Reloading window after discarding agentic session brings files back

[bpasero]

Steps to Reproduce:

1. do an agentic flow that creates new files
2. undo them all from the "Keep | Undo" area
3. notice how the files are still there
4. discard them via SCM
5. reload window

=> 🐛 when the chat session restores, the files are restored