fix: improve VLM validation with bug fixes and i18n

- Fix race condition in pendingValidationRef (reject previous pending validation)
- Fix response format consistency (use streaming for all responses)
- Remove dead code (unused lastRequestRef and ValidationRequest interface)
- Consolidate duplicate types (re-export from validation-schema.ts)
- Add 'success_with_warnings' status for valid diagrams with warnings
- Fix tool card auto-collapse (only collapse once, respect user toggle)
- Set VLM validation default to disabled
- Add i18n support for diagram validation settings (en/zh/ja)
- Mark feature as experimental in settings UI

app/api/validate-diagram/route.ts

@@ -25,12 +25,30 @@ const DEFAULT_VALID_RESULT: ValidationResult = {
     suggestions: [],
 }
 
+/**
+ * Create a streaming response for useObject compatibility.
+ * useObject expects text stream format, not plain JSON.
+ */
+function createStreamingResponse(result: ValidationResult): Response {
+    const encoder = new TextEncoder()
+    const stream = new ReadableStream({
+        start(controller) {
+            // Stream the JSON as text (useObject parses this)
+            controller.enqueue(encoder.encode(JSON.stringify(result)))
+            controller.close()
+        },
+    })
+    return new Response(stream, {
+        headers: { "Content-Type": "text/plain; charset=utf-8" },
+    })
+}
+
 export async function POST(req: Request): Promise<Response> {
     try {
         // Check if VLM validation is enabled (default: true)
         const enableValidation = process.env.ENABLE_VLM_VALIDATION !== "false"
         if (!enableValidation) {
-            return Response.json(DEFAULT_VALID_RESULT)
+            return createStreamingResponse(DEFAULT_VALID_RESULT)
         }
 
         const body: ValidateDiagramRequest = await req.json()
@@ -64,7 +82,7 @@ export async function POST(req: Request): Promise<Response> {
                 error,
             )
             // Return valid if no vision model is configured
-            return Response.json(DEFAULT_VALID_RESULT)
+            return createStreamingResponse(DEFAULT_VALID_RESULT)
         }
 
         // Parse timeout with validation (minimum 1000ms, default 10000ms)
@@ -113,6 +131,6 @@ export async function POST(req: Request): Promise<Response> {
         console.error("[validate-diagram] Error:", errorMessage)
 
         // On error, return valid to not block the user
-        return Response.json(DEFAULT_VALID_RESULT)
+        return createStreamingResponse(DEFAULT_VALID_RESULT)
     }
 }

components/chat-message-display.tsx

@@ -435,11 +435,15 @@ export function ChatMessageDisplay({
                         const toolPart = part as ToolPartLike
                         const { toolCallId, state, input } = toolPart
 
+                        // Auto-collapse on completion, but only if user hasn't manually toggled
                         if (state === "output-available") {
-                            setExpandedTools((prev) => ({
-                                ...prev,
-                                [toolCallId]: false,
-                            }))
+                            setExpandedTools((prev) => {
+                                // Only auto-collapse if not already set (user hasn't interacted)
+                                if (prev[toolCallId] === undefined) {
+                                    return { ...prev, [toolCallId]: false }
+                                }
+                                return prev
+                            })
                         }
 
                         if (

components/chat-panel.tsx

@@ -178,7 +178,7 @@ export default function ChatPanel({
     const [dailyTokenLimit, setDailyTokenLimit] = useState(0)
     const [tpmLimit, setTpmLimit] = useState(0)
     const [minimalStyle, setMinimalStyle] = useState(false)
-    const [vlmValidationEnabled, setVlmValidationEnabled] = useState(true)
+    const [vlmValidationEnabled, setVlmValidationEnabled] = useState(false)
     const [shouldFocusInput, setShouldFocusInput] = useState(false)
 
     // Restore input from sessionStorage on mount (when ChatPanel remounts due to key change)

components/chat/ToolCallCard.tsx

@@ -67,8 +67,8 @@ export function ToolCallCard({
 }: ToolCallCardProps) {
     const callId = part.toolCallId
     const { state, input, output } = part
-    // Default to collapsed if tool is complete, expanded if still streaming
-    const isExpanded = expandedTools[callId] ?? state !== "output-available"
+    // Default to expanded for all states (user can manually collapse if needed)
+    const isExpanded = expandedTools[callId] ?? true
     const toolName = part.type?.replace("tool-", "")
     const isCopied = copiedToolCallId === callId
 

components/chat/ValidationCard.tsx

@@ -19,6 +19,7 @@ export type ValidationStatus =
     | "capturing"
     | "validating"
     | "success"
+    | "success_with_warnings"
     | "failed"
     | "error"
     | "skipped"
@@ -95,7 +96,9 @@ export function ValidationCard({
     const showImproveButton =
         onImproveWithSuggestions &&
         state.result &&
-        (state.status === "success" || state.status === "skipped") &&
+        (state.status === "success" ||
+            state.status === "success_with_warnings" ||
+            state.status === "skipped") &&
         (state.result.issues.length > 0 || state.result.suggestions.length > 0)
 
     const getStatusDisplay = () => {
@@ -124,6 +127,14 @@ export function ValidationCard({
                     color: "text-green-600 bg-green-50",
                     icon: <Check className="h-4 w-4" aria-hidden="true" />,
                 }
+            case "success_with_warnings":
+                return {
+                    label: "Valid with Warnings",
+                    color: "text-amber-600 bg-amber-50",
+                    icon: (
+                        <AlertTriangle className="h-4 w-4" aria-hidden="true" />
+                    ),
+                }
             case "failed":
                 return {
                     label: "Issues Found",

components/settings-dialog.tsx

@@ -90,7 +90,7 @@ function SettingsContent({
     onToggleDarkMode,
     minimalStyle = false,
     onMinimalStyleChange = () => {},
-    vlmValidationEnabled = true,
+    vlmValidationEnabled = false,
     onVlmValidationChange = () => {},
 }: SettingsDialogProps) {
     const dict = useDictionary()
@@ -416,8 +416,8 @@ function SettingsContent({
 
                     {/* VLM Diagram Validation */}
                     <SettingItem
-                        label="Diagram Validation"
-                        description="Use AI vision to validate and improve generated diagrams"
+                        label={dict.settings.diagramValidation}
+                        description={dict.settings.diagramValidationDescription}
                     >
                         <div className="flex items-center gap-2">
                             <Switch
@@ -426,7 +426,9 @@ function SettingsContent({
                                 onCheckedChange={onVlmValidationChange}
                             />
                             <span className="text-sm text-muted-foreground">
-                                {vlmValidationEnabled ? "Enabled" : "Disabled"}
+                                {vlmValidationEnabled
+                                    ? dict.settings.enabled
+                                    : dict.settings.disabled}
                             </span>
                         </div>
                     </SettingItem>

hooks/use-diagram-tool-handlers.ts

@@ -325,9 +325,13 @@ ${finalXml}
                             }
 
                             // Notify UI of success (include the image)
+                            // Use "success_with_warnings" if valid but has issues
+                            const hasWarnings = result.issues.length > 0
                             updateValidationState(
                                 toolCall.toolCallId,
-                                "success",
+                                hasWarnings
+                                    ? "success_with_warnings"
+                                    : "success",
                                 { result, imageData: capturedPngData },
                             )
                         }

hooks/use-validate-diagram.ts

@@ -26,11 +26,6 @@ interface UseValidateDiagramOptions {
     onError?: (error: Error) => void
 }
 
-interface ValidationRequest {
-    imageData: string
-    sessionId?: string
-}
-
 // Track pending validation promises for imperative API
 type PendingValidation = {
     resolve: (result: ValidationResult) => void
@@ -40,7 +35,6 @@ type PendingValidation = {
 export function useValidateDiagram(options: UseValidateDiagramOptions = {}) {
     const { onSuccess, onError } = options
     const pendingValidationRef = useRef<PendingValidation | null>(null)
-    const lastRequestRef = useRef<ValidationRequest | null>(null)
 
     const { object, submit, isLoading, error, stop } = useObject({
         api: getApiEndpoint("/api/validate-diagram"),
@@ -87,8 +81,13 @@ export function useValidateDiagram(options: UseValidateDiagramOptions = {}) {
             imageData: string,
             sessionId?: string,
         ): Promise<ValidationResult> => {
-            // Store request for potential retry
-            lastRequestRef.current = { imageData, sessionId }
+            // Reject any pending validation to prevent promise leaks
+            if (pendingValidationRef.current) {
+                pendingValidationRef.current.reject(
+                    new Error("Validation superseded by new request"),
+                )
+                pendingValidationRef.current = null
+            }
 
             return new Promise((resolve, reject) => {
                 // Store the promise handlers

lib/diagram-validator.ts

@@ -3,17 +3,10 @@
  * The actual validation is performed via useValidateDiagram hook using AI SDK's useObject.
  */
 
-export interface ValidationIssue {
-    type: "overlap" | "edge_routing" | "text" | "layout" | "rendering"
-    severity: "critical" | "warning"
-    description: string
-}
+// Re-export types from the schema file (single source of truth)
+export type { ValidationIssue, ValidationResult } from "./validation-schema"
 
-export interface ValidationResult {
-    valid: boolean
-    issues: ValidationIssue[]
-    suggestions: string[]
-}
+import type { ValidationResult } from "./validation-schema"
 
 /**
  * Format validation feedback for display to the AI model.

lib/i18n/dictionaries/en.json

@@ -115,7 +115,11 @@
         "httpProxy": "HTTP Proxy",
         "httpsProxy": "HTTPS Proxy",
         "applyProxy": "Apply",
-        "proxyApplied": "Proxy settings applied"
+        "proxyApplied": "Proxy settings applied",
+        "diagramValidation": "Diagram Validation (Experimental)",
+        "diagramValidationDescription": "Use a vision language model to validate generated diagrams. Requires a VLM like GPT-5.2 or Sonnet-4.5.",
+        "enabled": "Enabled",
+        "disabled": "Disabled"
     },
     "save": {
         "title": "Save Diagram",

lib/i18n/dictionaries/ja.json

@@ -115,7 +115,11 @@
         "httpProxy": "HTTP プロキシ",
         "httpsProxy": "HTTPS プロキシ",
         "applyProxy": "適用",
-        "proxyApplied": "プロキシ設定が適用されました"
+        "proxyApplied": "プロキシ設定が適用されました",
+        "diagramValidation": "ダイアグラム検証（実験的）",
+        "diagramValidationDescription": "視覚言語モデルを使用して生成されたダイアグラムを検証します。GPT-5.2 や Sonnet-4.5 などの VLM が必要です。",
+        "enabled": "有効",
+        "disabled": "無効"
     },
     "save": {
         "title": "ダイアグラムを保存",

lib/i18n/dictionaries/zh.json

@@ -115,7 +115,11 @@
         "httpProxy": "HTTP 代理",
         "httpsProxy": "HTTPS 代理",
         "applyProxy": "应用",
-        "proxyApplied": "代理设置已应用"
+        "proxyApplied": "代理设置已应用",
+        "diagramValidation": "图表验证（实验性）",
+        "diagramValidationDescription": "使用视觉语言模型验证生成的图表。需要支持视觉的模型，如 GPT-5.2 或 Sonnet-4.5。",
+        "enabled": "已启用",
+        "disabled": "已禁用"
     },
     "save": {
         "title": "保存图表",

lib/validation-schema.ts

@@ -35,3 +35,4 @@ export const ValidationResultSchema = z.object({
 })
 
 export type ValidationResult = z.infer<typeof ValidationResultSchema>
+export type ValidationIssue = ValidationResult["issues"][number]