PR #21561 migrated liveness probes across 14 call sites from
`os.kill(pid, 0)` to `gateway.status._pid_exists` (psutil-first) so
the gateway doesn't Ctrl+C-itself on Windows via bpo-14484. A handful of
tests still patched the old `os.kill` seam and either happened to pass
on POSIX (when PID 12345 incidentally wasn't alive on the CI worker) or
failed outright — on CI runs they surfaced as 7 flaky/stable failures.
Migrate each affected test to patch the correct seam:
- tests/tools/test_browser_orphan_reaper.py (5 tests)
Patch `gateway.status._pid_exists` instead of `os.kill`.
Rename test_permission_error_on_kill_check_skips to
test_alive_legacy_daemon_is_reaped — the old assertion was
"PermissionError on sig 0 → skip dir"; post-migration the
untracked-alive-daemon path always reaps the dir after SIGTERM
(best-effort semantics were preserved).
- tests/tools/test_windows_native_support.py (4 tests)
Replace tests that asserted `os.kill` seam behavior with tests
that exercise `ProcessRegistry._is_host_pid_alive` as a
delegator and split out a new TestPidExistsOSErrorWidening class
that hits `gateway.status._pid_exists` directly via the POSIX
fallback branch (so Windows-style `OSError(WinError 87)` + `PermissionError`
widening is still covered on Linux CI).
- tests/tools/test_process_registry.py (1 test)
Mock `psutil.Process` + `_pid_exists` instead of `os.kill`
for the detached-session kill path.
- tests/tools/test_mcp_stability.py::test_kill_orphaned_uses_sigkill_when_available
SIGTERM → alive-check → SIGKILL flow now uses `_pid_exists`
for the middle step; assertion count drops from 3 to 2.
- tests/gateway/test_status.py::TestScopedLocks (2 tests)
`acquire_scoped_lock` consults `_pid_exists`; patch that
seam directly instead of trying to control the nested psutil
call via os.kill monkeypatch.
- tests/hermes_cli/test_gateway.py::test_stop_profile_gateway_keeps_pid_file_when_process_still_running
The stop loop sends one SIGTERM via os.kill then polls 20x via
_pid_exists; instrument both separately. Old assertion
`calls["kill"] == 21` split into `kill == 1` + `alive_probes == 20`.
- tests/hermes_cli/test_auth_toctou_file_modes.py::test_shared_nous_store_writes_0o600_with_0o700_parent
Commit c34884ea2 switched the pytest seat-belt guard in
`_nous_shared_store_path()` from `Path.home() / ".hermes"`
to `get_default_hermes_root()`, which honors HERMES_HOME. The
test sets both HERMES_HOME and HERMES_SHARED_AUTH_DIR to
subpaths of the same tmp_path, and the override now collapses
onto the same path the guard is refusing. Renamed the override
subdirectory so the two paths diverge — guard passes, test runs.
All 21 original CI failures and their local-flaky siblings now pass
(278 tests across the touched files, 0 failures).
Both fixes close process leaks observed in production (18+ orphaned
agent-browser node daemons, 15+ orphaned paste.rs sleep interpreters
accumulated over ~3 days, ~2.7 GB RSS).
## agent-browser daemon leak
Previously the orphan reaper (_reap_orphaned_browser_sessions) only ran
from _start_browser_cleanup_thread, which is only invoked on the first
browser tool call in a process. Hermes sessions that never used the
browser never swept orphans, and the cross-process orphan detection
relied on in-process _active_sessions, which doesn't see other hermes
PIDs' sessions (race risk).
- Write <session>.owner_pid alongside the socket dir recording the
hermes PID that owns the daemon (extracted into _write_owner_pid for
direct testability).
- Reaper prefers owner_pid liveness over in-process _active_sessions.
Cross-process safe: concurrent hermes instances won't reap each
other's daemons. Legacy tracked_names fallback kept for daemons
that predate owner_pid.
- atexit handler (_emergency_cleanup_all_sessions) now always runs
the reaper, not just when this process had active sessions —
every clean hermes exit sweeps accumulated orphans.
## paste.rs auto-delete leak
_schedule_auto_delete spawned a detached Python subprocess per call
that slept 6 hours then issued DELETE requests. No dedup, no tracking —
every 'hermes debug share' invocation added ~20 MB of resident Python
interpreters that stuck around until the sleep finished.
- Replaced the spawn with ~/.hermes/pastes/pending.json: records
{url, expire_at} entries.
- _sweep_expired_pastes() synchronously DELETEs past-due entries on
every 'hermes debug' invocation (run_debug() dispatcher).
- Network failures stay in pending.json for up to 24h, then give up
(paste.rs's own retention handles the 'user never runs hermes again'
edge case).
- Zero subprocesses; regression test asserts subprocess/Popen/time.sleep
never appear in the function source (skipping docstrings via AST).
## Validation
| | Before | After |
|------------------------------|---------------|--------------|
| Orphan agent-browser daemons | 18 accumulated| 2 (live) |
| paste.rs sleep interpreters | 15 accumulated| 0 |
| RSS reclaimed | - | ~2.7 GB |
| Targeted tests | - | 2253 pass |
E2E verified: alive-owner daemons NOT reaped; dead-owner daemons
SIGTERM'd and socket dirs cleaned; pending.json sweep deletes expired
entries without spawning subprocesses.
When a Python process exits uncleanly (SIGKILL, crash, gateway restart
via hermes update), in-memory _active_sessions tracking is lost but the
agent-browser node daemons and their Chromium child processes keep
running indefinitely. On a long-running system this causes unbounded
memory growth — 24 orphaned sessions consumed 7.6 GB on a production
machine over 9 days.
Add _reap_orphaned_browser_sessions() which scans the tmp directory for
agent-browser-{h_*,cdp_*} socket dirs on cleanup thread startup. For
each dir not tracked by the current process, reads the daemon PID file
and sends SIGTERM if the daemon is still alive. Handles edge cases:
dead PIDs, corrupt PID files, permission errors, foreign processes.
The reaper runs once on thread startup (not every 30s) to avoid races
with sessions being actively created by concurrent agents.
