Improve WebUI streaming and Python tooling

src/session_store.py

@@ -186,6 +186,11 @@ def serialize_runtime_config(runtime_config: AgentRuntimeConfig) -> JSONDict:
         ),
         'session_directory': str(runtime_config.session_directory),
         'scratchpad_root': str(runtime_config.scratchpad_root),
+        'python_env_dir': (
+            str(runtime_config.python_env_dir)
+            if runtime_config.python_env_dir is not None
+            else None
+        ),
     }
 
 
@@ -230,6 +235,11 @@ def deserialize_runtime_config(payload: JSONDict) -> AgentRuntimeConfig:
         output_schema=_deserialize_output_schema(output_schema_payload),
         session_directory=Path(str(payload.get('session_directory', DEFAULT_AGENT_SESSION_DIR))).resolve(),
         scratchpad_root=Path(str(payload.get('scratchpad_root', DEFAULT_SESSION_DIR / 'scratchpad'))).resolve(),
+        python_env_dir=(
+            Path(str(payload['python_env_dir'])).resolve()
+            if payload.get('python_env_dir') is not None
+            else None
+        ),
     )