EACCES/EIO would silently exit.
  Added `_PEER_GONE_ERRNOS = {EPIPE, ECONNRESET, EBADF, ESHUTDOWN, +WSA}`
  and narrowed the OSError handlers; non-peer-gone errnos re-raise.
  Docstring now lists OSError as peer-gone branch with the errno set.
- The `_DISABLE_FLUSH` test was named after the env var but actually
  patched the module constant. Renamed it to reflect the contract being
  tested (skips flush when constant is true) AND added a real
  end-to-end test that sets the env var, reloads transport.py, and
  asserts the constant flips. Cleanup reload restores defaults so
  parallel tests stay isolated.

Self-review (avoid round 4):
- Verified TeeTransport's secondary-swallow stays intentional.
- _log_signal grace path already covered by separate tests.
2026-04-28 17:54:06 -05:00
..
__init__.py feat: add tests and update mds 2026-04-08 19:31:25 -05:00
test_make_agent_provider.py fix: follow-up for salvaged PR #17061 2026-04-28 12:27:36 -07:00
test_protocol.py fix(tui-gateway): harden stdio transport against half-closed pipes + SIGTERM races (#17118) 2026-04-28 17:54:06 -05:00
test_render.py feat: add tests and update mds 2026-04-08 19:31:25 -05:00