Round 1: Two players, one screen

Build a two-player tic-tac-toe on one screen, in the repository's React + Vite + TypeScript app: X and O take turns on a 3×3 board, the game says who plays next, spots a win or a draw, shows the winning line, refuses illegal moves, and starts over on New game. [ARCHITECTURE.md](ARCHITECTURE.md) has the plan; this brief is the contract.

## The interface

The checks find everything by its `data-testid`: these names and texts are fixed, everything else is yours.

| `data-testid` | Contract |
| --- | --- |
| `board` | One element holding the 9 cells. |
| `cell-0` … `cell-8` | One `<button>` each, inside the board, row by row from the top left: `0 1 2` / `3 4 5` / `6 7 8`. Its text (`textContent`, trimmed) is exactly `X`, `O` or empty: put labels in `aria-label`, never in the text. |
| `status` | One element whose text (trimmed) is exactly `X to play`, `O to play`, `X wins`, `O wins` or `Draw`. |
| `new-game` | A button: empties the board, clears the marks, and the status reads `X to play`. |

The rules:

- X always starts; then O and X take turns, one move per click on an empty cell.
- A line is a row, a column or a diagonal. Three of a player's marks on a line win, and the game ends. A full board with no line is a draw; a move that fills the board and completes a line is a win, not a draw.
- Once the game is won, every cell of every completed line has `data-win="true"` (a move completing two lines marks both); no other cell has it, and none does while the game is on or after a draw.
- A click on an occupied cell, or any click once the game is won or drawn, changes nothing: neither the board nor the status. (Disabling those buttons is fine.)

## The constraints

- `npm ci && npm run build` writes a static site to `dist/`; `dist/index.html` works when `dist/` is served at `/` by a plain static server. Keep `npm run build` as it is (`tsc --noEmit`, then `vite build --configLoader native`): a type error fails the build, and the build must write nothing to `node_modules`, which the runner mounts read only.
- The page loads nothing from outside its own server (no CDN, no web font from elsewhere) and logs no error in the console. The checks run with no network.
- npm only: commit `package-lock.json` with any dependency you add (installed with `npm ci`, install scripts off). Do not touch `.launchpad/`.

## The checks

`.launchpad/checks/round-1/` builds your entry, serves `dist/` and plays it in headless Chromium. Each test is a sentence:

- the page shows an empty board of 9 buttons and the status X to play
- X and O take turns, and the status names who plays next
- X wins with three in a row on each of the 8 lines, and the status says X wins
- O wins with three in a row on each of the 8 lines, and the status says O wins
- only the cells of the winning lines have data-win set to true
- a full board with no line is a draw, and a win on the ninth move is a win
- a click on an occupied cell changes nothing
- no move is accepted once the game is won
- New game clears the board and the marks, and X plays first again
- a whole game plays with no console error and no request outside the page's own server

Run them yourself from the repository's root: `npx playwright-core install chromium-headless-shell` once, then `node .launchpad/checks/round-1/run.mjs`.

## How to run it

`npm ci && npm run dev`, then open the address Vite prints.

- C1 (code quality, counts double): read `src/`: where the rules live, whether they depend on React, and what the components do.
- C2 (look and feel): play a game to a win and one to a draw, at desktop width and then at 375 px wide.
- C3 (accessibility): play a game with the keyboard alone (Tab, Enter), and read the cells' accessible names and the status in the browser's accessibility tree.
- C4 (robustness): double-click cells fast, press New game in the middle of a game and after a win, and watch the console.