Add presence heartbeat to keep bot showing as online

matrix-nio's AsyncClient.set_presence() is called every 60s in a
background task so Matrix clients see the bot as online. On shutdown
the bot sets itself to offline.

https://claude.ai/code/session_01DuzWyMMXvLMB4VxEwJyV4X

app/main.py

@@ -4,7 +4,7 @@ from contextlib import asynccontextmanager
 from fastapi import FastAPI
 
 from app.database import close_db, get_thread_root, init_db, set_thread_root
-from app.matrix import THREAD_ROOT_MESSAGES, close_client, send_thread_root
+from app.matrix import THREAD_ROOT_MESSAGES, close_client, send_thread_root, start_presence
 from app.webhooks import router as webhook_router
 
 logging.basicConfig(
@@ -19,6 +19,7 @@ async def lifespan(app: FastAPI):
     log.info("Starting Melora")
     await init_db()
     await _ensure_thread_roots()
+    await start_presence()
     log.info("Melora ready")
     yield
     log.info("Shutting down Melora")

app/matrix.py

@@ -1,3 +1,4 @@
+import asyncio
 import logging
 
 from nio import AsyncClient, RoomSendResponse
@@ -7,6 +8,9 @@ from app.config import config
 log = logging.getLogger(__name__)
 
 _client: AsyncClient | None = None
+_presence_task: asyncio.Task | None = None
+
+PRESENCE_INTERVAL_SECONDS = 60
 
 THREAD_ROOT_MESSAGES: dict[str, str] = {
     "movies": "\U0001f3ac Movies",
@@ -25,12 +29,41 @@ async def get_client() -> AsyncClient:
 
 
 async def close_client() -> None:
-    global _client
+    global _client, _presence_task
+    if _presence_task is not None:
+        _presence_task.cancel()
+        try:
+            await _presence_task
+        except asyncio.CancelledError:
+            pass
+        _presence_task = None
     if _client is not None:
+        await _set_presence("offline")
         await _client.close()
         _client = None
 
 
+async def _set_presence(state: str) -> None:
+    client = await get_client()
+    try:
+        await client.set_presence(state)
+    except Exception:
+        log.debug("Presence update failed", exc_info=True)
+
+
+async def _presence_loop() -> None:
+    while True:
+        await _set_presence("online")
+        await asyncio.sleep(PRESENCE_INTERVAL_SECONDS)
+
+
+async def start_presence() -> None:
+    global _presence_task
+    await _set_presence("online")
+    _presence_task = asyncio.create_task(_presence_loop())
+    log.info("Presence heartbeat started (every %ds)", PRESENCE_INTERVAL_SECONDS)
+
+
 async def send_thread_root(media_type: str) -> str:
     client = await get_client()
     label = THREAD_ROOT_MESSAGES[media_type]