fix: the import recovery sweep no longer fails queued files that are waiting their turn

The orphan sweep in recover_interrupted_tasks failed every 'queued' row
older than 30 minutes. A queued row has its broker message, so in a batch
bigger than half an hour of work the sweep failed the whole tail: a
library import of 8,135 files lost 3,114 that way. Never-enqueued
'pending' rows are still swept after 30 minutes; a 'queued' row is swept
only when the broker's import queue is empty, and is kept when the queue
can't be read.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_maintenance.py

@@ -122,7 +122,10 @@ def test_recover_interrupted_sweeps_pending_orphans_to_failed(db_sync, monkeypat
     Banked 2026-05-25 after operator hit 5490 stuck pending rows.
     """
     from backend.app.tasks import import_file
+    from backend.app.tasks import maintenance as m
     monkeypatch.setattr(import_file.import_media_file, "delay", lambda *_: None)
+    # The broker's import queue is empty, so a stale 'queued' row's message is gone.
+    monkeypatch.setattr(m, "_import_queue_depth", lambda: 0)
 
     batch_id = _make_batch(db_sync)
     now = datetime.now(UTC)
@@ -170,6 +173,42 @@ def test_recover_interrupted_sweeps_pending_orphans_to_failed(db_sync, monkeypat
     assert "orphan" in (stale_pending.error or "")
 
 
+@pytest.mark.parametrize("depth", [7, None])
+def test_recover_interrupted_keeps_queued_rows_while_the_import_queue_holds_work(
+    db_sync, monkeypatch, depth,
+):
+    """A queued row in a batch bigger than half an hour of work is waiting its
+    turn, not orphaned: while the import queue holds messages (or can't be
+    read), only never-enqueued 'pending' rows are swept."""
+    from sqlalchemy import update as _upd
+
+    from backend.app.tasks import maintenance as m
+
+    monkeypatch.setattr(m, "_import_queue_depth", lambda: depth)
+    batch_id = _make_batch(db_sync)
+    waiting = ImportTask(
+        batch_id=batch_id, source_path="/import/waiting.jpg", task_type="media",
+        status="queued",
+    )
+    never_sent = ImportTask(
+        batch_id=batch_id, source_path="/import/never.jpg", task_type="media",
+        status="pending",
+    )
+    db_sync.add_all([waiting, never_sent])
+    db_sync.flush()
+    db_sync.execute(
+        _upd(ImportTask).where(ImportTask.id.in_([waiting.id, never_sent.id]))
+        .values(created_at=datetime.now(UTC) - timedelta(hours=2))
+    )
+    db_sync.commit()
+
+    assert m.recover_interrupted_tasks.apply().get() == 1
+    db_sync.refresh(waiting)
+    db_sync.refresh(never_sent)
+    assert waiting.status == "queued"
+    assert never_sent.status == "failed"
+
+
 def test_recover_interrupted_handles_both_stuck_and_orphans(db_sync, monkeypatch):
     """One sweep tick handles both 'processing' crashes AND
     'pending'/'queued' orphans in a single pass."""