Built this semaphore while working on our bootstrapped community dating platform (june.dating) after a traffic spike hit our SSR rendering path.It s a priority-queue semaphore with weighted permits, a saturation circuit breaker (trips on timeouts, not errors), and adaptive backoff. It has some baked in observability with status(), which gives you queue depth, latency, and circuit state for free. Zero dependencies, ~26KB minified, TypeScript, ESM+CJS.Written by a human, optimized by the bots.