golem-add-transactions-moonbit

Implement saga-pattern transactions manually using Golem's oplog APIs from @golem_sdk/api. Wrap each step in with_atomic_operation, track completed steps, and run compensating functions in reverse order when a step fails.

No, the MoonBit SDK does not yet provide high-level transaction macros like Rust's fallible_transaction or infallible_transaction. You must build sagas manually with oplog primitives, though a future SDK release may add dedicated support.

A fallible saga compensates completed steps and returns an error on failure. An infallible saga compensates and then calls set_oplog_index to rewind execution to a checkpoint, retrying the entire transaction automatically.

Compensation functions may be invoked more than once during retries, so they must produce the same result on repeated calls. Non-idempotent compensations can cause duplicate refunds or inconsistent state.

Save a checkpoint with get_oplog_index, then call set_oplog_index with that position to rewind execution. Golem re-executes side-effecting calls from that point, which may return different results on retry.