The Claude model manifest declares fast-mode support per model, and the `claude-opus-5` entry was added without `supportsFastMode`. Claude Code supports fast mode on Opus 5, so the composer and Command Center hid a toggle the model actually has. Set the flag. Everything downstream already keys off it: `claudeManifestModelSupportsFastMode` gates `buildClaudeFeatures`, which feeds `listFeatures`, the session `features` getter, `setFeature`, and the `setModel` auto-clear. Co-authored-by: Claude Opus 5 <noreply@anthropic.com>