Imported from fimdim/tic-tac-toe (AGENTS.md). Install upstream with npx skills add fimdim/tic-tac-toe. Copyright stays with the author.

AGENTS.md

Repository guidance for GitHub Copilot agents.

Project

• Vanilla HTML/CSS/JavaScript Tic Tac Toe app.
• Main app files:
  • tic-tac-toe/index.html
  • tic-tac-toe/style.css
  • tic-tac-toe/game.js

Commands

• Run locally: open tic-tac-toe/index.html in a browser.
• Run game logic tests: node tests/game.test.js.
• Check JavaScript syntax: node --check tic-tac-toe/game.js.

Coding rules

• Use ES6+ JavaScript with const/let.
• 2-space indentation.
• Single quotes in JavaScript.
• Kebab-case for CSS classes and HTML IDs.
• camelCase for JavaScript identifiers.
• Preserve the existing dark palette: #1a1a2e, #16213e, #0f3460, #e94560, #a8dadc.

Game logic contract

• board stores 'X', 'O', or null for 9 cells.
• WINNING_LINES contains all 8 winning combinations.
• checkWinner(board) should return:
  • { winner, line } on win
  • { draw: true } on draw
  • null while in progress
• The shipped game is two-player only; AI and undo are not implemented. Scores persist in browser-local storage when available.

Safety boundaries

• Do not introduce external dependencies unless explicitly requested.
• Do not commit secrets.
• Keep changes minimal and task-focused.