- Added a Codex rate-limit parser for `x-codex-*` headers and registered it with the Codex usage provider.
- Updated auth-storage to require parsed usage headers before ingesting usage data, treated exhaustion as non-throttled, and renamed ranked candidate drain fields.
- Reworked key ranking math to use `headroom / remainingHours` with a 1-minute minimum, then applied measured-usage precedence with hot-window demotion behavior.
- Updated session handling and tests to support provider-aware header ingestion with deterministic, exhaustion-aware account selection.