Normalize labels on merged external-plugin PRs (#1859)

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

.github/workflows/external-plugin-approval-command.yml

@@ -3,6 +3,8 @@ name: External Plugin Approval Commands
 on:
   issue_comment:
     types: [created]
+  pull_request:
+    types: [closed]
 
 permissions:
   contents: write
@@ -13,6 +15,7 @@ jobs:
   handle-command:
     runs-on: ubuntu-latest
     if: >-
+      github.event_name == 'issue_comment' &&
       !github.event.issue.pull_request &&
       (contains(github.event.comment.body, '/approve') || contains(github.event.comment.body, '/reject'))
     steps:
@@ -407,6 +410,65 @@ jobs:
               });
             }
 
+  sync-merged-pr-labels:
+    runs-on: ubuntu-latest
+    if: >-
+      github.event_name == 'pull_request' &&
+      github.event.action == 'closed' &&
+      github.event.pull_request.merged == true &&
+      contains(github.event.pull_request.labels.*.name, 'external-plugin')
+    steps:
+      - name: Normalize merged external plugin PR labels
+        uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7.1.0
+        with:
+          script: |
+            const prNumber = context.payload.pull_request.number;
+            const staleLabels = ['awaiting-review', 'awaiting-approval', 'ready-for-review', 'rejected'];
+
+            try {
+              await github.rest.issues.createLabel({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                name: 'approved',
+                color: '1D76DB',
+                description: 'Submission was approved by a maintainer'
+              });
+            } catch (error) {
+              if (error.status !== 422) {
+                throw error;
+              }
+            }
+
+            const { data: currentLabels } = await github.rest.issues.listLabelsOnIssue({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: prNumber,
+              per_page: 100
+            });
+            const labelNames = new Set(currentLabels.map((label) => label.name));
+
+            if (!labelNames.has('approved')) {
+              await github.rest.issues.addLabels({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: prNumber,
+                labels: ['approved']
+              });
+            }
+
+            for (const labelName of staleLabels) {
+              if (!labelNames.has(labelName)) {
+                continue;
+              }
+
+              await github.rest.issues.removeLabel({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: prNumber,
+                name: labelName
+              });
+            }
+
       - name: Finalize rejection
         if: steps.parse.outputs.should-run == 'true' && steps.parse.outputs.command == 'reject'
         uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v7.1.0