Why it matters
A Keycard and Temporal workshop demonstrates an expense agent moving from shared API credentials to explicit agent and user identities. Token exchange narrows access across the agent, MCP server and ledger API, while audit records preserve who acted for whom. Durable execution resumes recorded work, and an execution interceptor obtains credentials without storing them in workflow history. This is an instructional demo, not a general outage or authorization guarantee.
My takeaway: Test resource audience, scopes, delegation identity and self-approval denial at every hop. Keep bearer tokens out of durable history and acquire them when protected activities run. Exercise restart, expired-token and revoked-access cases, and use idempotent downstream operations to handle uncertain retry outcomes.