chore(api): disallow builtins getattr variants in new code (#38250)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

.github/workflows/style.yml

@@ -29,6 +29,8 @@ jobs:
         with:
           files: |
             api/**
+            scripts/check_no_new_getattr.py
+            scripts/ast_grep_rules/no_new_getattr.yml
             .github/workflows/style.yml
 
       - name: Setup UV and Python
@@ -51,6 +53,18 @@ jobs:
         if: steps.changed-files.outputs.any_changed == 'true'
         run: uv run --project api --dev python api/dev/lint_response_contracts.py --fail-on-mismatch
 
+      - name: Fetch merge target ref for getattr guard
+        if: steps.changed-files.outputs.any_changed == 'true'
+        run: git fetch --no-tags --depth=1 origin +refs/heads/main:refs/remotes/origin/main
+
+      - name: Bind merge target branch for getattr guard
+        if: steps.changed-files.outputs.any_changed == 'true'
+        run: git show-ref --verify --quiet refs/heads/main || git branch main origin/main
+
+      - name: Run No New Getattr Guard
+        if: steps.changed-files.outputs.any_changed == 'true'
+        run: uv run --project api python scripts/check_no_new_getattr.py --mode ci --merge-target main
+
       - name: Run Type Checks
         if: steps.changed-files.outputs.any_changed == 'true'
         env: