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).
MCP stdio servers are spawned via the SDK's stdio_client, which on
Linux uses start_new_session=True (setsid). When a cron job is
cancelled mid-way (timeout, agent finish, exception), the subprocess
often escapes the SDK's teardown and survives as a session leader.
Because setsid() detaches the child from the gateway's process group
/ cgroup tree, systemd does not reap it on service restart either —
so every cron tick that touches an MCP tool leaks a dangling server
process.
Fix:
* tools/mcp_tool.py — _run_stdio now wraps the whole stdio+session
context in try/finally. On any exit path (clean, exception,
cancellation), PIDs still alive are moved from the active
_stdio_pids set into a new _orphan_stdio_pids set. Orphan
detection is done via os.kill(pid, 0) — a cheap liveness probe
that never signals the target.
* tools/mcp_tool.py — _kill_orphaned_mcp_children gains an
include_active=False flag. Default behaviour now only reaps the
orphan set so concurrent sessions (other parallel cron jobs or
live user chats) are never disrupted. The existing shutdown path
passes include_active=True to keep the previous "kill everything"
semantics after the MCP loop is stopped.
* cron/scheduler.py — the cleanup hook is moved from run_job()'s
finally (which would race with parallel siblings after #13021)
into tick() after the ThreadPoolExecutor has joined every future.
At that point there are no in-flight sessions from this tick, so
sweeping the orphan set is always safe.
Net effect: zero regression for healthy sessions, and orphan MCP
servers no longer accumulate between gateway restarts.
Made-with: Cursor
- _stdio_pids: set → Dict[int,str] tracks pid→server_name
- SIGTERM-first with 2s grace before SIGKILL escalation
- hasattr guard for SIGKILL on platforms without it
- Updated tests for dict-based tracking and 3-phase kill sequence
Port two improvements inspired by Kilo-Org/kilocode analysis:
1. Error classifier: add context overflow patterns for vLLM, Ollama,
and llama.cpp/llama-server. These local inference servers return
different error formats than cloud providers (e.g., 'exceeds the
max_model_len', 'context length exceeded', 'slot context'). Without
these patterns, context overflow errors from local servers are
misclassified as format errors, causing infinite retries instead
of triggering compression.
2. MCP initial connection retry: previously, if the very first
connection attempt to an MCP server failed (e.g., transient DNS
blip at startup), the server was permanently marked as failed with
no retry. Post-connect reconnection had 5 retries with exponential
backoff, but initial connection had zero. Now initial connections
retry up to 3 times with backoff before giving up, matching the
resilience of post-connect reconnection.
(Inspired by Kilo Code's MCP server disappearing fix in v1.3.3)
Tests: 6 new error classifier tests, 4 new MCP retry tests, 1
updated existing test. All 276 affected tests pass.
Four fixes for MCP server stability issues reported by community member
(terminal lockup, zombie processes, escape sequence pollution, startup hang):
1. MCP reload timeout guard (cli.py): _check_config_mcp_changes now runs
_reload_mcp in a separate daemon thread with a 30s hard timeout. Previously,
a hung MCP server could block the process_loop thread indefinitely, freezing
the entire TUI (user can type but nothing happens, only Ctrl+D/Ctrl+\ work).
2. MCP stdio subprocess PID tracking (mcp_tool.py): Tracks child PIDs spawned
by stdio_client via before/after snapshots of /proc children. On shutdown,
_stop_mcp_loop force-kills any tracked PIDs that survived the SDK's graceful
SIGTERM→SIGKILL cleanup. Prevents zombie MCP server processes from
accumulating across sessions.
3. MCP event loop exception handler (mcp_tool.py): Installs
_mcp_loop_exception_handler on the MCP background event loop — same pattern
as the existing _suppress_closed_loop_errors on prompt_toolkit's loop.
Suppresses benign 'Event loop is closed' RuntimeError from httpx transport
__del__ during MCP shutdown. Salvaged from PR #2538 (acsezen).
4. MCP OAuth non-blocking (mcp_oauth.py): Replaces blocking input() call in
_wait_for_callback with OAuthNonInteractiveError raise. Adds _is_interactive()
TTY detection. In non-interactive environments, build_oauth_auth() still
returns a provider (cached tokens + refresh work), but the callback handler
raises immediately instead of blocking the MCP event loop for 120s. Re-raises
OAuth setup failures in _run_http so failed servers are reported cleanly
without blocking others. Salvaged from PRs #4521 (voidborne-d) and #4465
(heathley).
Closes#2537, closes#4462
Related: #4128, #3436
