fix(screenpipe): do not write a chosen frame onto a discarded observation

Discard and duplicate $unset media_data, media_filename, media_content_type and
content_hash on a closed observation. Applying the agent's frame choice to the
same update made Mongo reject the whole write — "Updating the path 'media_data'
would create a conflict at 'media_data'" — so every discard of a closed
observation carrying a shortlist failed.

The choice is still applied in memory, because the promotion path reads
item.media_data, but it is only written on the branches that keep an image.

Author: AnkushMalaker

backends/advanced/src/advanced_omi_backend/services/observation_curation.py

@@ -598,25 +598,30 @@ async def apply_curation_decision(
     action = decision["decision"]
 
     updates: dict[str, Any] = {"agent_reason": agent_reason}
-    # Promote the frame the agent chose to the observation's representative image, so
+    # The frame the agent chose becomes the observation's representative image, so
     # every downstream consumer — vault promotion, the 1280px source-media fetch, the
     # timeline thumbnail — uses the frame that was actually judged to depict this
     # session, not the one that scored highest before anyone looked at it.
+    #
+    # Applied in memory here because the promotion path below reads `item.media_data`,
+    # but written only on the branches that keep an image: discard and duplicate
+    # `$unset` these same paths, and Mongo rejects a `$set` and `$unset` of one path
+    # in a single update.
     selected = _selected_preview(item, decision)
+    selection_updates: dict[str, Any] = {}
     if selected is not None:
         item.media_data = selected["data"]
         item.media_content_type = selected["content_type"]
         item.media_filename = f"frame-{selected['frame_id']}.jpg"
-        updates.update(
-            {
-                "media_data": selected["data"],
-                "media_filename": item.media_filename,
-                "media_content_type": selected["content_type"],
-                "content_hash": hashlib.sha256(selected["data"]).hexdigest(),
-                "metadata.preview_frame_id": selected["frame_id"],
-                "metadata.thumbnail_available": True,
-            }
-        )
+        item.content_hash = hashlib.sha256(selected["data"]).hexdigest()
+        selection_updates = {
+            "media_data": item.media_data,
+            "media_filename": item.media_filename,
+            "media_content_type": item.media_content_type,
+            "content_hash": item.content_hash,
+            "metadata.preview_frame_id": selected["frame_id"],
+            "metadata.thumbnail_available": True,
+        }
     unset: tuple[str, ...] = ()
     if action == "duplicate":
         target_id = decision.get("duplicate_observation_id")
@@ -650,6 +655,7 @@ async def apply_curation_decision(
                 "content_hash",
             )
     else:
+        updates.update(selection_updates)
         retain_image = bool(decision.get("retain_image")) or action == "promote_image"
         immich_item_id = decision.get("immich_item_id") if retain_image else None
         if (

backends/advanced/tests/test_observation_curation.py

@@ -323,3 +323,38 @@ def test_only_a_shortlisted_frame_can_be_selected():
         observation_curation._selected_preview(item, {"selected_frame_id": None})
         is None
     )
+
+
+@pytest.mark.asyncio
+async def test_discarding_a_selected_frame_does_not_set_and_unset_one_path(monkeypatch):
+    """A discarded observation drops its image; it must not also write one.
+
+    Mongo rejects a `$set` and `$unset` of the same path in one update, so applying
+    the agent's frame choice unconditionally made every discard of a closed
+    observation fail with "Updating the path 'media_data' would create a conflict".
+    """
+
+    item = observation(
+        lifecycle="closed",
+        media_previews=[
+            {"frame_id": 7, "data": b"jpeg", "content_type": "image/jpeg"},
+        ],
+        curation="curating",
+    )
+    seen: list[tuple[dict, tuple]] = []
+
+    async def capture(target, fields, *, unset=()):
+        seen.append((fields, unset))
+        return True
+
+    monkeypatch.setattr(observation_curation, "_apply_curation_fields", capture)
+
+    await apply_curation_decision(
+        item,
+        {"decision": "discard", "reason": "Routine", "selected_frame_id": 7},
+        observation_revision(item),
+    )
+
+    fields, unset = seen[-1]
+    assert "media_data" in unset
+    assert not set(fields) & set(unset)