fix(agent): clear in-memory cooldown when hygiene overwrites the shared row

A later hygiene idle-timeout write can replace an aux-model cooldown on
the shared column. Drop the in-memory timer on that refresh so the
in-agent compressor is not still blocked after the DB row is hygiene.

agent/context_compressor.py

@@ -2484,6 +2484,11 @@ class ContextCompressor(ContextEngine):
         # 429/aux-model fault. The in-conversation compressor has its own
         # budget and must still be allowed to run (#86972).
         if _is_hygiene_idle_timeout_error(state.get("error")):
+            # A later hygiene write can overwrite a previous aux-model row
+            # on the shared column. Drop any in-memory cooldown so the
+            # in-agent compressor is not still blocked after this refresh.
+            self._summary_failure_cooldown_until = 0.0
+            self._last_summary_error = None
             return None
 
         self._summary_failure_cooldown_until = now_mono + remaining_seconds

tests/agent/test_hygiene_timeout_cooldown_isolation.py

@@ -65,3 +65,30 @@ def test_aux_model_fault_cooldown_still_blocks_in_agent_compressor(tmp_path: Pat
     assert state is not None
     assert state["error"] == "rate limited"
     db.close()
+
+
+def test_hygiene_row_clears_stale_in_memory_aux_cooldown(tmp_path: Path):
+    """A later hygiene overwrite must not leave the in-memory aux cooldown armed."""
+    db = SessionDB(db_path=tmp_path / "state.db")
+    session_id = "hyg-overwrite-sid"
+    db.create_session(session_id, source="telegram")
+    db.record_compression_failure_cooldown(
+        session_id,
+        time.time() + 300,
+        "rate limited",
+    )
+
+    compressor = _bound_compressor(db, session_id)
+    loaded = compressor.get_active_compression_failure_cooldown()
+    assert loaded is not None
+    assert loaded["error"] == "rate limited"
+
+    db.record_compression_failure_cooldown(
+        session_id,
+        time.time() + 300,
+        _HYGIENE_TIMEOUT_ERROR,
+    )
+
+    assert compressor.get_active_compression_failure_cooldown(refresh=True) is None
+    assert compressor.get_active_compression_failure_cooldown() is None
+    db.close()