What
The session diff pane (also shown for pull requests) can automatically open once changes cross a certain threshold. Before doing so, it now calls isCheckpointing(), which looks at your settings and the CLAUDE_CODE_DISABLE_FILE_CHECKPOINTING environment variable, and skips auto-opening if checkpointing is turned off.
Why
This keeps the diff pane's auto-open behavior consistent with whether file checkpointing, the feature that lets you use /rewind to restore prior code changes, is actually enabled, avoiding a pane that opens based on checkpoint data that isn't being tracked.
Names in the bundleCLAUDE_CODE_DISABLE_FILE_CHECKPOINTING
Documented inclaude-code/env-vars