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
+}