Changelog

0.6.0 (2026-03-04)

Resiliency.RateLimiter — new module. Token-bucket rate limiter with lazy refill, lock-free ETS CAS hot path (no GenServer message on grant or reject), weighted calls, on_reject callback, get_stats/1, reset/1, and built-in telemetry (start / rejected / stop events).

Duplicate start_link with the same name now returns {:error, {:already_started, pid}} instead of allowing split-brain state.
terminate/1 now deletes the ETS table before erasing persistent_term, preventing a brief window where callers could obtain a dead ETS reference.
Unknown name now raises a clear ArgumentError instead of a :badarg crash from persistent_term.get/1.

Built-in telemetry — all 10 modules now emit :telemetry events following the standard span convention (start / stop / exception) plus point events for significant occurrences (retry, hedge, rejected, permitted, state_change). Zero configuration required; attach handlers with the standard :telemetry API. See Resiliency.Telemetry for the complete event catalogue.
Resiliency.Bulkhead — new module. Isolates workloads with per-partition concurrency limits. Supports configurable queue depth (max_queue) and optional caller-side wait timeout (max_wait). Rejects immediately when queue is full.

Resiliency.WeightedSemaphore — try_acquire/3 now wraps the GenServer call in try/catch so process exits close the telemetry span instead of leaking it.
Resiliency.WeightedSemaphore — acquire/4 now handles all exit reasons, not just {:timeout, _}. Non-timeout exits re-exit after emitting a :stop event.
Resiliency.SingleFlight — flight/3 now wraps the GenServer call in try/catch, matching the behaviour of flight/4 and ensuring the span is always closed.

Add Resiliency.CircuitBreaker with sliding-window failure-rate tracking and automatic half-open probing.

Split TaskExtension into top-level Race, AllSettled, Map, FirstOk modules.

Initial public release with BackoffRetry, Hedged, SingleFlight, WeightedSemaphore, and task combinators.