GitLab squash merge strips checkpoint trailer

[blackgirlbytes]

Discord community member reported that following

When using GitLab's squash merge feature, the entire commit message body is discarded — GitLab only preserves the commit title (first line). This means the Entire-Checkpoint: trailer added by prepare-commit-msg hook is lost.

Original conversation found here

Impact

• Checkpoint metadata becomes unreachable after squash merges to main
• entire resume / entire rewind cannot link to the original session data

Community member is wondering if it would be valuable to Inject the checkpoint ID directly into the commit title instead of (or in addition to) the trailer:

feat: add login [ckpt:a3f9b2c1]

This format survives squash merge because GitLab preserves the title. They're not sure if that's the best solution though.

Implementation Options

1. Title only — Replace trailer with [ckpt:XXXX] suffix in title
2. Dual format — Keep both trailer and title format for compatibility
3. Config flag — Add settings.json option like checkpoint_title_format: true

References

• Existing squash handling for resume: see entire resume metadata branch fallback logic
• Related PRs: Support resuming from squash merge commits with multiple checkpoints #534, Only consider latest Checkpoint when resuming a branch which latest commit is a squash #602, Fix entire rewind for squash merged commits #612