Fix pilot burn-in selection manifest

runs/fidelity-headroom/prepare_pilot.py

@@ -227,7 +227,11 @@ def build_manifest(
         for level, multiplier in TARGET_MULTIPLIERS.items():
             target_rate = float(config["frontier_req_s_gpu"]) * multiplier
             target_count = round(target_rate * durations["low1"] * tp)
-            roles = [role for role in ROLES if role == "burnin" or role.startswith(level)]
+            roles = [
+                role
+                for role in ROLES
+                if role.startswith(level) or (level == "low" and role == "burnin")
+            ]
             selections = {}
             for role in roles:
                 anchor, selected = attainable_anchor(loaded[role][tier], target_count)