Changelog

0.1.0 (unreleased)

The first release. Everything below ships in it.

Core

• ResiliencePipelineBuilder with Polly v8’s API and defaults, plus PipelineBuilder + xStrategy() factories for tree-shaken bundles.
• execute, executeOutcome, settle (typed errors), executeStream (protects everything up to the first chunk; fallbacks may answer with a value or a stream; hedged attempts never mix streams) and wrap(fn).
• ResilienceContext with signal, operationKey, typed properties (ResiliencePropertyKey), attemptNumber (0-based) and idempotent.
• One-liners without a pipeline: retry(fn, options), withTimeout(fn, duration), NonRetryableError.
• Deadline propagation: a pipeline executed inside another inherits its signal. getResilienceSignal() / getResilienceContext() from anywhere in the call.
• Durations as milliseconds or strings ('250ms' … '2w'); delays past setTimeout’s ~24.8-day limit are chained.
• Kill switch (disable() / enable()), describe(), getStrategy(), dispose().
• ResiliencePipelineRegistry with live reload(), circuitBreakers() and limiters().
• Runs on Node.js ≥ 20.16, Bun, Deno, Cloudflare Workers and browsers. ESM, CommonJS and a script-tag build. Zero dependencies.

Strategies

• Retry: constant / linear / exponential backoff, factor, jitter (true, 'full', 'equal'), maxDelay, delayGenerator, Retry-After honoured, initialDelay, maxRetryTime, shouldConsumeRetry, onFailedAttempt, onRetryExhausted, shared RetryBudget.
• Timeout: aggressive by default, cooperative (Polly’s behaviour) and keepLateResult as options.
• Circuit breaker: time or count window, consecutiveFailures, minimumRps, halfOpenMaxCalls, halfOpenSuccessThreshold, halfOpenMaxWait, warmUpDuration, pluggable breaker policy, manual isolation (stacking), trip() / reset(), snapshots with the rolling window, circuitHealthCheck() and sharedCircuitState() extensions.
• Fallback: fallbackAction / fallbackValue, addFallbackOn(codes), addMapError, addStaleFallback.
• Hedging: latency, parallel and fallback modes, actionGenerator, per-attempt property copies.
• Concurrency: bulkhead with FIFO queue, queueTimeout, priority and overflow policies; adaptive concurrency (gradient2, vegas, aimd).
• Rate limiting: token bucket, fixed and sliding window, partitioned (per key), bursty limiter, weights, fair waiting, block / penalty / reward, allow / deny lists, insurance limiter, even spacing / minTime, snapshot / restore, getRateLimitInfo().
• Cache and coalesce: TTL, stale-if-error, single-flight, pluggable CacheStore.
• Lock: leases with renewal and fencing tokens, pluggable LockStore.
• Chaos: fault, outcome, latency and behavior injection with Polly’s event names, weighted() generators, setGlobalChaos().
• Batches: all, allSettled, map (with concurrency), waitFor, and createBatcher() for request batching.

Errors

• Every strategy error extends ExecutionRejectedError with a stable code, a source and toJSON().
• Guards that work across duplicate package copies: isResilienceError, isTimeoutError, isBrokenCircuitError, isRateLimitError, isRejection.
• Outcome.match / try / all / partition / unwrap / unwrapErr, registerResultAdapter() for other Result types, and the resilience-pipeline/outcome subpath.
• describeResilienceError() / httpStatusFor() (504 / 429 / 503 / 409 / 403).

Integrations (subpath exports)

• /fetch: createResilientFetch() with per-host breakers and per-request overrides. /axios: attachResilience().
• /http (Express, Connect, Hono), /fastify, /koa: request deadlines, load shedding, per-client rate limits with RateLimit-* headers.
• /nestjs: ResilienceModule.forRoot / forRootAsync and method decorators for providers.
• /redis: cache, lock (atomic fencing), rate limiter and shared circuit state, tested on Redis Cluster. /adapters: rate-limiter-flexible.
• /otel, /prometheus, createStats(), /hystrix; onTelemetry(), diagnostics_channel, instrument().
• /testing: FakeTimeProvider.
• The @resilient method decorator (standard and legacy decorators).