hookSpecificOutput.sessionTitle does not propagate to desktop app sidebar / remote session title (unlike /rename)

Environment

• Claude Code 2.1.153 (native build, macOS), session running inside the Claude desktop app
• Hook events: UserPromptSubmit / SessionStart

Description

A UserPromptSubmit (or SessionStart) hook that returns

{"hookSpecificOutput": {"hookEventName": "UserPromptSubmit", "sessionTitle": "<new title>"}}

updates the session picker, the terminal title, and writes a custom-title record to the session JSONL — but the desktop app's sidebar chat name and the remote (claude.ai) session title never change, even across later turns. The app-side session metadata keeps titleSource: "auto".

Typing /rename <new title> in the same session updates all of those live, including the desktop sidebar.

The SessionStart hook schema describes sessionTitle as "Set the session title (same effect as /rename)", so the hook path appears to be missing the remote/bridge title propagation the /rename path performs (the flow that updates the bridge session and PUTs the title to /v1/code/sessions/<id>, which the desktop app syncs from).

Steps to reproduce

1. Register a minimal hook in ~/.claude/settings.json:

``json
{"hooks": {"UserPromptSubmit": [{"matcher": "*", "hooks": [{"type": "command", "command": "echo '{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"sessionTitle\":\"hook-title-test\"}}'"}]}]}}
``

1. Open a session inside the Claude desktop app and send any prompt.
2. Observe: picker/terminal title update to hook-title-test and a custom-title record lands in the session JSONL — while the desktop sidebar name and the claude.ai session name keep the auto-generated title.
3. Type /rename hook-title-test — the sidebar updates immediately.

Expected

Hook-set sessionTitle propagates everywhere /rename does, per the schema's "same effect as /rename".

Impact

Hooks and agents can set durable session titles, but the desktop app's visible session list stays stale until app relaunch, so programmatic session naming desyncs from the UI.