ci: prune old release pages after a release

.github/prune-releases.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+"""
+Keeps the releases page short without touching a single tag.
+
+Packagist resolves a version from the git tag, not from the GitHub release, and
+a lock file names a version someone has to be able to install years from now.
+So this removes only the release page: `gh release delete` leaves the tag alone
+unless asked for --cleanup-tag, which is exactly what must never happen here.
+Nothing is lost either way — semantic-release writes the same notes into
+CHANGELOG.md, which is in the repository.
+
+Kept: every major, the last two feature releases, the last three fixes.
+"""
+
+import json
+import subprocess
+
+KEEP_FEATURE = 2
+KEEP_FIX = 3
+
+
+def gh(*args: str) -> str:
+    return subprocess.run(['gh', *args], capture_output=True, text=True, check=True).stdout
+
+
+def version(tag: str) -> tuple[int, int, int] | None:
+    try:
+        major, minor, patch = (int(part) for part in tag.lstrip('v').split('.')[:3])
+    except ValueError:
+        # Anything not shaped like a version is left alone rather than guessed at.
+        return None
+
+    return major, minor, patch
+
+
+def main() -> None:
+    listed = json.loads(gh('release', 'list', '--limit', '200', '--json', 'tagName,isLatest'))
+    releases = [release for release in listed if version(release['tagName'])]
+    releases.sort(key=lambda release: version(release['tagName']), reverse=True)
+
+    majors = [r for r in releases if version(r['tagName'])[1:] == (0, 0)]
+    features = [r for r in releases if version(r['tagName'])[2] == 0 and version(r['tagName'])[1] != 0]
+    fixes = [r for r in releases if version(r['tagName'])[2] != 0]
+
+    keep = {r['tagName'] for r in majors}
+    keep |= {r['tagName'] for r in features[:KEEP_FEATURE]}
+    keep |= {r['tagName'] for r in fixes[:KEEP_FIX]}
+    # Whatever GitHub is showing as current stays, whichever bucket it fell in.
+    keep |= {r['tagName'] for r in releases if r['isLatest']}
+
+    for release in releases:
+        tag = release['tagName']
+
+        if tag in keep:
+            continue
+
+        print(f'Removing the release page for {tag}; the tag itself stays.')
+        gh('release', 'delete', tag, '--yes')
+
+
+if __name__ == '__main__':
+    main()

.github/workflows/release.yml

@@ -40,3 +40,11 @@ jobs:
             conventional-changelog-conventionalcommits@8
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      # The releases page is for finding the current version, not for keeping a
+      # ledger — CHANGELOG.md is the ledger. Tags are never touched: Packagist
+      # resolves versions from them, and a lock file has to stay installable.
+      - name: Prune old release pages
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: python3 .github/prune-releases.py