Session terminated unexpectedly, losing context and wasting 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?

Description

My Claude Code session ended unexpectedly mid-conversation, causing me to lose all conversation context. When I started a new session, I had
to spend additional tokens just to discover that nothing had been preserved.

Impact

• Lost all conversation context from an active working session
• Wasted tokens attempting to recover state in the new session
• Lost time re-establishing context for ongoing work

Environment

• Model: Claude Opus 4.6 (1M context)
• Platform: macOS (Darwin 25.3.0)
• Shell: zsh

What Should Happen?

Expected behavior

• Sessions should not terminate without clear warning
• If a session must end, context should be preserved or the user should be given the opportunity to save state
• At minimum, a clear explanation of why the session ended should be provided

Error Messages/Logs

Steps to Reproduce

1. Launch Claude Code from the VS Code integrated terminal
2. Work on a multi-file project with extensive file reads (causal modeling project with 15+ Python scripts, markdown files, and data files)
3. Maintain an active session for ~45 minutes with continuous interaction
4. Session terminates silently — no error, no warning, no exit code

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.76

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_