feat(startup): show a dialog when startup fails

A failed startup removed the status hint and left a frozen window, with the error only in the log. Module loading in init.js and firstLoadInit now show one modal dialog with the error, stage and stack, a native clipboard copy and reload, and still throw the original error. In init.js the dialog module loads off the error path, since a module-loading failure can take the dialog's own imports down with it.

The dialog renders in a shadow root, and its host resets inherited styles inline because page rules outrank :host. It reopens when closed instead of cancelling the close request, because Chromium ignores preventDefault() on a close request without user activation.

Refs #332

docs/CurrentState/StartupOptimization.md

@@ -105,6 +105,8 @@
 
 设置与角色是启动必需数据，失败会阻止启动；群组、头像或密钥状态失败时保留可见错误并仅禁用对应能力，不阻止 `APP_READY`。
 
+启动失败只有两个出口：`src/init.js` 加载应用模块失败，或 `firstLoadInit()` 抛错。两处都调用 `showStartupFailure(error)` 显示不可关闭的模态失败对话框（错误、阶段与调用栈，可复制或重新加载），并继续抛出原错误，日志照常记录。展示不能替换原错误：`init.js` 的失败可能来自模块加载本身，所以对话框模块在错误路径之外加载，加载失败时作为第二个错误上报。对话框在 Shadow DOM 中渲染，不受主题与自定义 CSS 影响。
+
 后端采样入口见 [bootstrap_commands.rs](../../src-tauri/crates/tauritavern/src/presentation/commands/bootstrap_commands.rs)。
 
 ---
@@ -176,8 +178,8 @@ Panel Runtime 会在 `APP_READY` 后安装，用于在抽屉关闭时把部分
   - `src/tauri/main/bootstrap.js`：`tt:tauri:*`
   - `src/script.js`：`tt:startup:shell/core/full` + `tt:startup:ready`
 - 运行时提示：
-  - `src/scripts/tauri/startup/startup-status-overlay.js`：右下角非阻塞启动状态 overlay（`APP_READY` 后移除）
-- `pnpm run test:browser` 构建 vendor bundle 并运行 `tests/browser/*.test.mjs`。其中 `startup-order.test.mjs` 验证 Host-ready 模块先加载时主应用仍能正常初始化、早到的事件等待应用就绪后呈现。该测试组包含在 `pnpm test` 和 `pnpm run check` 中。
+  - `src/scripts/tauri/startup/startup-status-overlay.js`：右下角非阻塞启动状态 overlay（`APP_READY` 后移除）与启动失败对话框（见 §4）
+- `pnpm run test:browser` 构建 vendor bundle 并运行 `tests/browser/*.test.mjs`。其中 `startup-order.test.mjs` 验证 Host-ready 模块先加载时主应用仍能正常初始化、早到的事件等待应用就绪后呈现，以及启动失败时对话框显示错误且错误继续上报。该测试组包含在 `pnpm test` 和 `pnpm run check` 中。
 
 ---
 

src/init.js

@@ -304,7 +304,10 @@ async function initializeApplication() {
             safePerfMeasure('tt:init:import:app', 'tt:init:import:app:start', 'tt:init:import:app:end');
         }
     } catch (error) {
-        console.error('TauriTavern: Failed to initialize application:', error);
+        // Loading the dialog must not delay or replace the startup error.
+        void importWithRetry('./scripts/tauri/startup/startup-status-overlay.js')
+            .then(({ showStartupFailure }) => showStartupFailure(error));
+        throw error;
     } finally {
         if (PERF_ENABLED) {
             safePerfMark('tt:init:end');

src/locales/zh-cn.json

@@ -4684,6 +4684,9 @@
     "Starting: connecting to the backend…": "启动中：连接后端…",
     "Starting: loading core data…": "启动中：加载核心数据…",
     "Starting: loading extensions and optional modules…": "启动中：加载扩展与可选模块…",
+    "TauriTavern could not start": "TauriTavern 无法启动",
+    "Reload to try again. If this keeps happening, copy the details below into a bug report.": "请重新加载后再试。如果问题反复出现，请复制下方详情并提交问题报告。",
+    "Copy details": "复制详情",
     "Guide the Agent?": "是否引导Agent行为？",
     "This text will be inserted as user guidance into the next Agent model request. It will not be saved as a regular chat message.": "这条内容会作为用户指引插入下一次 Agent 模型请求，不会作为普通聊天消息保存。",
     "Could not save API key": "无法保存 API 密钥",

src/locales/zh-tw.json

@@ -5201,6 +5201,9 @@
     "Starting: connecting to the backend…": "啟動中：連接後端…",
     "Starting: loading core data…": "啟動中：載入核心資料…",
     "Starting: loading extensions and optional modules…": "啟動中：載入擴充功能與選用模組…",
+    "TauriTavern could not start": "TauriTavern 無法啟動",
+    "Reload to try again. If this keeps happening, copy the details below into a bug report.": "請重新載入後再試。如果問題反覆出現，請複製下方詳情並提交問題回報。",
+    "Copy details": "複製詳情",
     "Guide the Agent?": "是否引導Agent行為？",
     "This text will be inserted as user guidance into the next Agent model request. It will not be saved as a regular chat message.": "這則內容會作為使用者指引插入下一次 Agent 模型請求，不會作為一般聊天訊息儲存。",
     "Could not save API key": "無法儲存 API 金鑰",

src/script.js

@@ -406,7 +406,7 @@ import { MacroEnvBuilder } from './scripts/macros/engine/MacroEnvBuilder.js';
 import { MessageFormatter } from './scripts/message-formatter.js';
 import { addChatBackupsBrowser } from './scripts/chat-backups.js';
 import { onboardingExperimentalMacroEngine } from './scripts/macros/engine/MacroDiagnostics.js';
-import { createStartupStatusOverlay } from './scripts/tauri/startup/startup-status-overlay.js';
+import { createStartupStatusOverlay, showStartupFailure } from './scripts/tauri/startup/startup-status-overlay.js';
 import { canJumpToSwipeForMessage, canOpenSwipePickerForMessage, initSwipePicker } from './scripts/swipe-picker.js';
 
 // API OBJECT FOR EXTERNAL WIRING
@@ -1310,6 +1310,9 @@ async function firstLoadInit() {
             }
         })();
 
+    } catch (error) {
+        showStartupFailure(error);
+        throw error;
     } finally {
         startupStatus.remove();
     }

src/scripts/tauri/startup/startup-status-overlay.js

@@ -1,4 +1,41 @@
+import { writeClipboardText } from '../../../tauri-bridge.js';
+import { t } from '../../i18n.js';
+import { extractErrorText } from '../../util/command-error-utils.js';
+
 const OVERLAY_ID = 'tt-startup-status-overlay';
+const FAILURE_ID = 'tt-startup-failure';
+
+const FAILURE_STYLE = `
+    dialog {
+        box-sizing: border-box;
+        width: min(92vw, 560px);
+        padding: 20px;
+        border: 1px solid GrayText;
+        border-radius: 12px;
+        color-scheme: light dark;
+        background: Canvas;
+        color: CanvasText;
+        font: 14px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
+    }
+    dialog::backdrop { background: rgb(0 0 0 / 0.55); }
+    h2 { margin: 0 0 8px; font-size: 18px; }
+    p { margin: 0 0 12px; }
+    pre {
+        max-height: 40vh;
+        margin: 0 0 16px;
+        padding: 8px;
+        overflow: auto;
+        border-radius: 6px;
+        background: rgb(127 127 127 / 0.15);
+        font: 12px/1.4 ui-monospace, Menlo, Consolas, monospace;
+        white-space: pre-wrap;
+        overflow-wrap: anywhere;
+        -webkit-user-select: text;
+        user-select: text;
+    }
+    .actions { display: flex; justify-content: flex-end; gap: 8px; }
+    button { font: inherit; padding: 6px 14px; }
+`;
 
 function ensureOverlayElement() {
     const existing = document.getElementById(OVERLAY_ID);
@@ -38,3 +75,43 @@ export function createStartupStatusOverlay() {
         },
     };
 }
+
+/**
+ * Callers must still throw the error; this only presents it.
+ * @param {unknown} error
+ */
+export function showStartupFailure(error) {
+    const stage = globalThis.__TAURITAVERN_STARTUP_STAGE__;
+    const details = [extractErrorText(error), stage && `Stage: ${stage}`, /** @type {any} */ (error)?.stack]
+        .filter(Boolean).join('\n');
+
+    const host = document.createElement('div');
+    host.id = FAILURE_ID;
+    // Theme styles, inherited ones included, must not reach the dialog; keep this reset inline.
+    host.style.all = 'initial';
+    const root = host.attachShadow({ mode: 'open' });
+    root.innerHTML = `<style>${FAILURE_STYLE}</style>
+        <dialog role="alertdialog" aria-labelledby="title" aria-describedby="description">
+            <h2 id="title">${t`TauriTavern could not start`}</h2>
+            <p id="description">${t`Reload to try again. If this keeps happening, copy the details below into a bug report.`}</p>
+            <pre></pre>
+            <div class="actions">
+                <button type="button" name="copy">${t`Copy details`}</button>
+                <button type="button" name="reload" autofocus>${t`Reload`}</button>
+            </div>
+        </dialog>`;
+    root.querySelector('pre').textContent = details;
+
+    const copy = root.querySelector('button[name="copy"]');
+    copy.addEventListener('click', async () => {
+        await writeClipboardText(details);
+        copy.textContent = t`Copied!`;
+    });
+    root.querySelector('button[name="reload"]').addEventListener('click', () => location.reload());
+
+    const dialog = root.querySelector('dialog');
+    // The dialog must stay open; nothing usable remains behind it.
+    dialog.addEventListener('close', () => dialog.showModal());
+    document.body.append(host);
+    dialog.showModal();
+}

tests/browser/startup-order.test.mjs

@@ -19,6 +19,15 @@ try {
     await earlyToast;
     assert.deepEqual(toasts, ['Early sync event'], 'An event received before APP_READY must still be presented');
     console.log('PASS: main application initializes and early host events wait for APP_READY');
+
+    // The runtime rejects every network request, so startup stops while loading locales.
+    const failure = new Promise(resolve => window.addEventListener('error', resolve, { once: true }));
+    window.jQuery.holdReady(false);
+    const { error } = await failure;
+    const dialog = window.document.getElementById('tt-startup-failure').shadowRoot.querySelector('dialog');
+    assert.equal(dialog.open, true, 'A failed startup must stay visible');
+    assert.ok(dialog.querySelector('pre').textContent.includes(error.message), 'The dialog must show the startup error');
+    console.log('PASS: a failed startup shows its error and still reports it');
 } finally {
     await window.happyDOM.close();
 }