fix(logs): keep polling reads and a channel-less account out of the warnings

The reads the frontend polls (unread counts, /api/me, the download index,
sync status, subtitle progress) are logged at DEBUG: at INFO they were ~95%
of the stored log on prod. A scheduler job failure and a playlist sync
failure carry event codes, and a Google account without a YouTube channel
has an empty playlist list instead of a warning every six hours.

backend/app/logs.py

@@ -644,6 +644,27 @@ _REQUEST_ID_RE = re.compile(r"^[A-Za-z0-9._-]{8,64}$")
 # — this lowers the floor, it does not hide.
 _QUIET_PREFIXES = ("/healthz", "/assets/", "/static/", "/api/admin/logs")
 
+# The reads the frontend POLLS (a `useLiveQuery`, the `me` heartbeat, the sync status, the subtitle
+# progress), by route template, GET only — logged at DEBUG like the prefixes above. One open tab asked
+# for the two unread counts, `/api/me` and the download index every 30 s, and at INFO those were ~95%
+# of the stored log (measured on prod 2026-09-19): 11k lines a day per tab burying every line someone
+# caused. The same route answered with a failure still logs at WARNING/ERROR.
+_POLLED_ROUTES = frozenset(
+    {
+        "/api/me",
+        "/api/me/notifications/unread_count",
+        "/api/messages/unread_count",
+        "/api/downloads",
+        "/api/downloads/index",
+        "/api/downloads/usage",
+        "/api/sync/my-status",
+        "/api/admin/scheduler",
+        "/api/admin/downloads",
+        "/api/admin/downloads/storage",
+        "/api/plex/subtitle/{rating_key}/{sub_ord}/status",
+    }
+)
+
 # Not `siftlode.logs`: this is the replacement for uvicorn's ACCESS log, and `siftlode.http` is
 # what an operator pins a level on when they want request lines and nothing else. The module it
 # happens to live in is not what the name is about.
@@ -689,7 +710,9 @@ async def log_requests(request, call_next):
         raise
     duration_ms = round((time.perf_counter() - started) * 1000, 1)
     status = response.status_code
-    quiet = request.url.path.startswith(_QUIET_PREFIXES)
+    quiet = request.url.path.startswith(_QUIET_PREFIXES) or (
+        request.method == "GET" and _route_template(request) in _POLLED_ROUTES
+    )
     if status >= 500:
         level = logging.ERROR
     elif status >= 400:

backend/app/scheduler.py

@@ -208,7 +208,7 @@ def _job(name: str, fn) -> None:
         _audit_run(db, actor_id, name, "ok", summary, result)
     except Exception as exc:
         db.rollback()
-        log.exception("job %s failed", name)
+        log.exception("job %s failed", name, extra=logs.event("scheduler.job.failed", job=name))
         err = str(exc) or exc.__class__.__name__
         _record(name, status="error", last_finished=_now_iso(), last_error=err, progress=None)
         if actor_id is not None:

backend/app/sync/playlists.py

@@ -670,11 +670,19 @@ def sync_all_playlists(db: Session) -> dict:
         try:
             with quota.attribute(user.id, quota.QuotaAction.PLAYLISTS_PULL):
                 total += sync_user_playlists(db, user).get("synced", 0)
-        except YouTubeError:
+        except YouTubeError as exc:
             db.rollback()
-            log.warning("Playlist sync failed for user %s", user.id)
+            log.warning(
+                "Playlist sync failed for user %s",
+                user.id,
+                extra=logs.event("sync.playlists.failed", user_id=user.id, reason=exc.reason),
+            )
         except Exception:
             db.rollback()
-            log.exception("Playlist sync crashed for user %s", user.id)
+            log.exception(
+                "Playlist sync crashed for user %s",
+                user.id,
+                extra=logs.event("sync.playlists.crashed", user_id=user.id),
+            )
         progress.report(i, len(users), "playlist_sync")
     return {"users": len(users), "playlists_synced": total}

backend/app/youtube/client.py

@@ -6,6 +6,7 @@ so they don't depend on a specific user's token; subscriptions.list?mine=true al
 uses OAuth.
 """
 
+import logging
 from collections.abc import Iterator
 from datetime import datetime, timedelta, timezone
 
@@ -50,7 +51,9 @@ def _error_reason(resp: httpx.Response) -> str:
     return reasons or "<none>"
 
 
-def _upstream_failure(method: str, path: str, resp: httpx.Response) -> YouTubeError:
+def _upstream_failure(
+    method: str, path: str, resp: httpx.Response, expected: frozenset[str] = frozenset()
+) -> YouTubeError:
     """Report one upstream failure and build the error to raise. Every YouTube response that is
     not a success goes through here — the Data API's reads, writes and deletes and the OAuth
     token refresh — so what may appear in a log line cannot drift apart between them, and the
@@ -59,7 +62,11 @@ def _upstream_failure(method: str, path: str, resp: httpx.Response) -> YouTubeEr
     response at all is `_send`'s, with the reason `transport`.) The body is logged only under
     the requesting user's own Teljes consent: it is the request quoted back."""
     reason = _error_reason(resp)
-    log.warning(
+    # A reason the caller named as an answer rather than a failure (`channelNotFound` on a `mine`
+    # read: the account simply has no channel) is still raised, but it is not a warning — it came
+    # back every six hours for an account that will never have one.
+    log.log(
+        logging.DEBUG if reason in expected else logging.WARNING,
         "YouTube %s %s -> %s (%s)",
         method,
         path,
@@ -83,6 +90,10 @@ def _upstream_failure(method: str, path: str, resp: httpx.Response) -> YouTubeEr
     return YouTubeError(f"{method} {path} -> {resp.status_code}: {reason}", reason=reason)
 
 
+# The `mine` reads' answer for a Google account that has no YouTube channel.
+_NO_CHANNEL = frozenset({"channelNotFound"})
+
+
 def _chunks(items: list, size: int) -> Iterator[list]:
     for i in range(0, len(items), size):
         yield items[i : i + size]
@@ -167,7 +178,14 @@ class YouTubeClient:
         return access
 
     # --- core request ---
-    def _get(self, path: str, params: dict, cost: int = 1, allow_key: bool = True) -> dict:
+    def _get(
+        self,
+        path: str,
+        params: dict,
+        cost: int = 1,
+        allow_key: bool = True,
+        expected: frozenset[str] = frozenset(),
+    ) -> dict:
         p = dict(params)
         headers = {}
         api_key = sysconfig.get_str(self.db, "youtube_api_key")
@@ -178,7 +196,7 @@ class YouTubeClient:
         resp = self._send("GET", f"{API_BASE}/{path}", params=p, headers=headers)
         quota.record_usage(cost)
         if resp.status_code != 200:
-            raise _upstream_failure("GET", path, resp)
+            raise _upstream_failure("GET", path, resp, expected)
         return resp.json()
 
     # --- endpoints ---
@@ -218,7 +236,14 @@ class YouTubeClient:
             params = {"part": "snippet,contentDetails", "mine": "true", "maxResults": 50}
             if page_token:
                 params["pageToken"] = page_token
-            data = self._get("playlists", params, cost=1, allow_key=False)
+            try:
+                data = self._get("playlists", params, cost=1, allow_key=False, expected=_NO_CHANNEL)
+            except YouTubeError as exc:
+                # A Google account without a YouTube channel has no playlists, and YouTube says
+                # so as a 404. That is an empty list, not a failed sync.
+                if exc.reason in _NO_CHANNEL:
+                    return
+                raise
             for item in data.get("items", []):
                 sn = item.get("snippet", {})
                 yield {

backend/tests/test_logs.py

@@ -219,6 +219,14 @@ def _client() -> TestClient:
             raise HTTPException(status_code=400, detail={"code": "bad_cursor"})
         return {"ok": True}
 
+    @app.get("/api/messages/unread_count")
+    def _unread():
+        return {"count": 0}
+
+    @app.post("/api/messages/unread_count")
+    def _unread_write():
+        return {"ok": True}
+
     @app.get("/boom")
     def _boom():
         raise RuntimeError("kaboom")
@@ -323,6 +331,30 @@ def test_the_log_consoles_own_reads_are_debug_but_its_failures_are_not(sink):
     assert sink.objects()[-1]["level"] == "WARNING"
 
 
+def test_a_polled_read_is_debug_a_write_to_the_same_route_is_not(sink):
+    # One open tab polled the unread counts, /api/me and the download index every 30 s: at INFO
+    # that was ~95% of the stored log on prod.
+    http = logging.getLogger("siftlode.http")
+    http.setLevel(logs.TRACE)
+    client = _client()
+    client.get("/api/messages/unread_count")
+    assert sink.objects()[-1]["level"] == "DEBUG"
+    client.post("/api/messages/unread_count")
+    assert sink.objects()[-1]["level"] == "INFO"
+    client.get("/api/videos/abc")
+    assert sink.objects()[-1]["level"] == "INFO"
+
+
+def test_every_polled_route_is_a_route_the_app_has():
+    # The list names route TEMPLATES; one renamed on the router side would silently fall back to
+    # INFO, so the list is held to the app's own routes.
+    from app.main import app
+
+    # The schema, not `app.routes`: FastAPI 0.141 keeps an included router behind a wrapper there.
+    gets = {path for path, ops in app.openapi()["paths"].items() if "get" in ops}
+    assert logs._POLLED_ROUTES - gets == set()
+
+
 def test_a_failing_request_is_logged_by_status_and_an_unhandled_error_is_logged_at_all(sink):
     client = _client()
     client.get("/api/videos/missing/deeper")  # 404 from the router

backend/tests/test_youtube_no_channel.py

@@ -0,0 +1,38 @@
+"""A Google account without a YouTube channel: its `mine` playlists read answers 404
+`channelNotFound`. That is an empty list, not a failed sync — it came back as a warning every six
+hours on prod for an account that will never have a channel."""
+
+import logging
+
+import httpx
+import pytest
+
+from app.youtube import client as yt
+
+
+def _client(monkeypatch, status: int, reason: str) -> yt.YouTubeClient:
+    resp = httpx.Response(
+        status,
+        json={"error": {"code": status, "errors": [{"reason": reason, "message": "prose"}]}},
+        request=httpx.Request("GET", f"{yt.API_BASE}/playlists"),
+    )
+    c = yt.YouTubeClient.__new__(yt.YouTubeClient)  # no HTTP client: `_send` is the stub
+    c.db = None
+    monkeypatch.setattr(yt.sysconfig, "get_str", lambda db, key: "")
+    monkeypatch.setattr(yt.quota, "record_usage", lambda cost: None)
+    monkeypatch.setattr(c, "_access_token", lambda: "t")
+    monkeypatch.setattr(c, "_send", lambda *a, **k: resp)
+    return c
+
+
+def test_no_channel_is_an_empty_playlist_list_and_no_warning(monkeypatch, caplog):
+    caplog.set_level(logging.DEBUG, logger="siftlode")
+    assert list(_client(monkeypatch, 404, "channelNotFound").iter_my_playlists()) == []
+    assert not [r for r in caplog.records if r.levelno >= logging.WARNING]
+
+
+def test_any_other_failure_still_raises_and_warns(monkeypatch, caplog):
+    caplog.set_level(logging.DEBUG, logger="siftlode")
+    with pytest.raises(yt.YouTubeError):
+        list(_client(monkeypatch, 403, "quotaExceeded").iter_my_playlists())
+    assert [r for r in caplog.records if r.levelno == logging.WARNING]