[BUG] VS Code extension silently hangs after 1-2 messages — no error, no timeout, loses last message on restart

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?

The Claude Code VS Code extension frequently becomes completely unresponsive after processing 1-2 messages in a conversation. The UI shows no error, no spinner timeout, and no indication that anything has gone wrong — it simply stops responding. This can persist for hours with no resolution, forcing the user to manually close and reopen the chat.

When reopening the conversation from history, the last message sent before the hang is lost — it's as if it was never received.

Expected Behavior
The extension should either respond or surface a clear error/timeout within a reasonable window (30-60s)
If the backend connection is lost, the UI should notify the user immediately
Messages that were sent should be preserved in conversation history regardless of backend state

Actual Behavior
The extension silently hangs with no visual feedback that anything is wrong
No error message, no timeout, no retry prompt
The session state transitions to idle in the logs despite an unanswered pending message
The last message is lost when reopening the conversation

Frequency
Happens multiple times per day across different conversations and tasks. Not tied to a specific prompt or codebase operation — seems to be a session/connection management issue.

What Should Happen?

The extension should either respond or surface a clear error/timeout within a reasonable window (30-60s)
If the backend connection is lost, the UI should notify the user immediately
Messages that were sent should be preserved in conversation history regardless of backend state

Error Messages/Logs

2026-03-16 18:28:40.278 [info] Received message from webview: {"type":"request","requestId":"h135oi70q96","request":{"type":"update_session_state","sessionId":"68c809e3-8b09-463d-85b3-e631b65246f4","state":"idle","title":"npm run deploy dashboard  I want to be able to deploy qa and dev simultaniously"}}
2026-03-16 18:28:54.646 [info] Claude code extension is now active?
2026-03-16 18:28:54.646 [info] MCP Server running on port 56800 (localhost only)

Steps to Reproduce

Steps to Reproduce
Open a Claude Code chat in VS Code
Send 1-2 messages (typically involving tool use or codebase context)
Send a follow-up message
The extension appears to be "thinking" indefinitely — no response ever arrives
Close the chat and reopen from history
The last message sent is missing from the conversation

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.76

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_