workflows/eval: Reuse process-reviewers.sh

Filters out the PR author and avoids rerequesting reviews from people
that already left a review. In a future commit, this can be expanded to
also avoid requesting reviews from people not in the org

.github/workflows/eval.yml

@@ -219,7 +219,7 @@ jobs:
   tag:
     name: Tag
     runs-on: ubuntu-latest
-    needs: process
+    needs: [ attrs, process ]
     if: needs.process.outputs.baseRunId
     permissions:
       pull-requests: write
@@ -239,6 +239,21 @@ jobs:
           name: comparison
           path: comparison
 
+      - name: Install Nix
+        uses: cachix/install-nix-action@08dcb3a5e62fa31e2da3d490afc4176ef55ecd72 # v30
+
+      # Important: This workflow job runs with extra permissions,
+      # so we need to make sure to not run untrusted code from PRs
+      - name: Check out Nixpkgs at the base commit
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          ref: ${{ needs.attrs.outputs.baseSha }}
+          path: base
+          sparse-checkout: ci
+
+      - name: Build the requestReviews derivation
+        run: nix-build base/ci -A requestReviews
+
       - name: Tagging pull request
         run: |
           # Get all currently set rebuild labels
@@ -271,8 +286,8 @@ jobs:
           # maintainers.json contains GitHub IDs. Look up handles to request reviews from.
           # There appears to be no API to request reviews based on GitHub IDs
           jq -r 'keys[]' comparison/maintainers.json \
-            | while read -r id; do gh api /user/"$id"; done \
-            | jq -s '{ reviewers: map(.login) }' \
+            | while read -r id; do gh api /user/"$id" --jq .login; done \
+            | GH_TOKEN=${{ steps.app-token.outputs.token }} result/bin/process-reviewers.sh "$REPOSITORY" "$NUMBER" "$AUTHOR" \
             > reviewers.json
 
           # Request reviewers from maintainers of changed output paths
@@ -285,6 +300,7 @@ jobs:
           GH_TOKEN: ${{ github.token }}
           REPOSITORY: ${{ github.repository }}
           NUMBER: ${{ github.event.number }}
+          AUTHOR: ${{ github.event.pull_request.user.login }}
 
       - name: Add eval summary to commit statuses
         if: ${{ github.event_name == 'pull_request_target' }}