[BUG] Prompt submission yields no response in UI, but consumes usage limit/tokens

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When using Claude Code on the Web, submitting a prompt occasionally results in no response or UI update. The chat interface remains completely unresponsive (no text generation, no error message). However, the backend seems to process the request because my usage quota (tokens/message limit) is consumed.

What Should Happen?

The chat UI should stream the response normally. If there is a server error or connection loss, the UI should display an error message and not consume the user's message quota.

Error Messages/Logs

Steps to Reproduce

1. Open Claude Code on the Web
2. Type a prompt in the input field
3. Press Enter / click the submit button.
4. The UI shows no response or gets stuck.
5. Check the account usage limit, and notice that the message quota has decreased.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

Claude Code on the Web

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_