ci: derive release notes from CHANGELOG.md

.woodpecker.yml

@@ -146,6 +146,11 @@ steps:
           sha256sum ${ARTIFACT}.tar.gz > ${ARTIFACT}.tar.gz.sha256
         fi
 
+  - name: release-notes
+    image: *rust_image
+    commands:
+      - scripts/release-notes.sh "${CI_COMMIT_TAG}" release-notes.md
+
   - name: release
     image: plugins/gitea-release
     settings:
@@ -158,4 +163,4 @@ steps:
         - ${ARTIFACT}.zip
         - ${ARTIFACT}.zip.sha256
       title: Release ${CI_COMMIT_TAG}
-      note: "Release ${CI_COMMIT_TAG}"
+      note_file: release-notes.md

scripts/release-notes.sh

@@ -0,0 +1,57 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "${SCRIPT_DIR}/.." && pwd)"
+CHANGELOG="${REPO_ROOT}/CHANGELOG.md"
+
+TAG="${1:-}"
+OUTPUT="${2:-}"
+
+if [[ -z "${TAG}" ]]; then
+  echo "usage: $0 <tag> [output-file]" >&2
+  exit 1
+fi
+
+TAG="${TAG#v}"
+TAG="${TAG#V}"
+
+if [[ ! -f "${CHANGELOG}" ]]; then
+  echo "error: CHANGELOG.md not found at ${CHANGELOG}" >&2
+  exit 1
+fi
+
+NOTES=$(TAG="${TAG}" CHANGELOG_PATH="${CHANGELOG}" python - <<'PY'
+import os
+import re
+import sys
+from pathlib import Path
+
+changelog_path = Path(os.environ['CHANGELOG_PATH'])
+tag = os.environ['TAG']
+text = changelog_path.read_text(encoding='utf-8')
+pattern = re.compile(rf'^## \[{re.escape(tag)}\]\s*(?:-.*)?$', re.MULTILINE)
+match = pattern.search(text)
+if not match:
+    sys.stderr.write(f"No changelog section found for tag {tag}.\n")
+    sys.exit(1)
+start = match.end()
+rest = text[start:]
+next_heading = re.search(r'^## \[', rest, re.MULTILINE)
+section = rest[:next_heading.start()] if next_heading else rest
+lines = [line.rstrip() for line in section.strip().splitlines()]
+print('\n'.join(lines))
+PY
+)
+
+if [[ -z "${NOTES}" ]]; then
+  echo "error: no content generated for tag ${TAG}" >&2
+  exit 1
+fi
+
+if [[ -n "${OUTPUT}" ]]; then
+  printf '%s\n' "${NOTES}" > "${OUTPUT}"
+else
+  printf '%s\n' "${NOTES}"
+fi