Auto-compaction stopped working — sessions fill up and cut off

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?

Title: Auto-compaction stopped working — sessions fill up and cut off

Body: Sessions used to auto-compact (merge) when context got full, which allowed long multi-day working sessions. This stopped happening recently. Now sessions hit the context limit and stop working, forcing a new session that loses context. This is a major regression for users who work on complex long-running projects. The old auto-compaction behavior was essential.

What Should Happen?

Title: Auto-compaction stopped working — sessions fill up and cut off

Body: Sessions used to auto-compact (merge) when context got full, which allowed long multi-day working sessions. This stopped happening recently. Now sessions hit the context limit and stop working, forcing a new session that loses context. This is a major regression for users who work on complex long-running projects. The old auto-compaction behavior was essential.

Error Messages/Logs

Steps to Reproduce

Title: Auto-compaction stopped working — sessions fill up and cut off

Body: Sessions used to auto-compact (merge) when context got full, which allowed long multi-day working sessions. This stopped happening recently. Now sessions hit the context limit and stop working, forcing a new session that loses context. This is a major regression for users who work on complex long-running projects. The old auto-compaction behavior was essential.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Title: Auto-compaction stopped working — sessions fill up and cut off Body: Sessions used to auto-compact (merge) when context got full, which allowed long multi-day working sessions. This stopped happening recently. Now sessions hit the context limit and stop working, forcing a new session that loses context. This is a major regression for users who work on complex long-running projects. The old auto-compaction behavior was essential.

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Auto-compaction stopped working — sessions fill up and cut off