Local chat sessions cannot be opened anymore when entering workspace

[bpasero]

Steps to Reproduce:

1. be in an empty window
2. say "hi" to a local chat
3. verify you see a session entry you can click to open that session
4. add a folder to the workspace from the "File" menu
5. reload the window
6. click on the session card entry for the "hi" chat

=> it no longer opens

If you debug this you can see what we try to load the chat history JSON file from disk from a location that belonged to the empty window state. But when you add a folder to a workspace, the workspace ID changes. We need to migrate the chat sessions folder over in that case.

[joaomoreno]

Just hit this on my day-to-day.

Actually this can be more severe:

1. Be on a workspace with lots of chats
2. Transition to a multi folder workspace by adding another folder to it
3. Create new chats
4. Reload

🐛 I can no longer open any chats. If I go back to single folder mode, I can't see any of the new chats.

The experience after reloading is pretty jarring.

Screen.Recording.2026-02-03.at.16.05.57.mov

[roblourens]

@joaomoreno that's just what the bug is. It sucks but there's nothing new here. You should still be able to start new chats that are in the new workspace. I think it's important to fix but it seemed like not something that I can just throw at the agent.

[bpasero]

onDidEnterWorkspace landed, asking it to update the PR