Workflow Runtime

Key invariants

• Runs execute against a pinned published version (no drift).
• Node execution is idempotent (safe to retry after partial failure).
• Interrupts pause the run until resumed or cancelled.

Steps

1. Define the execution model:
   • Graph traversal rules
   • Dependency resolution (when a node becomes runnable)
2. Implement run state and node_run state:
   • Statuses: TO_DO, IN_PROGRESS, RESOLVED, ERROR, CANCELLED
   • Timestamps, attempts, last_error
3. Implement runtime state:
   • Workflow input variables (design-time schema)
   • Per-run state
   • Previous node outputs referenced by reference_id
4. Implement interrupt handling:
   • Create interrupt and transition run to WAITING_FOR_INPUT
   • Resume: validate input/files, update state, continue execution
5. Add robust retry controls:
   • Per-node max retries
   • Exponential backoff