Two invariant tests (red on main): the PKCE key lands as an api_key pool row that
resolve_provider("auto") picks up while the bare --api-key path keeps its default, and a forged
callback path is a 404 while the genuine nonce path yields the code. evals/openrouter_pkce_ab
drives the real auth_add_command against a local fake /api/v1/auth/keys (verifier check,
single-use codes) for legit / wrong-state / replayed-code / malformed-response / api-key-path.
