diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d5e1870ca..75a56e432 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -68,6 +68,7 @@ jobs:
     uses: ./.github/workflows/frontend-build.yml
     with:
       node_version: '24.x'
+      pull_number: ${{ github.event_name == 'pull_request' && github.event.pull_request.number || '' }}
 
   apphost-build:
     needs: changes
diff --git a/.github/workflows/frontend-build.yml b/.github/workflows/frontend-build.yml
index d83b8f7b1..2a8c67d39 100644
--- a/.github/workflows/frontend-build.yml
+++ b/.github/workflows/frontend-build.yml
@@ -8,6 +8,11 @@ on:
         required: true
         default: "24.x"
         type: string
+      pull_number:
+        description: Pull request number when available
+        required: false
+        default: ""
+        type: string
 
 permissions:
   contents: read
@@ -25,7 +30,27 @@ jobs:
           fetch-depth: 0
 
       - name: Ensure full git history for Lunaria
-        run: git fetch --unshallow 2>/dev/null || true
+        env:
+          PULL_NUMBER: ${{ inputs.pull_number }}
+        run: |
+          if [ -n "$PULL_NUMBER" ]; then
+            case "$PULL_NUMBER" in
+              (*[!0-9]*)
+                echo "Invalid pull_number input: '$PULL_NUMBER'" >&2
+                exit 1
+                ;;
+            esac
+
+            pull_ref="+refs/pull/${PULL_NUMBER}/head:refs/remotes/origin/pull/${PULL_NUMBER}/head"
+
+            if [ "$(git rev-parse --is-shallow-repository)" = "true" ]; then
+              git fetch origin "$pull_ref" --unshallow
+            else
+              git fetch origin "$pull_ref"
+            fi
+          elif [ "$(git rev-parse --is-shallow-repository)" = "true" ]; then
+            git fetch --unshallow
+          fi
 
       - uses: pnpm/action-setup@fc06bc1257f339d1d5d8b3a19a8cae5388b55320 # v5.0.0
         with: