feat(daemon): implement reload, fix PID race condition

- PluginSupervisor.reload(): cancels all running plugin tasks, resets
  restart counters, and re-creates them with fresh coroutines
- IPC reload command now calls supervisor.reload() instead of being a stub
- run_foreground(): wrap PID file acquisition in try/except PidFileError
  to produce a clean error if two daemon starts race on the PID file

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/pyra/daemon/core.py

@@ -68,6 +68,22 @@ class PluginSupervisor:
         if tasks:
             await asyncio.gather(*tasks, return_exceptions=True)
 
+    async def reload(self) -> None:
+        """Cancel all running tasks and restart them with fresh coroutines."""
+        for record in self._records:
+            if record.task and not record.task.done():
+                record.task.cancel()
+                try:
+                    await record.task
+                except (asyncio.CancelledError, Exception):
+                    pass
+            record.restart_count = 0
+            record.last_error = None
+            record.task = asyncio.create_task(
+                self._supervise(record), name=record.name
+            )
+        _log.info("Reloaded %d plugin task(s).", len(self._records))
+
     def status(self) -> list[dict]:
         return [
             {
@@ -131,8 +147,8 @@ def _make_ipc_handler(supervisor: PluginSupervisor):
                 supervisor.request_shutdown()
                 return {"ok": True, "data": {}}
             case "reload":
-                _log.info("Reload requested via IPC.")
-                return {"ok": True, "data": {}}
+                await supervisor.reload()
+                return {"ok": True, "data": {"tasks_reloaded": len(supervisor._records)}}
             case _:
                 return {"ok": False, "data": {"error": f"unknown command: {cmd}"}}
 
@@ -196,13 +212,17 @@ def run_foreground() -> None:
 
     _start_time = time.monotonic()
 
-    with pid_file:
-        _log.info("Pyra daemon starting (PID %d).", os.getpid())
-        try:
-            asyncio.run(_run_daemon(cfg, supervisor))
-        except KeyboardInterrupt:
-            pass
-        _log.info("Pyra daemon stopped.")
+    try:
+        with pid_file:
+            _log.info("Pyra daemon starting (PID %d).", os.getpid())
+            try:
+                asyncio.run(_run_daemon(cfg, supervisor))
+            except KeyboardInterrupt:
+                pass
+            _log.info("Pyra daemon stopped.")
+    except PidFileError as exc:
+        _log.error("Could not acquire PID file: %s", exc)
+        sys.exit(1)
 
 
 # ── Background spawn (pyra daemon start) ─────────────────────────────────────