G2.2: flush bridge state to disk before kill (control type=5 DUMP + Rust pre-kill)

src-tauri/src/lib.rs

@@ -44,10 +44,26 @@ fn set_bridge_child(app: &AppHandle, child: Option<CommandChild>) {
     }
 }
 
+/// G2.2: ask the bridge to flush its state file NOW (control type=5
+/// DUMP_STATE), then give the UiThread save job ~300ms to finish before
+/// the process is killed. Harmless when the bridge is already hung (SHM
+/// is owned by Rust; the control is simply never consumed).
+fn flush_bridge_state(app: &AppHandle) {
+    if let Some(state) = app.try_state::<ShmState>() {
+        if let Ok(guard) = state.0.lock() {
+            if let Some(shm) = guard.as_ref() {
+                let _ = shm.push_control(5, 0, 0, 0, "");
+            }
+        }
+    }
+    std::thread::sleep(std::time::Duration::from_millis(300));
+}
+
 /// Kill the currently managed bridge child (if any) — a restart MUST never
 /// leave the old bridge running, else two daw_vst_bridge.exe race on the same
 /// SHM (double instrument load, double OPEN_GUI, garbled control queue).
 fn kill_bridge(app: &AppHandle) -> bool {
+    flush_bridge_state(app);
     let state = app.state::<BridgeProcess>();
     let mut guard = match state.0.lock() {
         Ok(g) => g,
@@ -530,6 +546,8 @@ pub fn run() {
                     let _ = child.kill();
                     println!("daw_engine sidecar terminated.");
                 }
+                // G2.2: flush state to disk before killing the bridge
+                flush_bridge_state(window.app_handle());
                 // Terminate Native Host Bridge khi DAW window dong
                 let bridge_child = window
                     .state::<BridgeProcess>()