Constant CLAUDE_OAUTH_TOKEN_ACCOUNT 

const CLAUDE_OAUTH_TOKEN_ACCOUNT: &str = "system:claude-code-oauth-token";

Fixed, sentinel account id for the user-supplied long-lived CLAUDE_CODE_OAUTH_TOKEN (from claude setup-token), persisted via identity::secret_store::put/get. Those wrap it in account_key() ("acct:{account_id}"), so the actual keychain entry is "acct:system:claude-code-oauth-token" — this constant only needs to be distinct as an account id from the per-identity account ids used elsewhere (see identity::resolver, identity::oauth_client), which are account UUIDs and would never collide with this sentinel string. This is a single, system-wide fallback token, not tied to any AgentMux identity.