diff --git a/stores/bolt/bolt_test.go b/stores/bolt/bolt_test.go
index f1f931b..75e9085 100644
--- a/stores/bolt/bolt_test.go
+++ b/stores/bolt/bolt_test.go
@@ -17,7 +17,7 @@ func TestBoltStore(t *testing.T) {
 	tempDir, err := os.MkdirTemp("", "boltdb-test")
 	require.NoError(t, err)
 	defer os.RemoveAll(tempDir)
-	
+
 	// Create a temporary file for the test
 	tempFile := filepath.Join(tempDir, "test-embeddings.db")
 
@@ -70,7 +70,7 @@ func TestBoltStoreCancellation(t *testing.T) {
 	tempDir, err := os.MkdirTemp("", "boltdb-cancel-test")
 	require.NoError(t, err)
 	defer os.RemoveAll(tempDir)
-	
+
 	// Create a temporary file for the test
 	tempFile := filepath.Join(tempDir, "test-embeddings-cancel.db")
 
@@ -96,4 +96,108 @@ func TestBoltStoreCancellation(t *testing.T) {
 	// Test retrieving with cancelled context
 	_, err = store.Get(ctx, utterance.Utterance)
 	assert.Error(t, err)
+}
+
+// Test to ensure setting the same key overwrites the previous value.
+func TestBoltStoreOverwriteExistingKey(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "overwrite-test")
+	require.NoError(t, err)
+	defer os.RemoveAll(tempDir)
+
+	dbFile := filepath.Join(tempDir, "overwrite.db")
+	store, err := boltstore.NewStore(dbFile)
+	require.NoError(t, err)
+	defer store.Close()
+
+	ctx := context.Background()
+	key := "overwrite-key"
+	firstEmbed := []float64{1.1, 2.2}
+	require.NoError(t, store.Set(ctx, semanticrouter.Utterance{Utterance: key, Embed: firstEmbed}))
+
+	secondEmbed := []float64{3.3, 4.4}
+	require.NoError(t, store.Set(ctx, semanticrouter.Utterance{Utterance: key, Embed: secondEmbed}))
+
+	retrieved, err := store.Get(ctx, key)
+	require.NoError(t, err)
+	assert.Equal(t, secondEmbed, retrieved)
+}
+
+// Test storing and retrieving multiple distinct keys.
+func TestBoltStoreMultipleKeys(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "multiple-keys-test")
+	require.NoError(t, err)
+	defer os.RemoveAll(tempDir)
+
+	dbFile := filepath.Join(tempDir, "multiple.db")
+	store, err := boltstore.NewStore(dbFile)
+	require.NoError(t, err)
+	defer store.Close()
+
+	ctx := context.Background()
+	entries := []semanticrouter.Utterance{
+		{Utterance: "one", Embed: []float64{1.0}},
+		{Utterance: "two", Embed: []float64{2.0, 2.1}},
+		{Utterance: "three", Embed: []float64{3.0, 3.1, 3.2}},
+	}
+	for _, e := range entries {
+		require.NoError(t, store.Set(ctx, e))
+	}
+	for _, e := range entries {
+		retrieved, err := store.Get(ctx, e.Utterance)
+		require.NoError(t, err)
+		assert.Equal(t, e.Embed, retrieved)
+	}
+}
+
+// Test setting and retrieving an empty embedding slice.
+func TestBoltStoreEmptyEmbedding(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "empty-embed-test")
+	require.NoError(t, err)
+	defer os.RemoveAll(tempDir)
+
+	dbFile := filepath.Join(tempDir, "empty.db")
+	store, err := boltstore.NewStore(dbFile)
+	require.NoError(t, err)
+	defer store.Close()
+
+	ctx := context.Background()
+	entry := semanticrouter.Utterance{Utterance: "empty", Embed: []float64{}}
+	require.NoError(t, store.Set(ctx, entry))
+
+	retrieved, err := store.Get(ctx, entry.Utterance)
+	require.NoError(t, err)
+	assert.Empty(t, retrieved)
+}
+
+// Test behavior after closing the store: all operations should return an error.
+func TestBoltStoreCloseBehavior(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "close-behavior-test")
+	require.NoError(t, err)
+	defer os.RemoveAll(tempDir)
+
+	dbFile := filepath.Join(tempDir, "close.db")
+	store, err := boltstore.NewStore(dbFile)
+	require.NoError(t, err)
+	require.NoError(t, store.Close())
+
+	ctx := context.Background()
+	entry := semanticrouter.Utterance{Utterance: "post-close", Embed: []float64{0.0}}
+
+	err = store.Set(ctx, entry)
+	assert.Error(t, err)
+
+	_, err = store.Get(ctx, entry.Utterance)
+	assert.Error(t, err)
+}
+
+// Test NewStore returns an error when the parent directory does not exist.
+func TestBoltStoreNewStoreInvalidPath(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "invalid-path-test")
+	require.NoError(t, err)
+	defer os.RemoveAll(tempDir)
+
+	invalidDir := filepath.Join(tempDir, "no-such-dir")
+	invalidFile := filepath.Join(invalidDir, "db.db")
+	_, err = boltstore.NewStore(invalidFile)
+	assert.Error(t, err)
 }
\ No newline at end of file