Test ordered one-slot DFlash2 placements and preserve results

experiments/dflash2-medium-20260920/dflash-code-checks.json

@@ -0,0 +1,11 @@
+{
+  "scope": "Two checks of manually reviewed decode answer, not broad quality evaluation",
+  "fast_failure_then_success": {
+    "returned": 7,
+    "pass": true
+  },
+  "all_fail": {
+    "error": "NameError: name 'builtins' is not defined",
+    "pass": false
+  }
+}