Cloud no-folder starts use fresh chat folders
A Cloud start with no folder could pass the machine's existing workspace folder into remote start, reopening a prior chat. This keeps the no-folder path folderless for Cloud owner links so the daemon allocates the fresh per-chat ~/chats/<chat-id> directory, while non-Cloud peers retain their workspace fallback.
Leo asked that “I want us to be able to do this too”: a no-project Cloud chat should start immediately in its own fresh chat.
Tests: AgentTabRemoteStartTests.aModernCloudDaemonReceivesNoFolderForRustToChoose covers a stale workspace folder and verifies no cwd is sent. python3 scripts/cmux-next/prepush-gate.py passes.
Agent session: agent session
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Summary by cubic
Fixes Cloud starts with no folder so they use a fresh chat directory instead of reopening a prior chat.
Previously, a Cloud start with no folder could pass the machine's existing workspace folder into the remote start. Now Cloud owner links stay folderless so the daemon allocates a fresh ~/chats/<chat-id> directory, while non-Cloud peers retain their workspace fallback.