diff --git a/tests/tools/test_transcription.py b/tests/tools/test_transcription.py
index 32f0ad48798..606a3e100a2 100644
--- a/tests/tools/test_transcription.py
+++ b/tests/tools/test_transcription.py
@@ -28,6 +28,20 @@ def _clear_openai_env(monkeypatch):
     monkeypatch.delenv("OPENAI_API_KEY", raising=False)
 
 
+@pytest.fixture(autouse=True)
+def _disable_lazy_stt_install():
+    """Disarm the runtime lazy-install probe so static ``_HAS_FASTER_WHISPER``
+    patches accurately simulate 'faster-whisper not installed'.
+
+    Without this, ``_try_lazy_install_stt()`` calls
+    ``importlib.util.find_spec("faster_whisper")``, which returns truthy
+    whenever the package is installed in the dev / CI environment —
+    defeating the test's ``_HAS_FASTER_WHISPER=False`` patch.
+    """
+    with patch("tools.transcription_tools._try_lazy_install_stt", return_value=False):
+        yield
+
+
 class TestGetProvider:
     """_get_provider() picks the right backend based on config + availability."""
 
diff --git a/tests/tools/test_transcription_dotenv_fallback.py b/tests/tools/test_transcription_dotenv_fallback.py
index 365b910d4cc..6248d0acd06 100644
--- a/tests/tools/test_transcription_dotenv_fallback.py
+++ b/tests/tools/test_transcription_dotenv_fallback.py
@@ -28,6 +28,20 @@ def isolate_env(monkeypatch):
         monkeypatch.delenv(key, raising=False)
 
 
+@pytest.fixture(autouse=True)
+def _disable_lazy_stt_install():
+    """Disarm the runtime lazy-install probe so static ``_HAS_FASTER_WHISPER``
+    patches accurately simulate 'faster-whisper not installed'.
+
+    Without this, ``_try_lazy_install_stt()`` calls
+    ``importlib.util.find_spec("faster_whisper")``, which returns truthy
+    whenever the package is installed in the dev / CI environment —
+    defeating the test's ``_HAS_FASTER_WHISPER=False`` patch.
+    """
+    with patch("tools.transcription_tools._try_lazy_install_stt", return_value=False):
+        yield
+
+
 class TestProviderSelectionGate:
     """``_get_provider`` picks the STT backend. If it only consulted
     ``os.environ`` a user with keys in ``~/.hermes/.env`` would be told
diff --git a/tests/tools/test_transcription_tools.py b/tests/tools/test_transcription_tools.py
index 7f83565b5d8..953a68be79e 100644
--- a/tests/tools/test_transcription_tools.py
+++ b/tests/tools/test_transcription_tools.py
@@ -53,6 +53,20 @@ def clean_env(monkeypatch):
     monkeypatch.delenv("HERMES_LOCAL_STT_LANGUAGE", raising=False)
 
 
+@pytest.fixture(autouse=True)
+def _disable_lazy_stt_install():
+    """Disarm the runtime lazy-install probe so static ``_HAS_FASTER_WHISPER``
+    patches accurately simulate 'faster-whisper not installed'.
+
+    Without this, ``_try_lazy_install_stt()`` calls
+    ``importlib.util.find_spec("faster_whisper")``, which returns truthy
+    whenever the package is installed in the dev / CI environment —
+    defeating the test's ``_HAS_FASTER_WHISPER=False`` patch.
+    """
+    with patch("tools.transcription_tools._try_lazy_install_stt", return_value=False):
+        yield
+
+
 # ============================================================================
 # _get_provider — full permutation matrix
 # ============================================================================