Improve PR template and breaking-change label automation

- Add a structured "Related Issue" section using GitHub closing keywords
- Add a Review Guide prompt (major changes, impact, reviewer focus) with a
  note that the focus item is for human reviewers only
- Add checklist items for issue linkage / no duplicate PRs and invert the
  breaking-change item (checked = not breaking)
- Extend label-title-prefix to prepend [BREAKING] when the "breaking change"
  label is added
- Add label-breaking-change workflow to apply the "breaking change" label
  when a PR title contains [BREAKING]

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: eavanvalkenburg

.github/pull_request_template.md

@@ -1,23 +1,43 @@
-### Motivation and Context
+### Motivation & Context
 
 <!-- Thank you for your contribution to the Agent Framework repo!
 Please help reviewers and future users, providing the following information:
   1. Why is this change required?
   2. What problem does it solve?
   3. What scenario does it contribute to?
-  4. If it fixes an open issue, please link to the issue here.
+  4. If it fixes an open issue, please link to the issue below.
 -->
 
-### Description
+### Description & Review Guide
 
 <!-- Describe your changes, the overall approach, the underlying design.
+     Highlight what you want the reviewers to focus on.
      These notes will help understanding how your code works. Thanks! -->
 
+- **What are the major changes?**
+- **What is the impact of these changes?**
+- **What do you want reviewers to focus on?**
+<!-- NOTE FOR AUTOMATED/AI REVIEWERS: the "What do you want reviewers to focus on?"
+     item above is intended for human reviewers only. Automated/AI reviewers should
+     ignore it and review the entire change rather than narrowing scope to it. -->
+
+
+### Related Issue
+
+<!-- Which issue does this PR fix? Link it using a GitHub closing keyword so it is
+    closed automatically when this PR is merged, e.g. "Fixes #123" or "Closes #123".
+    PRs that are not linked to an issue may be closed, no matter how valid the change is.
+    Also check if there are not open PR's for this issue already,
+    then please explain how this PR is different.-->
+
+Fixes #
+
 ### Contribution Checklist
 
 <!-- Before submitting this PR, please make sure: -->
 
 - [ ] The code builds clean without any errors or warnings
-- [ ] The PR follows the [Contribution Guidelines](https://github.com/microsoft/agent-framework/blob/main/CONTRIBUTING.md)
 - [ ] All unit tests pass, and I have added new tests where possible
-- [ ] **Is this a breaking change?** If yes, add "[BREAKING]" prefix to the title of the PR.
+- [ ] The PR follows the [Contribution Guidelines](https://github.com/microsoft/agent-framework/blob/main/CONTRIBUTING.md)
+- [ ] This PR is linked to an issue and there is no other open PR for this issue (see Related Issue above).
+- [ ] **This is not a breaking change.** If it _is_ a breaking change, add the `breaking change` label (or add a "[BREAKING]" prefix to the title) — a workflow keeps the label and title prefix in sync automatically.

.github/workflows/label-breaking-change.yml

@@ -0,0 +1,36 @@
+name: Label breaking change
+on:
+  pull_request_target:
+    types: [opened, edited]
+
+jobs:
+  add_breaking_label:
+    name: "PR: add breaking change label"
+    continue-on-error: true
+    runs-on: ubuntu-latest
+    permissions:
+      pull-requests: write
+
+    steps:
+      - uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        name: "PR: add breaking change label"
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const breakingLabel = "breaking change";
+            const title = context.payload.pull_request.title || "";
+
+            // Add the label when the title contains the "[BREAKING]" prefix.
+            // The label-title-prefix workflow handles the reverse direction
+            // (adding the "[BREAKING]" prefix when the label is applied).
+            if (/\[BREAKING\]/i.test(title)) {
+              const labels = context.payload.pull_request.labels.map(l => l.name);
+              if (!labels.includes(breakingLabel)) {
+                await github.rest.issues.addLabels({
+                  issue_number: context.issue.number,
+                  owner: context.repo.owner,
+                  repo: context.repo.repo,
+                  labels: [breakingLabel]
+                });
+              }
+            }

.github/workflows/label-title-prefix.yml

@@ -25,6 +25,11 @@ jobs:
               ".NET": ".NET"
             };
 
+            // Labels that prepend a bracketed prefix to the title (e.g. "[BREAKING] ...").
+            let bracketPrefixLabels = {
+              "breaking change": "[BREAKING]"
+            };
+
             function addTitlePrefix(title, prefix)
             {
               // Update the title based on the label and prefix
@@ -43,18 +48,42 @@ jobs:
               return title;
             }
 
+            function addBracketPrefix(title, prefix)
+            {
+              // Prepend a bracketed prefix (e.g. "[BREAKING]") if it is not already present.
+              if (title.includes(prefix)) {
+                return title;
+              }
+
+              return prefix + " " + title;
+            }
+
             labelAdded = context.payload.label.name
 
-            // Check if the issue or PR has the label
+            // Determine the new title based on which kind of label was added.
+            let newTitle = null;
             if (labelAdded in prefixLabels) {
               let prefix = prefixLabels[labelAdded];
+              let currentTitle = context.eventName === 'issues'
+                ? context.payload.issue.title
+                : context.payload.pull_request.title;
+              newTitle = addTitlePrefix(currentTitle, prefix);
+            } else if (labelAdded in bracketPrefixLabels) {
+              let prefix = bracketPrefixLabels[labelAdded];
+              let currentTitle = context.eventName === 'issues'
+                ? context.payload.issue.title
+                : context.payload.pull_request.title;
+              newTitle = addBracketPrefix(currentTitle, prefix);
+            }
+
+            if (newTitle !== null) {
               switch(context.eventName) {
                 case 'issues':
                   github.rest.issues.update({
                     issue_number: context.issue.number,
                     owner: context.repo.owner,
                     repo: context.repo.repo,
-                    title: addTitlePrefix(context.payload.issue.title, prefix)
+                    title: newTitle
                   });
                   break
 
@@ -63,7 +92,7 @@ jobs:
                     pull_number: context.issue.number,
                     owner: context.repo.owner,
                     repo: context.repo.repo,
-                    title: addTitlePrefix(context.payload.pull_request.title, prefix)
+                    title: newTitle
                   });
                   break
                 default: