fix: pin workflow checkouts to github.sha instead of github.ref

github.ref resolves to the branch name (refs/heads/<branch>) for
workflow_dispatch events, so long-queued matrix jobs would check
out whatever was at HEAD when the runner picked them up — not the
commit that was HEAD at dispatch time. This meant a sweep could
end up running across multiple commits if the branch was updated
mid-sweep.

Switch the fallback to github.sha, which for workflow_dispatch is
the SHA at dispatch time and is inherited by reusable workflows
from the caller's context. All jobs in a single run now use the
same commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: cquil11

.github/workflows/benchmark-multinode-tmpl.yml

@@ -175,7 +175,7 @@ jobs:
         with:
           token: ${{ secrets.REPO_PAT }}
           fetch-depth: 1
-          ref: ${{ inputs.ref || github.ref }}
+          ref: ${{ inputs.ref || github.sha }}
           clean: true
           submodules: true
 

.github/workflows/benchmark-tmpl.yml

@@ -167,7 +167,7 @@ jobs:
         with:
           token: ${{ secrets.REPO_PAT }}
           fetch-depth: 0
-          ref: ${{ inputs.ref || github.ref }}
+          ref: ${{ inputs.ref || github.sha }}
           clean: true
           submodules: true
 

.github/workflows/e2e-tests.yml

@@ -51,6 +51,8 @@ jobs:
             - name: Checkout code (default)
               if: ${{ !inputs.ref || inputs.ref == '' }}
               uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+              with:
+                ref: ${{ github.sha }}
 
             - id: get-jobs
               run: |