diff --git a/tests/unit/test_part_a_decode_diagnostics.py b/tests/unit/test_part_a_decode_diagnostics.py
index 1664879d..f2fd4fe3 100644
--- a/tests/unit/test_part_a_decode_diagnostics.py
+++ b/tests/unit/test_part_a_decode_diagnostics.py
@@ -23,6 +23,9 @@ CHECKPOINT_DIR = os.environ.get(
 NUM_GPUS = int(os.environ.get("NUM_GPUS", "8"))
 DEVICE = "cuda:0"
 TEST_LAYERS = int(os.environ.get("TEST_LAYERS", "5"))
+# First layer index to test. L0-1 are hash routing, L2+ are dense/CSA/HCA.
+# Set to 0 to include hash layers.
+FIRST_LAYER = int(os.environ.get("FIRST_LAYER", "2"))
 
 
 def cosine(a, b):
@@ -280,6 +283,9 @@ def main():
             gpu = li % NUM_GPUS
             if X.device != torch.device(f"cuda:{gpu}"): X = X.to(f"cuda:{gpu}")
             torch.cuda.set_device(gpu)
+            if pi == 0:
+                r = routers.get(li)
+                print(f"  L{li} router: mode={r.mode if r else 'None'} has_gate_lin={r._gate_lin is not None if r and hasattr(r, '_gate_lin') else 'N/A'}", flush=True)
             X = forward_layer(X, layer_w[li], li, cfg, *rope_caches[gpu],
                 attn_mhcs.get(li), ffn_mhcs.get(li), attn_norms.get(li), ffn_norms.get(li),
                 kv_caches[li], pos, tid32, compressors.get(li), indexers.get(li),