Add cloud path handling for thumbnail generation

- Introduce is_cloud_path and to_backend_path helpers - Handle cloud vs
local paths in thumbnail generation - Download cloud files to a temp
file via the volume backend - Use backend-relative paths and clean up
the temp file after use - Slightly adjust dev-scAN comment block to
delay initialization (still disabled)

apps/tauri/src/App.tsx

@@ -29,9 +29,11 @@ function App() {
     // React Scan disabled - too heavy for development
     // Uncomment if you need to debug render performance:
     // if (import.meta.env.DEV) {
-    //   import("react-scan").then(({ scan }) => {
-    //     scan({ enabled: true, log: false });
-    //   });
+    //   setTimeout(() => {
+    //     import("react-scan").then(({ scan }) => {
+    //       scan({ enabled: true, log: false });
+    //     });
+    //   }, 2000);
     // }
 
     // Initialize Tauri native context menu handler

core/src/ops/media/thumbnail/job.rs

@@ -518,6 +518,33 @@ impl ThumbnailJob {
 		Ok(())
 	}
 
+	/// Strip cloud URL prefix from path to get backend-relative path
+	fn to_backend_path(path: &str) -> std::path::PathBuf {
+		if let Some(after_scheme) = path.strip_prefix("s3://") {
+			// Strip s3://bucket/ prefix to get just the key
+			if let Some(slash_pos) = after_scheme.find('/') {
+				let key = &after_scheme[slash_pos + 1..];
+				return std::path::PathBuf::from(key);
+			}
+		}
+		// Add support for other cloud services if needed
+		// For now, return as-is for local paths
+		std::path::PathBuf::from(path)
+	}
+
+	/// Check if a path is a cloud path (starts with a cloud scheme)
+	fn is_cloud_path(path: &str) -> bool {
+		path.starts_with("s3://")
+			|| path.starts_with("gdrive://")
+			|| path.starts_with("dropbox://")
+			|| path.starts_with("onedrive://")
+			|| path.starts_with("gcs://")
+			|| path.starts_with("azblob://")
+			|| path.starts_with("b2://")
+			|| path.starts_with("wasabi://")
+			|| path.starts_with("spaces://")
+	}
+
 	/// Generate thumbnails for a single entry
 	async fn generate_thumbnails_for_entry_static(
 		entry: &ThumbnailEntry,
@@ -564,12 +591,65 @@ impl ThumbnailJob {
 		// Create appropriate generator for the file type
 		let generator = ThumbnailGenerator::for_mime_type(mime_type)?;
 
-		// Get the full path to the source file
-		let source_path = library.path().join(&entry.relative_path);
+		// Check if this is a cloud path or local path
+		let is_cloud = Self::is_cloud_path(&entry.relative_path);
 
-		if !source_path.exists() {
-			return Err(ThumbnailError::FileNotFound(entry.relative_path.clone()));
-		}
+		// For cloud files, download to temp file. For local files, use direct path
+		let (source_path, temp_file): (std::path::PathBuf, Option<tempfile::NamedTempFile>) = if is_cloud {
+			// Cloud path - need to download via volume backend
+			let volume_manager = ctx.volume_manager()
+				.ok_or_else(|| ThumbnailError::other("VolumeManager not available for cloud file"))?;
+
+			// Parse the cloud path to get an SdPath
+			use crate::domain::addressing::SdPath;
+			let sdpath = SdPath::from_uri_with_context(&entry.relative_path, &library.core_context())
+				.await
+				.map_err(|e| ThumbnailError::other(format!("Failed to parse cloud path: {}", e)))?;
+
+			// Resolve the volume backend for this path
+			let volume = volume_manager
+				.resolve_volume_for_sdpath(&sdpath, &library)
+				.await
+				.map_err(|e| ThumbnailError::other(format!("Failed to resolve volume: {}", e)))?
+				.ok_or_else(|| ThumbnailError::other("No volume found for cloud path"))?;
+
+			let backend = volume.backend
+				.as_ref()
+				.ok_or_else(|| ThumbnailError::other("Volume has no backend"))?;
+
+			// Get the backend-relative path (strip s3://bucket/ prefix)
+			let backend_path = Self::to_backend_path(&entry.relative_path);
+
+			// Download file content from cloud
+			let file_data = backend
+				.read(&backend_path)
+				.await
+				.map_err(|e| ThumbnailError::other(format!("Failed to read cloud file: {}", e)))?;
+
+			// Write to temporary file
+			let mut temp = tempfile::NamedTempFile::new()
+				.map_err(|e| ThumbnailError::other(format!("Failed to create temp file: {}", e)))?;
+
+			use std::io::Write;
+			temp.write_all(&file_data)
+				.map_err(|e| ThumbnailError::other(format!("Failed to write temp file: {}", e)))?;
+			temp.flush()
+				.map_err(|e| ThumbnailError::other(format!("Failed to flush temp file: {}", e)))?;
+
+			let temp_path = temp.path().to_path_buf();
+			ctx.log(format!("Downloaded cloud file {} to temp location", entry.relative_path));
+
+			(temp_path, Some(temp))
+		} else {
+			// Local path - use direct filesystem access
+			let source_path = library.path().join(&entry.relative_path);
+
+			if !source_path.exists() {
+				return Err(ThumbnailError::FileNotFound(entry.relative_path.clone()));
+			}
+
+			(source_path, None)
+		};
 
 		let mut total_thumbnail_size = 0u64;
 
@@ -778,6 +858,9 @@ impl ThumbnailJob {
 			}
 		}
 
+		// Temp file (if any) is automatically cleaned up when dropped here
+		drop(temp_file);
+
 		Ok(total_thumbnail_size)
 	}
 }