Buffer startup drops until renderer readiness

Keep a bounded FIFO of drop payloads while the startup or recovery document is not validated. Flush each payload exactly once only after the generation-checked renderer Ready signal, retain immediate delivery for a ready renderer, and discard stale payloads when the main window is destroyed or replaced.

Wire renderer block, Ready, and window-close transitions through main and cover recovery, safe failure visibility, stale Ready signals, ordered multi-drop delivery, queue bounds, lifecycle cleanup, and duplicate prevention.

lib/startup-renderer.js

@@ -75,29 +75,95 @@ function createStartupRevealGate(window, { onBlock } = {}) {
   return { block, navigate, request, reveal };
 }
 
-function createStartupExternalRevealBindings({ getWindow, getRevealGate, sendDroppedFiles }) {
+function createStartupExternalRevealBindings({
+  getWindow,
+  getRevealGate,
+  sendDroppedFiles,
+  maxPendingDropPayloads = 32
+}) {
+  const pendingDropPayloads = [];
+  const pendingDropLimit = Number.isSafeInteger(maxPendingDropPayloads) && maxPendingDropPayloads > 0
+    ? maxPendingDropPayloads
+    : 32;
+  let pendingWindow = null;
+  let readyWindow = null;
+
+  function clearPendingDropPayloads(window) {
+    if (window && pendingWindow !== window) return false;
+    pendingDropPayloads.length = 0;
+    pendingWindow = null;
+    return true;
+  }
+
+  function clearWindowState(window) {
+    clearPendingDropPayloads(window);
+    if (!window || readyWindow === window) readyWindow = null;
+  }
+
   function getActiveWindow() {
     const window = getWindow();
-    if (!window || (typeof window.isDestroyed === 'function' && window.isDestroyed())) return null;
+    if (!window || (typeof window.isDestroyed === 'function' && window.isDestroyed())) {
+      clearWindowState();
+      return null;
+    }
+    if (pendingWindow && pendingWindow !== window) clearPendingDropPayloads();
+    if (readyWindow && readyWindow !== window) readyWindow = null;
     return window;
   }
 
   function requestReveal() {
-    if (!getActiveWindow()) return false;
+    const activeWindow = getActiveWindow();
+    if (!activeWindow) return false;
     const revealGate = getRevealGate();
     if (!revealGate || typeof revealGate.request !== 'function') return false;
     revealGate.request();
     return true;
   }
 
+  function queueDropPayload(window, paths) {
+    if (pendingWindow && pendingWindow !== window) clearPendingDropPayloads();
+    pendingWindow = window;
+    if (pendingDropPayloads.length >= pendingDropLimit) pendingDropPayloads.shift();
+    pendingDropPayloads.push(paths);
+  }
+
   function handleDropTargetFiles(_event, paths) {
     const window = getActiveWindow();
     if (!window) return false;
     if (!window.isVisible() || window.isMinimized()) requestReveal();
-    sendDroppedFiles(paths);
+    if (readyWindow === window) sendDroppedFiles(paths);
+    else queueDropPayload(window, paths);
     return true;
   }
 
+  function rendererBlocked(window) {
+    const activeWindow = getActiveWindow();
+    if (!activeWindow || activeWindow !== window) {
+      clearWindowState(window);
+      return false;
+    }
+    readyWindow = null;
+    return true;
+  }
+
+  function rendererReady(window) {
+    const activeWindow = getActiveWindow();
+    if (!activeWindow || activeWindow !== window) {
+      clearWindowState(window);
+      return false;
+    }
+    readyWindow = window;
+    if (pendingWindow !== window) return true;
+    const payloads = pendingDropPayloads.splice(0);
+    pendingWindow = null;
+    for (const paths of payloads) sendDroppedFiles(paths);
+    return true;
+  }
+
+  function windowClosed(window) {
+    clearWindowState(window);
+  }
+
   return {
     bindSecondInstance(app) {
       app.on('second-instance', requestReveal);
@@ -110,7 +176,10 @@ function createStartupExternalRevealBindings({ getWindow, getRevealGate, sendDro
     },
     bindDropTargetFiles(ipcMain) {
       ipcMain.on('drop-target:files', handleDropTargetFiles);
-    }
+    },
+    rendererBlocked,
+    rendererReady,
+    windowClosed
   };
 }