feat: add file existence check to scene queue validation

eink/backend/background/scene_processor.py

@@ -401,6 +401,14 @@ async def update_scene_queue(scene, session):
                 ):
                     needs_work = True
 
+                if not needs_work and record.filename:
+                    # Check if file exists on disk
+                    path = os.path.join(
+                        get_storage_path("scene_display"), record.filename
+                    )
+                    if not os.path.exists(path):
+                        needs_work = True
+
                 if needs_work:
                     to_queue.add((display_id, image_id))
 

eink/backend/tests/integration/test_scene_queue.py

@@ -1,6 +1,8 @@
+import os
 import pytest
 from sqlalchemy import select
 from backend import models, database
+from backend.utils.storage import get_storage_path
 
 
 @pytest.mark.asyncio
@@ -171,6 +173,11 @@ async def test_scene_save_populates_queue(aiohttp_client, app):
         session.add(sdi)
         await session.commit()
 
+    # Create dummy file to pass the existence check in update_scene_queue
+    path = os.path.join(get_storage_path("scene_display"), "slice.png")
+    with open(path, "w") as f:
+        f.write("dummy")
+
     # 6. Save scene again - should now have 0 in queue as it's up to date
     resp = await client.put(f"/api/scene/{scene_id}", json=update_data)
     assert resp.status == 200

eink/backend/tests/unit/test_scene_processor.py

@@ -390,3 +390,106 @@ async def test_scene_processor_rotation(db_setup, tmp_path):
             assert config["height"] == 480
             # Rotation should be 90 because landscape panel used as portrait
             assert config["rotation"] == 90
+
+
+@pytest.mark.asyncio
+async def test_scene_processor_retriggers_if_file_missing(db_setup, tmp_path):
+    """Test that scene_processor retriggers if the file is missing from disk."""
+
+    async with database.get_session() as session:
+        # Minimal setup for one display
+        dt = models.DisplayType(
+            id="dt1",
+            name="7.5",
+            width_mm=163,
+            height_mm=98,
+            panel_width_mm=163,
+            panel_height_mm=98,
+            width_px=800,
+            height_px=480,
+            colour_type="BW",
+            frame={},
+            mat={},
+        )
+        session.add(dt)
+        layout = models.Layout(
+            id="l1",
+            name="L",
+            canvas_width_mm=200,
+            canvas_height_mm=200,
+            items=[{"id": "d1", "display_type_id": "dt1", "x_mm": 0, "y_mm": 0}],
+            status="active",
+        )
+        session.add(layout)
+        img = models.Image(
+            id="i1",
+            name="I",
+            file_path="t.png",
+            width=100,
+            height=100,
+            file_type="png",
+            status="ACTIVE",
+            file_hash="h1",
+        )
+        session.add(img)
+        await session.commit()
+        await session.refresh(img)
+
+        scene = models.Scene(
+            id="s1",
+            name="S",
+            layout_id="l1",
+            status="active",
+            items=[
+                {
+                    "id": "it1",
+                    "type": "image",
+                    "displays": ["d1"],
+                    "images": [
+                        {
+                            "image_id": "i1",
+                            "scaling_factor": 100,
+                            "offset": {"x": 0, "y": 0},
+                        }
+                    ],
+                }
+            ],
+        )
+        session.add(scene)
+        await session.commit()
+        await session.refresh(scene)
+
+        # Create record with matching hashes but MISSING file on disk
+        record = models.SceneDisplayImage(
+            scene_id="s1",
+            display_id="d1",
+            image_id="i1",
+            image_hash=img.settings_hash,
+            scene_hash=scene.scene_hash,
+            file_hash="some-hash",
+            filename="slice_s1_i1_d1.png",
+        )
+        session.add(record)
+        await session.commit()
+
+        # Ensure the file does NOT exist on disk
+        # (It shouldn't anyway in this clean tmp_path test)
+        path = os.path.join(str(tmp_path), "slice_s1_i1_d1.png")
+        if os.path.exists(path):
+            os.remove(path)
+
+        # Mock get_storage_path to point to our tmp_path
+        with patch(
+            "backend.background.scene_processor.get_storage_path",
+            return_value=str(tmp_path),
+        ):
+            await scene_handler._update_scene_queue(scene, session)
+            await session.commit()
+
+            # Verify that it was added to the queue
+            stmt = select(models.SceneQueue).where(models.SceneQueue.scene_id == "s1")
+            result = await session.execute(stmt)
+            queued = result.scalars().all()
+            assert len(queued) == 1
+            assert queued[0].display_id == "d1"
+            assert queued[0].image_id == "i1"