Add ui.custom() for custom hook components with keyboard focus

- Add custom() to HookUIContext: returns { close, requestRender }
- Component receives keyboard input via handleInput()
- CustomMessageComponent default rendering now limits to 5 lines when collapsed
- Add snake.ts example hook with /snake command

packages/coding-agent/examples/hooks/snake.ts

@@ -0,0 +1,251 @@
+/**
+ * Snake game hook - play snake with /snake command
+ */
+
+import type { HookAPI } from "../../src/core/hooks/types.js";
+
+const GAME_WIDTH = 40;
+const GAME_HEIGHT = 15;
+const TICK_MS = 100;
+
+type Direction = "up" | "down" | "left" | "right";
+type Point = { x: number; y: number };
+
+interface GameState {
+	snake: Point[];
+	food: Point;
+	direction: Direction;
+	nextDirection: Direction;
+	score: number;
+	gameOver: boolean;
+	highScore: number;
+}
+
+function createInitialState(): GameState {
+	const startX = Math.floor(GAME_WIDTH / 2);
+	const startY = Math.floor(GAME_HEIGHT / 2);
+	return {
+		snake: [
+			{ x: startX, y: startY },
+			{ x: startX - 1, y: startY },
+			{ x: startX - 2, y: startY },
+		],
+		food: spawnFood([{ x: startX, y: startY }]),
+		direction: "right",
+		nextDirection: "right",
+		score: 0,
+		gameOver: false,
+		highScore: 0,
+	};
+}
+
+function spawnFood(snake: Point[]): Point {
+	let food: Point;
+	do {
+		food = {
+			x: Math.floor(Math.random() * GAME_WIDTH),
+			y: Math.floor(Math.random() * GAME_HEIGHT),
+		};
+	} while (snake.some((s) => s.x === food.x && s.y === food.y));
+	return food;
+}
+
+class SnakeComponent {
+	private state: GameState;
+	private interval: ReturnType<typeof setInterval> | null = null;
+	private onClose: () => void;
+	private requestRender: () => void;
+	private cachedLines: string[] = [];
+	private cachedWidth = 0;
+	private version = 0;
+	private cachedVersion = -1;
+
+	constructor(onClose: () => void, requestRender: () => void) {
+		this.state = createInitialState();
+		this.onClose = onClose;
+		this.requestRender = requestRender;
+		this.startGame();
+	}
+
+	private startGame(): void {
+		this.interval = setInterval(() => {
+			if (!this.state.gameOver) {
+				this.tick();
+				this.version++;
+				this.requestRender();
+			}
+		}, TICK_MS);
+	}
+
+	private tick(): void {
+		// Apply queued direction change
+		this.state.direction = this.state.nextDirection;
+
+		// Calculate new head position
+		const head = this.state.snake[0];
+		let newHead: Point;
+
+		switch (this.state.direction) {
+			case "up":
+				newHead = { x: head.x, y: head.y - 1 };
+				break;
+			case "down":
+				newHead = { x: head.x, y: head.y + 1 };
+				break;
+			case "left":
+				newHead = { x: head.x - 1, y: head.y };
+				break;
+			case "right":
+				newHead = { x: head.x + 1, y: head.y };
+				break;
+		}
+
+		// Check wall collision
+		if (newHead.x < 0 || newHead.x >= GAME_WIDTH || newHead.y < 0 || newHead.y >= GAME_HEIGHT) {
+			this.state.gameOver = true;
+			return;
+		}
+
+		// Check self collision
+		if (this.state.snake.some((s) => s.x === newHead.x && s.y === newHead.y)) {
+			this.state.gameOver = true;
+			return;
+		}
+
+		// Move snake
+		this.state.snake.unshift(newHead);
+
+		// Check food collision
+		if (newHead.x === this.state.food.x && newHead.y === this.state.food.y) {
+			this.state.score += 10;
+			if (this.state.score > this.state.highScore) {
+				this.state.highScore = this.state.score;
+			}
+			this.state.food = spawnFood(this.state.snake);
+		} else {
+			this.state.snake.pop();
+		}
+	}
+
+	handleInput(data: string): void {
+		// ESC or q to quit
+		if (data === "\x1b" || data === "q" || data === "Q") {
+			this.dispose();
+			this.onClose();
+			return;
+		}
+
+		// Arrow keys
+		if (data === "\x1b[A" || data === "w" || data === "W") {
+			if (this.state.direction !== "down") this.state.nextDirection = "up";
+		} else if (data === "\x1b[B" || data === "s" || data === "S") {
+			if (this.state.direction !== "up") this.state.nextDirection = "down";
+		} else if (data === "\x1b[C" || data === "d" || data === "D") {
+			if (this.state.direction !== "left") this.state.nextDirection = "right";
+		} else if (data === "\x1b[D" || data === "a" || data === "A") {
+			if (this.state.direction !== "right") this.state.nextDirection = "left";
+		}
+
+		// Restart on game over
+		if (this.state.gameOver && (data === "r" || data === "R" || data === " ")) {
+			const highScore = this.state.highScore;
+			this.state = createInitialState();
+			this.state.highScore = highScore;
+			this.version++;
+			this.requestRender();
+		}
+	}
+
+	invalidate(): void {
+		this.cachedWidth = 0;
+	}
+
+	render(width: number): string[] {
+		if (width === this.cachedWidth && this.cachedVersion === this.version) {
+			return this.cachedLines;
+		}
+
+		const lines: string[] = [];
+
+		// Clamp game width to available terminal width (leaving space for border)
+		const effectiveWidth = Math.min(GAME_WIDTH, width - 4);
+		const effectiveHeight = GAME_HEIGHT;
+
+		// Header
+		const header = ` SNAKE | Score: ${this.state.score} | High: ${this.state.highScore} `;
+		lines.push(this.padLine(header, width));
+		lines.push(this.padLine(`+${"-".repeat(effectiveWidth)}+`, width));
+
+		// Game grid
+		for (let y = 0; y < effectiveHeight; y++) {
+			let row = "|";
+			for (let x = 0; x < effectiveWidth; x++) {
+				const isHead = this.state.snake[0].x === x && this.state.snake[0].y === y;
+				const isBody = this.state.snake.slice(1).some((s) => s.x === x && s.y === y);
+				const isFood = this.state.food.x === x && this.state.food.y === y;
+
+				if (isHead) {
+					row += "\x1b[32m@\x1b[0m"; // Green head
+				} else if (isBody) {
+					row += "\x1b[32mo\x1b[0m"; // Green body
+				} else if (isFood) {
+					row += "\x1b[31m*\x1b[0m"; // Red food
+				} else {
+					row += " ";
+				}
+			}
+			row += "|";
+			lines.push(this.padLine(row, width));
+		}
+
+		lines.push(this.padLine(`+${"-".repeat(effectiveWidth)}+`, width));
+
+		// Footer
+		if (this.state.gameOver) {
+			lines.push(this.padLine("\x1b[31m GAME OVER! \x1b[0m Press R to restart, ESC to quit", width));
+		} else {
+			lines.push(this.padLine(" Arrow keys or WASD to move, ESC to quit", width));
+		}
+
+		this.cachedLines = lines;
+		this.cachedWidth = width;
+		this.cachedVersion = this.version;
+
+		return lines;
+	}
+
+	private padLine(line: string, width: number): string {
+		// Calculate visible length (strip ANSI codes)
+		const visibleLen = line.replace(/\x1b\[[0-9;]*m/g, "").length;
+		const padding = Math.max(0, width - visibleLen);
+		return line + " ".repeat(padding);
+	}
+
+	dispose(): void {
+		if (this.interval) {
+			clearInterval(this.interval);
+			this.interval = null;
+		}
+	}
+}
+
+export default function (pi: HookAPI) {
+	pi.registerCommand("snake", {
+		description: "Play Snake!",
+		handler: async (ctx) => {
+			if (!ctx.hasUI) {
+				ctx.ui.notify("Snake requires interactive mode", "error");
+				return;
+			}
+
+			let ui: { close: () => void; requestRender: () => void } | null = null;
+
+			const component = new SnakeComponent(
+				() => ui?.close(),
+				() => ui?.requestRender(),
+			);
+
+			ui = ctx.ui.custom(component);
+		},
+	});
+}