proper tests

cht/window.py

@@ -1,6 +1,7 @@
 """Main application window — wires Timeline to all components."""
 
 import logging
+import os
 from pathlib import Path
 
 import gi
@@ -301,7 +302,8 @@ class ChtWindow(Adw.ApplicationWindow):
         self._connect_btn.remove_css_class("suggested-action")
         self._connect_btn.add_css_class("destructive-action")
 
-        mgr = self._lifecycle.start(session_id=session_id, rust_transport=True)
+        rust = os.environ.get("_CHT_RUST_TRANSPORT", "0") == "1"
+        mgr = self._lifecycle.start(session_id=session_id, rust_transport=rust)
         if mgr is None:
             log.error("Failed to start stream — no cht-server session found")
             self._connect_btn.set_label("Connect")