Add a preferred language dropdown

src/core/Cline.ts

@@ -769,8 +769,8 @@ export class Cline {
 			throw new Error("MCP hub not available")
 		}
 
-		const { browserLargeViewport } = await this.providerRef.deref()?.getState() ?? {}
-		const systemPrompt = await SYSTEM_PROMPT(cwd, this.api.getModel().info.supportsComputerUse ?? false, mcpHub, this.diffStrategy, browserLargeViewport) + await addCustomInstructions(this.customInstructions ?? '', cwd)
+		const { browserLargeViewport, preferredLanguage } = await this.providerRef.deref()?.getState() ?? {}
+		const systemPrompt = await SYSTEM_PROMPT(cwd, this.api.getModel().info.supportsComputerUse ?? false, mcpHub, this.diffStrategy, browserLargeViewport) + await addCustomInstructions(this.customInstructions ?? '', cwd, preferredLanguage)
 
 		// If the previous API request's total token usage is close to the context window, truncate the conversation history to free up space for the new request
 		if (previousApiReqIndex >= 0) {

src/core/prompts/system.ts

@@ -772,9 +772,17 @@ async function loadRuleFiles(cwd: string): Promise<string> {
     return combinedRules
 }
 
-export async function addCustomInstructions(customInstructions: string, cwd: string): Promise<string> {
+export async function addCustomInstructions(customInstructions: string, cwd: string, preferredLanguage?: string): Promise<string> {
     const ruleFileContent = await loadRuleFiles(cwd)
-    const allInstructions = [customInstructions.trim()]
+    const allInstructions = []
+
+    if (preferredLanguage) {
+        allInstructions.push(`You should always speak and think in the ${preferredLanguage} language.`)
+    }
+    
+    if (customInstructions.trim()) {
+        allInstructions.push(customInstructions.trim())
+    }
 
     if (ruleFileContent && ruleFileContent.trim()) {
         allInstructions.push(ruleFileContent.trim())

src/core/webview/ClineProvider.ts

@@ -71,6 +71,7 @@ type GlobalStateKey =
 	| "alwaysAllowMcp"
 	| "browserLargeViewport"
 	| "fuzzyMatchThreshold"
+	| "preferredLanguage" // Language setting for Cline's communication
 
 export const GlobalFileNames = {
 	apiConversationHistory: "api_conversation_history.json",
@@ -622,6 +623,10 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 						await this.updateGlobalState("fuzzyMatchThreshold", message.value)
 						await this.postStateToWebview()
 						break
+					case "preferredLanguage":
+						await this.updateGlobalState("preferredLanguage", message.text)
+						await this.postStateToWebview()
+						break
 				}
 			},
 			null,
@@ -951,6 +956,7 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 			taskHistory,
 			soundVolume,
 			browserLargeViewport,
+			preferredLanguage,
 		} = await this.getState()
 		
 		const allowedCommands = vscode.workspace
@@ -977,6 +983,7 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 			allowedCommands,
 			soundVolume: soundVolume ?? 0.5,
 			browserLargeViewport: browserLargeViewport ?? false,
+			preferredLanguage: preferredLanguage ?? 'English',
 		}
 	}
 
@@ -1072,6 +1079,7 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 			soundVolume,
 			browserLargeViewport,
 			fuzzyMatchThreshold,
+			preferredLanguage,
 		] = await Promise.all([
 			this.getGlobalState("apiProvider") as Promise<ApiProvider | undefined>,
 			this.getGlobalState("apiModelId") as Promise<string | undefined>,
@@ -1112,6 +1120,7 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 			this.getGlobalState("soundVolume") as Promise<number | undefined>,
 			this.getGlobalState("browserLargeViewport") as Promise<boolean | undefined>,
 			this.getGlobalState("fuzzyMatchThreshold") as Promise<number | undefined>,
+			this.getGlobalState("preferredLanguage") as Promise<string | undefined>,
 		])
 
 		let apiProvider: ApiProvider
@@ -1170,6 +1179,27 @@ export class ClineProvider implements vscode.WebviewViewProvider {
 			soundVolume,
 			browserLargeViewport: browserLargeViewport ?? false,
 			fuzzyMatchThreshold: fuzzyMatchThreshold ?? 1.0,
+			preferredLanguage: preferredLanguage ?? (() => {
+				// Get VSCode's locale setting
+				const vscodeLang = vscode.env.language;
+				// Map VSCode locale to our supported languages
+				const langMap: { [key: string]: string } = {
+					'en': 'English',
+					'es': 'Spanish',
+					'fr': 'French',
+					'de': 'German',
+					'it': 'Italian',
+					'pt': 'Portuguese',
+					'zh': 'Chinese',
+					'ja': 'Japanese',
+					'ko': 'Korean',
+					'ru': 'Russian',
+					'ar': 'Arabic',
+					'hi': 'Hindi'
+				};
+				// Return mapped language or default to English
+				return langMap[vscodeLang.split('-')[0]] ?? 'English';
+			})(),
 		}
 	}
 

src/core/webview/__tests__/ClineProvider.test.ts

@@ -73,7 +73,8 @@ jest.mock('vscode', () => ({
         onDidCloseTextDocument: jest.fn(() => ({ dispose: jest.fn() }))
     },
     env: {
-        uriScheme: 'vscode'
+        uriScheme: 'vscode',
+        language: 'en'
     }
 }))
 
@@ -235,6 +236,7 @@ describe('ClineProvider', () => {
         
         const mockState: ExtensionState = {
             version: '1.0.0',
+            preferredLanguage: 'English',
             clineMessages: [],
             taskHistory: [],
             shouldShowAnnouncement: false,
@@ -248,7 +250,7 @@ describe('ClineProvider', () => {
             alwaysAllowBrowser: false,
             uriScheme: 'vscode',
             soundEnabled: false,
-            diffEnabled: false
+            diffEnabled: false,
         }
         
         const message: ExtensionMessage = { 
@@ -300,6 +302,22 @@ describe('ClineProvider', () => {
         expect(state).toHaveProperty('diffEnabled')
     })
 
+    test('preferredLanguage defaults to VSCode language when not set', async () => {
+        // Mock VSCode language as Spanish
+        (vscode.env as any).language = 'es-ES';
+        
+        const state = await provider.getState();
+        expect(state.preferredLanguage).toBe('Spanish');
+    });
+
+    test('preferredLanguage defaults to English for unsupported VSCode language', async () => {
+        // Mock VSCode language as an unsupported language
+        (vscode.env as any).language = 'unsupported-LANG';
+        
+        const state = await provider.getState();
+        expect(state.preferredLanguage).toBe('English');
+    });
+
     test('diffEnabled defaults to true when not set', async () => {
         // Mock globalState.get to return undefined for diffEnabled
         (mockContext.globalState.get as jest.Mock).mockReturnValue(undefined)