resonate-external-system-of-record-pattern-python

What problem does it solve?

This Skill addresses the challenge of keeping business state consistent when durable Resonate workflows interact with external systems that have their own durability guarantees, by ensuring writes to the system of record are idempotent and authoritative.

Core Features & Use Cases

• Idempotent writes first: Write to the external system of record before any dependent side effects to ensure a single source of truth.
• Checkpointed interactions: Use deterministic checkpointing so external calls are durably recorded and not re-executed on replay.
• Practical integrations: Patterns and examples for PostgreSQL, TigerBeetle/ledger systems, and HTTP/message brokers in Python-based workflows.
• Anti-pattern guidance: Advice on avoiding in-memory, non-durable reads and on handling secondary systems (e.g., search indexes) as compensatable or best-effort writes.

Quick Start

Write to the external system of record first, wrap all I/O in ctx.run so results are checkpointed, and use an external idempotency key to avoid duplicates.