Guard poll() against a mode-apply mid-flight; two doc corrections

Extends the OnTimer guard to skip session.poll() itself while modeApplyInProgress(), preventing an undo/redo or project-switch reload from replacing the view model under an in-flight applyMode.

src/app/main.cpp

@@ -180,7 +180,13 @@ static void OnTimer()
     // the idle fast-path is a SINGLE POINTER TEST — drive only when a capture is live.
     if (capture::g_rtCapture) capture::DriveRealtimeCapture(g_session);
 
-    g_session.poll();
+    // poll()'s undo/redo-reload and project-switch Load branches call
+    // loadFromProject, replacing g_session.view() wholesale — deferred here while
+    // an applyMode is on the stack (reachable if a pumped message loop re-enters
+    // this timer mid-apply), same retry-next-tick shape as the consume guard below.
+    // Deferred WHOLE, not just the reload branches: poll()'s identity tracking is
+    // cheap to skip for one tick and resumes correctly, unlatched, on the next.
+    if (!reasampler::modeApplyInProgress()) g_session.poll();
 
     // persist stays MODEL-ONLY (loads the saved view model but does not apply
     // visibility, to avoid coupling persist to the view shell); poll() raises a