fix: sanitize SQL and narrow exception handling in indexer

tests/test_indexer.py

@@ -153,3 +153,32 @@ def test_full_index_creates_vectors(mock_embedder_cls):
         indexer = Indexer(config, store)
         indexer.full_index()
         assert store.count() == 1
+
+
+@patch("companion.rag.indexer.OllamaEmbedder")
+def test_sync_updates_changed_files(mock_embedder_cls):
+    mock_embedder = MagicMock()
+    mock_embedder.embed.return_value = [[1.0, 0.0, 0.0, 0.0]]
+    mock_embedder_cls.return_value = mock_embedder
+
+    with tempfile.TemporaryDirectory() as tmp:
+        vault = Path(tmp) / "vault"
+        vault.mkdir()
+        file_path = vault / "hello.md"
+        file_path.write_text("hello world", encoding="utf-8")
+        vs_path = Path(tmp) / "vectors"
+        config = _make_config(vault, vs_path)
+        store = VectorStore(uri=vs_path, dimensions=4)
+        indexer = Indexer(config, store)
+
+        indexer.full_index()
+        assert store.count() == 1
+        first_text = store.table.to_pandas()["text"].iloc[0]
+        assert first_text == "hello world"
+
+        file_path.write_text("updated content", encoding="utf-8")
+        indexer.sync()
+
+        assert store.count() == 1
+        updated_text = store.table.to_pandas()["text"].iloc[0]
+        assert updated_text == "updated content"