feat(import): /api/import/clear-stuck endpoint + Clear stuck UI button — escape hatch for the autoretry-loop case the automatic sweep can't break

Operator hit 3 large PNGs stuck in 'processing' for 2 days 2026-05-25:
the existing recover_interrupted_tasks flips processing > 5min back to
queued + .delay(), but if the underlying file is unfixably broken (e.g.,
PIL OSError, also patched in 68cffce), the loop never terminates and the
'Scanning...' banner sticks at 0/0 forever blocking new scans.

/api/import/clear-stuck:
- Flips every task in pending/queued/processing to 'failed' with a clear
  marker error message
- Finalizes any 'running' ImportBatch that has no remaining active children
- Idempotent + non-destructive: rows survive, can be retried once the
  underlying cause is resolved

UI button 'Clear stuck...' sits next to 'Retry failed' / 'Clear completed'
with a warning-tonal alert in the confirm dialog explaining what it does
and recommending Retry failed once the cause is fixed.

Tests: clears mixed non-terminal states, untouches complete rows,
finalizes orphan batch, no-op when nothing stuck.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/api/import_admin.py

@@ -120,6 +120,83 @@ async def retry_failed():
     return jsonify({"retried": len(failed_ids)})
 
 
+@import_admin_bp.route("/clear-stuck", methods=["POST"])
+async def clear_stuck():
+    """Force any non-terminal ImportTask (status in pending/queued/
+    processing) to 'failed' AND finalize any ImportBatch that ends up
+    with no active children. Escape hatch for the operator when the
+    automatic recover_interrupted_tasks sweep keeps re-queueing the
+    same stuck row forever (e.g., underlying file is genuinely broken
+    and the import keeps OSError-looping at PIL load).
+
+    Idempotent + non-destructive: rows survive as 'failed' so the
+    Retry-Failed button can re-attempt them once whatever was broken
+    is fixed. Banked 2026-05-25 — operator hit 3 large PNGs that
+    autoretry-looped for 2 days after a corrupt-data PIL OSError.
+    """
+    async with get_session() as session:
+        stuck_ids = (
+            await session.execute(
+                select(ImportTask.id).where(
+                    ImportTask.status.in_(["pending", "queued", "processing"])
+                )
+            )
+        ).scalars().all()
+        if stuck_ids:
+            await session.execute(
+                update(ImportTask)
+                .where(ImportTask.id.in_(stuck_ids))
+                .values(
+                    status="failed",
+                    finished_at=datetime.now(UTC),
+                    error=(
+                        "manually cleared via /api/import/clear-stuck "
+                        "— stuck in non-terminal state; retry once "
+                        "underlying cause (corrupt file, missing model, "
+                        "etc.) is resolved"
+                    ),
+                )
+            )
+
+        # Finalize any 'running' ImportBatch that no longer has any
+        # active children. The "Scanning..." banner is driven by
+        # /api/import/status finding a running batch; left untouched,
+        # it would persist forever after the stuck-task clear.
+        running_batches = (
+            await session.execute(
+                select(ImportBatch.id).where(ImportBatch.status == "running")
+            )
+        ).scalars().all()
+        finalized_batches = 0
+        for batch_id in running_batches:
+            still_active = (
+                await session.execute(
+                    select(ImportTask.id)
+                    .where(ImportTask.batch_id == batch_id)
+                    .where(ImportTask.status.in_(
+                        ["pending", "queued", "processing"]
+                    ))
+                    .limit(1)
+                )
+            ).scalar_one_or_none()
+            if still_active is None:
+                await session.execute(
+                    update(ImportBatch)
+                    .where(ImportBatch.id == batch_id)
+                    .values(
+                        status="complete",
+                        finished_at=datetime.now(UTC),
+                    )
+                )
+                finalized_batches += 1
+        await session.commit()
+
+    return jsonify({
+        "tasks_failed": len(stuck_ids),
+        "batches_finalized": finalized_batches,
+    })
+
+
 @import_admin_bp.route("/clear-completed", methods=["POST"])
 async def clear_completed():
     body = await request.get_json(silent=True) or {}

frontend/src/components/settings/ImportTaskList.vue

@@ -17,6 +17,12 @@
       >
         Retry failed
       </v-btn>
+      <v-btn
+        variant="text" rounded="pill" size="small" color="warning"
+        :disabled="!hasStuck" @click="onClearStuckOpen"
+      >
+        Clear stuck…
+      </v-btn>
       <v-btn
         variant="text" rounded="pill" size="small" color="error"
         @click="onClearOpen"
@@ -69,6 +75,31 @@
         </v-card-actions>
       </v-card>
     </v-dialog>
+
+    <v-dialog v-model="clearStuckDialog" max-width="480">
+      <v-card>
+        <v-card-title>Clear stuck tasks</v-card-title>
+        <v-card-text>
+          <v-alert type="warning" variant="tonal" density="compact" class="mb-3">
+            Force every <strong>pending / queued / processing</strong> task to
+            <strong>failed</strong> and finalize any active batch that
+            has no remaining work. Use this when the automatic recovery
+            sweep keeps re-queueing the same row (e.g., corrupt file in
+            an autoretry loop, or worker model missing).
+          </v-alert>
+          <p class="text-body-2">
+            Tasks remain in the database with status=<code>failed</code>;
+            click <em>Retry failed</em> once the underlying cause is
+            resolved to re-queue them.
+          </p>
+        </v-card-text>
+        <v-card-actions>
+          <v-spacer />
+          <v-btn @click="clearStuckDialog = false">Cancel</v-btn>
+          <v-btn color="warning" rounded="pill" @click="onClearStuckConfirm">Clear stuck</v-btn>
+        </v-card-actions>
+      </v-card>
+    </v-dialog>
   </v-card>
 </template>
 
@@ -80,6 +111,7 @@ const store = useImportStore()
 const statusFilter = ref(null)
 const clearDialog = ref(false)
 const clearAgeDays = ref(7)
+const clearStuckDialog = ref(false)
 
 const statusOptions = [
   { title: 'All', value: null },
@@ -100,6 +132,9 @@ const headers = [
 ]
 
 const hasFailed = computed(() => store.tasks.some(t => t.status === 'failed'))
+const hasStuck = computed(() => store.tasks.some(
+  t => t.status === 'pending' || t.status === 'queued' || t.status === 'processing'
+))
 
 function statusColor(s) {
   return {
@@ -138,4 +173,9 @@ async function onClearConfirm() {
   await store.clearCompleted(clearAgeDays.value)
   clearDialog.value = false
 }
+function onClearStuckOpen() { clearStuckDialog.value = true }
+async function onClearStuckConfirm() {
+  await store.clearStuck()
+  clearStuckDialog.value = false
+}
 </script>

frontend/src/stores/import.js

@@ -92,6 +92,13 @@ export const useImportStore = defineStore('import', () => {
     await loadTasks(true)
   }
 
+  async function clearStuck() {
+    const body = await api.post('/api/import/clear-stuck')
+    await loadTasks(true)
+    await refreshStatus()
+    return body
+  }
+
   const hasMore = computed(() => tasksNextCursor.value !== null)
 
   return {
@@ -101,6 +108,6 @@ export const useImportStore = defineStore('import', () => {
     triggerError,
     loadSettings, patchSettings,
     refreshStatus, triggerScan,
-    loadTasks, setStatusFilter, retryFailed, clearCompleted
+    loadTasks, setStatusFilter, retryFailed, clearCompleted, clearStuck
   }
 })

tests/test_api_import_admin.py

@@ -86,6 +86,61 @@ async def test_clear_completed(client, db):
     assert body["deleted"] == 1
 
 
+@pytest.mark.asyncio
+async def test_clear_stuck_fails_non_terminal_and_finalizes_orphan_batch(client, db):
+    """Operator-flagged 2026-05-25: 3 large PNGs got stuck in 'processing'
+    for 2 days, the active ImportBatch never finalized, and the UI's
+    'Scanning...' banner persisted with 0/0 files. /api/import/clear-stuck
+    is the escape hatch to break the autoretry loop manually."""
+    from sqlalchemy import select as _select
+
+    batch = ImportBatch(triggered_by="manual", source_path="/import", scan_mode="quick")
+    db.add(batch)
+    await db.flush()
+    # Three stuck rows in mixed non-terminal states.
+    db.add(ImportTask(
+        batch_id=batch.id, source_path="/p1", task_type="media", status="processing",
+    ))
+    db.add(ImportTask(
+        batch_id=batch.id, source_path="/p2", task_type="media", status="queued",
+    ))
+    db.add(ImportTask(
+        batch_id=batch.id, source_path="/p3", task_type="media", status="pending",
+    ))
+    # One already-complete row should be untouched.
+    db.add(ImportTask(
+        batch_id=batch.id, source_path="/done", task_type="media",
+        status="complete", finished_at=datetime.now(UTC),
+    ))
+    await db.commit()
+
+    resp = await client.post("/api/import/clear-stuck")
+    body = await resp.get_json()
+    assert resp.status_code == 200
+    assert body["tasks_failed"] == 3
+    assert body["batches_finalized"] == 1
+
+    statuses = {
+        row.status for row in
+        (await db.execute(_select(ImportTask).where(ImportTask.batch_id == batch.id)))
+        .scalars().all()
+    }
+    assert statuses == {"failed", "complete"}
+
+    batch_status = (await db.execute(
+        _select(ImportBatch.status).where(ImportBatch.id == batch.id)
+    )).scalar_one()
+    assert batch_status == "complete"
+
+
+@pytest.mark.asyncio
+async def test_clear_stuck_no_op_when_nothing_stuck(client, db):
+    resp = await client.post("/api/import/clear-stuck")
+    body = await resp.get_json()
+    assert resp.status_code == 200
+    assert body == {"tasks_failed": 0, "batches_finalized": 0}
+
+
 @pytest.mark.asyncio
 async def test_trigger_accepts_deep(client, monkeypatch):
     # Stub the task dispatch — assert the API accepts 'deep' and forwards