What persists: every card (kind, position, size, title, note text, ptyId, z-order) + viewport pan/zoom + maxZ counter,

in a single board.json under app_data_dir() (~/.local/share/{appName}/board.json on Linux).

  Write pattern: tmp file + atomic rename, debounced 400ms. A crash mid-write can't corrupt the existing file; worst
  case you lose ~400ms of recent edits.

  Read pattern: load on app start, gate the Canvas render on the result. Missing file → default welcome board. Parse
  error → log and fall back to default (won't overwrite the bad file until the user makes changes; actually it will save
   over it after the next change — if you want to preserve a corrupt file for recovery that's a one-line tweak).

  Terminal caveat: live PTY processes die with the app session, so sanitize() in App.tsx clears every terminal card's
  ptyId on load. Each terminal card respawns a fresh shell on mount via the existing pty.spawn path. The card's
  position, size, and title are preserved.

src-tauri/src/lib.rs

@@ -1,6 +1,8 @@
 mod pty;
+mod storage;
 
 use pty::{pty_kill, pty_resize, pty_spawn, pty_write, PtyState};
+use storage::{board_load, board_save};
 
 #[cfg_attr(mobile, tauri::mobile_entry_point)]
 pub fn run() {
@@ -33,6 +35,8 @@ pub fn run() {
             pty_write,
             pty_resize,
             pty_kill,
+            board_save,
+            board_load,
         ])
         .run(tauri::generate_context!())
         .expect("error while running tauri application");