Release-cycle review: the per-workspace cost cap was fixed-window + per-instance
(allowed ~2x at a window boundary and K*cap behind K instances) on an anonymous
endpoint that spends the owner's provider budget. Rewrite it as a sliding-window,
CLUSTER-WIDE Redis limiter: one atomic Lua EVAL does ZREMRANGEBYSCORE (age out)
-> ZCARD -> ZADD with PEXPIRE, so concurrent instances share one budget and the
true rate over any trailing window is <= cap. Fails OPEN on a Redis error (logged)
— it's a cost backstop, not access control (the funnel gates + per-IP throttle
still apply), so a Redis blip must not take the assistant offline. Per-IP @Throttle
kept; commented that it needs an XFF-rewriting trusted proxy to be meaningful.
Extract deriveShareAccess (resolvedShareId===requestedShareId + isSharingAllowed +
!restricted, equality-only, never widening) and filterShareTranscript into pure
helpers, and add tests: limiter sliding-window + boundary-burst + fail-open;
access derivation; and red-team boundary locks (cross-share/cross-workspace swap
rejected, forged shareId can't widen tool scope, transcript injection filtered).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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