openevidence-rate-limits

# OpenEvidence Rate Limits Self-harnessing rate limiter for the OpenEvidence cookie API. Tuned so the client never bursts above its own configured RPM, even before the server returns a 429. ## Overview OpenEvidence does not publish a stable `X-RateLimit-*` contract for the cookie-based web API. This skill ships a defense-in-depth limiter that: 1. **Sliding-window self-throttle** caps requests-per-window at a configurable target usage (default 80% of `maxRequestsPerWindow`). 2. **Hard burst cap** prevents tight loops from firing more than `burstCap` requests in any 1-second slice. 3. **Priority queue** — `stat` > `urgent` > `routine` > `research` — so a STAT clinical query jumps ahead of a research batch. 4. **Exponential backoff with jitter** on 408/425/429/5xx, with `Retry-After` honored verbatim when the server sends it. 5. **Opportunistic header parsing** — if `X-RateLimit-Remaining` / `X-RateLimit-Reset` ever appear, they tighten the limiter; otherwise we rely on the client-side counters. The limiter is fully testable: clock and sleeper are injectable so the test suite runs in ~1 second. ## Implementation map | File | Role | | --- | --- | | `src/rate-limit.ts` | `RateLimitController`, `withExponentialBackoff`, `computeBackoffDelay`, `parseRetryAfterMs`, `HttpError`. | | `src/openevidence-client.ts` | `requestWithRateLimit` wraps every fetch with `acquire/observe/release` + retry. | | `src/config.ts` | `resolveRateLimitConfig` reads env vars and fo...