fix(agent-evolution-pool-supervisor): Fix sandbox step unpacking to match list[_SandboxInfo] return type

features/steps/sandbox_create_for_plan_steps.py

@@ -116,9 +116,13 @@ def step_call_create_sandbox(context: Context) -> None:
         "cleveragents.application.container.get_container",
         return_value=context.scfp_container,
     ):
-        context.scfp_sandbox_root, context.scfp_sandbox_obj = _create_sandbox_for_plan(
+        sandbox_root, sandbox_infos = _create_sandbox_for_plan(
             _PLAN_ID, context.scfp_service
         )
+    context.scfp_sandbox_root = sandbox_root
+    # _create_sandbox_for_plan returns (str | None, list[_SandboxInfo]).
+    # Extract the first sandbox object from the list, or None if empty.
+    context.scfp_sandbox_obj = sandbox_infos[0].sandbox_obj if sandbox_infos else None
     if context.scfp_sandbox_obj is not None:
         context.add_cleanup(context.scfp_sandbox_obj.cleanup)
 
@@ -166,3 +170,4 @@ def step_sandbox_root_differs(context: Context) -> None:
 @then("the cleanup call should complete without error for scfp")
 def step_cleanup_no_error(context: Context) -> None:
     assert context.scfp_cleanup_done is True
+