diff --git a/nanobot/channels/websocket/tests/conftest.py b/nanobot/channels/websocket/tests/conftest.py
new file mode 100644
index 000000000..d5a23abd5
--- /dev/null
+++ b/nanobot/channels/websocket/tests/conftest.py
@@ -0,0 +1,14 @@
+"""Shared isolation for WebSocket tests that persist runtime state."""
+
+from pathlib import Path
+
+import pytest
+
+
+@pytest.fixture(autouse=True)
+def isolate_websocket_runtime_data(
+    tmp_path: Path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """Keep transcripts and other runtime files out of the active user data directory."""
+    monkeypatch.setattr("nanobot.config.paths.get_data_dir", lambda: tmp_path)