[BUG] /cost command output not visible in VSCode extension chat

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?

Ran /cost in the VSCode extension chat panel. The command appears to be accepted but no output is shown — no cost summary, no response, nothing. Running the same command in the CLI terminal works correctly and displays the cost summary.

What Should Happen?

The /cost command should display a cost summary in the VSCode extension chat panel, the same way it does in the CLI terminal.

Error Messages/Logs

[ERROR] 1P event logging: 28 events failed to export (status=429, code=ERR_BAD_REQUEST, Request failed with status code 429)
[ERROR] Failed to create shell snapshot: Command failed: /bin/zsh -c -l ... (SIGTERM - process killed during .zshrc sourcing)

Steps to Reproduce

1. Open Claude Code in VSCode extension
2. Start a chat session
3. Type /cost and press Enter
4. Observe: no output appears in the chat panel
5. Run the same /cost command in CLI terminal → output appears correctly

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

claude-sonnet-4-6

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

macOS 15.7.3
The logs show OTEL telemetry 429 errors and a shell snapshot creation failure (SIGTERM during .zshrc sourcing). It's unclear if these are related to the /cost output not appearing.
The command works fine in the CLI but not in the VSCode extension chat panel.