Merged via /merge-batch (v3.8.51 provenance sweep). Boarded and validated together with the batch's other retirement PRs in a combined worktree — full gate suite green. This PR's conflicts (against #11720's Designer retirement, both introducing a retirement-guard mechanism across executors/index.ts, executorProxy.ts, providers.ts, reservedProviderPrefixes.ts, auth.ts, chat.ts, chatHelpers.ts, model.ts) were reconciled by combining both guards at every chokepoint, with the shared reserved-prefix count recomputed (not guessed) at 400. Re-validated with this PR's own 72 node:test + 20 vitest focused tests, all passing, and pushed before merge. Thank you.
⭐5 — freeAccessPolicy "strict" opt-in (default off): verifica candidatos de auto-combo contra estado de quota ao vivo + segurança econômica por conexão antes do dispatch (fail-closed — estado desconhecido/stale/incompleto é excluído). Zero mudança de comportamento com o default "off". 82 testes focados, eslint/prettier/typecheck limpos, docs em docs/routing/STRICT_ZERO_COST.md.
