Guard generic topology search from introducing EP

src/aituner/harness.py

@@ -1482,6 +1482,11 @@ def _legal_topology_points(
         and current_ep > 1
     ):
         ep_values = [current_ep]
+    elif not current_enable_ep and current_ep <= 1:
+        # Generic topology search should not introduce EP. EP is a separate
+        # intervention family and needs direct EP-specific evidence; otherwise
+        # TTFT/TPOT topology probes can waste trials on launch-risky EP variants.
+        ep_values = [1]
     elif constraints is not None and constraints.allowed_expert_parallel_sizes:
         ep_values = sorted(set(constraints.allowed_expert_parallel_sizes))
     elif "expert-parallel-size" in tunable: