fix(provider): 修正媒体请求转换与上游错误透传

按上游协议能力延迟处理媒体资源：OpenAI 兼容平台默认使用 multipart，显式配置后才发送 JSON URL；Gemini 官方协议使用 Files API，兼容协议使用内嵌 Base64，并同步覆盖相关媒体客户端。\n\n安全的上游 400/422 原始错误会作为下游 message 返回，同时保留结构化诊断信息和历史任务兼容。\n\n验证：API 全量无缓存测试、go vet、pnpm lint、pnpm test、pnpm build、pnpm openapi、git diff --check。

apps/web/src/pages/admin/PlatformManagementPanel.tsx

@@ -504,6 +504,16 @@ export function PlatformManagementPanel(props: {
             <ToggleField checked={form.supportBase64Input} label="支持 Base64 输入" onChange={(checked) => setForm({ ...form, supportBase64Input: checked })} />
             <ToggleField checked={form.supportUrlInput} label="支持 URL 输入" onChange={(checked) => setForm({ ...form, supportUrlInput: checked })} />
           </div>
+          <Label>
+            OpenAI 图片编辑请求格式
+            <Select
+              value={form.imageEditRequestFormat}
+              onChange={(event) => setForm({ ...form, imageEditRequestFormat: event.target.value as PlatformWizardForm['imageEditRequestFormat'] })}
+            >
+              <option value="multipart">Multipart 文件（默认）</option>
+              <option value="json_url">JSON URL（仅平台明确支持）</option>
+            </Select>
+          </Label>
         </FormSection>
 
         <FormSection icon={<Boxes size={16} />} title={`模型绑定 · ${selectedModels.length}/${availableModels.length}`}>
@@ -1192,6 +1202,7 @@ function platformToForm(
     httpProxy: networkProxy.httpProxy,
     supportBase64Input: readBoolean(config, 'supportBase64Input', true),
     supportUrlInput: readBoolean(config, 'supportUrlInput', true),
+    imageEditRequestFormat: readImageEditRequestFormat(config),
     selectedModelIds: platformModelBaseIds(platform, baseModels, currentModels),
     modelDiscountFactors: platformModelDiscountFactors(platform, baseModels, currentModels),
     modelNameMappings: platformModelNameMappings(platform, baseModels, currentModels),
@@ -1210,6 +1221,11 @@ function platformToForm(
   };
 }
 
+function readImageEditRequestFormat(config: Record<string, unknown>): PlatformWizardForm['imageEditRequestFormat'] {
+  const value = String(config.imageEditRequestFormat ?? '').trim().toLowerCase().replaceAll('-', '_').replaceAll(' ', '_');
+  return value === 'json' || value === 'json_url' ? 'json_url' : 'multipart';
+}
+
 function defaultSelectedModelIds(models: BaseModelCatalogItem[], provider: string) {
   return modelsForProvider(models, provider).map((model) => model.id);
 }

apps/web/src/pages/admin/platform-form.test.ts

@@ -26,6 +26,14 @@ function selectedForm() {
 }
 
 describe('platform model rate limit payload', () => {
+  it('uses multipart unless JSON URL image edits are explicitly configured', () => {
+    const defaultConfig = platformPayload(selectedForm()).config ?? {};
+    expect(defaultConfig.imageEditRequestFormat).toBeUndefined();
+
+    const jsonConfig = platformPayload({ ...selectedForm(), imageEditRequestFormat: 'json_url' }).config ?? {};
+    expect(jsonConfig.imageEditRequestFormat).toBe('json_url');
+  });
+
   it('preserves an existing model policy when the edit form was not touched', () => {
     const [payload] = platformModelPayloads([baseModel], selectedForm());
 

apps/web/src/pages/admin/platform-form.ts

@@ -39,6 +39,7 @@ export interface PlatformWizardForm {
   httpProxy: string;
   supportBase64Input: boolean;
   supportUrlInput: boolean;
+  imageEditRequestFormat: 'multipart' | 'json_url';
   modelDiscountFactor: string;
   modelDiscountFactors: Record<string, string>;
   modelNameMappings: Record<string, string>;
@@ -109,6 +110,7 @@ export function createEmptyPlatformForm(provider = '', defaults?: ProviderConnec
     httpProxy: '',
     supportBase64Input: true,
     supportUrlInput: true,
+    imageEditRequestFormat: 'multipart',
     modelDiscountFactor: '',
     modelDiscountFactors: {},
     modelNameMappings: {},
@@ -171,6 +173,7 @@ export function platformPayload(form: PlatformWizardForm, options: { preserveEmp
       networkProxy: networkProxyPayload(form),
       supportBase64Input: form.supportBase64Input,
       supportUrlInput: form.supportUrlInput,
+      ...(form.imageEditRequestFormat === 'json_url' ? { imageEditRequestFormat: 'json_url' } : {}),
       source: 'gateway-admin',
     },
     retryPolicy: {