fix: add progress indicator for background editing in all file edit tools

When the preventFocusDisruption (Background Editing) experiment is enabled,
file writing operations now display a progress indicator (spinner) in the
chat UI before file operations begin.

This addresses Issue #10504 where users would see no visual feedback while
Roo was preparing and writing files in the background, causing confusion
about whether the app had frozen.

Files updated:
- WriteToFileTool.ts
- ApplyDiffTool.ts
- MultiApplyDiffTool.ts
- SearchAndReplaceTool.ts
- SearchReplaceTool.ts
- EditFileTool.ts

src/core/tools/ApplyDiffTool.ts

@@ -152,6 +152,10 @@ export class ApplyDiffTool extends BaseTool<"apply_diff"> {
 			}
 
 			if (isPreventFocusDisruptionEnabled) {
+				// Show progress indicator in UI while preparing the file
+				const partialMessage = JSON.stringify(sharedMessageProps)
+				await task.ask("tool", partialMessage, true).catch(() => {})
+	
 				// Direct file write without diff view
 				const completeMessage = JSON.stringify({
 					...sharedMessageProps,

src/core/tools/EditFileTool.ts

@@ -276,6 +276,12 @@ export class EditFileTool extends BaseTool<"edit_file"> {
 				diffStats,
 			} satisfies ClineSayTool)
 
+			// Show progress indicator in UI while preparing the file when background editing is enabled
+			if (isPreventFocusDisruptionEnabled) {
+				const partialMessage = JSON.stringify(sharedMessageProps)
+				await task.ask("tool", partialMessage, true).catch(() => {})
+			}
+
 			// Show diff view if focus disruption prevention is disabled
 			if (!isPreventFocusDisruptionEnabled) {
 				await task.diffViewProvider.open(relPath)

src/core/tools/MultiApplyDiffTool.ts

@@ -631,6 +631,10 @@ ${errorDetails ? `\nTechnical details:\n${errorDetails}\n` : ""}
 						await cline.diffViewProvider.update(originalContent!, true)
 						cline.diffViewProvider.scrollToFirstDiff()
 					} else {
+						// Show progress indicator in UI while preparing the file
+						const partialMessage = JSON.stringify(sharedMessageProps)
+						await cline.ask("tool", partialMessage, true).catch(() => {})
+	
 						// For direct save, we still need to set originalContent
 						cline.diffViewProvider.originalContent = await fs.readFile(absolutePath, "utf-8")
 					}

src/core/tools/SearchAndReplaceTool.ts

@@ -211,6 +211,12 @@ export class SearchAndReplaceTool extends BaseTool<"search_and_replace"> {
 				diffStats,
 			} satisfies ClineSayTool)
 
+			// Show progress indicator in UI while preparing the file when background editing is enabled
+			if (isPreventFocusDisruptionEnabled) {
+				const partialMessage = JSON.stringify(sharedMessageProps)
+				await task.ask("tool", partialMessage, true).catch(() => {})
+			}
+
 			// Show diff view if focus disruption prevention is disabled
 			if (!isPreventFocusDisruptionEnabled) {
 				await task.diffViewProvider.open(relPath)

src/core/tools/SearchReplaceTool.ts

@@ -198,6 +198,12 @@ export class SearchReplaceTool extends BaseTool<"search_replace"> {
 				diffStats,
 			} satisfies ClineSayTool)
 
+			// Show progress indicator in UI while preparing the file when background editing is enabled
+			if (isPreventFocusDisruptionEnabled) {
+				const partialMessage = JSON.stringify(sharedMessageProps)
+				await task.ask("tool", partialMessage, true).catch(() => {})
+			}
+
 			// Show diff view if focus disruption prevention is disabled
 			if (!isPreventFocusDisruptionEnabled) {
 				await task.diffViewProvider.open(relPath)

src/core/tools/WriteToFileTool.ts

@@ -116,6 +116,10 @@ export class WriteToFileTool extends BaseTool<"write_to_file"> {
 			)
 
 			if (isPreventFocusDisruptionEnabled) {
+				// Show progress indicator in UI while preparing the file
+				const partialMessage = JSON.stringify(sharedMessageProps)
+				await task.ask("tool", partialMessage, true).catch(() => {})
+	
 				task.diffViewProvider.editType = fileExists ? "modify" : "create"
 				if (fileExists) {
 					const absolutePath = path.resolve(task.cwd, relPath)