- Pro board: drag/drop, pre-moves, arrows, highlights, keyboard nav, coords
- Pro timer: Fischer/Bronstein/delay, tenths/hundredths, low-time warnings
- Pro move stack: clickable, scrollable, opening detection (100+ openings)
- Post-game analysis: eval bar, eval graph, move classification, accuracy %
- Puzzle trainer: daily puzzles, streak mode, rush mode, themed puzzles
- Sound system: move/capture/check/castle/game-end via Web Audio API
- Eval bar: real-time position evaluation display
- PGN export, FEN copy, analyze button
- 50 seeded puzzles in database with ELO rating system
- New icons: eye, download, copy, chart, puzzle, brain
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>