fix(timeline): require grounded agent episodes

Author: AnkushMalaker

backends/advanced/src/advanced_omi_backend/services/timeline/prompt.py

@@ -71,12 +71,17 @@
                                 "evidence_ids": {
                                     "type": "array",
                                     "items": {"type": "string"},
+                                    "minItems": 1,
                                 },
                             },
                             "required": ["claim", "role", "confidence", "evidence_ids"],
                         },
                     },
-                    "evidence_ids": {"type": "array", "items": {"type": "string"}},
+                    "evidence_ids": {
+                        "type": "array",
+                        "items": {"type": "string"},
+                        "minItems": 1,
+                    },
                     "related_conversation_ids": {
                         "type": "array",
                         "items": {"type": "string"},
@@ -140,6 +145,8 @@ def build_prompt(output_path: str) -> str:
 - Accessibility/OCR can include background or offscreen text.
 - Assistant-generated text is not evidence that its claims happened.
 - Every important boundary/assertion must cite supplied evidence IDs.
+- Every episode must include at least one supplied evidence ID; otherwise leave the
+  interval unassigned instead of creating an ungrounded episode.
 - Never invent an evidence ID. Include every window ID exactly once in covered_window_ids.
 - Salience is display value, not confidence.
 - Express optional episode metadata as short string key/value entries in `attributes`.

backends/advanced/tests/test_timeline_prompt.py

@@ -14,3 +14,10 @@ def _assert_strict_objects(schema: object) -> None:
 
 def test_timeline_output_schema_has_no_open_objects():
     _assert_strict_objects(OUTPUT_SCHEMA)
+
+
+def test_timeline_output_schema_requires_grounded_episodes_and_assertions():
+    episode = OUTPUT_SCHEMA["properties"]["episodes"]["items"]
+    assert episode["properties"]["evidence_ids"]["minItems"] == 1
+    assertion = episode["properties"]["assertions"]["items"]
+    assert assertion["properties"]["evidence_ids"]["minItems"] == 1