@

fix(gateway): self-heal state file PID on server startup

After /restart on Windows, the gateway process gets a new PID (os.execv
creates a new process on Windows), but the state file at
run/gateway.<suffix>.json still contains the old PID from the initial
background spawn.  Nothing rewrites it, leaving state inconsistent.

Add GatewayRuntime.refresh_state_pid() — a classmethod that reads the
existing state file, updates the PID and identity to the current
process, and writes atomically.  Call it early in _run_gateway() so the
state file is always correct regardless of how the process was started
(initial spawn, os.execv, or subprocess.Popen).

On POSIX os.execv preserves the PID, so this is a no-op in normal
operation there, but still beneficial after any unusual restart path.

Fixes #4511
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nanobot/gateway/runtime.py

@@ -127,6 +127,25 @@ class GatewayRuntime:
         self._subprocess_run = subprocess_run
         self._sleep = sleep
 
+    @classmethod
+    def refresh_state_pid(cls, *, paths: GatewayRuntimePaths) -> None:
+        """Update the PID in an existing state file to ``os.getpid()``.
+
+        Called early in gateway server startup so the state file self-heals
+        after any restart, regardless of platform or restart mechanism.
+        """
+        if not paths.state_path.exists():
+            return
+        try:
+            state = json.loads(paths.state_path.read_text(encoding="utf-8"))
+        except (json.JSONDecodeError, OSError):
+            return
+        state["pid"] = os.getpid()
+        rt = cls(paths=paths)
+        state["identity"] = rt._process_identity(os.getpid())
+        state["started_at"] = _utc_now()
+        rt._write_state(state)
+
     def start_background(self, options: GatewayStartOptions) -> RuntimeResult:
         """Start gateway as a detached background process."""
         current = self.status()