diff --git a/src/core/processor/tkg.rs b/src/core/processor/tkg.rs
index d6c2b89..1ed9778 100644
--- a/src/core/processor/tkg.rs
+++ b/src/core/processor/tkg.rs
@@ -3175,4 +3175,90 @@ mod tests {
         assert_eq!(r.object_nodes, 10);
         assert_eq!(r.speaker_nodes, 3);
     }
+
+    // ── Integration Tests for TKG Optimizations ─────────────────────
+
+    #[test]
+    fn test_build_frame_index() {
+        let points = vec![
+            FacePoint { trace_id: 1, frame: 0, x: 100.0, y: 100.0, w: 50.0, h: 50.0 },
+            FacePoint { trace_id: 1, frame: 0, x: 200.0, y: 200.0, w: 50.0, h: 50.0 },
+            FacePoint { trace_id: 2, frame: 1, x: 150.0, y: 150.0, w: 50.0, h: 50.0 },
+            FacePoint { trace_id: 1, frame: 2, x: 120.0, y: 120.0, w: 50.0, h: 50.0 },
+        ];
+
+        let index = build_frame_index(&points);
+
+        assert_eq!(index.len(), 3); // 3 unique frames
+        assert_eq!(index.get(&0).map(|v| v.len()), Some(2));
+        assert_eq!(index.get(&1).map(|v| v.len()), Some(1));
+        assert_eq!(index.get(&2).map(|v| v.len()), Some(1));
+    }
+
+    #[test]
+    fn test_build_frame_index_empty() {
+        let points: Vec<FacePoint> = vec![];
+        let index = build_frame_index(&points);
+        assert!(index.is_empty());
+    }
+
+    #[test]
+    fn test_find_trace_in_frame_exact_match() {
+        let points = vec![
+            FacePoint { trace_id: 1, frame: 0, x: 100.0, y: 100.0, w: 100.0, h: 100.0 },
+            FacePoint { trace_id: 2, frame: 0, x: 300.0, y: 300.0, w: 100.0, h: 100.0 },
+        ];
+        let index = build_frame_index(&points);
+
+        // Query face exactly matches trace 1's bbox
+        let result = find_trace_in_frame(&index, 0, 100.0, 100.0, 100.0, 100.0);
+        assert_eq!(result, Some(1));
+    }
+
+    #[test]
+    fn test_find_trace_in_frame_closest_match() {
+        let points = vec![
+            FacePoint { trace_id: 1, frame: 0, x: 100.0, y: 100.0, w: 100.0, h: 100.0 },
+            FacePoint { trace_id: 2, frame: 0, x: 500.0, y: 500.0, w: 100.0, h: 100.0 },
+        ];
+        let index = build_frame_index(&points);
+
+        // Query face is closer to trace 1
+        let result = find_trace_in_frame(&index, 0, 110.0, 110.0, 100.0, 100.0);
+        assert_eq!(result, Some(1));
+    }
+
+    #[test]
+    fn test_find_trace_in_frame_no_matching_frame() {
+        let points = vec![
+            FacePoint { trace_id: 1, frame: 0, x: 100.0, y: 100.0, w: 100.0, h: 100.0 },
+        ];
+        let index = build_frame_index(&points);
+
+        // Query for frame 1 which doesn't exist
+        let result = find_trace_in_frame(&index, 1, 100.0, 100.0, 100.0, 100.0);
+        assert_eq!(result, None);
+    }
+
+    #[test]
+    fn test_find_trace_in_frame_empty_index() {
+        let points: Vec<FacePoint> = vec![];
+        let index = build_frame_index(&points);
+
+        let result = find_trace_in_frame(&index, 0, 100.0, 100.0, 100.0, 100.0);
+        assert_eq!(result, None);
+    }
+
+    #[test]
+    fn test_node_id_map_lookup() {
+        let mut map: HashMap<(String, String), i64> = HashMap::new();
+        map.insert(("face_track".to_string(), "face_track_1".to_string()), 100);
+        map.insert(("speaker".to_string(), "SPEAKER_0".to_string()), 200);
+        map.insert(("object".to_string(), "person".to_string()), 300);
+
+        assert_eq!(map.get(&("face_track".to_string(), "face_track_1".to_string())), Some(&100));
+        assert_eq!(map.get(&("speaker".to_string(), "SPEAKER_0".to_string())), Some(&200));
+        assert_eq!(map.get(&("object".to_string(), "person".to_string())), Some(&300));
+        assert_eq!(map.get(&("face_track".to_string(), "face_track_99".to_string())), None);
+    }
 }