fix: Image Agent 模式下图片不回显、不调用生成工具的问题

三个连锁 Bug 的根因修复：

1. route.ts — 图片 base64 数据保留
   - 之前：文件存盘后一律清空 base64 data（包括图片）
   - 现在：只对非图片文件清空 data，图片始终保留 base64
   - 确保 SDK 收到有效的 image content block 用于 vision

2. types/index.ts — ClaudeStreamOptions 增加 imageAgentMode 标记
   - 新增 imageAgentMode?: boolean 字段
   - 由 route.ts 根据 systemPromptAppend 是否存在来设置

3. claude-client.ts — buildFinalPrompt 在 imageAgentMode 下跳过文件路径引用
   - imageAgentMode=true 时不添加 [User attached image: /path] 文本
   - 防止 Claude 看到路径后调用 analyze_image 等内置工具
   - Claude 仅通过 vision（base64 content blocks）看到图片
   - 遵循 IMAGE_AGENT_SYSTEM_PROMPT 输出 image-gen-request 块
   - 普通模式行为不变，仍保留路径引用供 skill/工具使用

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/api/chat/route.ts

@@ -149,7 +149,7 @@ export async function POST(request: NextRequest) {
             name: f.name,
             type: f.type,
             size: f.size,
-            data: meta?.filePath ? '' : f.data, // Skip base64 data if file is already saved to disk
+            data: (meta?.filePath && !f.type.startsWith('image/')) ? '' : f.data, // Keep base64 for images (needed for vision); clear for non-images (read from disk)
             filePath: meta?.filePath,
           };
         })
@@ -189,6 +189,7 @@ export async function POST(request: NextRequest) {
       abortController,
       permissionMode,
       files: fileAttachments,
+      imageAgentMode: !!systemPromptAppend,
       toolTimeoutSeconds: toolTimeout || 300,
       provider: resolvedProvider,
       conversationHistory: historyMsgs,

src/lib/claude-client.ts

@@ -279,6 +279,7 @@ export function streamClaude(options: ClaudeStreamOptions): ReadableStream<strin
     toolTimeoutSeconds = 0,
     conversationHistory,
     onRuntimeStatusChange,
+    imageAgentMode,
   } = options;
 
   return new ReadableStream<string>({
@@ -612,14 +613,21 @@ export function streamClaude(options: ClaudeStreamOptions): ReadableStream<strin
           }
 
           if (imageFiles.length > 0) {
-            // Append image disk paths to the text prompt so Claude knows where
-            // the files are on disk (enables skills to reference them by path).
-            const workDir = workingDirectory || os.homedir();
-            const imagePaths = getUploadedFilePaths(imageFiles, workDir);
-            const imageReferences = imagePaths
-              .map((p, i) => `[User attached image: ${p} (${imageFiles[i].name})]`)
-              .join('\n');
-            const textWithImageRefs = `${imageReferences}\n\n${textPrompt}`;
+            // In imageAgentMode, skip file path references so Claude doesn't
+            // try to use built-in tools to analyze images from disk. It will
+            // see the images via vision (base64 content blocks) and follow the
+            // IMAGE_AGENT_SYSTEM_PROMPT to output image-gen-request blocks.
+            // In normal mode, append disk paths so skills can reference them.
+            const textWithImageRefs = imageAgentMode
+              ? textPrompt
+              : (() => {
+                  const workDir = workingDirectory || os.homedir();
+                  const imagePaths = getUploadedFilePaths(imageFiles, workDir);
+                  const imageReferences = imagePaths
+                    .map((p, i) => `[User attached image: ${p} (${imageFiles[i].name})]`)
+                    .join('\n');
+                  return `${imageReferences}\n\n${textPrompt}`;
+                })();
 
             const contentBlocks: Array<
               | { type: 'image'; source: { type: 'base64'; media_type: string; data: string } }

src/types/index.ts

@@ -644,6 +644,7 @@ export interface ClaudeStreamOptions {
   abortController?: AbortController;
   permissionMode?: string;
   files?: FileAttachment[];
+  imageAgentMode?: boolean;
   toolTimeoutSeconds?: number;
   provider?: ApiProvider;
   /** Recent conversation history from DB — used as fallback context when SDK resume is unavailable or fails */