Side chat (/btw) hangs indefinitely after Claude's first reply, including on questions requiring no tool use

Description
The side chat panel (invoked via /btw — "Ask a quick side question without adding to the session") consistently hangs after Claude's first turn. I ask a question, Claude replies once (sometimes saying it will look something up, sometimes not), and then the panel never progresses to an actual answer — it just shows a loading spinner indefinitely in the "Follow up..." state.

Steps to reproduce

1. Open the desktop app, start or continue a session.
2. Invoke /btw and ask a question.
3. Observe Claude's first reply.
4. If the reply requires further work (e.g. "let me check X"), or even if it doesn't, the panel hangs on a spinner and never returns a final answer.

Expected behavior
The side chat should complete its response after Claude's tool use (if any) finishes, and support follow-up turns via the "Follow up…" box without hanging.

Actual behavior
Hangs indefinitely on a spinner after the first reply. Reproduces consistently, including on questions that need no tool use at all (ruling out a stuck permission prompt for a tool call).

Environment

• Platform: Windows 11 (10.0.26200)
• Client: Claude desktop app, Code tab
• Tried: restarting the app (does not fix it)

Impact
The side chat / /btw feature is unusable — it never completes a question.