Introduction

@haskou/flow provides dependency-light classes for coordinating async work in TypeScript services.

Use it when promise-producing work needs rules around when it starts, how often it runs, how long it may take, how failures are retried, or which fallback source should be used.

The main classes are:

• Semaphore to share a fixed concurrency capacity across unrelated code paths.
• Queue to run submitted tasks with bounded concurrency.
• RateLimiter and Throttler to space task starts over time.
• Timeout to fail work that takes too long.
• Retrier to retry transient failures.
• Racer to run alternative async sources and keep the first successful result.
• Abortable to cancel running work.
• Scheduler to run repeated jobs without overlap.
• Debouncer to collapse bursts into one latest task.
• CircuitBreaker to protect unstable dependencies.
• FallbackChain to read from ordered sources such as memory, Redis, database, and remote API.
• Flow to combine several controls around one task.

Numbers are accepted at public boundaries where they are convenient. Time values can also be passed as Duration from @haskou/value-objects.