Invalidate graph cache after capacity trimming

Author: QUSETIONS

minicode/memory_graph.py

@@ -451,6 +451,7 @@ def _invalidate_search_cache(self) -> None:
         self._search_cache.clear()
 
     def _trim(self) -> None:
+        trimmed = False
         if len(self.facts) > self.max_facts:
             keep = sorted(
                 self.facts.values(),
@@ -466,13 +467,21 @@ def _trim(self) -> None:
             }
             self._rebuild_indexes()
             self._pending_fact_ids.intersection_update(keep_ids)
+            trimmed = True
         if len(self.edges) > self.max_edges:
             keep_edges = sorted(
                 self.edges.values(),
                 key=lambda edge: (edge.weight, edge.created_at),
                 reverse=True,
             )[: self.max_edges]
             self.edges = {edge.id: edge for edge in keep_edges}
+            trimmed = True
+        if trimmed:
+            # Trimming can happen during save after a search has populated the
+            # cache.  Any cached result may reference a fact or edge that was
+            # just evicted, so it must not survive the capacity bound.
+            self._dirty = True
+            self._invalidate_search_cache()
 
     def save(self) -> bool:
         """Persist the sidecar atomically; return whether the write succeeded."""

tests/test_memory_graph.py

@@ -214,6 +214,50 @@ def test_graph_search_cache_hits_and_invalidates_on_graph_mutation():
     assert store.stats()["search_cache_misses"] >= 2
 
 
+def test_graph_save_trim_invalidates_cached_evicted_facts(tmp_path: Path):
+    store = MemoryGraphStore(
+        storage_path=tmp_path / "memory-graph.json",
+        max_facts=2,
+    )
+    evicted = store.add_fact(
+        memory_id="evicted",
+        scope="project",
+        subject="obsolete",
+        predicate="choice",
+        value="evict this fact",
+        confidence=0.1,
+        observed_at=1,
+    )
+    store.add_fact(
+        memory_id="kept-1",
+        scope="project",
+        subject="current",
+        predicate="choice",
+        value="keep this fact",
+        confidence=0.9,
+        observed_at=2,
+    )
+    store.add_fact(
+        memory_id="kept-2",
+        scope="project",
+        subject="current",
+        predicate="choice",
+        value="keep another fact",
+        confidence=0.9,
+        observed_at=3,
+    )
+
+    assert [result.memory_id for result in store.search("obsolete evict")] == [
+        evicted.memory_id
+    ]
+    assert store.stats()["search_cache_size"] == 1
+
+    assert store.save()
+    assert evicted.id not in store.facts
+    assert store.search("obsolete evict") == []
+    assert store.stats()["search_cache_hits"] == 0
+
+
 def test_graph_relation_prioritises_support_over_similarity():
     store = MemoryGraphStore()
     source = store.add_fact(