Retry and retirement

Retry and retirement — contract and behavior

• Random selectors retry the remaining randomized candidates; task selectors retry the remaining ranked candidates.
• Provider failure is isolated to the current candidate and does not mutate request content for the next provider.
• Retirement markers are non-secret journal records and prevent retired subscriptions from re-entering the active pool.
• Brama does not persist provider credentials, refreshed tokens, or encrypted secret overlays as retry state.