Verify download completeness by comparing file sizes

__init__.py

@@ -559,6 +559,39 @@ async def cancel_download(request):
         return web.json_response({"error": str(e)}, status=500)
 
 
+@PromptServer.instance.routes.post(f"/{API_PREFIX}/server_download/local_filesize")
+async def get_local_filesize(request):
+    """Get local file size to verify download completeness"""
+    try:
+        data = await request.json()
+        save_path = data.get("save_path", "").strip()
+        filename = data.get("filename", "").strip()
+
+        if not save_path or not filename:
+            return web.json_response({"error": "Missing save_path or filename"}, status=400)
+
+        mapped_folder = folder_paths.map_legacy(save_path)
+        if mapped_folder not in folder_paths.folder_names_and_paths:
+            return web.json_response({"success": True, "size": -1})
+
+        paths, _ = folder_paths.folder_names_and_paths[mapped_folder]
+        if not paths:
+            return web.json_response({"success": True, "size": -1})
+
+        # Search for the file in all configured paths
+        for path in paths:
+            file_path = os.path.join(path, filename)
+            resolved = os.path.realpath(file_path)
+            if os.path.isfile(resolved):
+                local_size = os.path.getsize(resolved)
+                return web.json_response({"success": True, "size": local_size})
+
+        return web.json_response({"success": True, "size": -1})
+    except Exception as e:
+        logging.error(f"[ComfyUI-Downloader] Error getting local filesize: {e}")
+        return web.json_response({"error": str(e)}, status=500)
+
+
 @PromptServer.instance.routes.get(f"/{API_PREFIX}/supported_extensions")
 async def get_supported_extensions(request):
     """Get supported model file extensions from folder_paths"""

web/js/UI.js

@@ -132,6 +132,27 @@ export class DownloaderUI {
         }
     }
 
+    /**
+     * Fetch local file size for a given save_path and filename
+     */
+    async fetchLocalFileSize(savePath, filename) {
+        if (!savePath || !filename) return -1;
+        try {
+            const response = await api.fetchApi(`/${API_PREFIX}/server_download/local_filesize`, {
+                method: "POST",
+                headers: { "Content-Type": "application/json" },
+                body: JSON.stringify({ save_path: savePath, filename })
+            });
+            if (!response.ok) return -1;
+            const data = await response.json();
+            if (data.success) return data.size;
+            return -1;
+        } catch (error) {
+            console.warn("[DownloaderUI] Error fetching local file size:", error);
+            return -1;
+        }
+    }
+
     /**
      * Start a server download
      */
@@ -838,11 +859,33 @@ export class DownloaderUI {
             const modelIndex = parseInt(button.dataset.modelIndex);
             const model = this.modelsInWorkflow[modelIndex];
 
-            // Check if file already exists in ComfyUI
+            // Check if file already exists in ComfyUI and verify completeness
             const fileExists = await this.isFileDownloaded(model.directory || '', model.filenamePath);
             if (fileExists) {
-                button.textContent = '✓ Downloaded';
-                button.style.backgroundColor = '#4CAF50';
+                const sizeSpan = listContainer.querySelector(`.downloader-filesize[data-model-index="${modelIndex}"]`);
+                const url = model.url || '';
+
+                if (url && model.directory) {
+                    // Fetch remote and local sizes in parallel to verify completeness
+                    const [remoteSize, localSize] = await Promise.all([
+                        this.fetchFileSize(url),
+                        this.fetchLocalFileSize(model.directory, model.filenamePath)
+                    ]);
+
+                    if (remoteSize && localSize > 0 && localSize < remoteSize) {
+                        button.textContent = '⚠ Incomplete';
+                        button.style.backgroundColor = '#FF9800';
+                        button.title = `Local: ${this.formatFileSize(localSize)} / Remote: ${this.formatFileSize(remoteSize)}`;
+                        if (sizeSpan) sizeSpan.textContent = `${this.formatFileSize(localSize)} / ${this.formatFileSize(remoteSize)}`;
+                    } else {
+                        button.textContent = '✓ Downloaded';
+                        button.style.backgroundColor = '#4CAF50';
+                        if (sizeSpan && remoteSize) sizeSpan.textContent = this.formatFileSize(remoteSize) || '';
+                    }
+                } else {
+                    button.textContent = '✓ Downloaded';
+                    button.style.backgroundColor = '#4CAF50';
+                }
                 button.disabled = false;
             }