ADR 0006: MVP Accounting, Circuit, and Replay Defaults

  • Status: Accepted
  • Date: 2026-07-18
  • Gate: LF-2 before LF-5B

Decision

The initial measurable configuration keys are:

  • llm-router.accounting.estimatorId, estimatorVersion, safetyMarginBps, maxInputUnits, maxOutputUnits, maxReservedCostMicros, and unknownPricingMode;
  • llm-router.circuit.failureThreshold=5, openCooldownMs=30000, and halfOpenProbePermits=1;
  • llm-router.retry.maxAttempts=1 for the first buffered slice and maxReplayBytes=1048576.

Reservations are per replica and keyed by host/principal/alias; they are explicitly non-distributed. The conservative local estimator is identified by wire profile and is never reported as provider billing usage. Hard accounting fails closed on unknown pricing; observational profiles preserve unknown and incomplete evidence.

Timeout/cancellation reconciliation remains conservative. Passive circuits count configured transport, timeout, throttling, and provider 5xx categories. Retry-After cooldown belongs to provider-account/quota-group and deployment state. Any future multi-attempt policy whose canonical replay body exceeds maxReplayBytes is rejected at publication.

Numeric defaults remain manifest inputs and may change only with new benchmark and pricing evidence.