修复渠道配置替换窗口契约导致的系统标题栏回归与登录请求被拒

- 渠道 --config 改为从基线 tauri.conf.json 读取完整 client 窗口对象后展开、只覆盖 title，避免 Tauri JSON Merge Patch 整体替换 app.windows 丢掉 label / decorations / 尺寸
- build-release.test.mjs 新增合并守卫用例：按同一 merge patch 语义复现 Tauri 合并，断言 label=client、decorations=false、1280x800、min 1280x720，且承载 http:default 的 capability 必须包含该 label
- check-config.mjs 增补基线 client 窗口 decorations 必须为 false 的门禁
- 更新 AGC 客户端更新检查与下载技术方案，写明渠道配置必须下发完整窗口对象的约定
- pitfalls.md 记录本次回归的现象、根因、现行口径与验证证据

apps/ai-game-creator-shell/scripts/build-release.mjs

@@ -373,6 +373,24 @@ export function buildTauriBuildArguments(
   ];
 }
 
+/**
+ * 基线 client 窗口契约：渠道配置只允许覆盖标题，其余字段必须逐字沿用。
+ *
+ * `tauri build --config` 走 JSON Merge Patch（tauri-utils 用 `json_patch::merge`）：
+ * 对象递归合并，**数组整体替换**。只下发 `{ title }` 会让
+ * `label` / `decorations` / 尺寸全部回落到 Tauri 默认值（label=main、
+ * decorations=true、800x600），结果是原生系统标题栏重新出现，并且按 label
+ * 绑定的 capability（平台 HTTP 权限等）一起失效。
+ */
+function readBaseClientWindow() {
+  const base = JSON.parse(fs.readFileSync(tauriConfigPath, 'utf8'));
+  const clientWindow = base.app?.windows?.[0];
+  if (!clientWindow || typeof clientWindow.label !== 'string') {
+    throw new Error('AGC 基线配置缺少 client 主窗口，渠道配置无法安全合并');
+  }
+  return clientWindow;
+}
+
 /**
  * 渠道端点与安装身份必须由构建期注入：官方更新插件的端点配置不支持运行期改渠道，
  * 而 `productName` / `identifier` 决定安装目录、卸载项与客户端数据目录，
@@ -381,13 +399,14 @@ export function buildTauriBuildArguments(
 export function createChannelConfig(
   channel = resolveReleaseChannel(),
   target = defaultTarget(),
+  baseClientWindow = readBaseClientWindow(),
 ) {
   const { productName, identifier } = resolveChannelInstallIdentity(channel);
   return {
     productName,
     identifier,
     app: {
-      windows: [{ title: productName }],
+      windows: [{ ...baseClientWindow, title: productName }],
     },
     plugins: {
       updater: {

apps/ai-game-creator-shell/scripts/build-release.test.mjs

@@ -1,5 +1,11 @@
 import assert from 'node:assert/strict';
-import { mkdtempSync, readFileSync, rmSync, writeFileSync } from 'node:fs';
+import {
+  mkdtempSync,
+  readdirSync,
+  readFileSync,
+  rmSync,
+  writeFileSync,
+} from 'node:fs';
 import os from 'node:os';
 import path from 'node:path';
 import { test } from 'node:test';
@@ -180,7 +186,18 @@ test('channel manifest URL and build-time endpoint follow the channel', () => {
       productName: `${AGC_PRODUCT_NAME}开发版`,
       identifier: AGC_APP_IDENTIFIER,
       app: {
-        windows: [{ title: `${AGC_PRODUCT_NAME}开发版` }],
+        windows: [
+          {
+            label: 'client',
+            title: `${AGC_PRODUCT_NAME}开发版`,
+            url: 'index.html',
+            width: 1280,
+            height: 800,
+            decorations: false,
+            minWidth: 1280,
+            minHeight: 720,
+          },
+        ],
       },
       plugins: {
         updater: {
@@ -245,6 +262,78 @@ test('channel install identity is baked into the same build-time config as the e
   });
 });
 
+/**
+ * RFC 7386（tauri-utils 用 `json_patch::merge`）语义：对象递归合并，数组整体替换。
+ * 这里按同样语义复现 Tauri CLI 的 `--config` 合并，用来守住"渠道配置不得丢窗口契约"。
+ */
+function applyJsonMergePatch(base, patch) {
+  if (Array.isArray(patch) || typeof patch !== 'object' || patch === null) {
+    return patch;
+  }
+  const merged =
+    typeof base === 'object' && base !== null && !Array.isArray(base)
+      ? { ...base }
+      : {};
+  for (const [key, value] of Object.entries(patch)) {
+    if (value === null) delete merged[key];
+    else merged[key] = applyJsonMergePatch(merged[key], value);
+  }
+  return merged;
+}
+
+function readBaseTauriConfig() {
+  return JSON.parse(
+    readFileSync(
+      new URL('../src-tauri/tauri.conf.json', import.meta.url),
+      'utf8',
+    ),
+  );
+}
+
+test('channel config keeps the client window contract across the Tauri config merge', () => {
+  const base = readBaseTauriConfig();
+  const merged = applyJsonMergePatch(base, {
+    ...createChannelConfig('release', windowsTarget),
+    version: base.version,
+  });
+  const [clientWindow] = merged.app.windows;
+  assert.deepEqual(clientWindow, {
+    ...base.app.windows[0],
+    title: '陶泥儿 Release',
+  });
+  // 原生标题栏、尺寸与默认窗口标签都是回归点：任何一项回落都会让自绘标题栏失效，
+  // 并让按 label 绑定的 capability（平台 HTTP 权限）不再命中。
+  assert.equal(clientWindow.label, 'client');
+  assert.equal(clientWindow.decorations, false);
+  assert.equal(clientWindow.width, 1280);
+  assert.equal(clientWindow.height, 800);
+  assert.equal(clientWindow.minWidth, 1280);
+  assert.equal(clientWindow.minHeight, 720);
+
+  const capabilitiesDirectory = new URL(
+    '../src-tauri/capabilities/',
+    import.meta.url,
+  );
+  const capabilities = readdirSync(capabilitiesDirectory)
+    .filter((name) => name.endsWith('.json'))
+    .map((name) =>
+      JSON.parse(readFileSync(new URL(name, capabilitiesDirectory), 'utf8')),
+    );
+  const httpCapability = capabilities.find((capability) =>
+    (capability.permissions ?? []).some(
+      (permission) =>
+        permission === 'http:default' ||
+        (typeof permission === 'object' &&
+          permission?.identifier === 'http:default'),
+    ),
+  );
+  assert.ok(httpCapability, '客户端必须保留承载平台 HTTP 权限的 capability');
+  assert.ok(
+    (httpCapability.windows ?? []).includes(clientWindow.label),
+    `平台 HTTP capability 必须绑定 ${clientWindow.label} 窗口，实际：${httpCapability.windows}`,
+  );
+});
+
 test('channel products keep first-install selection working under the channel product name', () => {
   const root = mkdtempSync(path.join(os.tmpdir(), 'agc-channel-dmg-'));
   try {

apps/ai-game-creator-shell/scripts/check-config.mjs

@@ -1567,6 +1567,14 @@ if (
   );
 }
 
+// 窗口外壳由前端 WindowChrome 自绘：基线配置一旦放开 decorations，
+// 打包产物会出现系统标题栏与自绘标题栏并存。
+if (clientWindow.decorations !== false) {
+  throw new Error(
+    'AI game creator shell client window must keep native decorations disabled',
+  );
+}
+
 if (tauriConfig.build?.devUrl !== 'http://127.0.0.1:3080/') {
   throw new Error(
     'AI game creator shell Tauri config must retain the non-launcher fallback devUrl',