azd up should fail if the agent id doesn't exist

[qubitron]

When providing an agent id that doesn't exist in the project (using azd env set), the template deployment succeeds but then you discover upon chatting that it created a new agent.

Instead the deployment should fail so that you can fix it. I had to run locally to debug.

(.venv) C:\dev\agents-golden-path\src>python -m uvicorn "api.main:create_app" --factory --reload
INFO:     Will watch for changes in these directories: ['C:\\dev\\agents-golden-path\\src']
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     Started reloader process [30908] using WatchFiles
2025-06-25 14:39:18,747 [INFO] azureaiapp: Tracing is not enabled
INFO:     Started server process [21080]
INFO:     Waiting for application startup.
2025-06-25 14:39:19,246 [INFO] azureaiapp: Created AIProjectClient
2025-06-25 14:39:25,532 [ERROR] azureaiapp: Error fetching agent: (None) No assistant found with id 'asst_Qd7wvcXRK8gVNo31404E4o7S'.
Code: None
Message: No assistant found with id 'asst_Qd7wvcXRK8gVNo31404E4o7S'.
Traceback (most recent call last):
  File "C:\dev\agents-golden-path\src\api\main.py", line 54, in lifespan
    agent = await ai_project.agents.get_agent(agent_id)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\dev\agents-golden-path\.venv\Lib\site-packages\azure\core\tracing\decorator_async.py", line 119, in wrapper_use_tracer
    return await func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\dev\agents-golden-path\.venv\Lib\site-packages\azure\ai\agents\aio\operations\_operations.py", line 4355, in get_agent
    map_error(status_code=response.status_code, response=response, error_map=error_map)
  File "C:\dev\agents-golden-path\.venv\Lib\site-packages\azure\core\exceptions.py", line 163, in map_error
    raise error
azure.core.exceptions.ResourceNotFoundError: (None) No assistant found with id 'asst_Qd7wvcXRK8gVNo31404E4o7S'.

[howieleung]

Thanks for the feedback. On top of my head, the only way to do it is to have a sh script in the hook that run az command to grab a token and run rest api to validate the agent id. But users might not have the role for this check although he has user access manager role to provision a container app.