Problem

Fixes #14359.

On Windows, os.kill(existing_pid, 0) raises OSError([WinError 11]) (and other OSError variants) instead of ProcessLookupError when the process no longer exists. The current handler only catches ProcessLookupError and PermissionError:

# Before
except (ProcessLookupError, PermissionError):
    stale = True

This causes every gateway restart on Windows after a non-graceful shutdown (terminal close, crash, Ctrl+C) to fail with an unhandled OSError — requiring manual deletion of the PID file each time.

Root Cause

Windows does not raise ProcessLookupError (ESRCH) for dead PIDs in os.kill. It raises a platform-specific OSError. This is a known Python/Windows platform difference.

Fix

Add OSError to the exception tuple at the one affected call site:

# After
except (ProcessLookupError, PermissionError, OSError):
    stale = True

This matches the pattern already used at two other os.kill call sites in the same file (lines 522 and 633 in the current main), which already include OSError.

Changes

Tests

New test file tests/test_gateway_status_pid_check.py covers:

• ✅ Windows path: os.kill raises OSError(11, ...) → treated as stale (the regression)
• ✅ Unix path: os.kill raises ProcessLookupError → treated as stale (non-regression)
• ✅ PermissionError path — no unhandled exception (non-regression)
• ✅ Missing PID file → None returned (baseline)

python -m pytest tests/test_gateway_status_pid_check.py -v