fix(gateway): reset approval and yolo state on session boundary

gateway/run.py

@@ -7217,6 +7217,7 @@ class GatewayRunner:
         new_entry = self.session_store.switch_session(session_key, target_id)
         if not new_entry:
             return "Failed to switch session."
+        self._clear_session_boundary_security_state(session_key)
 
         # Get the title for confirmation
         title = self._session_db.get_session_title(target_id) or name
@@ -7306,6 +7307,7 @@ class GatewayRunner:
         new_entry = self.session_store.switch_session(session_key, new_session_id)
         if not new_entry:
             return "Branch created but failed to switch to it."
+        self._clear_session_boundary_security_state(session_key)
 
         # Evict any cached agent for this session
         self._evict_cached_agent(session_key)
@@ -8680,6 +8682,29 @@ class GatewayRunner:
         if hasattr(self, "_busy_ack_ts"):
             self._busy_ack_ts.pop(session_key, None)
 
+    def _clear_session_boundary_security_state(self, session_key: str) -> None:
+        """Clear approval state that must not survive a real conversation switch."""
+        if not session_key:
+            return
+
+        pending_approvals = getattr(self, "_pending_approvals", None)
+        if isinstance(pending_approvals, dict):
+            pending_approvals.pop(session_key, None)
+
+        try:
+            from tools.approval import clear_session as _clear_approval_session
+        except Exception:
+            return
+
+        try:
+            _clear_approval_session(session_key)
+        except Exception as e:
+            logger.debug(
+                "Failed to clear approval state for session boundary %s: %s",
+                session_key,
+                e,
+            )
+
     def _begin_session_run_generation(self, session_key: str) -> int:
         """Claim a fresh run generation token for ``session_key``.