fix(km): tolerate legacy knowledge rows

apps/api/tests/test_knowledge_repository_read_model.py

@@ -65,6 +65,33 @@ def test_knowledge_read_model_accepts_lowercase_enum_values() -> None:
     assert entry.status == EntryStatus.PUBLISHED
 
 
+def test_knowledge_read_model_falls_back_for_unknown_legacy_enum_values() -> None:
+    repo = KnowledgeDBRepository(db=object())  # type: ignore[arg-type]
+
+    entry = repo._to_model(
+        _record(
+            entry_type="analysis_note",
+            source="system_import",
+            status="needs_ai_review",
+        )
+    )
+
+    assert entry.entry_type == EntryType.BEST_PRACTICE
+    assert entry.source == EntrySource.AI_EXTRACTED
+    assert entry.status == EntryStatus.REVIEW
+
+
+def test_knowledge_read_model_normalizes_legacy_tag_shapes_and_null_counts() -> None:
+    repo = KnowledgeDBRepository(db=object())  # type: ignore[arg-type]
+
+    json_tag_entry = repo._to_model(_record(tags='["telegram", " ai_loop "]', view_count=None))
+    scalar_tag_entry = repo._to_model(_record(tags="telegram"))
+
+    assert json_tag_entry.tags == ["telegram", "ai_loop"]
+    assert json_tag_entry.view_count == 0
+    assert scalar_tag_entry.tags == ["telegram"]
+
+
 def test_knowledge_read_model_defaults_null_or_blank_category() -> None:
     repo = KnowledgeDBRepository(db=object())  # type: ignore[arg-type]