diff --git a/tests/test_comfyui_integration.py b/tests/test_comfyui_integration.py
index 454e240..9d26551 100644
--- a/tests/test_comfyui_integration.py
+++ b/tests/test_comfyui_integration.py
@@ -65,5 +65,86 @@ class TestSaveImageNotPatched(unittest.TestCase):
         self.assertEqual(integration.get_current_prompt_text("pm_1"), "hello")
 
 
+import threading  # noqa: E402
+import unittest.mock as mock  # noqa: E402
+
+from utils import comfyui_integration  # noqa: E402
+from utils.comfyui_integration import get_comfyui_integration  # noqa: E402
+
+
+class IntegrationTestCase(unittest.TestCase):
+    def setUp(self):
+        ComfyUIMetadataIntegration._instance = None
+        comfyui_integration._integration_instance = None
+        self.clock = mock.patch.object(
+            comfyui_integration.time, "time", side_effect=self._now
+        )
+        self.clock.start()
+        self.addCleanup(self.clock.stop)
+        self._ticks = 1000.0
+        self.integration = get_comfyui_integration()
+
+    def tearDown(self):
+        ComfyUIMetadataIntegration._instance = None
+        comfyui_integration._integration_instance = None
+
+    def _now(self):
+        self._ticks += 1.0
+        return self._ticks
+
+
+class TestSingletonAndRegistry(IntegrationTestCase):
+    def test_singleton_keeps_registrations_across_constructions(self):
+        self.assertIs(get_comfyui_integration(), self.integration)
+        self.assertIs(ComfyUIMetadataIntegration(), self.integration)
+        self.integration.register_prompt("n1", "hello", {"category": "x"})
+        ComfyUIMetadataIntegration()  # __init__ runs again: must not reset state
+        self.assertEqual(self.integration.get_current_prompt_text("n1"), "hello")
+
+    def test_latest_prompt_of_this_thread_wins_without_a_node_id(self):
+        self.integration.register_prompt("n1", "first", {})
+        self.integration.register_prompt("n2", "second", {})
+        self.assertEqual(self.integration.get_current_prompt_text(), "second")
+        self.assertEqual(self.integration.get_current_prompt_text("missing"), "second")
+        self.assertEqual(self.integration.get_current_prompt_text("n1"), "first")
+
+    def test_nothing_registered_returns_none(self):
+        self.assertIsNone(self.integration.get_current_prompt_text())
+        self.assertIsNone(self.integration.get_current_prompt_text("n1"))
+
+
+class TestCrossThreadLookup(IntegrationTestCase):
+    def _register_in_thread(self, text):
+        worker = threading.Thread(
+            target=self.integration.register_prompt, args=("w1", text, {})
+        )
+        worker.start()
+        worker.join()
+
+    def test_recent_prompt_from_another_thread_is_used(self):
+        self._register_in_thread("from worker")
+        self.assertEqual(self.integration.get_current_prompt_text(), "from worker")
+
+    def test_stale_prompt_from_another_thread_is_ignored(self):
+        self._register_in_thread("from worker")
+        self._ticks += 400.0
+        self.assertIsNone(self.integration.get_current_prompt_text())
+
+    def test_global_entry_of_this_thread_is_found_without_thread_local(self):
+        self.integration.register_prompt("n1", "mine", {})
+        self.integration._thread_local = threading.local()
+        self.assertEqual(self.integration.get_current_prompt_text(), "mine")
+
+    def test_cleanup_removes_old_registrations_only(self):
+        self._register_in_thread("old")
+        self._ticks += 700.0
+        self.integration.register_prompt("n2", "new", {})
+        self.integration.cleanup_old_prompts(max_age_seconds=600)
+        texts = sorted(v["text"] for v in self.integration._current_prompts.values())
+        self.assertEqual(texts, ["new"])
+        self.integration.cleanup_old_prompts(max_age_seconds=600)  # nothing to do
+        self.assertEqual(len(self.integration._current_prompts), 1)
+
+
 if __name__ == "__main__":
     unittest.main()