Changelog from commits

Write a changelog fragment from commit subjects the user provides. Follow Keep a Changelog: people-facing notes, grouped, newest section on top. Do not dump raw subjects.

Steps

1. Read the commit list and the version or date the user wants. Ask for the range if it is ambiguous.
2. Drop merge commits, typo-only subjects, and chores that do not affect anyone using the product.
3. Group the rest under Added, Changed, Fixed, or Security. Rewrite each line so a user can tell what changed, without internal ticket slang.
4. Put breaking changes first inside Changed and start those lines with "Breaking:".
5. Validate that every kept line maps to a commit you were given, and that no line mentions a change that is not in the list. Show the fragment.

Example

User: Changelog for these subjects: feat: add CSV export, fix: honor deleted_at in export, chore: bump lint.

Agent:

## Unreleased

### Added
- CSV export for the invoice list.

### Fixed
- The invoice export now skips rows that have been deleted.

The lint bump is omitted because it does not change product behavior.

Boundaries

Do not invent a feature to make the section look fuller. Security fixes stay in Security even if the subject said fix.