feat(renderer): useExportSource hook (shared by export dialogs)

src/renderer/hooks/use-export-source.ts

@@ -0,0 +1,26 @@
+import { useFileStore } from '@/stores/file-store';
+import { useEditorStore } from '@/stores/editor-store';
+
+export interface ExportSource {
+  source: string;
+  path: string;
+  title: string;
+}
+
+/**
+ * Read the active buffer's content from the editor store. Returns null if
+ * no buffer is open. Components handle the null case (prompt to open a file).
+ */
+export function useExportSource(): ExportSource | null {
+  const activeTabId = useFileStore((s) => s.activeTabId);
+  const openTabs = useFileStore((s) => s.openTabs);
+  const buffer = useEditorStore((s) => (activeTabId ? s.buffers.get(activeTabId) : undefined));
+
+  if (!activeTabId || !buffer) return null;
+  const tab = openTabs.find((t) => t.id === activeTabId);
+  return {
+    source: buffer.content,
+    path: activeTabId,
+    title: tab?.title ?? activeTabId,
+  };
+}