🐛 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/App.tsx

@@ -70,6 +70,7 @@ import {
   normalizeShortcutCombo,
 } from './utils/shortcuts';
 import { resolveTitleBarToggleIconKey, shouldToggleMaximisedWindowForScaleFix } from './utils/windowStateUi';
+import { resolveVisibleStartupWindowBounds } from './utils/windowRestoreBounds';
 import {
   SIDEBAR_UTILITY_ITEM_KEYS,
   resolveAIEntryPlacement,
@@ -522,8 +523,26 @@ function App() {
           const bounds = state.windowBounds;
           if (!bounds || bounds.width < 400 || bounds.height < 300) return;
           try {
-              WindowSetSize(bounds.width, bounds.height);
-              WindowSetPosition(bounds.x, bounds.y);
+              const nextBounds = resolveVisibleStartupWindowBounds(bounds, {
+                  availWidth: window.screen?.availWidth || 0,
+                  availHeight: window.screen?.availHeight || 0,
+                  availLeft: (window.screen as Screen & { availLeft?: number })?.availLeft || 0,
+                  availTop: (window.screen as Screen & { availTop?: number })?.availTop || 0,
+              });
+              if (
+                  nextBounds.x !== bounds.x ||
+                  nextBounds.y !== bounds.y ||
+                  nextBounds.width !== bounds.width ||
+                  nextBounds.height !== bounds.height
+              ) {
+                  void emitWindowDiagnostic('adjust:startup-window-bounds', {
+                      from: bounds,
+                      to: nextBounds,
+                  });
+                  state.setWindowBounds(nextBounds);
+              }
+              WindowSetSize(nextBounds.width, nextBounds.height);
+              WindowSetPosition(nextBounds.x, nextBounds.y);
           } catch (e) {
               console.warn('Failed to restore window bounds', e);
           }

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)),
+  };
+};