diff --git a/tests/test_prometheus_sigma.py b/tests/test_prometheus_sigma.py
index a70c519..93e849a 100644
--- a/tests/test_prometheus_sigma.py
+++ b/tests/test_prometheus_sigma.py
@@ -2,7 +2,10 @@
 
 Phase 0 is doc-only — these tests are the **scaffolding** the §16.2
 implementation contract names. All of them skip until Phase 1 lands
-the controller module (``arborist/v9/prometheus.py`` per §13).
+the controller module (``arborist/substrate/prometheus.py``,
+per the post-2026-05-10 topic-named convention; the original
+§13 sketch said ``arborist/v9/prometheus.py`` before the v-dir
+namespace pattern was retired).
 
 Why land scaffolding while Phase 0 is still doc-only:
 
@@ -30,7 +33,7 @@ from __future__ import annotations
 import pytest
 
 try:
-    from arborist.v9 import prometheus as _prom  # noqa: F401
+    from arborist.substrate import prometheus as _prom  # noqa: F401
     CONTROLLER_AVAILABLE = True
 except ImportError:
     CONTROLLER_AVAILABLE = False
@@ -39,7 +42,7 @@ skip_until_phase_1 = pytest.mark.skipif(
     not CONTROLLER_AVAILABLE,
     reason=(
         "ticket #000037 Phase 1 not landed; controller module "
-        "arborist/v9/prometheus.py absent. Skip is the contract — "
+        "arborist/substrate/prometheus.py absent. Skip is the contract — "
         "implementer flips this when the module exists."
     ),
 )