diff --git a/.github/workflows/pr-test.yml b/.github/workflows/pr-test.yml
index 69d572d20..fbccef871 100644
--- a/.github/workflows/pr-test.yml
+++ b/.github/workflows/pr-test.yml
@@ -209,10 +209,20 @@ jobs:
           elif [[ "${{ github.event_name }}" == "pull_request" && "${{ contains(github.event.pull_request.labels.*.name, 'high priority') }}" == "true" ]]; then
             echo "max_parallel=14" >> $GITHUB_OUTPUT
             echo "High priority PR detected, setting max_parallel to 14"
-          elif [[ -n "${{ inputs.pr_head_sha }}" ]]; then
+          elif [[ -n "${{ inputs.target_stage }}" ]]; then
             # /rerun-stage (workflow_dispatch): query PR labels via GitHub API
-            LABELS=$(gh api "repos/${{ github.repository }}/commits/${{ inputs.pr_head_sha }}/pulls" \
-              --jq '.[0].labels[].name' 2>/dev/null || true)
+            # Try SHA lookup first (fork PRs), fallback to branch name (non-fork PRs)
+            LABELS=""
+            PR_HEAD_SHA="${{ inputs.pr_head_sha }}"
+            if [[ -n "$PR_HEAD_SHA" ]]; then
+              LABELS=$(gh api "repos/${{ github.repository }}/commits/${PR_HEAD_SHA}/pulls" \
+                --jq '.[0].labels[].name' 2>/dev/null || true)
+            fi
+            if [[ -z "$LABELS" ]]; then
+              LABELS=$(gh pr list --head "${{ github.ref_name }}" --repo "${{ github.repository }}" \
+                --json labels --jq '.[0].labels[].name' 2>/dev/null || true)
+            fi
+            echo "PR labels: ${LABELS:-"(none)"}"
             if echo "$LABELS" | grep -Fxq "high priority"; then
               echo "max_parallel=14" >> $GITHUB_OUTPUT
               echo "High priority PR detected via API (/rerun-stage), setting max_parallel to 14"