From da974ef14171ca6662ad1e345232853b1e06befb Mon Sep 17 00:00:00 2001
From: pulimsr <pulimsr@amazon.com>
Date: Mon, 30 Mar 2026 22:36:43 -0400
Subject: [PATCH 1/3] updating the github workflow

---
 .github/workflows/pull-request-build.yml | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/.github/workflows/pull-request-build.yml b/.github/workflows/pull-request-build.yml
index 59c8b3e694fe..cda39faeedc1 100644
--- a/.github/workflows/pull-request-build.yml
+++ b/.github/workflows/pull-request-build.yml
@@ -30,17 +30,18 @@ jobs:
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
-          BASE_SHA="${{ github.event.merge_group.base_sha }}"
-          BASE_REF="${{ github.event.merge_group.base_ref }}"
-          # base_ref is in refs/heads/<branch> format, strip prefix for API call
-          BRANCH_NAME="${BASE_REF#refs/heads/}"
-          TARGET_SHA=$(gh api repos/${{ github.repository }}/git/ref/heads/${BRANCH_NAME} --jq '.object.sha')
-          if [ "$BASE_SHA" == "$TARGET_SHA" ]; then
+          MERGE_GROUP_BASE_SHA="${{ github.event.merge_group.base_sha }}"
+          HEAD_REF="${{ github.event.merge_group.head_ref }}"
+          PR_NUM=$(echo "$HEAD_REF" | grep -oP 'pr-\K[0-9]+')
+          PR_BASE_SHA=$(gh api repos/${{ github.repository }}/pulls/$PR_NUM --jq '.base.sha')
+          echo "Merge group base SHA: $MERGE_GROUP_BASE_SHA"
+          echo "PR #$PR_NUM base SHA: $PR_BASE_SHA"
+          if [ "$MERGE_GROUP_BASE_SHA" == "$PR_BASE_SHA" ]; then
             echo "skip=true" >> "$GITHUB_OUTPUT"
-            echo "First in queue — PR build already validated this combination, skipping."
+            echo "Merge group base matches PR base — PR build already validated this, skipping."
           else
             echo "skip=false" >> "$GITHUB_OUTPUT"
-            echo "Not first in queue — merge group includes changes from other PRs, build needed."
+            echo "Merge group base differs from PR base — other PRs ahead or base moved, build needed."
           fi
       - name: Configure AWS Credentials
         if: steps.queue-check.outputs.skip != 'true'

From d55fba8e16d57b4c5a18e93e56741b9ca117c52c Mon Sep 17 00:00:00 2001
From: pulimsr <pulimsr@amazon.com>
Date: Tue, 31 Mar 2026 01:54:06 -0400
Subject: [PATCH 2/3] Strip refs/heads/ prefix from merge group head_ref and
 add skip logic

---
 .github/workflows/pull-request-build.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.github/workflows/pull-request-build.yml b/.github/workflows/pull-request-build.yml
index cda39faeedc1..2809b42b9db8 100644
--- a/.github/workflows/pull-request-build.yml
+++ b/.github/workflows/pull-request-build.yml
@@ -66,6 +66,7 @@ jobs:
           PR_NUMBER: ${{ github.event.pull_request.number || '0' }}
           RUN_ID: ${{ github.run_id }}
         run: |
+          HEAD_REF="${HEAD_REF#refs/heads/}"
           ./$DOWNLOAD_FOLDER/$SCRIPT_LOCATION \
             --repo "$REPO" \
             --branch "$HEAD_REF" \

From 0e0e8bf6557078be0e54849930465d3351042ad5 Mon Sep 17 00:00:00 2001
From: pulimsr <pulimsr@amazon.com>
Date: Tue, 31 Mar 2026 02:35:05 -0400
Subject: [PATCH 3/3] base_sha

---
 .github/workflows/pull-request-build.yml | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/pull-request-build.yml b/.github/workflows/pull-request-build.yml
index 2809b42b9db8..445f035971a1 100644
--- a/.github/workflows/pull-request-build.yml
+++ b/.github/workflows/pull-request-build.yml
@@ -24,24 +24,29 @@ jobs:
       pull-requests: write
       contents: read
     steps:
+      - name: Checkout merge group (shallow)
+        if: github.event_name == 'merge_group'
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 2
       - name: Check if merge queue build is needed
         if: github.event_name == 'merge_group'
         id: queue-check
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
-          MERGE_GROUP_BASE_SHA="${{ github.event.merge_group.base_sha }}"
           HEAD_REF="${{ github.event.merge_group.head_ref }}"
           PR_NUM=$(echo "$HEAD_REF" | grep -oP 'pr-\K[0-9]+')
           PR_BASE_SHA=$(gh api repos/${{ github.repository }}/pulls/$PR_NUM --jq '.base.sha')
-          echo "Merge group base SHA: $MERGE_GROUP_BASE_SHA"
+          PARENT_SHA=$(git rev-parse HEAD~1)
           echo "PR #$PR_NUM base SHA: $PR_BASE_SHA"
-          if [ "$MERGE_GROUP_BASE_SHA" == "$PR_BASE_SHA" ]; then
+          echo "Merge group HEAD~1:   $PARENT_SHA"
+          if [ "$PARENT_SHA" == "$PR_BASE_SHA" ]; then
             echo "skip=true" >> "$GITHUB_OUTPUT"
-            echo "Merge group base matches PR base — PR build already validated this, skipping."
+            echo "First in queue, same base — PR build already validated this, skipping."
           else
             echo "skip=false" >> "$GITHUB_OUTPUT"
-            echo "Merge group base differs from PR base — other PRs ahead or base moved, build needed."
+            echo "Other PRs ahead or base moved — build needed."
           fi
       - name: Configure AWS Credentials
         if: steps.queue-check.outputs.skip != 'true'