Cache OCR-negative bubbles

tests/test_wechat_local_ocr.py

@@ -689,6 +689,46 @@ class OcrCacheTests(unittest.TestCase):
         self.assertEqual(engine.last_cache_hits, 0)
         self.assertEqual(engine.last_cache_misses, 1)
 
+    def test_antialias_drift_reuses_visual_signature_cache(self):
+        engine = MODULE.OcrEngine.__new__(MODULE.OcrEngine)
+        bubble = MODULE.Bubble(50, 60, 132, 40, 5000)
+        first = MODULE.Image.new("RGB", (300, 180), (238, 238, 240))
+        second = MODULE.Image.new("RGB", (300, 180), (242, 242, 244))
+        first.putpixel((70, 75), (20, 20, 20))
+        second.putpixel((70, 75), (35, 35, 35))
+
+        with mock.patch.object(
+            engine,
+            "_recognize_bubble",
+            return_value=self.message(60),
+        ) as recognize:
+            engine.recognize_messages(first, [bubble])
+            messages, _ = engine.recognize_messages(second, [bubble])
+
+        self.assertEqual(recognize.call_count, 1)
+        self.assertEqual(len(messages), 1)
+        self.assertEqual(engine.last_cache_hits, 1)
+        self.assertEqual(engine.last_cache_misses, 0)
+
+    def test_unrecognized_bubble_reuses_negative_cache(self):
+        engine = MODULE.OcrEngine.__new__(MODULE.OcrEngine)
+        image = MODULE.Image.new("RGB", (300, 180), "white")
+        bubble = MODULE.Bubble(50, 60, 132, 40, 5000)
+
+        with mock.patch.object(
+            engine,
+            "_recognize_bubble",
+            return_value=None,
+        ) as recognize:
+            first_messages, _ = engine.recognize_messages(image, [bubble])
+            second_messages, _ = engine.recognize_messages(image, [bubble])
+
+        self.assertEqual(first_messages, [])
+        self.assertEqual(second_messages, [])
+        self.assertEqual(recognize.call_count, 1)
+        self.assertEqual(engine.last_cache_hits, 1)
+        self.assertEqual(engine.last_cache_misses, 0)
+
     def test_periodic_refresh_revalidates_cached_bubbles(self):
         engine = MODULE.OcrEngine.__new__(MODULE.OcrEngine)
         image = MODULE.Image.new("RGB", (300, 180), "white")