X_OVERLOADED
Means
in-flight requests are at the configured ceiling
Typical cause
more concurrent requests than maxInflight (1,000). Shed before any work — no route match, no auth, no body, no query — because the alternative is not "serve everyone" but "serve nobody": every request queues behind the same pool, p99 walks off the chart and client retries multiply the load. @ultimat3/realtime's AcceptBudget is the same decision for sockets. Classified retry-after, and the response carries the header; also thrown by @ultimat3/auth's KDF gate, which refuses a password hash when 8 are running and 64 are queued — each argon2id arena is ~19 MiB, so the caps bound memory the per-IP limiters cannot
Fix
retry after the Retry-After header; to serve more at once call configureHttp({ maxInflight: 2000 }) at module scope in a file under apps/*/, and add replicas to match. For the KDF half, installKdfGate({ maxConcurrent, maxQueued }) from @ultimat3/auth/adapter, in apps/web/runtime.ts