Write each entry for users, in terms of what they see, not from the commit subject. Drop refactors, tests, and CI. Read the commit's diff before writing the line, and take nothing from outside the release range.
Fixed means the old behavior was a bug; an intentional behavior change is Changed, even if calling it a fix avoids a bump.
Mark breaking entries **Breaking:** with the replacement, and verify the replacement exists at the release (git grep at the tag). Do not invent migration paths, dates, or versions.
New changes go under ## [Unreleased], which stays first. At release time rename it to [X.Y.Z] - YYYY-MM-DD, add a fresh empty Unreleased above it, and fix the comparison links. Do not add a release section for work that is not released.
Never renumber, redate, or delete a published release section; users and registries already have that version. Mark a withdrawn release [YANKED] and name the replacement.
The version follows the highest-ranked entry: any Removed or breaking Changed is major, Added or Deprecated is minor, Fixed only is patch (in 0.y.z, a break is minor). Take the entries and the version from the same diff, and compute it with $bump-semver.
Keep the file's existing format. The audit script checks Keep a Changelog only; on another format, follow the file and skip the audit, saying so.
Do not commit, tag, or publish because a changelog was written.

Workflow

Read the changelog's first sections, the manifest version, and the last final tag (git describe --tags --abbrev=0 --exclude '*-*', reachable from HEAD).
Read git log --oneline PREV..HEAD, merged PR titles, and each commit's diff.
Write the entries under Unreleased, or cut the dated section for a release, then run python3 scripts/audit_changelog.py CHANGELOG.md.
Report the range, each entry with its commit, the version and the entry that decided it, and the script output.

Scripts

python3 scripts/audit_changelog.py [CHANGELOG.md] [--json] checks the Keep a Changelog profile (dates, categories, Unreleased order, duplicate or empty releases, heading versions), one finding per line. Exit 0 clean, 1 findings, 2 usage. Tests: scripts/test_audit_changelog.py.
On Windows, use py -3 for python3.

Read references/changelog.md when creating or normalizing a changelog, cutting a release section, yanking a release, or choosing between Fixed and Changed.