@lankajs/optimistic

▸ module · Optimistic mutations

Two concurrency strategies with real request cancellation.

A library in the same box. The app imports and calls it; core does not know it exists.

Runs in: the browser, node and React Native — everywhere.

How to use it: GUIDE.md — the user guide, with examples. How to change it: SKILL.md.

Contents

• LankaOptimisticActions — runLatest (last click wins) and runExclusive (per-item lock)

Rollback is what separates the two strategies

runLatest does NOT roll back a cancelled request: a fresher click superseded it, and restoring the previous state would undo what the user just chose.

runExclusive has no superseding click, so it rolls back on ANY failure including cancellation and timeout. Its lock expires on a timeout for the same reason — a hung server would otherwise freeze the button forever.

Cancellation is recognised from LankaError{kind:"aborted"}, from DOMException, and from the error name: the framework transport classifies it, but in node AbortController throws a plain Error. A missed cancellation costs more than a string comparison.

Repository map: ../../README.md