初始提交：三玩法 Web 原型与设计文档

- 玩法一 数字一笔：规则库、求解器、26 关、竖屏触摸 Web 原型、测试
- 玩法二 连连气球：连消畅玩版核心、Web 原型、Cocos 球槽组件与导出脚本
- 玩法三 六边一笔：规则库、求解器、10 关 + 转墙实验包、Web 原型、测试
- 产品文档、UI 设计规范、各玩法 GDD / HANDOFF
- 文档移除全部外部参考作引用；删除玩法二 v0 旧稿

modes/02-connect-1234/src/cascade.ts

@@ -0,0 +1,46 @@
+import { adjacent, points, resultNumber } from './rules';
+import { legalFlow } from './flow-rules';
+import type { Ball } from './types';
+
+export const balloonRadius = (n: number): number => 24 + Math.min(9, n - 1) * 3.2;
+export const copyBalls = (balls: Ball[]): Ball[] => balls.map(b => ({ ...b }));
+export interface Reaction { before: Ball[]; path: Ball[]; created: Ball; points: number; index: number }
+export interface Cascade { stages: Reaction[]; balls: Ball[]; score: number; popped: number; flight: Ball | null }
+
+/** 自动接上 n−2 → n−1 → 新球；新球一直留在玩家选择的链尾。 */
+export function continuation(balls: Ball[], head: Ball): number[] | null {
+  const seconds = balls.filter(b => b.n === head.n - 1 && adjacent(b, head))
+    .sort((a, b) => Math.hypot(a.x - head.x, a.y - head.y) - Math.hypot(b.x - head.x, b.y - head.y));
+  for (const second of seconds) {
+    const first = balls.find(b => b.n === head.n - 2 && adjacent(b, second));
+    if (first) return [first.id, second.id, head.id];
+  }
+  const same = balls.filter(b => b.id !== head.id && b.n === head.n);
+  for (const second of same.filter(b => adjacent(b, head))) {
+    const first = same.find(b => b.id !== second.id && adjacent(b, second));
+    if (first) return [first.id, second.id, head.id];
+  }
+  return null;
+}
+
+export function cascade(source: Ball[], ids: number[], fever = false, offset = 0): Cascade | null {
+  let balls = copyBalls(source), next: number[] | null = ids;
+  const initial = ids.map(id => balls.find(b => b.id === id));
+  if (initial.some(b => !b) || !legalFlow(initial as Ball[])) return null;
+  const stages: Reaction[] = [];
+  let score = 0, popped = 0, flight: Ball | null = null;
+  while (next && stages.length + offset < (fever ? 4 : 3)) {
+    const path = next.map(id => balls.find(b => b.id === id)!);
+    const tail = path[path.length - 1], n = resultNumber(path), index = stages.length + offset + 1;
+    const created = { ...tail, n, r: balloonRadius(n), vx: 0, vy: 0 };
+    const gain = points(path) * index * (fever ? 2 : 1) + (n >= 10 ? 10000 : 0);
+    stages.push({ before: copyBalls(balls), path: copyBalls(path), created: { ...created }, points: gain, index });
+    score += gain; popped += path.length;
+    const removed = new Set(next);
+    balls = balls.filter(b => !removed.has(b.id));
+    if (n >= 10) { flight = created; break; }
+    balls.push(created);
+    next = continuation(balls, created);
+  }
+  return { stages, balls, score, popped, flight };
+}