diff --git a/tests/mock_concurrent_mma.py b/tests/mock_concurrent_mma.py
index 467268bd..81d5e298 100644
--- a/tests/mock_concurrent_mma.py
+++ b/tests/mock_concurrent_mma.py
@@ -67,23 +67,19 @@ def main() -> None:
   return
 
  # 2. Sprint Planning (different tickets for different tracks)
- # The gemini_cli_adapter reuses the session_id from the epic call
- # (mock-epic) for all subsequent calls. We use the global call counter
- # to cycle through Track A (call #2) and Track B (call #3).
- if session_id == "mock-epic" and call_n == 2:
-  _emit_sprint_ticket("A")
-  return
- if session_id == "mock-epic" and call_n == 3:
-  _emit_sprint_ticket("B")
-  return
- if "mock-sprint-A" in session_id:
-  _emit_sprint_ticket("A")
-  return
- if "mock-sprint-B" in session_id:
-  _emit_sprint_ticket("B")
-  return
+ # Route on prompt content (the production passes the track_brief which
+ # contains "Track A" or "Track B"). The prior session_id-based routing was
+ # fragile because:
+ #   1. The call_n counter is shared across tests in the same session, so
+ #      call_n != 2 for the 1st sprint if a prior test ran.
+ #   2. session_id="mock-sprint-A" means "this is a follow-up call after
+ #      the 1st sprint returned mock-sprint-A", so the response should be
+ #      sprint-B (2nd track), not sprint-A.
  if 'generate the implementation tickets' in prompt:
-  track_label = "A" if "Track A" in prompt else "B"
+  if "Track A" in prompt: track_label = "A"
+  elif "Track B" in prompt: track_label = "B"
+  elif "Track C" in prompt: track_label = "C"
+  else: track_label = "A"
   _emit_sprint_ticket(track_label)
   return