fix: selector overflow for 10+ items, drag-drop status guard, filename claim set for parallel safety

- Queue selector uses min-width instead of fixed width for double-digit numbers
- Drag-start handler validates item is still pending before allowing drag
- ensureUniqueFilename uses in-memory claim set to prevent TOCTOU race

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/main.ts

@@ -685,20 +685,26 @@ function formatDurationDashed(seconds: number): string {
     return `${h.toString().padStart(2, '0')}-${m.toString().padStart(2, '0')}-${s.toString().padStart(2, '0')}`;
 }
 
+const claimedFilenames = new Set<string>();
+
 function ensureUniqueFilename(filePath: string): string {
-    if (!fs.existsSync(filePath)) return filePath;
     const dir = path.dirname(filePath);
     const ext = path.extname(filePath);
     const base = path.basename(filePath, ext);
-    let counter = 1;
     let candidate = filePath;
-    while (fs.existsSync(candidate)) {
-        candidate = path.join(dir, `${base}_${counter}${ext}`);
+    let counter = 0;
+    while (fs.existsSync(candidate) || claimedFilenames.has(candidate)) {
         counter++;
+        candidate = path.join(dir, `${base}_${counter}${ext}`);
     }
+    claimedFilenames.add(candidate);
     return candidate;
 }
 
+function releaseClaimedFilename(filePath: string): void {
+    claimedFilenames.delete(filePath);
+}
+
 function sanitizeFilenamePart(input: string, fallback = 'unnamed'): string {
     const cleaned = (input || '')
         .replace(/[<>:"|?*\x00-\x1f]/g, '_')

src/renderer-queue.ts

@@ -216,6 +216,15 @@ function initQueueDragDrop(): void {
     list.addEventListener('dragstart', (e: DragEvent) => {
         const el = (e.target as HTMLElement).closest('.queue-item') as HTMLElement;
         if (!el) return;
+        // Prevent dragging items that are no longer pending (race window between status change and re-render)
+        const itemId = el.dataset.id;
+        if (itemId) {
+            const item = queue.find(i => i.id === itemId);
+            if (!item || item.status !== 'pending') {
+                e.preventDefault();
+                return;
+            }
+        }
         draggedQueueItemId = el.dataset.id || null;
         el.classList.add('dragging');
         if (e.dataTransfer) e.dataTransfer.effectAllowed = 'move';

src/styles.css

@@ -358,8 +358,9 @@ body {
 }
 
 .queue-selector {
-    width: 22px;
+    min-width: 22px;
     height: 22px;
+    padding: 0 3px;
     border: 2px solid var(--text-secondary);
     border-radius: 4px;
     cursor: pointer;
@@ -367,7 +368,7 @@ body {
     display: flex;
     align-items: center;
     justify-content: center;
-    font-size: 12px;
+    font-size: 11px;
     font-weight: 700;
     color: var(--bg-primary);
     user-select: none;