support filter chains on model listeners

cli/planoai/config_generator.py

@@ -426,6 +426,16 @@ def validate_and_render_schema():
                     "Please provide model_providers either under listeners or at root level, not both. Currently we don't support multiple listeners with model_providers"
                 )
 
+    # Validate filter_chain IDs on listeners reference valid agent/filter IDs
+    for listener in listeners:
+        listener_filter_chain = listener.get("filter_chain", [])
+        for fc_id in listener_filter_chain:
+            if fc_id not in agent_id_keys:
+                raise Exception(
+                    f"Listener '{listener.get('name', 'unknown')}' references filter_chain id '{fc_id}' "
+                    f"which is not defined in agents or filters. Available ids: {', '.join(sorted(agent_id_keys))}"
+                )
+
     # Validate model aliases if present
     if "model_aliases" in config_yaml:
         model_aliases = config_yaml["model_aliases"]