chore: fix release changelog update

Author: matthewgetz

.github/workflows/release.yml

@@ -31,6 +31,47 @@ jobs:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           dry: true
 
+      - name: Promote CHANGELOG.md [Unreleased] section
+        if: steps.semrel.outputs.version != ''
+        env:
+          VERSION: ${{ steps.semrel.outputs.version }}
+        run: |
+          set -euo pipefail
+          DATE=$(date -u +%Y-%m-%d)
+          if ! grep -qE '^## \[Unreleased\]$' CHANGELOG.md; then
+            echo "::error::CHANGELOG.md is missing the '## [Unreleased]' section. Add the section back to maintain release-stamping."
+            exit 1
+          fi
+          # Insert a versioned heading immediately after [Unreleased] so the
+          # entries authored under [Unreleased] become the new release block.
+          # The next [Unreleased] section starts empty for the following release.
+          awk -v ver="$VERSION" -v date="$DATE" '
+            /^## \[Unreleased\]$/ {
+              print
+              print ""
+              print "## [" ver "] - " date
+              next
+            }
+            { print }
+          ' CHANGELOG.md > CHANGELOG.md.tmp
+          mv CHANGELOG.md.tmp CHANGELOG.md
+
+      - name: Commit CHANGELOG.md
+        if: steps.semrel.outputs.version != ''
+        env:
+          VERSION: ${{ steps.semrel.outputs.version }}
+        run: |
+          set -euo pipefail
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add CHANGELOG.md
+          if git diff --cached --quiet; then
+            echo "CHANGELOG.md unchanged; skipping commit."
+            exit 0
+          fi
+          git commit -m "chore(release): stamp CHANGELOG for v${VERSION} [skip ci]"
+          git push origin HEAD:main
+
       - name: Generate SBOM
         if: steps.semrel.outputs.version != ''
         uses: anchore/sbom-action@e22c389904149dbc22b58101806040fa8d37a610 # v0

CHANGELOG.md

@@ -5,7 +5,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## 0.1.0
+## [Unreleased]
 
 ### Added