feat(web): render durable session titles

packages/client/web/src/DocumentTitle.tsx

@@ -0,0 +1,22 @@
+import { useEffect, useRef } from 'react'
+
+/** Props for the shell-owned browser title projection. */
+export interface DocumentTitleProps {
+  /** Durable title of the selected session, or undefined for the product title. */
+  title?: string
+}
+
+/**
+ * Project the selected durable session title into the browser title and
+ * restore the shell's original product title when unmounted.
+ * @param props - selected session title projection.
+ * @returns no rendered content.
+ */
+export function DocumentTitle({ title }: DocumentTitleProps): null {
+  const original = useRef(document.title)
+  useEffect(() => {
+    document.title = title === undefined ? original.current : `${title} — ${original.current}`
+    return () => { document.title = original.current }
+  }, [title])
+  return null
+}

packages/client/web/src/app.tsx

@@ -11,6 +11,7 @@ import {
   createSessionProvider, RootBindingProvider, scopedSlots,
 } from '@deepseek-ai/dsh-client-web-react'
 import type { SessionId, SessionsService } from '@deepseek-ai/dsh-client-runtime/client'
+import { DocumentTitle } from './DocumentTitle.tsx'
 
 type LayoutExports = typeof import('@deepseek-ai/dsh-client-ui-layout/client')
 
@@ -47,6 +48,11 @@ export function buildRenderApp(deps: AssemblyDeps): () => ReactNode {
   const useDetails = layout.details.useSelector
   const setSidebarWidth = (px: number): void => { layout.setSidebarWidth(px) }
   const setDetailsWidth = (px: number): void => { layout.setDetailsWidth(px) }
+  const SessionDocumentTitle = (): ReactNode => {
+    const id = useCurrent()
+    const title = sessions.list.useSelector(state => id === undefined ? undefined : state.byId[id]?.title)
+    return <DocumentTitle {...title === undefined ? {} : { title }} />
+  }
 
   const renderBody = (id: SessionId): ReactNode => (
     <>
@@ -75,6 +81,7 @@ export function buildRenderApp(deps: AssemblyDeps): () => ReactNode {
 
   return () => (
     <RootBindingProvider value={rootBinding}>
+      <SessionDocumentTitle />
       <AppFrame
         useSidebar={useSidebar}
         useDetails={useDetails}

packages/client/web/src/index.ts

@@ -8,4 +8,5 @@
 export { bootWebShell } from './boot.tsx'
 export { AppRoot, type AppRootProps } from './AppRoot.tsx'
 export { buildRenderApp, type AssemblyDeps } from './app.tsx'
+export { DocumentTitle, type DocumentTitleProps } from './DocumentTitle.tsx'
 export { seedModules } from './seed.ts'