- visualize input, output, and cache token segments in usage charts
- add usage period selector for 7d, 30d, 90d, and 365d
- guard usage stats against stale overlapping period requests
- normalize blank model usage into unknown buckets
- add client and server coverage for usage analytics behavior
Implement runtime theme switching using CSS custom properties delegated through SCSS variables, with light/dark/system modes, FOUC prevention, sidebar toggle, and settings selector. Add theme-aware video assets for sidebar and chat thinking indicator.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>