fix(ci): fix slack release announcement json payload

- JSON-escape release notes (backslashes, quotes, newlines) via sed
  pipeline before storing in $GITHUB_ENV as SLACK_RELEASE_NOTES
- Add 2700-char truncation with link to full release notes
- Wrap payload block in {} to form a valid JSON object
- Reference pre-escaped env var as a quoted JSON string value

Author: olivermeyer

.github/workflows/_package-publish.yml

@@ -237,30 +237,36 @@ jobs:
           release: ${{ github.ref_name }}
 
       - name: Convert release notes from Markdown to Slack mrkdwn
-        id: slack-notes
         shell: bash
         env:
           GIT_CLIFF_CONTENT: ${{ steps.git-cliff.outputs.content }}
         run: |
           # Convert Markdown links [text](url) to Slack mrkdwn <url|text>
           # Convert bold **text** to *text*
-          SLACK_RELEASE_NOTES=$(printf '%s\n' "$GIT_CLIFF_CONTENT" | \
+          NOTES_CONVERTED=$(printf '%s\n' "$GIT_CLIFF_CONTENT" | \
             sed -E 's/\[([^]]+)\]\(([^)]+)\)/<\2|\1>/g' | \
             sed -E 's/\*\*([^*]+)\*\*/*\1*/g')
-          echo "content<<SLACKEOF" >> "$GITHUB_OUTPUT"
-          echo "$SLACK_RELEASE_NOTES" >> "$GITHUB_OUTPUT"
-          echo "SLACKEOF" >> "$GITHUB_OUTPUT"
+          RELEASE_URL="${{ github.server_url }}/${{ github.repository }}/releases/tag/${{ github.ref_name }}"
+          if [ "$(printf '%s' "$NOTES_CONVERTED" | wc -c)" -gt 2700 ]; then
+            NOTES_TRUNCATED=$(printf '%s' "$NOTES_CONVERTED" | head -c 2700)
+            NOTES_CONVERTED="${NOTES_TRUNCATED}"$'\n'"...<${RELEASE_URL}|Read full release notes>"
+          fi
+          # JSON-escape: backslashes first, then double quotes, then collapse newlines to \n
+          NOTES=$(printf '%s' "$NOTES_CONVERTED" | sed 's/\\/\\\\/g' | sed 's/"/\\"/g' | sed ':a;N;$!ba;s/\n/\\n/g')
+          echo "SLACK_RELEASE_NOTES=$NOTES" >> "$GITHUB_ENV"
 
       - name: Release Announcement
         uses: slackapi/slack-github-action@af78098f536edbc4de71162a307590698245be95 # v3.0.1
         with:
           webhook: ${{ secrets.SLACK_WEBHOOK_URL_RELEASE_ANNOUNCEMENT }}
           webhook-type: webhook-trigger
           payload: |
-            "repository": "${{ github.repository }}",
-            "version": "${{ steps.git-cliff.outputs.version }}",
-            "release_notes": ${{ steps.slack-notes.outputs.content }},
-            "channel_id": "${{ secrets.SLACK_CHANNEL_ID_RELEASE_ANNOUNCEMENT }}"
+            {
+              "repository": "${{ github.repository }}",
+              "version": "${{ steps.git-cliff.outputs.version }}",
+              "release_notes": "${{ env.SLACK_RELEASE_NOTES }}",
+              "channel_id": "${{ secrets.SLACK_CHANNEL_ID_RELEASE_ANNOUNCEMENT }}"
+            }
 
       - name: Allow other workflows to trigger on release
         env: