Add PR comment with fix instructions when workflow fails

Author: spbolton

.github/workflows/issue_comp_link-issue-to-pr.yml

@@ -130,6 +130,7 @@ jobs:
             echo "::error::1. Link via GitHub UI: Go to PR → Development section → Link issue"
             echo "::error::2. Add 'fixes #123' (or closes/resolves) to PR body, or"
             echo "::error::3. Use branch naming like 'issue-123-feature' or '123-feature'"
+            echo "failure_detected=true" >> "$GITHUB_OUTPUT"
             exit 1
           fi
           
@@ -256,4 +257,50 @@ jobs:
             echo "Added issue #$issue_number reference to PR #$pr_number body"
           else
             echo "Issue #$issue_number already referenced in PR #$pr_number body"
-          fi
+          fi
+
+      - name: Add failure comment to PR
+        if: failure() && steps.determine_issue.outputs.failure_detected == 'true'
+        run: |
+          pr_url="${{ inputs.pr_url }}"
+          pr_number=$(echo "$pr_url" | grep -o '[0-9]*$')
+          
+          comment_body=$(cat <<'EOF'
+## ❌ Issue Linking Required
+
+This PR could not be linked to an issue. **All PRs must be linked to an issue** for tracking purposes.
+
+### How to fix this:
+
+**Option 1: Link via GitHub UI** (Recommended)
+1. Go to the PR → Development section (right sidebar)
+2. Click "Link issue" and select an existing issue
+
+**Option 2: Add keyword to PR body**
+Edit this PR's description and add one of these lines:
+- `This PR fixes: #123`
+- `This PR closes: #123` 
+- `This PR resolves: #123`
+
+**Option 3: Use branch naming**
+Create a new branch with one of these patterns:
+- `issue-123-feature-description`
+- `123-feature-description`
+- `feature-issue-123-description`
+
+### Why is this required?
+Issue linking ensures proper tracking, documentation, and helps maintain project history. It connects your code changes to the problem they solve.
+
+---
+*This comment was automatically generated by the issue linking workflow*
+EOF
+)
+          
+          curl -X POST \
+            -H "Accept: application/vnd.github+json" \
+            -H "Authorization: Bearer ${{ env.GH_TOKEN }}" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            "https://api.github.com/repos/${{ github.repository }}/issues/$pr_number/comments" \
+            -d "{\"body\":$(echo "$comment_body" | jq -R -s .)}"
+          
+          echo "Added failure comment to PR #$pr_number"