fix: pass selected language to AI agent when generating flow scripts (#8680)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/lib/components/copilot/chat/AIChatManager.svelte.ts

@@ -227,6 +227,7 @@ class AIChatManager {
 		pendingPrompt?: string,
 		options?: {
 			closeScriptSettings?: boolean
+			lang?: ScriptLang | 'bunnative'
 		}
 	) {
 		if (mode === AIMode.SCRIPT && !tryGetCurrentModel()) return
@@ -235,7 +236,7 @@ class AIChatManager {
 		if (mode === AIMode.SCRIPT) {
 			const currentModel = getCurrentModel()
 			const customPrompt = getCombinedCustomPrompt(mode)
-			const lang = this.scriptEditorOptions?.lang ?? 'bun'
+			const lang = options?.lang ?? this.scriptEditorOptions?.lang ?? 'bun'
 			const context = this.contextManager.getSelectedContext()
 			this.systemMessage = prepareScriptSystemMessage(currentModel, lang, {}, customPrompt)
 			this.systemMessage.content = this.systemMessage.content
@@ -445,10 +446,7 @@ class AIChatManager {
 					if (!pendingPrompt) return undefined
 					this.pendingPrompt = ''
 					if (this.mode === AIMode.SCRIPT) {
-						return prepareScriptUserMessage(
-							pendingPrompt,
-							this.contextManager.getSelectedContext()
-						)
+						return prepareScriptUserMessage(pendingPrompt, this.contextManager.getSelectedContext())
 					} else if (this.mode === AIMode.FLOW) {
 						return prepareFlowUserMessage(
 							pendingPrompt,
@@ -574,9 +572,9 @@ class AIChatManager {
 		} = {}
 	) => {
 		if (options.mode) {
-			this.changeMode(options.mode)
+			this.changeMode(options.mode, undefined, { lang: options.lang })
 		} else {
-			this.changeMode(this.mode)
+			this.changeMode(this.mode, undefined, { lang: options.lang })
 		}
 		if (options.instructions) {
 			this.instructions = options.instructions