Added changelog-release skill.

skills/changelog-release/SKILL.md

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+---
+name: changelog-release
+description: The user's release methodology - how CHANGELOG.md (or debian/changelog) is written, how its newest untagged entry collects every change, and how release.mjs / release.py commit, tag and push from it. Use this skill before EVERY edit of a CHANGELOG.md or debian/changelog, whenever a change is finished and has to be recorded, when a version has to be chosen (patch or minor), when the user mentions a release, a tag, a version bump, release.mjs or release.py, or when a repository needs a changelog and a release script set up - even for a one-line addition to a changelog.
+---
+
+# Changelog and release
+
+The user releases with a release script (`release.mjs` or `release.py`) that reads the newest
+changelog entry, commits everything with the entry's summary line as the message, tags the commit
+with the entry's version and pushes. The changelog is therefore both the history of the project and
+the source of every commit message and tag. Getting the entry right is what makes a release a
+one-command step for the user.
+
+## The rule that matters most: check the tag and the commit before every changelog edit
+
+The user commits, tags and pushes between your edits, often without telling you. An entry whose
+version is tagged is released: changing it rewrites history that is already published, and the next
+release fails because the tag exists. This mistake has happened many times and the user finds it
+very annoying, so treat the check as part of the edit itself, not as a once-per-session step.
+
+Right before each edit of the changelog, also for a one-line addition, run:
+
+```sh
+git tag --sort=-v:refname | head -5
+git log --oneline -3
+git status --short
+```
+
+Then decide:
+
+- **The newest entry's version is not in the tags**: the entry is open. Add your items to it, and
+  raise its version if your change needs a bigger bump (a feature in an open patch entry makes it a
+  minor entry; keep one entry per release).
+- **The newest entry's version is tagged**: it is released. Add a new entry above it with the next
+  version and your items. Never change the tagged entry, not even its wording.
+- **The newest commit is a release commit** (its message is the summary line of the newest entry):
+  the user has just released; the same holds as for a tagged entry.
+
+A check made earlier in the session does not count, because a release may have happened since.
+
+## CHANGELOG.md format
+
+```markdown
+# Changelog
+
+## 1.4.1
+
+fix: the export page saves the chosen date range instead of the default one.
+
+- The date range of the export page is kept when the export starts.
+- The file name of an export names the date range.
+
+## 1.4.0
+
+feature: the reports are exported as CSV files from the export page.
+
+- ...
+```
+
+- `# Changelog` once at the top; entries newest first.
+- An entry is a `## x.y.z` heading, a blank line, one summary line, a blank line, and the changes
+  as `-` items. The blank lines around the summary are what the release script looks for.
+- **The summary line is the commit message.** It starts with a type prefix as in the git history,
+  `feature:`, `fix:` or `update:` (check `git log --oneline` of the repository for the prefixes it
+  uses), then one sentence. It must not start with `-` or `#`, or the script finds no summary.
+  When an entry collects several changes, rewrite the summary so it covers all of them.
+- **Items describe what changed for the user** of the software: behaviour, options, paths, pages,
+  commands. Not the reasoning and not the implementation story. Reasons and design decisions go to
+  `ADR.md`, which describes only the decisions behind the current code; the changelog is the only
+  place for history.
+- Wrap items at about 100 columns, continuation lines indented by two spaces. Separate the list
+  from the summary line with a blank line. Plain ASCII only.
+
+### Versions
+
+- Patch (`x.y.Z`) for fixes, minor (`x.Y.0`) for features; the user decides about major versions.
+- `x.y.z-n`, `n` from 2, is a later release of the same code with changes that are not code
+  changes (documentation, packaging); `release.mjs` accepts it.
+- Every change you make goes into the newest untagged entry; when there is none, add one. A
+  repository's `CLAUDE.md` may add rules; follow them.
+
+## debian/changelog format (repositories that build a Debian package)
+
+Some repositories keep the changelog in `debian-package/debian/changelog` and release with
+`release.py`. The same rules apply in Debian's format:
+
+```text
+example-app (1.4.0-1) unstable; urgency=medium
+
+  feature: the service reads and changes its settings at /settings.
+
+  * GET and PUT /settings show and change the settings; a password is
+    never shown, and an empty one keeps it.
+  * The service starts after the database is reachable.
+
+ -- Maintainer Name <maintainer@example.org>  Mon, 02 Mar 2026 10:00:00 +0100
+```
+
+- The summary is the first text line, indented by exactly two spaces, between blank lines, not a
+  `*` item. Items are `  * ` with continuation lines indented by four spaces.
+- The tag is the version without the Debian revision `1`: `(1.4.0-1)` is tagged `1.4.0`,
+  `(1.4.0-2)` is tagged `1.4.0-2`.
+- The trailer line ` -- name <email>  date` follows Debian policy (`date -R` format); keep the
+  maintainer of the previous entries.
+
+## Releasing
+
+The user runs the release. Committing, tagging and pushing are the user's decisions, so:
+
+- Do not run a release script without `-n` (`--dry-run`), which prints the git commands instead of
+  running them. Use the dry run to show the user what a release would do.
+- Do not commit, tag or push on your own; only when the user asks.
+- The script refuses when the tag exists ("add a new CHANGELOG.md entry first"); that means an
+  entry was released and the next change needs a new entry.
+
+What the scripts do, in order: read the newest entry's version and summary, refuse when the tag
+exists, `git add -A`, `git commit -m <summary>`, `git tag <version>`, and
+`git push origin main --tags` unless `--no-push`. `-m` overrides the message.
+
+## Setting up a new repository
+
+When a repository needs this setup, copy the script that fits its language and changelog:
+
+- `scripts/release.mjs` - Node.js, `CHANGELOG.md` in the repository root.
+- `scripts/release.py` - Python, `debian-package/debian/changelog`; change `CHANGELOG` for another
+  path.
+
+Make it executable, add a `## Releasing` section to the README describing the commands
+(`./release.mjs`, `-m`, `-n`, `--no-push`), and add a repository `CLAUDE.md` section with the
+changelog rules above when the user wants one.

skills/changelog-release/scripts/release.mjs

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+#!/usr/bin/env node
+
+// Commits everything, tags the version of the newest CHANGELOG.md entry and pushes main with the tags.
+
+import { spawnSync } from 'node:child_process';
+import { readFileSync } from 'node:fs';
+import { parseArgs } from 'node:util';
+
+const CHANGELOG = `${import.meta.dirname}/CHANGELOG.md`;
+
+const usage = `Usage: release.mjs [-h|--help] [-n|--dry-run] [--no-push] [-m|--message <message>]
+
+  -m, --message  commit message; default: the summary line of the newest CHANGELOG.md entry,
+                 the line between blank lines right after its "## x.y.z" or "## x.y.z-n" heading
+
+The tag is the version of the heading: x.y.z for a release of the code, x.y.z-n, n from 2, for a
+later release of the same code with changes that are not code changes.
+  -n, --dry-run  print the git commands instead of running them
+  --no-push      commit and tag, but do not push`;
+
+const { values } = parseArgs({
+  options: {
+    message: { type: 'string', short: 'm' },
+    'dry-run': { type: 'boolean', short: 'n', default: false },
+    'no-push': { type: 'boolean', default: false },
+    help: { type: 'boolean', short: 'h', default: false },
+  },
+});
+
+if (values.help) {
+  console.log(usage);
+  process.exit(0);
+}
+
+function fail(message) {
+  console.error(`release: ${message}`);
+  process.exit(1);
+}
+
+// Runs git in the repository, or prints the command on a dry run; stops with git's exit status when it fails.
+function git(...args) {
+  if (values['dry-run']) {
+    console.log(['git', ...args].map((arg) => (/^[\w@%+=:,./-]+$/.test(arg) ? arg : `'${arg.replaceAll("'", "'\\''")}'`)).join(' '));
+    return;
+  }
+  const { status } = spawnSync('git', args, { cwd: import.meta.dirname, stdio: 'inherit' });
+  if (status !== 0) process.exit(status ?? 1);
+}
+
+// The newest entry: its version from the first "## x.y.z" or "## x.y.z-n" heading, n from 2, and its summary line when
+// the heading is followed by a blank line, one line that is not a "-" item, and another blank line.
+const lines = readFileSync(CHANGELOG, 'utf8').split('\n');
+const heading = lines.findIndex((line) => line.startsWith('## '));
+if (heading === -1) fail(`${CHANGELOG} has no "## x.y.z" entry`);
+const tag = lines[heading].slice(3).trim();
+const [version, revision, ...rest] = tag.split('-');
+const parts = version.split('.');
+const number = (part) => part !== '' && String(Number(part)) === part;
+if (rest.length > 0 || parts.length !== 3 || !parts.every(number) || (revision !== undefined && !(number(revision) && Number(revision) >= 2))) {
+  fail(`${CHANGELOG}: "${tag}" is not a version such as 0.8.0 or 0.8.0-2`);
+}
+const [above, line, below] = lines.slice(heading + 1, heading + 4);
+const summary = above?.trim() === '' && below?.trim() === '' && line?.trim() && !line.startsWith('-') && !line.startsWith('#') ? line.trim() : undefined;
+
+const message = values.message ?? summary;
+if (!message) {
+  fail(`no commit message: pass -m, or put a summary line between blank lines right after the newest heading of ${CHANGELOG}`);
+}
+
+if (spawnSync('git', ['rev-parse', '-q', '--verify', `refs/tags/${tag}`], { cwd: import.meta.dirname }).status === 0) {
+  fail(`tag ${tag} exists; add a new CHANGELOG.md entry first`);
+}
+
+git('add', '-A');
+git('commit', '-m', message);
+git('tag', tag);
+if (!values['no-push']) git('push', 'origin', 'main', '--tags');

skills/changelog-release/scripts/release.py

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+#!/usr/bin/env python3
+"""Commit everything, tag the version of the newest changelog entry and push main with the tags.
+
+The tag is the version of the first entry of debian-package/debian/changelog, without the
+Debian revision 1: example-app (0.5.1-1) is tagged 0.5.1 and (0.5.1-2) 0.5.1-2. The tag
+starts the release workflow.
+"""
+
+import argparse
+import pathlib
+import shlex
+import subprocess
+import sys
+
+ROOT = pathlib.Path(__file__).resolve().parent
+CHANGELOG = ROOT / 'debian-package' / 'debian' / 'changelog'
+
+
+#: Print the git commands instead of running them; set by -n/--dry-run.
+DRY_RUN = False
+
+
+def git(*args):
+    """Run git in the repository, or print the command on a dry run; stop with git's exit status when it fails."""
+    command = ['git', *args]
+    if DRY_RUN:
+        print(shlex.join(command))
+        return
+    result = subprocess.run(command, cwd=ROOT)
+    if result.returncode != 0:
+        sys.exit(result.returncode)
+
+
+def summary():
+    """The summary line of the first changelog entry, or None when it has none.
+
+    The summary is the entry's first text line: indented by two spaces, not a "*" item,
+    with a blank line between it and the header and a blank line after it.
+    """
+    lines = CHANGELOG.read_text(encoding='utf-8').splitlines()
+    if len(lines) < 4 or lines[1].strip() or lines[3].strip():
+        return None
+    line = lines[2]
+    text = line.strip()
+    if not line.startswith('  ') or line.startswith('   ') or not text or text.startswith('*') or line.startswith(' -- '):
+        return None
+    return text
+
+
+def version():
+    """The tag of the first changelog entry: its version, without the Debian revision when that is 1."""
+    first = CHANGELOG.read_text(encoding='utf-8').splitlines()[0]
+    start, end = first.find('('), first.find(')')
+    if start == -1 or end < start:
+        sys.exit(f'{CHANGELOG}: the first line has no version: {first}')
+    full = first[start + 1:end]
+    upstream, _, revision = full.rpartition('-')
+    return upstream if upstream and revision == '1' else full
+
+
+def main():
+    global DRY_RUN
+    parser = argparse.ArgumentParser(description=__doc__.splitlines()[0])
+    parser.add_argument('-m', '--message', help='commit message; default: the summary line of the newest changelog entry, a line without "*" between blank lines right after its header')
+    parser.add_argument('-n', '--dry-run', action='store_true', help='print the git commands instead of running them')
+    parser.add_argument('--no-push', action='store_true', help='commit and tag, but do not push')
+    args = parser.parse_args()
+    DRY_RUN = args.dry_run
+
+    message = args.message or summary()
+    if not message:
+        sys.exit(f'no commit message: pass -m, or start the newest entry of {CHANGELOG} with a summary line '
+                 'without "*", indented by two spaces, with a blank line above and below it')
+    tag = version()
+    if subprocess.run(['git', 'rev-parse', '-q', '--verify', f'refs/tags/{tag}'], cwd=ROOT,
+                      capture_output=True).returncode == 0:
+        sys.exit(f'tag {tag} exists; add a new changelog entry first')
+
+    git('add', '-A')
+    git('commit', '-m', message)
+    git('tag', tag)
+    if not args.no_push:
+        git('push', 'origin', 'main', '--tags')
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main())