feat: app state module with status enum and subscriber pattern

api/state.py

@@ -0,0 +1,36 @@
+import asyncio
+from dataclasses import dataclass, field
+from enum import Enum
+from typing import Callable
+
+
+class Status(str, Enum):
+    IDLE = "idle"
+    RECORDING = "recording"
+    PROCESSING = "processing"
+    ERROR = "error"
+
+
+@dataclass
+class AppState:
+    status: Status = Status.IDLE
+    recording_user: str | None = None  # which user triggered the current recording
+    last_error: str | None = None
+    _listeners: list[Callable] = field(default_factory=list, repr=False)
+
+    def subscribe(self, callback: Callable):
+        self._listeners.append(callback)
+
+    async def notify(self):
+        for cb in self._listeners:
+            if asyncio.iscoroutinefunction(cb):
+                await cb(self)
+            else:
+                cb(self)
+
+    async def set_status(self, status: Status):
+        self.status = status
+        await self.notify()
+
+
+state = AppState()