fix: use OpenAI provider for Doubao multimodal models (#519)

DeepSeek provider was not properly formatting image content for Doubao's
API. Now uses OpenAI provider for Doubao models (multimodal support),
while keeping DeepSeek provider for DeepSeek/Kimi models on the platform.

app/api/validate-model/route.ts

@@ -251,13 +251,26 @@ export async function POST(req: Request) {
             }
 
             case "doubao": {
-                // ByteDance Doubao uses DeepSeek-compatible API
+                // ByteDance Doubao: use DeepSeek for DeepSeek/Kimi models, OpenAI for others
-                const doubao = createDeepSeek({
+                const doubaoBaseUrl =
-                    apiKey,
+                    baseUrl || "https://ark.cn-beijing.volces.com/api/v3"
-                    baseURL:
+                const lowerModelId = modelId.toLowerCase()
-                        baseUrl || "https://ark.cn-beijing.volces.com/api/v3",
+                if (
-                })
+                    lowerModelId.includes("deepseek") ||
-                model = doubao(modelId)
+                    lowerModelId.includes("kimi")
+                ) {
+                    const doubao = createDeepSeek({
+                        apiKey,
+                        baseURL: doubaoBaseUrl,
+                    })
+                    model = doubao(modelId)
+                } else {
+                    const doubao = createOpenAI({
+                        apiKey,
+                        baseURL: doubaoBaseUrl,
+                    })
+                    model = doubao.chat(modelId)
+                }
                 break
             }
 

lib/ai-providers.ts

@@ -871,11 +871,24 @@ export function getAIModel(overrides?: ClientOverrides): ModelConfig {
                 overrides?.baseUrl ||
                 process.env.DOUBAO_BASE_URL ||
                 "https://ark.cn-beijing.volces.com/api/v3"
-            const doubaoProvider = createDeepSeek({
+            const lowerModelId = modelId.toLowerCase()
-                apiKey,
+            // Use DeepSeek provider for DeepSeek/Kimi models, OpenAI for others (multimodal support)
-                baseURL,
+            if (
-            })
+                lowerModelId.includes("deepseek") ||
-            model = doubaoProvider(modelId)
+                lowerModelId.includes("kimi")
+            ) {
+                const doubaoProvider = createDeepSeek({
+                    apiKey,
+                    baseURL,
+                })
+                model = doubaoProvider(modelId)
+            } else {
+                const doubaoProvider = createOpenAI({
+                    apiKey,
+                    baseURL,
+                })
+                model = doubaoProvider.chat(modelId)
+            }
             break
         }