refactor(serve): one place maps "process gone" to orphaned in the watchdog

The inner ProcessLookupError handler around the marker probe made the outer one reachable only through an injected pid_exists that raises (gateway.status._pid_exists never does). Keep the single mapping; the degrade-to-liveness fixture no longer models a stderr the probe now classifies as a missing process.

hermes_cli/web_server_lifecycle.py

@@ -75,9 +75,8 @@ def _process_start_marker(pid: int) -> str:
     marker = result.stdout.strip()
     if result.returncode == 0 and marker:
         return f"ps:{marker}"
-    # rc==1 with empty output is the portable "no such pid"; "No such process" widens that for ps
-    # builds that say so explicitly. Any other failure stays an OSError so the watchdog degrades to
-    # pid liveness instead of exiting on a healthy backend.
+    # Only known "missing pid" signals become ProcessLookupError; anything else stays OSError so the
+    # watchdog degrades to pid liveness instead of exiting on a healthy backend.
     if (result.returncode == 1 and not marker) or "no such process" in result.stderr.lower():
         raise ProcessLookupError(pid)
     raise OSError(f"ps could not inspect PID {pid}: {result.stderr.strip()}")
@@ -300,8 +299,6 @@ def _is_serve_orphaned(
 
             pid_exists = _pid_exists
         return not bool(pid_exists(int(desktop_pid)))
-    except ProcessLookupError:
-        return True
     except Exception:
         return False
 

tests/hermes_cli/test_serve_parent_watchdog.py

@@ -183,7 +183,7 @@ def test_parent_watchdog_degrades_to_pid_liveness_when_marker_probe_raises_oserr
     """#80204: a probe failure must fall through to ``pid_exists`` instead of pinning the
     watchdog to "not orphaned" forever on a dead Desktop parent."""
     def broken_marker_probe(pid: int) -> str:
-        raise OSError(f"ps could not inspect PID {pid}: ps: {pid}: No such process")
+        raise OSError(f"ps could not inspect PID {pid}: process table temporarily unavailable")
 
     marker = "ps:Thu Aug 20 22:33:11 2026"
     assert _is_serve_orphaned(4242, marker, pid_exists=lambda _pid: False,