plan.md

## Persistent answer room
Submissions are written atomically to JSON at `DATA_DIR/submissions.json`, defaulting to `/data` when available and falling back to the project data directory locally. The home page discovers the latest saved submission after refresh or in another browser, then asks for `OWNER_VIEW_PASSWORD` before returning the answer. The `/owner` dashboard uses the same password-protected API and keeps the key only in the current tab. A Hugging Face persistent storage volume mounted at `/data` is required for the JSON file to survive Space/container replacement; without it, answers still survive browser refreshes while the current container is running, but not a recreated container.