### Bug Description I am attempting to use a token generated by `snapcraft export-login` to login to the snap store API. When I store this token in an env var and try to login with the code included in the repro steps, I get ``` craft_store.errors.CredentialsNotParseable: Credentials could not be parsed. Expected valid Candid credentials. ``` The token generated by `snapcraft export-login` is formatted like `{"t": "u1-macaroon", "v": {"r": "<string>", "d": "<string>"}}`. I get the same output when setting the env var mentioned in the help `export SNAPCRAFT_STORE_AUTH=candid`. I can see from the `craft_store` code that the `"v"` value in the token is supposed to be a string, not a dict, but can't figure out how to generate a token that has a string `"v"` value. Versions: - snapcraft: 8.5.1.post36+git0a7f753ac - craft_store: 3.2.0 - python: 3.12 - OS: Ubuntu 22.04.5 ### To Reproduce 1. On Ubuntu 22, with `snapcraft` 8.5.1 installed, run ``` export SNAPCRAFT_STORE_AUTH=candid sudo snapcraft export-login snapcraft_store_credentials ``` and login with your ubuntu one account. Inspect the contents of `snapcraft_store_credentials` with ``` cat snapcraft_store_credentials | base64 -d ``` and see that it has the structure `{"t": "u1-macaroon", "v": {"r": "<string>", "d": "<string>"}}`. 2. Store the token from `snapcraft_store_credentials` in a `SNAPCRAFT_STORE_CREDENTIALS` env var and run the following code in python 3.12 with `craft_store==3.2.0` installed. ``` from craft_store import StoreClient, endpoints store_client = StoreClient( base_url="https://dashboard.snapcraft.io", storage_base_url="https://upload.apps.ubuntu.com", endpoints=endpoints.SNAP_STORE, user_agent="test-agent", application_name="test-app", environment_auth="SNAPCRAFT_STORE_CREDENTIALS", ) store_client.whoami() ``` See exception traceback in included logs. ### part yaml ```shell ``` ### Relevant log output ```shell Traceback (most recent call last): File "/usr/local/lib/python3.12/site-packages/craft_store/creds.py", line 94, in unmarshal_candid_credentials return CandidModel.unmarshal(data).value ^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/craft_store/creds.py", line 42, in unmarshal return cls.model_validate(data) ^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/pydantic/main.py", line 568, in model_validate return cls.__pydantic_validator__.validate_python( ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ pydantic_core._pydantic_core.ValidationError: 2 validation errors for CandidModel t Input should be 'macaroon' [type=literal_error, input_value='u1-macaroon', input_type=str] For further information visit https://errors.pydantic.dev/2.8/v/literal_error v Input should be a valid string [type=string_type, input_value={'r': 'MDAyOWxvY2F0aW9uIG...zQXgG8mV7-uBK008LJ3igo'}, input_type=dict] For further information visit https://errors.pydantic.dev/2.8/v/string_type The above exception was the direct cause of the following exception: Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/local/lib/python3.12/site-packages/craft_store/base_client.py", line 199, in whoami return dict(self.request("GET", self._base_url + self._endpoints.whoami).json()) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/craft_store/base_client.py", line 187, in request headers["Authorization"] = self._get_authorization_header() ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/craft_store/store_client.py", line 109, in _get_authorization_header auth = creds.unmarshal_candid_credentials(self._auth.get_credentials()) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/local/lib/python3.12/site-packages/craft_store/creds.py", line 97, in unmarshal_candid_credentials raise errors.CredentialsNotParseable( craft_store.errors.CredentialsNotParseable: Credentials could not be parsed. Expected valid Candid credentials. ```