Function patchWithRetry

Read-compute-write loop that retries on version conflict, using getWithVersion

• putIfMatch under the hood. The right primitive for counter-like updates where two handlers might read the same pre-state and otherwise lose one write.

update receives the current document (or null if the row doesn't exist) and returns the next document. Returning null aborts without writing.

await patchWithRetry(ctx.store, 'media_buys', 'mb_1', (current) => ({
  ...(current ?? {}),
  budget_spent: (current?.budget_spent ?? 0) + cost,
}));
Copy

Throws PatchConflictError after maxAttempts consecutive conflicts. Throws PatchConflictError with reason: 'deleted_during_retry' if the row is deleted between the initial read and the write (opt into resurrection via allowResurrection: true).

Requires the store to implement both getWithVersion and putIfMatch.

Mutation caveat: always build a fresh object in update — never mutate the current argument in place. In-memory stores hand out a shallow copy (nested references shared across retries) while Postgres deserializes JSONB fresh each time; the safe pattern ({ ...current, field: newValue }) works on both.

Error propagation: if update throws, the exception propagates immediately and no retry happens.

Backoff: default is jittered exponential (low single-digit ms). Override with options.backoffMs. Return 0 to disable.

Size: each retry re-reads the full document. Avoid on rows close to maxDocumentBytes — split into per-entity rows instead.