feat: add user-configurable fuzzy match threshold setting

- Add fuzzyMatchThreshold to GlobalSettings schema (0-1 range, optional)
- Update Task class to accept and pass threshold to MultiSearchReplaceDiffStrategy
- Add UI slider control in ContextManagementSettings (80-100% range)
- Add English translations for the new setting

This allows users to adjust how strictly search content must match when
editing files, addressing issues where models like gemini-2-flash-preview
produce output with 89-96% similarity that fails with 100% exact match.

Fixes #11087

Author: roomote

packages/types/src/global-settings.ts

@@ -101,6 +101,17 @@ export const globalSettingsSchema = z.object({
 	alwaysAllowWriteOutsideWorkspace: z.boolean().optional(),
 	alwaysAllowWriteProtected: z.boolean().optional(),
 	writeDelayMs: z.number().min(0).optional(),
+	/**
+	 * Fuzzy match threshold for diff operations.
+	 * Controls how strictly the search content must match the original file content.
+	 * Value between 0 and 1 where:
+	 * - 1.0 (100%) = exact match required (default)
+	 * - 0.9 (90%) = allows minor differences (recommended for some models)
+	 * - 0.8 (80%) = more lenient matching
+	 * Lower values allow more flexibility but may increase false positives.
+	 * @default 1.0
+	 */
+	fuzzyMatchThreshold: z.number().min(0).max(1).optional(),
 	alwaysAllowBrowser: z.boolean().optional(),
 	requestDelaySeconds: z.number().optional(),
 	alwaysAllowMcp: z.boolean().optional(),

src/core/task/Task.ts

@@ -159,6 +159,13 @@ export interface TaskOptions extends CreateTaskOptions {
 	workspacePath?: string
 	/** Initial status for the task's history item (e.g., "active" for child tasks) */
 	initialStatus?: "active" | "delegated" | "completed"
+	/**
+	 * Fuzzy match threshold for diff operations (0-1).
+	 * 1.0 = exact match required (default)
+	 * 0.9 = 90% similarity (recommended for some models)
+	 * @default 1.0
+	 */
+	fuzzyMatchThreshold?: number
 }
 
 export class Task extends EventEmitter<TaskEvents> implements TaskLike {
@@ -565,6 +572,7 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 		initialTodos,
 		workspacePath,
 		initialStatus,
+		fuzzyMatchThreshold,
 	}: TaskOptions) {
 		super()
 
@@ -683,8 +691,8 @@ export class Task extends EventEmitter<TaskEvents> implements TaskLike {
 		// Listen for provider profile changes to update parser state
 		this.setupProviderProfileChangeListener(provider)
 
-		// Set up diff strategy
-		this.diffStrategy = new MultiSearchReplaceDiffStrategy()
+		// Set up diff strategy with optional fuzzy match threshold
+		this.diffStrategy = new MultiSearchReplaceDiffStrategy(fuzzyMatchThreshold)
 
 		this.toolRepetitionDetector = new ToolRepetitionDetector(this.consecutiveMistakeLimit)
 

src/core/webview/ClineProvider.ts

@@ -969,8 +969,15 @@ export class ClineProvider
 			}
 		}
 
-		const { apiConfiguration, enableCheckpoints, checkpointTimeout, experiments, cloudUserInfo, taskSyncEnabled } =
-			await this.getState()
+		const {
+			apiConfiguration,
+			enableCheckpoints,
+			checkpointTimeout,
+			experiments,
+			cloudUserInfo,
+			taskSyncEnabled,
+			fuzzyMatchThreshold,
+		} = await this.getState()
 
 		const task = new Task({
 			provider: this,
@@ -980,6 +987,7 @@ export class ClineProvider
 			consecutiveMistakeLimit: apiConfiguration.consecutiveMistakeLimit,
 			historyItem,
 			experiments,
+			fuzzyMatchThreshold,
 			rootTask: historyItem.rootTask,
 			parentTask: historyItem.parentTask,
 			taskNumber: historyItem.number,
@@ -2877,6 +2885,7 @@ export class ClineProvider
 			experiments,
 			cloudUserInfo,
 			remoteControlEnabled,
+			fuzzyMatchThreshold,
 		} = await this.getState()
 
 		// Single-open-task invariant: always enforce for user-initiated top-level tasks
@@ -2901,6 +2910,7 @@ export class ClineProvider
 			task: text,
 			images,
 			experiments,
+			fuzzyMatchThreshold,
 			rootTask: this.clineStack.length > 0 ? this.clineStack[0] : undefined,
 			parentTask,
 			taskNumber: this.clineStack.length + 1,

webview-ui/src/components/settings/ContextManagementSettings.tsx

@@ -39,6 +39,7 @@ type ContextManagementSettingsProps = HTMLAttributes<HTMLDivElement> & {
 	includeDiagnosticMessages?: boolean
 	maxDiagnosticMessages?: number
 	writeDelayMs: number
+	fuzzyMatchThreshold?: number
 	includeCurrentTime?: boolean
 	includeCurrentCost?: boolean
 	maxGitStatusFiles?: number
@@ -57,6 +58,7 @@ type ContextManagementSettingsProps = HTMLAttributes<HTMLDivElement> & {
 		| "includeDiagnosticMessages"
 		| "maxDiagnosticMessages"
 		| "writeDelayMs"
+		| "fuzzyMatchThreshold"
 		| "includeCurrentTime"
 		| "includeCurrentCost"
 		| "maxGitStatusFiles"
@@ -78,6 +80,7 @@ export const ContextManagementSettings = ({
 	includeDiagnosticMessages,
 	maxDiagnosticMessages,
 	writeDelayMs,
+	fuzzyMatchThreshold,
 	includeCurrentTime,
 	includeCurrentCost,
 	maxGitStatusFiles,
@@ -406,6 +409,29 @@ export const ContextManagementSettings = ({
 					</div>
 				</SearchableSetting>
 
+				<SearchableSetting
+					settingId="context-fuzzy-match-threshold"
+					section="contextManagement"
+					label={t("settings:contextManagement.fuzzyMatchThreshold.label")}>
+					<span className="block font-medium mb-1">
+						{t("settings:contextManagement.fuzzyMatchThreshold.label")}
+					</span>
+					<div className="flex items-center gap-2">
+						<Slider
+							min={80}
+							max={100}
+							step={1}
+							value={[Math.round((fuzzyMatchThreshold ?? 1.0) * 100)]}
+							onValueChange={([value]) => setCachedStateField("fuzzyMatchThreshold", value / 100)}
+							data-testid="fuzzy-match-threshold-slider"
+						/>
+						<span className="w-12">{Math.round((fuzzyMatchThreshold ?? 1.0) * 100)}%</span>
+					</div>
+					<div className="text-vscode-descriptionForeground text-sm mt-1">
+						{t("settings:contextManagement.fuzzyMatchThreshold.description")}
+					</div>
+				</SearchableSetting>
+
 				<SearchableSetting
 					settingId="context-include-current-time"
 					section="contextManagement"

webview-ui/src/components/settings/SettingsView.tsx

@@ -192,6 +192,7 @@ const SettingsView = forwardRef<SettingsViewRef, SettingsViewProps>(({ onDone, t
 		terminalZshP10k,
 		terminalZdotdir,
 		writeDelayMs,
+		fuzzyMatchThreshold,
 		showRooIgnoredFiles,
 		enableSubfolderRules,
 		remoteBrowserEnabled,
@@ -857,6 +858,7 @@ const SettingsView = forwardRef<SettingsViewRef, SettingsViewProps>(({ onDone, t
 								includeDiagnosticMessages={includeDiagnosticMessages}
 								maxDiagnosticMessages={maxDiagnosticMessages}
 								writeDelayMs={writeDelayMs}
+								fuzzyMatchThreshold={fuzzyMatchThreshold}
 								includeCurrentTime={includeCurrentTime}
 								includeCurrentCost={includeCurrentCost}
 								maxGitStatusFiles={maxGitStatusFiles}

webview-ui/src/i18n/locales/en/settings.json

@@ -738,6 +738,10 @@
 				"description": "Time to wait after file writes before proceeding, allowing diagnostic tools to process changes and detect issues."
 			}
 		},
+		"fuzzyMatchThreshold": {
+			"label": "Fuzzy match threshold for file edits",
+			"description": "Controls how strictly the search content must match when editing files. Lower values allow more tolerance for minor formatting differences that some models produce. 100% requires exact match (default), 90% is recommended for models that produce slight variations."
+		},
 		"condensingThreshold": {
 			"label": "Condensing Trigger Threshold",
 			"selectProfile": "Configure threshold for profile",