The test was calling handleWriteCommand/handleReadCommand with a BrowserManager
in the session: TabSession slot — the API diverged when TabSession became a
distinct type. Fix: capture bm.getActiveSession() after launch() and thread
it as the session arg through all 17 call-sites.
All 6 tests now pass (previously 0/6 with 'session.clearLoadedHtml is not a
function').