fix: task runs record the lane Celery really routes them to, and no healthy long job is swept as stalled (#4432)

celery_signals._queue_for was a hand-kept copy of task_routes and had
drifted:

- backup, admin and library_audit jobs, and backfill_phash, run on
  maintenance_long but were recorded as `maintenance`;
- translation and gpu_queue jobs were recorded as `default`, where the
  5-minute stall sweep failed healthy 35-minute translation runs.

It now asks the router, cached per task name.

A new guard test checks every registered task's hard time limit against
the stall threshold the sweep would use for it. It also caught these
sweeps, which failed healthy runs mid-flight and are fixed here:

- ml's scheduled sweeps (35 min, previously swept at 25);
- train_heads and apply_head_tags (65 min);
- import_media_file (6 min, previously swept at 5);
- the long lane, which now has its own 45-minute threshold.

UI changes:

- the admin job poller follows a job by celery_task_id, via a new filter
  on /runs, instead of by lane;
- the archive re-extract and missing-file repair cards show the long
  lane's backlog, where their jobs actually wait;
- the queue table lists maintenance_long.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LVjrnpQjRgHdvq95rASoiR

tests/test_celery_routing.py

@@ -2,6 +2,8 @@
 `maintenance_long` lane so a 30-min backup or a multi-chunk audit can't starve
 the quick recovery sweeps / vacuum on the concurrency-1 `maintenance` lane
 (operator-flagged 2026-06-07)."""
+import pytest
+
 from backend.app.celery_app import celery
 
 
@@ -20,23 +22,64 @@ def test_quick_maintenance_stays_on_maintenance():
     assert routes["backend.app.tasks.maintenance.*"]["queue"] == "maintenance"
 
 
-def test_queue_for_mirrors_external_to_download():
-    """celery_signals._queue_for is a hand-maintained mirror of task_routes
-    that stamps TaskRun.queue. external.* routes to the download lane, so the
-    mirror must agree — else TaskRun.queue lies 'default' for external fetches
-    and per-queue dashboard filters / threshold overrides miss them
-    (operator-flagged 2026-06-17)."""
+@pytest.mark.parametrize(("name", "queue"), [
+    ("backend.app.tasks.external.fetch_external_link", "download"),
+    # The rows #4432 found recorded on the wrong lane:
+    ("backend.app.tasks.translation.translate_posts", "maintenance_long"),
+    ("backend.app.tasks.gpu_queue.enqueue_gpu_backfill", "maintenance"),
+    ("backend.app.tasks.maintenance.backfill_phash", "maintenance_long"),
+    ("backend.app.tasks.admin.normalize_tags_task", "maintenance_long"),
+    ("backend.app.tasks.backup.backup_db_task", "maintenance_long"),
+    ("backend.app.tasks.maintenance.vacuum_analyze", "maintenance"),
+    ("backend.app.tasks.not_routed.anything", "default"),
+])
+def test_task_run_records_the_queue_the_router_sends_to(name, queue):
+    """TaskRun.queue comes from the router, not a copy of task_routes (#4432):
+    the stall sweep's per-queue thresholds and the System activity filters both
+    key off it."""
     from backend.app.celery_signals import _queue_for
 
     class _T:
-        name = "backend.app.tasks.external.fetch_external_link"
+        pass
 
-    assert _queue_for(_T()) == "download"
-    assert (
-        celery.conf.task_routes["backend.app.tasks.external.*"]["queue"]
-        == "download"
+    t = _T()
+    t.name = name
+    t.app = celery
+    assert _queue_for(t) == queue
+
+
+def test_no_task_outlives_its_stall_threshold():
+    """A task whose hard time limit is longer than the stall sweep's threshold
+    for it gets failed 'RecoverySweep' while it is still healthy — the class
+    #4432 found on the ml, import and long-maintenance lanes. The threshold is
+    resolved the way recover_stalled_task_runs resolves it: task-name override,
+    then queue, then the default."""
+    from backend.app.celery_signals import _queue_for
+    from backend.app.tasks.maintenance import (
+        QUEUE_STUCK_THRESHOLD_MINUTES,
+        STUCK_THRESHOLD_MINUTES,
+        TASK_STUCK_THRESHOLD_MINUTES,
     )
 
+    celery.loader.import_default_modules()
+    checked = 0
+    too_short = []
+    for name, task in sorted(celery.tasks.items()):
+        if name.startswith("celery."):
+            continue
+        limit = getattr(task, "time_limit", None)
+        if not limit:
+            continue
+        threshold = TASK_STUCK_THRESHOLD_MINUTES.get(
+            name,
+            QUEUE_STUCK_THRESHOLD_MINUTES.get(_queue_for(task), STUCK_THRESHOLD_MINUTES),
+        )
+        checked += 1
+        if limit / 60 > threshold:
+            too_short.append(f"{name}: limit {limit / 60:.0f} min > sweep {threshold} min")
+    assert checked > 20, "the task registry did not load — this guard checked nothing"
+    assert not too_short, "\n".join(too_short)
+
 
 def test_backfill_phash_runs_on_the_long_lane():
     """It lives in maintenance.py, so the quick-lane glob matches it too —