Bind visualization status to snapshot freshness

tests/test_adapter_contract.py

@@ -533,6 +533,20 @@ class AdapterContractTests(unittest.TestCase):
             self.assertEqual(0, read_counters["adapter_source_extractions"])
             self.assertEqual(0, read_counters["index_builds"])
 
+            pinned_state = project.incremental_state()
+            assert pinned_state is not None
+            loader.sources["guide.foundation"] = "Changed after viewer pin."
+            client = ViewerManagerClient(index)
+            self.assertEqual(
+                "stale",
+                client._source_state(
+                    {
+                        "revision": pinned_state.revision,
+                        "source_hash": pinned_state.source_hash,
+                    }
+                ),
+            )
+
             legacy = AdapterProject(
                 Loader(self.projection(root)),
                 cache_root=root / ".cache" / "legacy",
@@ -544,6 +558,15 @@ class AdapterContractTests(unittest.TestCase):
             self.assertEqual(1, legacy_counters["project_loads"])
             self.assertEqual(1, legacy_counters["adapter_projection_loads"])
             self.assertEqual(0, legacy_counters["adapter_source_extractions"])
+            self.assertEqual(
+                "unknown",
+                ViewerManagerClient(ProjectIndex(legacy))._source_state(
+                    {
+                        "revision": "legacy",
+                        "source_hash": "0" * 64,
+                    }
+                ),
+            )
 
     def test_incremental_adapter_reuses_sources_and_invalidates_reverse_dependencies(self) -> None:
         with tempfile.TemporaryDirectory() as directory: