🐛 fix(window): 修正启动窗口恢复到不可见区域

- 启动恢复普通窗口时先校验持久化 bounds 是否仍与可视区域相交
- 完全掉出可视区域时自动回正并回写新的窗口位置到 store
- 补充窗口恢复 helper 回归测试并验证前端构建通过

Fixes #384

frontend/src/utils/windowRestoreBounds.test.ts

@@ -0,0 +1,26 @@
+import { describe, expect, it } from 'vitest';
+
+import { resolveVisibleStartupWindowBounds } from './windowRestoreBounds';
+
+describe('windowRestoreBounds', () => {
+  it('keeps existing bounds when the window still overlaps the visible area', () => {
+    expect(resolveVisibleStartupWindowBounds(
+      { width: 1280, height: 820, x: -120, y: 40 },
+      { availWidth: 1920, availHeight: 1080, availLeft: 0, availTop: 0 },
+    )).toEqual({ width: 1280, height: 820, x: -120, y: 40 });
+  });
+
+  it('recenters bounds when the saved window is fully outside the visible area', () => {
+    expect(resolveVisibleStartupWindowBounds(
+      { width: 1280, height: 820, x: 3200, y: 1800 },
+      { availWidth: 1920, availHeight: 1080, availLeft: 0, availTop: 0 },
+    )).toEqual({ width: 1280, height: 820, x: 320, y: 130 });
+  });
+
+  it('recenters bounds when the saved window is fully above and left of the visible area', () => {
+    expect(resolveVisibleStartupWindowBounds(
+      { width: 900, height: 640, x: -1600, y: -900 },
+      { availWidth: 1600, availHeight: 900, availLeft: 0, availTop: 0 },
+    )).toEqual({ width: 900, height: 640, x: 350, y: 130 });
+  });
+});

frontend/src/utils/windowRestoreBounds.ts

@@ -0,0 +1,47 @@
+export type WindowRestoreBounds = {
+  width: number;
+  height: number;
+  x: number;
+  y: number;
+};
+
+type VisibleViewport = {
+  availWidth: number;
+  availHeight: number;
+  availLeft?: number;
+  availTop?: number;
+};
+
+const MIN_VISIBLE_WIDTH = 160;
+const MIN_VISIBLE_HEIGHT = 120;
+
+export const resolveVisibleStartupWindowBounds = (
+  bounds: WindowRestoreBounds,
+  viewport: VisibleViewport,
+): WindowRestoreBounds => {
+  const visibleWidth = Math.trunc(Number(viewport.availWidth) || 0);
+  const visibleHeight = Math.trunc(Number(viewport.availHeight) || 0);
+  if (visibleWidth <= 0 || visibleHeight <= 0) {
+    return bounds;
+  }
+
+  const visibleLeft = Math.trunc(Number(viewport.availLeft) || 0);
+  const visibleTop = Math.trunc(Number(viewport.availTop) || 0);
+  const visibleRight = visibleLeft + visibleWidth;
+  const visibleBottom = visibleTop + visibleHeight;
+
+  const overlapWidth = Math.min(bounds.x + bounds.width, visibleRight) - Math.max(bounds.x, visibleLeft);
+  const overlapHeight = Math.min(bounds.y + bounds.height, visibleBottom) - Math.max(bounds.y, visibleTop);
+  if (
+    overlapWidth >= Math.min(MIN_VISIBLE_WIDTH, bounds.width) &&
+    overlapHeight >= Math.min(MIN_VISIBLE_HEIGHT, bounds.height)
+  ) {
+    return bounds;
+  }
+
+  return {
+    ...bounds,
+    x: visibleLeft + Math.max(0, Math.trunc((visibleWidth - bounds.width) / 2)),
+    y: visibleTop + Math.max(0, Math.trunc((visibleHeight - bounds.height) / 2)),
+  };
+};