diff --git a/package.json b/package.json
index 0161fa3..0c6bae3 100644
--- a/package.json
+++ b/package.json
@@ -7,10 +7,14 @@
     "dev": "tsx watch src/index.ts",
     "build": "tsc",
     "start": "node dist/index.js",
+    "test:image-paths": "node test/unit-image-paths.mjs",
+    "test:openai-image-file": "node test/unit-openai-image-file.mjs",
+    "test:openai-chat-input": "node test/unit-openai-chat-input.mjs",
+    "test:vision": "node test/unit-vision.mjs",
     "test:unit": "node test/unit-tolerant-parse.mjs",
     "test:tool-fixer": "node test/unit-tool-fixer.mjs",
     "test:openai-compat": "node test/unit-openai-compat.mjs",
-    "test:all": "node test/unit-tolerant-parse.mjs && node test/unit-tool-fixer.mjs && node test/unit-openai-compat.mjs && node test/unit-proxy-agent.mjs",
+    "test:all": "node test/unit-tolerant-parse.mjs && node test/unit-tool-fixer.mjs && node test/unit-openai-compat.mjs && node test/unit-proxy-agent.mjs && node test/unit-image-paths.mjs && node test/unit-vision.mjs && node test/unit-openai-chat-input.mjs && node test/unit-openai-image-file.mjs",
     "test:e2e": "node test/e2e-chat.mjs",
     "test:agentic": "node test/e2e-agentic.mjs"
   },
diff --git a/src/converter.ts b/src/converter.ts
index 614e89c..a5bf047 100644
--- a/src/converter.ts
+++ b/src/converter.ts
@@ -957,6 +957,22 @@ function shortId(): string {
     return uuidv4().replace(/-/g, '').substring(0, 16);
 }
 
+function normalizeFileUrlToLocalPath(url: string): string {
+    if (!url.startsWith('file:///')) return url;
+
+    const rawPath = url.slice('file:///'.length);
+    let decodedPath = rawPath;
+    try {
+        decodedPath = decodeURIComponent(rawPath);
+    } catch {
+        // 忽略非法编码，保留原始路径
+    }
+
+    return /^[A-Za-z]:[\\/]/.test(decodedPath)
+        ? decodedPath
+        : '/' + decodedPath;
+}
+
 // ==================== 图片预处理 ====================
 
 /**
@@ -991,6 +1007,15 @@ async function preprocessImages(messages: AnthropicMessage[]): Promise<void> {
                 console.log(`[Converter] 🔄 归一化 Anthropic URL 图片: source.url → source.data`);
             }
 
+            // ★ file:// 本地文件 URL → 归一化为系统路径，复用后续本地文件读取逻辑
+            if (block.source?.type === 'url' && typeof block.source.data === 'string' && block.source.data.startsWith('file:///')) {
+                block.source.data = normalizeFileUrlToLocalPath(block.source.data);
+                if (!block.source.media_type) {
+                    block.source.media_type = guessMediaType(block.source.data);
+                }
+                console.log(`[Converter] 🔄 修正 file:// URL → 本地路径: ${block.source.data.substring(0, 120)}`);
+            }
+
             // ★ 兜底：source.data 是完整 data: URI 但 type 仍标为 'url'
             if (block.source?.type === 'url' && block.source.data?.startsWith('data:')) {
                 const match = block.source.data.match(/^data:([^;]+);base64,(.+)$/);
@@ -1011,7 +1036,8 @@ async function preprocessImages(messages: AnthropicMessage[]): Promise<void> {
     //   B) content 是数组，但 text block 中嵌入了路径
     // 支持格式：
     //   - 本地文件路径: /Users/.../file_362---eb90f5a2.jpg（含连字符、UUID）
-    //   - file:// URL: file:///Users/.../file.jpg
+    //   - Windows 本地路径: C:\Users\...\file.jpg / C:/Users/.../file.jpg
+    //   - file:// URL: file:///Users/.../file.jpg / file:///C:/Users/.../file.jpg
     //   - HTTP(S) URL 以图片后缀结尾
     //
     // 使用 [^\s"')\]] 匹配路径中任意非空白/非引号字符（包括 -、UUID、中文等）
@@ -1020,21 +1046,31 @@ async function preprocessImages(messages: AnthropicMessage[]): Promise<void> {
     /** 从文本中提取所有图片 URL/路径 */
     function extractImageUrlsFromText(text: string): string[] {
         const urls: string[] = [];
-        // file:// URLs → /path
+        // file:// URLs → 本地路径
         const fileRe = /file:\/\/\/([^\s"')\]]+\.(?:jpg|jpeg|png|gif|webp|bmp|svg))/gi;
         for (const m of text.matchAll(fileRe)) {
-            urls.push('/' + m[1]);
+            const normalizedPath = normalizeFileUrlToLocalPath(`file:///${m[1]}`);
+            urls.push(normalizedPath);
         }
         // HTTP(S) URLs
         const httpRe = /(https?:\/\/[^\s"')\]]+\.(?:jpg|jpeg|png|gif|webp|bmp|svg)(?:\?[^\s"')\]]*)?)/gi;
         for (const m of text.matchAll(httpRe)) {
             if (!urls.includes(m[1])) urls.push(m[1]);
         }
-        // 本地绝对路径 (/开头，支持 UUID、连字符等)
-        const localRe = /(?:^|[\s"'(\[,:])(\/[^\s"')\]]+\.(?:jpg|jpeg|png|gif|webp|bmp|svg))/gi;
+        // 本地绝对路径：Unix /path 或 Windows C:\path / C:/path，排除协议相对 URL（//example.com/a.jpg）
+        const localRe = /(?:^|[\s"'(\[,:])((?:\/(?!\/)|[A-Za-z]:[\\/])[^\s"')\]]+\.(?:jpg|jpeg|png|gif|webp|bmp|svg))/gi;
         for (const m of text.matchAll(localRe)) {
-            const path = m[1].trim();
-            if (!urls.includes(path)) urls.push(path);
+            const localPath = m[1].trim();
+            const fullMatch = m[0];
+            const matchStart = m.index ?? 0;
+            const pathOffsetInMatch = fullMatch.lastIndexOf(localPath);
+            const pathStart = matchStart + Math.max(pathOffsetInMatch, 0);
+            const beforePath = text.slice(Math.max(0, pathStart - 12), pathStart);
+
+            // 避免 file:///C:/foo.jpg 中的 /foo.jpg 被再次当作 Unix 路径提取
+            if (/file:\/\/\/[A-Za-z]:$/i.test(beforePath)) continue;
+            if (localPath.startsWith('//')) continue;
+            if (!urls.includes(localPath)) urls.push(localPath);
         }
         return [...new Set(urls)];
     }
@@ -1129,8 +1165,8 @@ async function preprocessImages(messages: AnthropicMessage[]): Promise<void> {
                 if (block.source?.type === 'url' && block.source.data && !block.source.data.startsWith('data:')) {
                     const imageUrl = block.source.data;
 
-                    // ★ 本地文件路径检测：/开头 或 ~/ 开头 或 Windows 绝对路径
-                    const isLocalPath = /^(\/|~\/|[A-Za-z]:\\)/.test(imageUrl);
+                    // ★ 本地文件路径检测：/开头 或 ~/ 开头 或 Windows 绝对路径（支持 \ 和 /）
+                    const isLocalPath = /^(\/|~\/|[A-Za-z]:[\\/])/.test(imageUrl);
 
                     if (isLocalPath) {
                         localImages++;
diff --git a/src/openai-handler.ts b/src/openai-handler.ts
index bb03112..3b544a6 100644
--- a/src/openai-handler.ts
+++ b/src/openai-handler.ts
@@ -50,6 +50,43 @@ function toolCallId(): string {
     return 'call_' + uuidv4().replace(/-/g, '').substring(0, 24);
 }
 
+class OpenAIRequestError extends Error {
+    status: number;
+    type: string;
+    code: string;
+
+    constructor(message: string, status = 400, type = 'invalid_request_error', code = 'invalid_request') {
+        super(message);
+        this.name = 'OpenAIRequestError';
+        this.status = status;
+        this.type = type;
+        this.code = code;
+    }
+}
+
+function stringifyUnknownContent(value: unknown): string {
+    if (value === null || value === undefined) return '';
+    if (typeof value === 'string') return value;
+    if (typeof value === 'number' || typeof value === 'boolean' || typeof value === 'bigint') {
+        return String(value);
+    }
+    try {
+        return JSON.stringify(value);
+    } catch {
+        return String(value);
+    }
+}
+
+function unsupportedImageFileError(fileId?: string): OpenAIRequestError {
+    const suffix = fileId ? ` (file_id: ${fileId})` : '';
+    return new OpenAIRequestError(
+        `Unsupported content part: image_file${suffix}. This proxy does not support OpenAI Files API image references. Please send the image as image_url, input_image, data URI, or a local file path instead.`,
+        400,
+        'invalid_request_error',
+        'unsupported_content_part'
+    );
+}
+
 // ==================== 请求转换：OpenAI → Anthropic ====================
 
 /**
@@ -238,6 +275,7 @@ function toBlocks(content: string | AnthropicContentBlock[]): AnthropicContentBl
 /**
  * 从 OpenAI 消息中提取文本或多模态内容块
  * 处理多种客户端格式：
+ *   - 文本块: { type: 'text'|'input_text', text: '...' }
  *   - OpenAI 标准: { type: 'image_url', image_url: { url: '...' } }
  *   - Anthropic 透传: { type: 'image', source: { type: 'url', url: '...' } }
  *   - 部分客户端: { type: 'input_image', image_url: { url: '...' } }
@@ -248,7 +286,7 @@ function extractOpenAIContentBlocks(msg: OpenAIMessage): string | AnthropicConte
     if (Array.isArray(msg.content)) {
         const blocks: AnthropicContentBlock[] = [];
         for (const p of msg.content as (OpenAIContentPart | Record<string, unknown>)[]) {
-            if (p.type === 'text' && (p as OpenAIContentPart).text) {
+            if ((p.type === 'text' || p.type === 'input_text') && (p as OpenAIContentPart).text) {
                 blocks.push({ type: 'text', text: (p as OpenAIContentPart).text! });
             } else if (p.type === 'image_url' && (p as OpenAIContentPart).image_url?.url) {
                 const url = (p as OpenAIContentPart).image_url!.url;
@@ -310,11 +348,9 @@ function extractOpenAIContentBlocks(msg: OpenAIMessage): string | AnthropicConte
                     });
                 }
             } else if (p.type === 'image_file' && (p as any).image_file) {
-                // ★ Assistants API 格式: { type: 'image_file', image_file: { file_id: '...', detail?: '...' } }
-                // file_id 无法直接使用，但记录下来以便调试
-                const fileId = (p as any).image_file.file_id;
-                console.log(`[OpenAI] ⚠️ 收到 image_file 格式 (file_id: ${fileId})，此格式需要 Files API 支持`);
-                blocks.push({ type: 'text', text: `[Image file reference: file_id=${fileId}. This format requires Files API support which is not available.]` });
+                const fileId = (p as any).image_file.file_id as string | undefined;
+                console.log(`[OpenAI] ⚠️ 收到不支持的 image_file 格式 (file_id: ${fileId || 'unknown'})`);
+                throw unsupportedImageFileError(fileId);
             } else if ((p.type === 'image_url' || p.type === 'input_image') && (p as any).url) {
                 // ★ 扁平 URL 格式：某些客户端将 url 直接放在顶层而非 image_url.url
                 const url = (p as any).url as string;
@@ -368,7 +404,7 @@ function extractOpenAIContentBlocks(msg: OpenAIMessage): string | AnthropicConte
         }
         return blocks.length > 0 ? blocks : '';
     }
-    return String(msg.content);
+    return stringifyUnknownContent(msg.content);
 }
 
 /**
@@ -459,11 +495,14 @@ export async function handleOpenAIChatCompletions(req: Request, res: Response):
     } catch (err: unknown) {
         const message = err instanceof Error ? err.message : String(err);
         log.fail(message);
-        res.status(500).json({
+        const status = err instanceof OpenAIRequestError ? err.status : 500;
+        const type = err instanceof OpenAIRequestError ? err.type : 'server_error';
+        const code = err instanceof OpenAIRequestError ? err.code : 'internal_error';
+        res.status(status).json({
             error: {
                 message,
-                type: 'server_error',
-                code: 'internal_error',
+                type,
+                code,
             },
         });
     }
@@ -1157,8 +1196,11 @@ export async function handleOpenAIResponses(req: Request, res: Response): Promis
     } catch (err: unknown) {
         const message = err instanceof Error ? err.message : String(err);
         console.error(`[OpenAI] /v1/responses 处理失败:`, message);
-        res.status(500).json({
-            error: { message, type: 'server_error', code: 'internal_error' },
+        const status = err instanceof OpenAIRequestError ? err.status : 500;
+        const type = err instanceof OpenAIRequestError ? err.type : 'server_error';
+        const code = err instanceof OpenAIRequestError ? err.code : 'internal_error';
+        res.status(status).json({
+            error: { message, type, code },
         });
     }
 }
@@ -1628,26 +1670,29 @@ export function responsesToChatCompletions(body: Record<string, unknown>): OpenA
             if (item.type === 'function_call_output') {
                 messages.push({
                     role: 'tool',
-                    content: (item.output as string) || '',
+                    content: stringifyUnknownContent(item.output),
                     tool_call_id: (item.call_id as string) || '',
                 });
                 continue;
             }
             const role = (item.role as string) || 'user';
             if (role === 'system' || role === 'developer') {
-                const text = typeof item.content === 'string'
-                    ? item.content
-                    : Array.isArray(item.content)
-                        ? (item.content as Array<Record<string, unknown>>).filter(b => b.type === 'input_text').map(b => b.text as string).join('\n')
-                        : String(item.content || '');
+                const text = extractOpenAIContent({
+                    role: 'system',
+                    content: (item.content as string | OpenAIContentPart[] | null) ?? null,
+                } as OpenAIMessage);
                 messages.push({ role: 'system', content: text });
             } else if (role === 'user') {
-                const content = typeof item.content === 'string'
-                    ? item.content
-                    : Array.isArray(item.content)
-                        ? (item.content as Array<Record<string, unknown>>).filter(b => b.type === 'input_text').map(b => b.text as string).join('\n')
-                        : String(item.content || '');
-                messages.push({ role: 'user', content });
+                const rawContent = (item.content as string | OpenAIContentPart[] | null) ?? null;
+                const normalizedContent = typeof rawContent === 'string'
+                    ? rawContent
+                    : Array.isArray(rawContent) && rawContent.every(b => b.type === 'input_text')
+                        ? rawContent.map(b => b.text || '').join('\n')
+                        : rawContent;
+                messages.push({
+                    role: 'user',
+                    content: normalizedContent || '',
+                });
             } else if (role === 'assistant') {
                 const blocks = Array.isArray(item.content) ? item.content as Array<Record<string, unknown>> : [];
                 const text = blocks.filter(b => b.type === 'output_text').map(b => b.text as string).join('\n');
diff --git a/src/openai-types.ts b/src/openai-types.ts
index b378cf6..225ae5f 100644
--- a/src/openai-types.ts
+++ b/src/openai-types.ts
@@ -31,9 +31,10 @@ export interface OpenAIMessage {
 }
 
 export interface OpenAIContentPart {
-    type: 'text' | 'image_url' | 'image' | 'input_image';
+    type: 'text' | 'input_text' | 'image_url' | 'image' | 'input_image' | 'image_file';
     text?: string;
     image_url?: { url: string; detail?: string };
+    image_file?: { file_id: string; detail?: string };
     // Anthropic-style image source (when type === 'image')
     source?: { type: string; media_type?: string; data?: string; url?: string };
 }
diff --git a/src/vision.ts b/src/vision.ts
index da3bf52..7a088ec 100644
--- a/src/vision.ts
+++ b/src/vision.ts
@@ -8,6 +8,7 @@ export async function applyVisionInterceptor(messages: AnthropicMessage[]): Prom
     if (!config.vision?.enabled) return;
 
     for (const msg of messages) {
+        if (msg.role !== 'user') continue;
         if (!Array.isArray(msg.content)) continue;
 
         let hasImages = false;
diff --git a/test/unit-image-paths.mjs b/test/unit-image-paths.mjs
new file mode 100644
index 0000000..429879e
--- /dev/null
+++ b/test/unit-image-paths.mjs
@@ -0,0 +1,141 @@
+/**
+ * test/unit-image-paths.mjs
+ *
+ * 单元测试：图片路径提取与本地路径识别
+ * 运行方式：node test/unit-image-paths.mjs
+ */
+
+let passed = 0;
+let failed = 0;
+
+function test(name, fn) {
+    try {
+        fn();
+        console.log(`  ✅  ${name}`);
+        passed++;
+    } catch (e) {
+        console.error(`  ❌  ${name}`);
+        console.error(`      ${e.message}`);
+        failed++;
+    }
+}
+
+function assert(condition, msg) {
+    if (!condition) throw new Error(msg || 'Assertion failed');
+}
+
+function assertEqual(a, b, msg) {
+    const as = JSON.stringify(a), bs = JSON.stringify(b);
+    if (as !== bs) throw new Error(msg || `Expected ${bs}, got ${as}`);
+}
+
+function normalizeFileUrlToLocalPath(url) {
+    if (!url.startsWith('file:///')) return url;
+
+    const rawPath = url.slice('file:///'.length);
+    let decodedPath = rawPath;
+    try {
+        decodedPath = decodeURIComponent(rawPath);
+    } catch {
+        // 忽略非法编码，保留原始路径
+    }
+
+    return /^[A-Za-z]:[\\/]/.test(decodedPath)
+        ? decodedPath
+        : '/' + decodedPath;
+}
+
+function extractImageUrlsFromText(text) {
+    const urls = [];
+
+    const fileRe = /file:\/\/\/([^\s"')\]]+\.(?:jpg|jpeg|png|gif|webp|bmp|svg))/gi;
+    for (const m of text.matchAll(fileRe)) {
+        const normalizedPath = normalizeFileUrlToLocalPath(`file:///${m[1]}`);
+        urls.push(normalizedPath);
+    }
+
+    const httpRe = /(https?:\/\/[^\s"')\]]+\.(?:jpg|jpeg|png|gif|webp|bmp|svg)(?:\?[^\s"')\]]*)?)/gi;
+    for (const m of text.matchAll(httpRe)) {
+        if (!urls.includes(m[1])) urls.push(m[1]);
+    }
+
+    const localRe = /(?:^|[\s"'(\[,:])((?:\/(?!\/)|[A-Za-z]:[\\/])[^\s"')\]]+\.(?:jpg|jpeg|png|gif|webp|bmp|svg))/gi;
+    for (const m of text.matchAll(localRe)) {
+        const localPath = m[1].trim();
+        const fullMatch = m[0];
+        const matchStart = m.index ?? 0;
+        const pathOffsetInMatch = fullMatch.lastIndexOf(localPath);
+        const pathStart = matchStart + Math.max(pathOffsetInMatch, 0);
+        const beforePath = text.slice(Math.max(0, pathStart - 12), pathStart);
+
+        if (/file:\/\/\/[A-Za-z]:$/i.test(beforePath)) continue;
+        if (localPath.startsWith('//')) continue;
+        if (!urls.includes(localPath)) urls.push(localPath);
+    }
+
+    return [...new Set(urls)];
+}
+
+function isLocalPath(imageUrl) {
+    return /^(\/|~\/|[A-Za-z]:[\\/])/.test(imageUrl);
+}
+
+console.log('\n📦 [1] 协议相对 URL 排除\n');
+
+test('不提取 //example.com/image.jpg', () => {
+    const text = 'look //example.com/image.jpg and https://example.com/real.jpg';
+    const urls = extractImageUrlsFromText(text);
+    assertEqual(urls, ['https://example.com/real.jpg']);
+});
+
+console.log('\n📦 [2] file:// Windows 路径归一化\n');
+
+test('file:///C:/Users/name/a.jpg → C:/Users/name/a.jpg', () => {
+    const text = 'please inspect file:///C:/Users/name/a.jpg';
+    const urls = extractImageUrlsFromText(text);
+    assertEqual(urls, ['C:/Users/name/a.jpg']);
+});
+
+test('file:///Users/name/a.jpg → /Users/name/a.jpg', () => {
+    const text = 'please inspect file:///Users/name/a.jpg';
+    const urls = extractImageUrlsFromText(text);
+    assertEqual(urls, ['/Users/name/a.jpg']);
+});
+
+test('直接 image block 的 file:// URL 也能归一化', () => {
+    assertEqual(
+        normalizeFileUrlToLocalPath('file:///C:/Users/name/a.jpg'),
+        'C:/Users/name/a.jpg'
+    );
+    assertEqual(
+        normalizeFileUrlToLocalPath('file:///Users/name/a.jpg'),
+        '/Users/name/a.jpg'
+    );
+});
+
+console.log('\n📦 [3] Windows 本地路径识别\n');
+
+test('提取 C:\\Users\\name\\a.jpg', () => {
+    const text = '看看这张图 C:\\Users\\name\\a.jpg';
+    const urls = extractImageUrlsFromText(text);
+    assertEqual(urls, ['C:\\Users\\name\\a.jpg']);
+});
+
+test('提取 C:/Users/name/a.jpg', () => {
+    const text = '看看这张图 C:/Users/name/a.jpg';
+    const urls = extractImageUrlsFromText(text);
+    assertEqual(urls, ['C:/Users/name/a.jpg']);
+});
+
+test('Windows 路径被视为本地文件', () => {
+    assert(isLocalPath('C:\\Users\\name\\a.jpg'), 'backslash path should be local');
+    assert(isLocalPath('C:/Users/name/a.jpg'), 'slash path should be local');
+    assert(isLocalPath(normalizeFileUrlToLocalPath('file:///C:/Users/name/a.jpg')), 'normalized file URL should be local');
+    assert(isLocalPath(normalizeFileUrlToLocalPath('file:///Users/name/a.jpg')), 'normalized unix file URL should be local');
+});
+
+console.log('\n' + '═'.repeat(55));
+console.log(`  结果: ${passed} 通过 / ${failed} 失败 / ${passed + failed} 总计`);
+console.log('═'.repeat(55) + '\n');
+
+if (failed > 0) process.exit(1);
diff --git a/test/unit-openai-chat-input.mjs b/test/unit-openai-chat-input.mjs
new file mode 100644
index 0000000..0a190ef
--- /dev/null
+++ b/test/unit-openai-chat-input.mjs
@@ -0,0 +1,143 @@
+/**
+ * test/unit-openai-chat-input.mjs
+ *
+ * 单元测试：/v1/chat/completions 输入内容块兼容性
+ * 运行方式：node test/unit-openai-chat-input.mjs
+ */
+
+let passed = 0;
+let failed = 0;
+
+function test(name, fn) {
+    try {
+        fn();
+        console.log(`  ✅  ${name}`);
+        passed++;
+    } catch (e) {
+        console.error(`  ❌  ${name}`);
+        console.error(`      ${e.message}`);
+        failed++;
+    }
+}
+
+function assert(condition, msg) {
+    if (!condition) throw new Error(msg || 'Assertion failed');
+}
+
+function assertEqual(a, b, msg) {
+    const as = JSON.stringify(a), bs = JSON.stringify(b);
+    if (as !== bs) throw new Error(msg || `Expected ${bs}, got ${as}`);
+}
+
+function extractOpenAIContentBlocks(msg) {
+    if (msg.content === null || msg.content === undefined) return '';
+    if (typeof msg.content === 'string') return msg.content;
+    if (Array.isArray(msg.content)) {
+        const blocks = [];
+        for (const p of msg.content) {
+            if ((p.type === 'text' || p.type === 'input_text') && p.text) {
+                blocks.push({ type: 'text', text: p.text });
+            } else if (p.type === 'image_url' && p.image_url?.url) {
+                blocks.push({
+                    type: 'image',
+                    source: { type: 'url', media_type: 'image/jpeg', data: p.image_url.url },
+                });
+            } else if (p.type === 'input_image' && p.image_url?.url) {
+                blocks.push({
+                    type: 'image',
+                    source: { type: 'url', media_type: 'image/jpeg', data: p.image_url.url },
+                });
+            }
+        }
+        return blocks.length > 0 ? blocks : '';
+    }
+    return String(msg.content);
+}
+
+function extractOpenAIContent(msg) {
+    const blocks = extractOpenAIContentBlocks(msg);
+    if (typeof blocks === 'string') return blocks;
+    return blocks.filter(b => b.type === 'text').map(b => b.text).join('\n');
+}
+
+function convertToAnthropicRequest(body) {
+    const rawMessages = [];
+    let systemPrompt;
+
+    for (const msg of body.messages) {
+        switch (msg.role) {
+            case 'system':
+                systemPrompt = (systemPrompt ? systemPrompt + '\n\n' : '') + extractOpenAIContent(msg);
+                break;
+            case 'user': {
+                const contentBlocks = extractOpenAIContentBlocks(msg);
+                rawMessages.push({
+                    role: 'user',
+                    content: Array.isArray(contentBlocks) ? contentBlocks : (contentBlocks || ''),
+                });
+                break;
+            }
+        }
+    }
+
+    return {
+        system: systemPrompt,
+        messages: rawMessages,
+    };
+}
+
+console.log('\n📦 [1] chat.completions input_text 兼容\n');
+
+test('user input_text 不应丢失', () => {
+    const req = convertToAnthropicRequest({
+        model: 'gpt-4.1',
+        messages: [{
+            role: 'user',
+            content: [
+                { type: 'input_text', text: '请描述这张图' },
+                { type: 'input_image', image_url: { url: 'https://example.com/a.jpg' } },
+            ],
+        }],
+    });
+
+    assertEqual(req.messages.length, 1);
+    assert(Array.isArray(req.messages[0].content), 'content should be block array');
+    assertEqual(req.messages[0].content[0], { type: 'text', text: '请描述这张图' });
+    assertEqual(req.messages[0].content[1].type, 'image');
+});
+
+test('system input_text 应拼接进 system prompt', () => {
+    const req = convertToAnthropicRequest({
+        model: 'gpt-4.1',
+        messages: [{
+            role: 'system',
+            content: [
+                { type: 'input_text', text: '你是一个严谨的助手。' },
+                { type: 'input_text', text: '请直接回答。' },
+            ],
+        }, {
+            role: 'user',
+            content: 'hi',
+        }],
+    });
+
+    assertEqual(req.system, '你是一个严谨的助手。\n请直接回答。');
+});
+
+test('传统 text 块仍然兼容', () => {
+    const req = convertToAnthropicRequest({
+        model: 'gpt-4.1',
+        messages: [{
+            role: 'user',
+            content: [{ type: 'text', text: 'hello' }],
+        }],
+    });
+
+    assertEqual(req.messages[0].content[0], { type: 'text', text: 'hello' });
+});
+
+console.log('\n' + '═'.repeat(55));
+console.log(`  结果: ${passed} 通过 / ${failed} 失败 / ${passed + failed} 总计`);
+console.log('═'.repeat(55) + '\n');
+
+if (failed > 0) process.exit(1);
diff --git a/test/unit-openai-compat.mjs b/test/unit-openai-compat.mjs
index 910c005..9c12ea1 100644
--- a/test/unit-openai-compat.mjs
+++ b/test/unit-openai-compat.mjs
@@ -34,6 +34,50 @@ function assertEqual(a, b, msg) {
     if (as !== bs) throw new Error(msg || `Expected ${bs}, got ${as}`);
 }
 
+function stringifyUnknownContent(value) {
+    if (value === null || value === undefined) return '';
+    if (typeof value === 'string') return value;
+    if (typeof value === 'number' || typeof value === 'boolean' || typeof value === 'bigint') {
+        return String(value);
+    }
+    try {
+        return JSON.stringify(value);
+    } catch {
+        return String(value);
+    }
+}
+
+function extractOpenAIContentBlocks(msg) {
+    if (msg.content === null || msg.content === undefined) return '';
+    if (typeof msg.content === 'string') return msg.content;
+    if (Array.isArray(msg.content)) {
+        const blocks = [];
+        for (const p of msg.content) {
+            if ((p.type === 'text' || p.type === 'input_text') && p.text) {
+                blocks.push({ type: 'text', text: p.text });
+            } else if (p.type === 'image_url' && p.image_url?.url) {
+                blocks.push({
+                    type: 'image',
+                    source: { type: 'url', media_type: 'image/jpeg', data: p.image_url.url },
+                });
+            } else if (p.type === 'input_image' && p.image_url?.url) {
+                blocks.push({
+                    type: 'image',
+                    source: { type: 'url', media_type: 'image/jpeg', data: p.image_url.url },
+                });
+            }
+        }
+        return blocks.length > 0 ? blocks : '';
+    }
+    return stringifyUnknownContent(msg.content);
+}
+
+function extractOpenAIContent(msg) {
+    const blocks = extractOpenAIContentBlocks(msg);
+    if (typeof blocks === 'string') return blocks;
+    return blocks.filter(b => b.type === 'text').map(b => b.text).join('\n');
+}
+
 // ─── 内联 mergeConsecutiveRoles（与 src/openai-handler.ts 保持同步）────
 function toBlocks(content) {
     if (typeof content === 'string') {
@@ -75,26 +119,29 @@ function responsesToChatCompletions(body) {
             if (item.type === 'function_call_output') {
                 messages.push({
                     role: 'tool',
-                    content: item.output || '',
+                    content: stringifyUnknownContent(item.output),
                     tool_call_id: item.call_id || '',
                 });
                 continue;
             }
             const role = item.role || 'user';
             if (role === 'system' || role === 'developer') {
-                const text = typeof item.content === 'string'
-                    ? item.content
-                    : Array.isArray(item.content)
-                        ? item.content.filter(b => b.type === 'input_text').map(b => b.text).join('\n')
-                        : String(item.content || '');
+                const text = extractOpenAIContent({
+                    role: 'system',
+                    content: item.content ?? null,
+                });
                 messages.push({ role: 'system', content: text });
             } else if (role === 'user') {
-                const content = typeof item.content === 'string'
-                    ? item.content
-                    : Array.isArray(item.content)
-                        ? item.content.filter(b => b.type === 'input_text').map(b => b.text).join('\n')
-                        : String(item.content || '');
-                messages.push({ role: 'user', content });
+                const rawContent = item.content ?? null;
+                const normalizedContent = typeof rawContent === 'string'
+                    ? rawContent
+                    : Array.isArray(rawContent) && rawContent.every(b => b.type === 'input_text')
+                        ? rawContent.map(b => b.text || '').join('\n')
+                        : rawContent;
+                messages.push({
+                    role: 'user',
+                    content: normalizedContent,
+                });
             } else if (role === 'assistant') {
                 const blocks = Array.isArray(item.content) ? item.content : [];
                 const text = blocks.filter(b => b.type === 'output_text').map(b => b.text).join('\n');
@@ -220,6 +267,24 @@ test('function_call_output → tool 消息', () => {
     assertEqual(result.messages[2].tool_call_id, 'call_123');
 });
 
+test('function_call_output 对象 → JSON 字符串', () => {
+    const result = responsesToChatCompletions({
+        model: 'gpt-4',
+        input: [
+            { role: 'user', content: 'Summarize tool output' },
+            {
+                type: 'function_call_output',
+                call_id: 'call_obj',
+                output: { files: ['a.ts', 'b.ts'], count: 2 }
+            },
+        ],
+    });
+    assertEqual(result.messages.length, 2);
+    assertEqual(result.messages[1].role, 'tool');
+    assertEqual(result.messages[1].content, '{"files":["a.ts","b.ts"],"count":2}');
+    assertEqual(result.messages[1].tool_call_id, 'call_obj');
+});
+
 test('助手消息带 function_call → tool_calls', () => {
     const result = responsesToChatCompletions({
         model: 'gpt-4',
@@ -277,6 +342,25 @@ test('input_text content 数组', () => {
     assertEqual(result.messages[0].content, 'Part 1\nPart 2');
 });
 
+test('Responses user input_image 不应丢失', () => {
+    const result = responsesToChatCompletions({
+        model: 'gpt-4',
+        input: [
+            {
+                role: 'user',
+                content: [
+                    { type: 'input_text', text: '请描述这张图' },
+                    { type: 'input_image', image_url: { url: 'https://example.com/image.jpg' } },
+                ]
+            },
+        ],
+    });
+    assertEqual(result.messages.length, 1);
+    assert(Array.isArray(result.messages[0].content), 'content should remain multimodal blocks');
+    assertEqual(result.messages[0].content[0], { type: 'input_text', text: '请描述这张图' });
+    assertEqual(result.messages[0].content[1], { type: 'input_image', image_url: { url: 'https://example.com/image.jpg' } });
+});
+
 test('stream 默认为 true', () => {
     const result = responsesToChatCompletions({ model: 'gpt-4', input: 'hi' });
     assertEqual(result.stream, true);
diff --git a/test/unit-openai-image-file.mjs b/test/unit-openai-image-file.mjs
new file mode 100644
index 0000000..951bb45
--- /dev/null
+++ b/test/unit-openai-image-file.mjs
@@ -0,0 +1,101 @@
+/**
+ * test/unit-openai-image-file.mjs
+ *
+ * 单元测试：image_file 输入应显式报错，而不是静默降级
+ * 运行方式：node test/unit-openai-image-file.mjs
+ */
+
+let passed = 0;
+let failed = 0;
+
+function test(name, fn) {
+    try {
+        fn();
+        console.log(`  ✅  ${name}`);
+        passed++;
+    } catch (e) {
+        console.error(`  ❌  ${name}`);
+        console.error(`      ${e.message}`);
+        failed++;
+    }
+}
+
+function assert(condition, msg) {
+    if (!condition) throw new Error(msg || 'Assertion failed');
+}
+
+class OpenAIRequestError extends Error {
+    constructor(message, status = 400, type = 'invalid_request_error', code = 'invalid_request') {
+        super(message);
+        this.name = 'OpenAIRequestError';
+        this.status = status;
+        this.type = type;
+        this.code = code;
+    }
+}
+
+function unsupportedImageFileError(fileId) {
+    const suffix = fileId ? ` (file_id: ${fileId})` : '';
+    return new OpenAIRequestError(
+        `Unsupported content part: image_file${suffix}. This proxy does not support OpenAI Files API image references. Please send the image as image_url, input_image, data URI, or a local file path instead.`,
+        400,
+        'invalid_request_error',
+        'unsupported_content_part'
+    );
+}
+
+function extractOpenAIContentBlocks(msg) {
+    if (msg.content === null || msg.content === undefined) return '';
+    if (typeof msg.content === 'string') return msg.content;
+    if (Array.isArray(msg.content)) {
+        const blocks = [];
+        for (const p of msg.content) {
+            if (p.type === 'text' || p.type === 'input_text') {
+                if (p.text) blocks.push({ type: 'text', text: p.text });
+            } else if (p.type === 'image_file' && p.image_file) {
+                throw unsupportedImageFileError(p.image_file.file_id);
+            }
+        }
+        return blocks.length > 0 ? blocks : '';
+    }
+    return String(msg.content);
+}
+
+console.log('\n📦 [1] image_file 显式报错\n');
+
+test('image_file 应抛出 OpenAIRequestError', () => {
+    let thrown;
+    try {
+        extractOpenAIContentBlocks({
+            role: 'user',
+            content: [
+                { type: 'input_text', text: '请描述图片' },
+                { type: 'image_file', image_file: { file_id: 'file_123' } },
+            ],
+        });
+    } catch (e) {
+        thrown = e;
+    }
+
+    assert(thrown instanceof OpenAIRequestError, 'should throw OpenAIRequestError');
+    assert(thrown.message.includes('image_file'), 'message should mention image_file');
+    assert(thrown.message.includes('file_123'), 'message should include file_id');
+    assert(thrown.status === 400, 'status should be 400');
+    assert(thrown.type === 'invalid_request_error', 'type should be invalid_request_error');
+    assert(thrown.code === 'unsupported_content_part', 'code should be unsupported_content_part');
+});
+
+test('普通文本块仍可正常通过', () => {
+    const blocks = extractOpenAIContentBlocks({
+        role: 'user',
+        content: [{ type: 'input_text', text: 'hello' }],
+    });
+    assert(Array.isArray(blocks), 'blocks should be array');
+    assert(blocks[0].text === 'hello', 'text block should remain intact');
+});
+
+console.log('\n' + '═'.repeat(55));
+console.log(`  结果: ${passed} 通过 / ${failed} 失败 / ${passed + failed} 总计`);
+console.log('═'.repeat(55) + '\n');
+
+if (failed > 0) process.exit(1);
diff --git a/test/unit-vision.mjs b/test/unit-vision.mjs
new file mode 100644
index 0000000..8649db1
--- /dev/null
+++ b/test/unit-vision.mjs
@@ -0,0 +1,90 @@
+/**
+ * test/unit-vision.mjs
+ *
+ * 单元测试：Vision 拦截器仅处理 user 图片消息
+ * 运行方式：node test/unit-vision.mjs
+ */
+
+let passed = 0;
+let failed = 0;
+
+async function test(name, fn) {
+    try {
+        await fn();
+        console.log(`  ✅  ${name}`);
+        passed++;
+    } catch (e) {
+        console.error(`  ❌  ${name}`);
+        console.error(`      ${e.message}`);
+        failed++;
+    }
+}
+
+function assert(condition, msg) {
+    if (!condition) throw new Error(msg || 'Assertion failed');
+}
+
+async function applyVisionInterceptor(messages) {
+    for (const msg of messages) {
+        if (msg.role !== 'user') continue;
+        if (!Array.isArray(msg.content)) continue;
+
+        const newContent = [];
+        const imagesToAnalyze = [];
+
+        for (const block of msg.content) {
+            if (block.type === 'image') {
+                imagesToAnalyze.push(block);
+            } else {
+                newContent.push(block);
+            }
+        }
+
+        if (imagesToAnalyze.length > 0) {
+            newContent.push({
+                type: 'text',
+                text: `[System: The user attached ${imagesToAnalyze.length} image(s). Visual analysis/OCR extracted the following context:\nmock vision result]`,
+            });
+            msg.content = newContent;
+        }
+    }
+}
+
+console.log('\n📦 [1] Vision 角色范围\n');
+
+await test('仅处理 user 消息中的图片', async () => {
+    const messages = [
+        {
+            role: 'assistant',
+            content: [
+                { type: 'text', text: 'assistant says hi' },
+                { type: 'image', source: { type: 'url', data: 'https://example.com/a.jpg' } },
+            ],
+        },
+        {
+            role: 'user',
+            content: [
+                { type: 'text', text: 'please inspect this image' },
+                { type: 'image', source: { type: 'url', data: 'https://example.com/b.jpg' } },
+            ],
+        },
+    ];
+
+    await applyVisionInterceptor(messages);
+
+    assert(messages[0].content.some(block => block.type === 'image'), 'assistant image should remain untouched');
+    assert(messages[1].content.every(block => block.type !== 'image'), 'user images should be converted away');
+    assert(messages[1].content.some(block => block.type === 'text' && block.text.includes('mock vision result')), 'user message should receive vision text');
+});
+
+await test('忽略非数组内容的 user 消息', async () => {
+    const messages = [{ role: 'user', content: 'plain text only' }];
+    await applyVisionInterceptor(messages);
+    assert(messages[0].content === 'plain text only', 'plain text content should stay unchanged');
+});
+
+console.log('\n' + '═'.repeat(55));
+console.log(`  结果: ${passed} 通过 / ${failed} 失败 / ${passed + failed} 总计`);
+console.log('═'.repeat(55) + '\n');
+
+if (failed > 0) process.exit(1);