feat(desktop): route assistant message links to in-app preview surfaces

Wire L1 link routing into assistant message rendering. AssistantMessage now
accepts an optional sessionId and, when present, builds an onLinkClick that runs
handlePreviewLink against the running local server base (getServerBaseUrl) and
the browser/workspace panel stores, preventing default on handled links.
MessageList passes sessionId through in the assistant_text case.

Adds getServerBaseUrl() to desktopRuntime as a synchronous wrapper over the api
client's cached getBaseUrl().

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

desktop/src/components/chat/AssistantMessage.linkrouting.test.tsx

@@ -0,0 +1,24 @@
+import '@testing-library/jest-dom'
+import { fireEvent, render, screen } from '@testing-library/react'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+const { openBrowser } = vi.hoisted(() => ({ openBrowser: vi.fn() }))
+vi.mock('../../stores/browserPanelStore', () => ({
+  useBrowserPanelStore: { getState: () => ({ open: openBrowser }) },
+}))
+vi.mock('../../lib/desktopRuntime', async (orig) => ({
+  ...(await orig<Record<string, unknown>>()),
+  getServerBaseUrl: () => 'http://127.0.0.1:4321',
+}))
+
+import { AssistantMessage } from './AssistantMessage'
+
+afterEach(() => openBrowser.mockReset())
+
+describe('AssistantMessage link routing', () => {
+  it('opens a localhost link in the in-app browser', () => {
+    render(<AssistantMessage sessionId="s1" content={'打开 [预览](http://localhost:5173/)'} />)
+    fireEvent.click(screen.getByText('预览'))
+    expect(openBrowser).toHaveBeenCalledWith('s1', 'http://localhost:5173/')
+  })
+})

desktop/src/components/chat/AssistantMessage.tsx

@@ -1,15 +1,43 @@
-import { memo } from 'react'
+import { memo, useCallback } from 'react'
+import type { MouseEvent as ReactMouseEvent } from 'react'
 import { MarkdownRenderer } from '../markdown/MarkdownRenderer'
 import { MessageActionBar, type MessageBranchAction } from './MessageActionBar'
 import { InlineImageGallery } from './InlineImageGallery'
+import { handlePreviewLink } from '../../lib/handlePreviewLink'
+import { getServerBaseUrl } from '../../lib/desktopRuntime'
+import { useBrowserPanelStore } from '../../stores/browserPanelStore'
+import { useWorkspacePanelStore } from '../../stores/workspacePanelStore'
 
 type Props = {
   content: string
   isStreaming?: boolean
   branchAction?: MessageBranchAction
+  sessionId?: string
 }
 
-export const AssistantMessage = memo(function AssistantMessage({ content, isStreaming, branchAction }: Props) {
+export const AssistantMessage = memo(function AssistantMessage({ content, isStreaming, branchAction, sessionId }: Props) {
+  const handleLinkClick = useCallback(
+    (href: string, event: ReactMouseEvent<HTMLDivElement>): boolean => {
+      if (!sessionId) return false
+      const handled = handlePreviewLink(href, {
+        sessionId,
+        serverBaseUrl: getServerBaseUrl(),
+        openBrowser: (id, url) => useBrowserPanelStore.getState().open(id, url),
+        openFilePreview: (id, path) => {
+          void useWorkspacePanelStore.getState().openPreview(id, path, 'file')
+        },
+        openExternal: (url) => {
+          void import('@tauri-apps/plugin-shell')
+            .then((m) => m.open(url))
+            .catch(() => window.open(url, '_blank'))
+        },
+      })
+      if (handled) event.preventDefault()
+      return handled
+    },
+    [sessionId],
+  )
+
   if (!content.trim()) return null
 
   const documentLayout = shouldUseDocumentLayout(content)
@@ -32,6 +60,7 @@ export const AssistantMessage = memo(function AssistantMessage({ content, isStre
             content={content}
             variant={documentLayout ? 'document' : 'default'}
             streaming={isStreaming}
+            onLinkClick={sessionId ? handleLinkClick : undefined}
           />
           {!isStreaming && <InlineImageGallery text={content} />}
           {isStreaming && (

desktop/src/components/chat/MessageList.tsx

@@ -1960,7 +1960,7 @@ export const MessageBlock = memo(function MessageBlock({
           role="assistant"
           content={message.content}
         >
-          <AssistantMessage content={message.content} branchAction={branchAction} />
+          <AssistantMessage content={message.content} branchAction={branchAction} sessionId={sessionId ?? undefined} />
         </SelectableChatMessage>
       )
     case 'thinking':

desktop/src/lib/desktopRuntime.ts

@@ -1,5 +1,6 @@
 import {
   api,
+  getBaseUrl,
   getDefaultBaseUrl,
   hasExplicitDefaultBaseUrl,
   setAuthToken,
@@ -41,6 +42,19 @@ export function isBrowserH5Runtime() {
   return typeof window !== 'undefined' && !isTauriRuntime()
 }
 
+/**
+ * Synchronously return the running local server's base URL (e.g.
+ * `http://127.0.0.1:<port>`).
+ *
+ * The api client caches the resolved base after startup: `initializeDesktopServerUrl`
+ * calls `invoke('get_server_url')` (desktop) or resolves a browser/H5 URL, then
+ * `setBaseUrl(...)`. Until that runs, `getBaseUrl()` returns the default
+ * (`http://127.0.0.1:3456` or `VITE_DESKTOP_SERVER_URL`).
+ */
+export function getServerBaseUrl(): string {
+  return getBaseUrl()
+}
+
 export function readStoredH5Connection(): StoredH5Connection {
   if (typeof window === 'undefined') {
     return { serverUrl: null, token: null }