diff --git a/.github/scripts/compose-chronicle-release-notes.py b/.github/scripts/compose-chronicle-release-notes.py
new file mode 100644
index 000000000..916b1d83e
--- /dev/null
+++ b/.github/scripts/compose-chronicle-release-notes.py
@@ -0,0 +1,196 @@
+#!/usr/bin/env python3
+"""Compose the pull request body for a Chronicle dependency update.
+
+The body doubles as Arc's release notes - `cratis/release-action` publishes the merged
+pull request's body verbatim as the GitHub release - so it has to follow
+`.github/pull_request_template.md` exactly: an optional short summary plus the
+`Added`/`Changed`/`Fixed`/`Removed`/`Security`/`Deprecated` sections that apply, and
+nothing else. Anything about CI belongs in a pull request comment, never in the body.
+
+Chronicle's own release notes follow the same template, so every Chronicle release picked
+up by the update contributes its bullets to the matching section here, attributed to the
+release it came from. Issue references are rewritten to point at Chronicle's issue tracker
+rather than resolving against this repository.
+"""
+
+import argparse
+import json
+import re
+import subprocess
+import sys
+
+SECTIONS = ['Added', 'Changed', 'Fixed', 'Removed', 'Security', 'Deprecated']
+PACKAGES = '`Cratis.Chronicle`, `Cratis.Chronicle.AspNetCore` and `Cratis.Chronicle.Testing`'
+
+HEADING = re.compile(r'^#{1,6}\s+(.*?)\s*#*\s*$')
+TOP_LEVEL_BULLET = re.compile(r'^[-*]\s+')
+ISSUE_REFERENCE = re.compile(r'(?<![\w/#])#(\d+)\b')
+
+
+def version_key(version):
+    """Sort key for a semantic version, ordering a prerelease before its release."""
+    core, _, prerelease = version.lstrip('v').partition('-')
+    parts = [int(piece) if piece.isdigit() else 0 for piece in core.split('.')]
+    parts = (parts + [0, 0, 0])[:3]
+    return (parts[0], parts[1], parts[2], 0 if prerelease else 1, prerelease)
+
+
+def fetch_releases(repository):
+    """All published releases of the repository, newest first. Empty when they can't be read."""
+    try:
+        result = subprocess.run(
+            ['gh', 'api', '-H', 'Accept: application/vnd.github+json',
+             f'repos/{repository}/releases?per_page=100'],
+            capture_output=True, text=True, timeout=120)
+    except (OSError, subprocess.SubprocessError) as error:
+        print(f'Could not reach the GitHub API for {repository}: {error}', file=sys.stderr)
+        return []
+
+    if result.returncode != 0:
+        print(f'Could not read releases for {repository}: {result.stderr.strip()}', file=sys.stderr)
+        return []
+
+    return json.loads(result.stdout)
+
+
+def releases_in_range(releases, previous, target):
+    """The published releases that the update picks up - everything after previous, up to target.
+
+    Without a known previous version there is no lower bound to work from, so the range
+    narrows to the target release alone rather than folding in the entire history.
+    """
+    target_key = version_key(target)
+    previous_key = version_key(previous) if previous else None
+
+    picked = []
+    for release in releases:
+        if release.get('draft') or release.get('prerelease'):
+            continue
+        version = (release.get('tag_name') or '').lstrip('v')
+        if not version:
+            continue
+        key = version_key(version)
+        if key > target_key:
+            continue
+        if previous_key is None:
+            if key != target_key:
+                continue
+        elif key <= previous_key:
+            continue
+        picked.append((version, release))
+
+    picked.sort(key=lambda entry: version_key(entry[0]))
+    return picked
+
+
+def parse_sections(body):
+    """The template sections of a release body, each as a list of top-level bullets."""
+    sections = {name: [] for name in SECTIONS}
+    section = None
+    bullet = None
+
+    def flush():
+        nonlocal bullet
+        if section is not None and bullet:
+            sections[section].append(bullet)
+        bullet = None
+
+    for line in (body or '').replace('\r\n', '\n').split('\n'):
+        heading = HEADING.match(line)
+        if heading:
+            flush()
+            title = heading.group(1).strip()
+            section = title if title in sections else None
+            continue
+
+        if section is None:
+            continue
+
+        if TOP_LEVEL_BULLET.match(line):
+            flush()
+            bullet = [line.rstrip()]
+        elif bullet is not None and line.strip():
+            # A wrapped line or a nested bullet - it belongs to the bullet above it.
+            bullet.append(line.rstrip())
+        else:
+            flush()
+
+    flush()
+    return sections
+
+
+def render_bullet(lines, version, repository):
+    """One inherited bullet, attributed to the Chronicle release it came from."""
+    text = TOP_LEVEL_BULLET.sub('', lines[0], count=1)
+    rendered = '\n'.join([f'- Chronicle {version}: {text}'] + lines[1:])
+    return ISSUE_REFERENCE.sub(rf'{repository}#\1', rendered)
+
+
+def compose_summary(previous, target, picked):
+    """The summary line - the cohesive theme of the update, with links to dig into."""
+    if previous and previous != target:
+        sentence = f'{PACKAGES} are updated from `{previous}` to `{target}`'
+    else:
+        sentence = f'{PACKAGES} are updated to `{target}`'
+
+    links = [f'[{version}]({release.get("html_url")})'
+             for version, release in picked if release.get('html_url')]
+
+    if not links:
+        return f'{sentence}.'
+    if len(links) == 1:
+        return f'{sentence}, picking up {links[0]}.'
+    return f'{sentence}, picking up {", ".join(links[:-1])} and {links[-1]}.'
+
+
+def compose(previous, target, repository, picked):
+    """The full pull request body, in pull_request_template.md shape."""
+    inherited = {name: [] for name in SECTIONS}
+    for version, release in picked:
+        for name, bullets in parse_sections(release.get('body')).items():
+            inherited[name].extend(render_bullet(bullet, version, repository) for bullet in bullets)
+
+    changed = [f'- {PACKAGES} are updated to `{target}`'] + inherited['Changed']
+
+    # Without the Chronicle releases to point at, the summary would only restate the single
+    # bullet below it - the template says to drop it in exactly that case.
+    body = ['# Summary', '', compose_summary(previous, target, picked)] if picked else []
+
+    for name in SECTIONS:
+        bullets = changed if name == 'Changed' else inherited[name]
+        if bullets:
+            body += ['', f'## {name}', ''] + bullets
+
+    return '\n'.join(body).strip() + '\n'
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--repository', default='cratis/chronicle', help='Repository the release notes are read from.')
+    parser.add_argument('--previous', default='', help='Chronicle version currently pinned. Empty when unknown.')
+    parser.add_argument('--target', required=True, help='Chronicle version being updated to.')
+    parser.add_argument('--output', help='File to write the body to. Defaults to standard output.')
+    arguments = parser.parse_args()
+
+    previous = arguments.previous.strip().lstrip('v')
+    target = arguments.target.strip().lstrip('v')
+
+    picked = releases_in_range(fetch_releases(arguments.repository), previous, target)
+    if not picked:
+        print(f'No {arguments.repository} release notes were found for the update - '
+              'falling back to the bare version bump.', file=sys.stderr)
+    else:
+        print(f'Folding in {len(picked)} {arguments.repository} release(s): '
+              f'{", ".join(version for version, _ in picked)}.', file=sys.stderr)
+
+    body = compose(previous, target, arguments.repository, picked)
+
+    if arguments.output:
+        with open(arguments.output, 'w', encoding='utf-8') as file:
+            file.write(body)
+    else:
+        sys.stdout.write(body)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/.github/workflows/chronicle-published.yml b/.github/workflows/chronicle-published.yml
index 133bf831f..a30c2bb2d 100644
--- a/.github/workflows/chronicle-published.yml
+++ b/.github/workflows/chronicle-published.yml
@@ -59,6 +59,19 @@ jobs:
           echo "version=$version" >> "$GITHUB_OUTPUT"
           echo "bump=$bump" >> "$GITHUB_OUTPUT"
 
+      # Read before the pins are rewritten - it is the lower bound of the range of Chronicle
+      # releases this update picks up, and it tells the supersede step which open pull
+      # requests main has already moved past.
+      - name: Read the currently pinned Chronicle version
+        id: pinned
+        run: |
+          pinned=$(grep -oE 'Include="Cratis\.Chronicle" Version="[^"]+"' Directory.Packages.props \
+            | head -1 \
+            | grep -oE 'Version="[^"]+"' \
+            | cut -d'"' -f2)
+          echo "Currently pinned at ${pinned:-<unknown>}."
+          echo "version=$pinned" >> "$GITHUB_OUTPUT"
+
       - name: Update Chronicle package pins
         id: bump
         run: |
@@ -73,6 +86,19 @@ jobs:
             git diff -- "$file"
           fi
 
+      # The pull request body is published verbatim as Arc's release notes when the pull
+      # request merges, so it is composed to follow pull_request_template.md and carries
+      # nothing about CI - that goes into a comment further down.
+      - name: Compose release notes
+        if: steps.bump.outputs.changed == 'true'
+        env:
+          GH_TOKEN: ${{ secrets.PAT_WORKFLOWS }}
+        run: |
+          python3 .github/scripts/compose-chronicle-release-notes.py \
+            --previous "${{ steps.pinned.outputs.version }}" \
+            --target "${{ steps.inputs.outputs.version }}" \
+            --output "${{ runner.temp }}/release-notes.md"
+
       - name: Setup .Net
         if: steps.bump.outputs.changed == 'true'
         uses: actions/setup-dotnet@v4
@@ -154,28 +180,115 @@ jobs:
           commit-message: "Update Cratis.Chronicle to ${{ steps.inputs.outputs.version }}"
           title: "Update Cratis.Chronicle to ${{ steps.inputs.outputs.version }}"
           labels: ${{ steps.inputs.outputs.bump }}
-          body: |
-            Automated update of `Cratis.Chronicle`, `Cratis.Chronicle.AspNetCore` and `Cratis.Chronicle.Testing` to `${{ steps.inputs.outputs.version }}`, triggered by a Chronicle release.
+          body-path: ${{ runner.temp }}/release-notes.md
 
-            ### Verification gate
+      # Only the newest Chronicle update is worth reviewing - each one pins the same three
+      # packages, so an older one has nothing left to contribute once a newer one exists.
+      # Runs whether or not this run produced a pull request, so that an update landing on
+      # main also clears out the open pull requests it made redundant.
+      - name: Supersede older Chronicle updates
+        id: supersede
+        env:
+          GH_TOKEN: ${{ secrets.PAT_WORKFLOWS }}
+          REPOSITORY: ${{ github.repository }}
+          PINNED: ${{ steps.pinned.outputs.version }}
+        run: |
+          set -euo pipefail
 
-            | Step | Result |
-            |------|--------|
-            | Build | `${{ steps.build.outcome }}` |
-            | Specs | `${{ steps.specs.outcome }}` |
+          # Whether $1 is greater than $2, semantically rather than lexically (16.10.0 > 16.9.0).
+          is_newer_than() {
+            [ "$1" != "$2" ] && [ "$(printf '%s\n%s\n' "$1" "$2" | sort -V | tail -1)" = "$1" ]
+          }
 
-            ${{ (steps.gate.outputs.verified == 'true' && steps.inputs.outputs.bump != 'major') && '✅ All specs passed — auto-merge enabled.' || '⚠️ Requires human review before merging (verification failed or a major bump).' }}
+          close_with_comment() {
+            local number="$1" branch="$2" reason="$3"
+            echo "Closing #$number — $reason"
+            gh pr close "$number" --repo "$REPOSITORY" --comment "$reason"
+            # The pull request is what matters; a lingering branch must not fail the run.
+            gh api -X DELETE "repos/$REPOSITORY/git/refs/heads/$branch" >/dev/null 2>&1 || true
+          }
 
-      - name: Enable auto-merge
-        if: steps.bump.outputs.changed == 'true' && steps.pr.outputs.pull-request-number && steps.gate.outputs.verified == 'true' && steps.inputs.outputs.bump != 'major'
+          # Assigned rather than piped, so that a failing `gh` fails the step instead of
+          # silently looking like "there is nothing open to supersede".
+          open_updates=$(gh pr list --repo "$REPOSITORY" --state open --limit 100 \
+            --json number,headRefName \
+            --jq '.[] | select(.headRefName | startswith("chronicle-update/"))
+                      | "\(.number) \(.headRefName | sub("^chronicle-update/"; "")) \(.headRefName)"')
+
+          winner_number=""
+          winner_version=""
+          candidates=()
+
+          while read -r number version branch; do
+            [ -n "${number:-}" ] || continue
+
+            # main already carries this version or newer, so the pull request has nothing to add.
+            if [ -n "$PINNED" ] && ! is_newer_than "$version" "$PINNED"; then
+              close_with_comment "$number" "$branch" \
+                "\`Cratis.Chronicle\` is already at \`$PINNED\` on \`main\`, so this update no longer changes anything. Closing it."
+              continue
+            fi
+
+            candidates+=("$number $version $branch")
+            if [ -z "$winner_version" ] || is_newer_than "$version" "$winner_version"; then
+              winner_number="$number"
+              winner_version="$version"
+            fi
+          done <<< "$open_updates"
+
+          for candidate in "${candidates[@]:-}"; do
+            [ -n "$candidate" ] || continue
+            read -r number version branch <<< "$candidate"
+            if [ "$number" != "$winner_number" ]; then
+              close_with_comment "$number" "$branch" \
+                "Superseded by #$winner_number, which updates \`Cratis.Chronicle\` to \`$winner_version\` and includes everything this update carried. Closing it so only the newest Chronicle update stays open."
+            fi
+          done
+
+          echo "winner=$winner_number" >> "$GITHUB_OUTPUT"
+          echo "Newest open Chronicle update: ${winner_number:-none} (${winner_version:-n/a})."
+
+      # The verification result is CI bookkeeping, not release notes - it belongs in a
+      # comment so that it never reaches the published Arc release.
+      - name: Report the verification gate
+        if: steps.bump.outputs.changed == 'true' && steps.pr.outputs.pull-request-number
         env:
           GH_TOKEN: ${{ secrets.PAT_WORKFLOWS }}
-        run: gh pr merge --auto --squash "${{ steps.pr.outputs.pull-request-number }}" --repo ${{ github.repository }}
+          SUPERSEDED: ${{ steps.supersede.outputs.winner != steps.pr.outputs.pull-request-number }}
+        run: |
+          if [ "$SUPERSEDED" = "true" ]; then
+            outcome="⏭️ Superseded by a newer Chronicle update — not auto-merged."
+          elif [ "${{ steps.gate.outputs.verified }}" != "true" ]; then
+            outcome="⚠️ Requires human review before merging — verification failed."
+          elif [ "${{ steps.inputs.outputs.bump }}" = "major" ]; then
+            outcome="⚠️ Requires human review before merging — major bump."
+          else
+            outcome="✅ All specs passed — auto-merge enabled."
+          fi
+
+          cat > "$RUNNER_TEMP/verification-gate.md" <<EOF
+          ### Verification gate
+
+          | Step | Result |
+          |------|--------|
+          | Build | \`${{ steps.build.outcome }}\` |
+          | Specs | \`${{ steps.specs.outcome }}\` |
+          | Bump | \`${{ steps.inputs.outputs.bump }}\` |
+
+          $outcome
+          EOF
 
-      - name: Comment when review is required
-        if: steps.bump.outputs.changed == 'true' && steps.pr.outputs.pull-request-number && (steps.gate.outputs.verified != 'true' || steps.inputs.outputs.bump == 'major')
+          gh pr comment "${{ steps.pr.outputs.pull-request-number }}" \
+            --repo "${{ github.repository }}" \
+            --body-file "$RUNNER_TEMP/verification-gate.md"
+
+      - name: Enable auto-merge
+        if: >-
+          steps.bump.outputs.changed == 'true' &&
+          steps.pr.outputs.pull-request-number &&
+          steps.supersede.outputs.winner == steps.pr.outputs.pull-request-number &&
+          steps.gate.outputs.verified == 'true' &&
+          steps.inputs.outputs.bump != 'major'
         env:
           GH_TOKEN: ${{ secrets.PAT_WORKFLOWS }}
-        run: |
-          gh pr comment "${{ steps.pr.outputs.pull-request-number }}" --repo ${{ github.repository }} --body \
-            "This Chronicle update was **not** auto-merged. Build outcome: \`${{ steps.build.outcome }}\`, specs outcome: \`${{ steps.specs.outcome }}\`, bump: \`${{ steps.inputs.outputs.bump }}\`. Please review before merging."
+        run: gh pr merge --auto --squash "${{ steps.pr.outputs.pull-request-number }}" --repo ${{ github.repository }}