The dashboard prefill flow in AssistantChatPage set activeChatId after
creating a new session but never updated currentChatRef.current. Every
later handleSend / handleTaskSubmit then tripped the
`currentChatRef.current !== sentForChatId` guard that was supposed to
discard responses for stale chats — and silently dropped the AI's
follow-up. The user saw their submitted message but no assistant
reply, no toast, no task-lane update.
Mirrors what handleNewChat and handleResumeNew already do. Adds an
e2e regression test that drives the dashboard prefill, submits a
partial task-lane response, and asserts the second AI turn renders.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
