fix(proxy): atomic Durable Object rate limiting#151
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Replace eventually-consistent KV counters (read-then-write race let concurrent requests bypass the perMinute/perDay caps) with a Cloudflare Durable Object that does check-and-increment inside blockConcurrencyWhile. - Per-IP DO holds minute/day/burst counters - Service-wide global cap routed through a single dedicated `__global__` DO instance via one atomic /global/check-increment endpoint (no cross-DO TOCTOU); fail-closed on binding/fetch/parse errors - Lower globalPerDay 5000 -> 500 as a cost backstop (real backstop is an upstream OpenAI account spend cap) - Prune previous-window bucket keys to bound DO storage growth Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Problem
The proxy's rate limiting used Cloudflare KV, which is eventually consistent. Concurrent requests all read the same low count and passed the cap before any increment landed — so
perMinute/perDay/globalPerDaywere not actually enforced (cost / denial-of-wallet risk).Fix
blockConcurrencyWhile(serialized, strongly consistent).__global__DO instance via one atomic/global/check-incrementendpoint — decision + mutation in one serialized gate, so there's no cross-DO TOCTOU. Fail-closed on missing binding / fetch error / malformed response.globalPerDay5000 → 500 as a cost backstop.Testing
__global__DO, and asserts exactly one is allowed (would fail against the old split check/increment design).node --checkclean on all changed sources.Deploy note
Not deployed.
wrangler.tomladds theRateLimiterDO binding +new_sqlite_classesmigration; deploying will requirewrangler deploy.🤖 Generated with Claude Code