inngest-durable-functions

Use inngest.createFunction with a unique id, a triggers array (event, cron, or invoke), and an async handler receiving event and step. Wrap all side effects like API calls and database writes in step.run() so they are memoized and retried independently.

Each step retries automatically up to the configured retries count (default 4) with exponential backoff. Throw NonRetriableError for permanent failures like missing users, or RetryAfterError to respect API rate limits with custom retry timing.

Put API calls, database operations, file I/O, and any non-deterministic logic inside step.run so results are memoized. Keep pure calculations, validation, and conditionals outside steps, since code outside steps re-executes on every replay.

Yes, a function's triggers array accepts up to 10 triggers mixing events and cron expressions, including timezone-aware cron like TZ=Europe/Paris. Event triggers also support conditional if expressions to filter which events start a run.

Each function run allows a maximum of 1,000 steps, 4MB of returned data per step, and 32MB of combined run state. To exceed these, split work into smaller functions connected via step.invoke() or step.sendEvent().

Logging outside steps duplicates because function code re-executes during replay while steps are memoized. Move logger calls inside step.run blocks and pass a logger like Winston or ConsoleLogger to the Inngest client for consistent output.