open diff views in beside column to preserve user's work

Open diff editors in ViewColumn.Beside instead of the current column
to avoid hiding the user's active editor. Previously, diffs would
replace the visible tab in the same editor group despite preserveFocus.

- Add viewColumn parameter to showTextDocument and vscode.diff commands
- Remove outdated comments explaining the previous behavior limitation

.changeset/eager-facts-shave.md

@@ -0,0 +1,5 @@
+---
+"claude-dev": patch
+---
+
+Preserves user's editor focus when diff editor is opened.

src/hosts/vscode/VscodeDiffViewProvider.ts

@@ -23,7 +23,9 @@ export class VscodeDiffViewProvider extends DiffViewProvider {
 		const tabs = vscode.window.tabGroups.all
 			.flatMap((tg) => tg.tabs)
 			.filter((tab) => tab.input instanceof vscode.TabInputText && arePathsEqual(tab.input.uri.fsPath, this.absolutePath))
+
 		for (const tab of tabs) {
+			const isInDiffViewScheme = tab.input instanceof vscode.TabInputText && tab.input.uri.scheme === DIFF_VIEW_URI_SCHEME
 			if (!tab.isDirty) {
 				try {
 					await vscode.window.tabGroups.close(tab)
@@ -31,7 +33,9 @@ export class VscodeDiffViewProvider extends DiffViewProvider {
 					console.warn("Tab close retry failed:", error.message)
 				}
 			}
-			this.documentWasOpen = true
+			if (isInDiffViewScheme) {
+				this.documentWasOpen = true
+			}
 		}
 
 		const uri = vscode.Uri.file(this.absolutePath)
@@ -45,22 +49,32 @@ export class VscodeDiffViewProvider extends DiffViewProvider {
 					arePathsEqual(tab.input.modified.fsPath, uri.fsPath),
 			)
 
+		// Always open in beside column to avoid hiding the user's current work
+		const viewColumn = vscode.ViewColumn.Beside
+
 		if (diffTab && diffTab.input instanceof vscode.TabInputTextDiff) {
 			// Use already open diff editor.
 			this.activeDiffEditor = await vscode.window.showTextDocument(diffTab.input.modified, {
 				preserveFocus: true,
+				viewColumn,
 			})
 		} else {
 			// Open new diff editor.
+			// Always use preserveFocus: true to avoid stealing focus from the user's current editor.
+			// We use onDidChangeVisibleTextEditors to detect when the diff editor becomes visible,
+			// since onDidChangeActiveTextEditor won't fire when preserveFocus is true.
 			this.activeDiffEditor = await new Promise<vscode.TextEditor>((resolve, reject) => {
 				const fileName = path.basename(uri.fsPath)
 				const fileExists = this.editType === "modify"
-				const disposable = vscode.window.onDidChangeActiveTextEditor((editor) => {
-					if (editor && arePathsEqual(editor.document.uri.fsPath, uri.fsPath)) {
+
+				const disposable = vscode.window.onDidChangeVisibleTextEditors((editors) => {
+					const editor = editors.find((e) => e.document && arePathsEqual(e.document.uri.fsPath, uri.fsPath))
+					if (editor) {
 						disposable.dispose()
 						resolve(editor)
 					}
 				})
+
 				vscode.commands.executeCommand(
 					"vscode.diff",
 					vscode.Uri.from({
@@ -72,6 +86,7 @@ export class VscodeDiffViewProvider extends DiffViewProvider {
 					`${fileName}: ${fileExists ? "Original ↔ Cline's Changes" : "New File"} (Editable)`,
 					{
 						preserveFocus: true,
+						viewColumn,
 					},
 				)
 				// This may happen on very slow machines ie project idx
@@ -81,7 +96,6 @@ export class VscodeDiffViewProvider extends DiffViewProvider {
 				}, 10_000)
 			})
 		}
-
 		this.fadedOverlayController = new DecorationController("fadedOverlay", this.activeDiffEditor)
 		this.activeLineController = new DecorationController("activeLine", this.activeDiffEditor)
 		// Apply faded overlay to all lines initially
@@ -96,9 +110,13 @@ export class VscodeDiffViewProvider extends DiffViewProvider {
 		if (!this.activeDiffEditor || !this.activeDiffEditor.document) {
 			throw new Error("User closed text editor, unable to edit file...")
 		}
-		// Place cursor at the beginning of the diff editor to keep it out of the way of the stream animation
-		const beginningOfDocument = new vscode.Position(0, 0)
-		this.activeDiffEditor.selection = new vscode.Selection(beginningOfDocument, beginningOfDocument)
+		// Only update cursor position if the diff editor is currently active to avoid stealing focus
+		const isActiveDiffEditorFocused = vscode.window.activeTextEditor === this.activeDiffEditor
+		if (isActiveDiffEditorFocused) {
+			// Place cursor at the beginning of the diff editor to keep it out of the way of the stream animation
+			const beginningOfDocument = new vscode.Position(0, 0)
+			this.activeDiffEditor.selection = new vscode.Selection(beginningOfDocument, beginningOfDocument)
+		}
 
 		// Replace the text in the diff editor document.
 		const document = this.activeDiffEditor?.document

src/integrations/editor/DiffViewProvider.ts

@@ -224,8 +224,8 @@ export abstract class DiffViewProvider {
 		}
 	}
 
-	async showFile(absolutePath: string): Promise<void> {
-		await openFile(absolutePath, true)
+	async showFile(absolutePath: string, preserveFocus: boolean = false): Promise<void> {
+		await openFile(absolutePath, preserveFocus)
 	}
 
 	/**
@@ -268,7 +268,11 @@ export abstract class DiffViewProvider {
 		// get text after save in case there is any auto-formatting done by the editor
 		const postSaveContent = (await this.getDocumentText()) || ""
 
-		await this.showFile(this.absolutePath)
+		// Only show the file if it was already open before we started editing
+		// This avoids forcing the user back to a file they may have navigated away from
+		if (this.documentWasOpen) {
+			await this.showFile(this.absolutePath, true)
+		}
 		await this.closeAllDiffViews()
 
 		const newProblems = await this.getNewDiagnosticProblems()