golem-add-transactions-scala

Define operations with Transactions.operation, providing an async execute function and an async compensate function. Then run them inside Transactions.fallibleTransaction or Transactions.infallibleTransaction using tx.execute for each step.

A fallible transaction compensates completed steps and returns the error when a step fails. An infallible transaction compensates completed steps and then retries the entire transaction until it eventually succeeds.

Convert the JS Promise to a Scala Future with FutureInterop.fromPromise and chain it with map or flatMap. Never fire a Promise and ignore the result, because that breaks operation ordering and compensation determinism.

Compensation functions may be called more than once, especially when infallible transactions retry. Writing idempotent compensation ensures repeated undo calls do not corrupt state or cause additional failures.

Use sagas when an operation spans multiple independent steps or external services that cannot share one atomic commit. Each step gets its own compensation action, and completed steps are undone in reverse order if a later step fails.