diff --git a/tests/mock_concurrent_mma.py b/tests/mock_concurrent_mma.py
index e3ba0a08..79648936 100644
--- a/tests/mock_concurrent_mma.py
+++ b/tests/mock_concurrent_mma.py
@@ -46,6 +46,10 @@ def main() -> None:
    session_id = argv[i + 1]
 
  call_n = _next_call_count()
+ try:
+  with open(b"C:\\projects\\manual_slop_tier2\\tests\\artifacts\\tier2_state\\fix_mma_concurrent_tracks_sim_20260627\\mock_diag.log", "ab") as _df:
+   _df.write(f"[MOCK] call_n={call_n} session_id={session_id!r}\n".encode())
+ except Exception: pass
 
  # 1. Sprint Planning (different tickets for different tracks)
  # Route on prompt content (the production passes the track_brief which
@@ -63,11 +67,22 @@ def main() -> None:
   elif "Track C" in prompt: track_label = "C"
   else: track_label = "A"
   _emit_sprint_ticket(track_label)
+  try:
+   with open(b"C:\\projects\\manual_slop_tier2\\tests\\artifacts\\tier2_state\\fix_mma_concurrent_tracks_sim_20260627\\mock_diag.log", "ab") as _df:
+    _df.write(f"[MOCK] ROUTED TO: sprint track={track_label}\n".encode())
+  except Exception: pass
   return
 
  # 2. Worker Execution
  # CHECK BEFORE epic so worker takes priority over the catch-all epic branch.
- if 'You are assigned to Ticket' in prompt or session_id.startswith("mock-worker-"):
+ if 'You are assigned to Ticket' in prompt:
+  # NOTE: Removed session_id.startswith("mock-worker-") fallback. The session_id
+  # persists across tests in the same session (gemini_cli_adapter is a singleton).
+  # The fallback caused test_mma_concurrent_tracks_stress_sim to fail when it ran
+  # AFTER test_mma_concurrent_tracks_execution: the execution test set the session_id
+  # to mock-worker-ticket-A-1, and the stress test's epic call used --resume with that
+  # session_id, which the fallback incorrectly matched, returning a worker response
+  # instead of an epic response.
   import re
   match = re.search(r'Ticket (ticket-[A-Ba-b]-1)', prompt, re.IGNORECASE)
   if match:
@@ -77,6 +92,10 @@ def main() -> None:
   else:
    tid = "unknown"
 
+  try:
+   with open(b"C:\\projects\\manual_slop_tier2\\tests\\artifacts\\tier2_state\\fix_mma_concurrent_tracks_sim_20260627\\mock_diag.log", "ab") as _df:
+    _df.write(f"[MOCK] ROUTED TO: worker tid={tid}\n".encode())
+  except Exception: pass
   print(json.dumps({
    "type": "message",
    "role": "assistant",
@@ -113,9 +132,17 @@ def main() -> None:
    "stats": {"total_tokens": 100, "input_tokens": 50, "output_tokens": 50},
    "session_id": "mock-epic"
   }), flush=True)
+  try:
+   with open(b"C:\\projects\\manual_slop_tier2\\tests\\artifacts\\tier2_state\\fix_mma_concurrent_tracks_sim_20260627\\mock_diag.log", "ab") as _df:
+    _df.write(b"[MOCK] ROUTED TO: epic_catchall\n")
+  except Exception: pass
   return
 
  # Default
+ try:
+  with open(b"C:\\projects\\manual_slop_tier2\\tests\\artifacts\\tier2_state\\fix_mma_concurrent_tracks_sim_20260627\\mock_diag.log", "ab") as _df:
+   _df.write(b"[MOCK] ROUTED TO: default\n")
+ except Exception: pass
  print(json.dumps({
   "type": "message",
   "role": "assistant",