How would you design a workflow automation platform?

Short explanation:

A workflow platform stores a definition of steps and executes separate runs of that definition over time. Because runs can wait, retry or survive a restart, their progress must be durable rather than only held in a process. A queue and worker layer lets execution capacity grow separately from the request API.

Key points:

• Ask about step types, duration, branching and external actions.

• API → workflow/run database → queue → workers; persist each step's state.

• Use unique step IDs, safe retries, timeouts and an audit trail; mark failed runs clearly.

• Model WorkflowDefinition, WorkflowRun and StepRun with status, attempt count and a stable operation ID.

• Choose a policy for editing definitions while old runs exist, and monitor oldest pending work rather than only queue size.

Interview point:

• Walk through a worker crash immediately after an external action succeeds and explain how the next attempt avoids a duplicate effect.