fix: use createDeepSeek for kimi provider to handle reasoning_content in multi-turn conversations (fixes #824) (#825)

Kimi thinking models (e.g. kimi-k2.6) return reasoning_content in their
responses. The previous createOpenAI-based implementation silently ignored
this field, so reasoning was never captured or replayed in subsequent turns.
Switching to createDeepSeek (which natively understands reasoning_content)
ensures that reasoning context is preserved across conversation turns,
resolving the "cannot interact a second time" error with Kimi k2.6.

This mirrors the existing doubao provider pattern, which already uses
createDeepSeek for kimi-based models routed through Doubao.

Co-authored-by: octo-patch <[email protected]>

lib/ai-providers.ts

@@ -1262,7 +1262,6 @@ export function getAIModel(overrides?: ClientOverrides): ModelConfig {
         case "glm":
         case "qwen":
         case "qiniu":
-        case "kimi":
         case "novita": {
             const envVar = PROVIDER_ENV_VARS[provider]
             if (!envVar) {
@@ -1288,6 +1287,23 @@ export function getAIModel(overrides?: ClientOverrides): ModelConfig {
             break
         }
 
+        case "kimi": {
+            const apiKey = resolveApiKey(overrides, "KIMI_API_KEY")
+            const baseURL = resolveBaseURL(
+                overrides?.apiKey,
+                overrides?.baseUrl,
+                resolveBaseUrlEnv(overrides, "KIMI_BASE_URL"),
+                PROVIDER_INFO["kimi"]?.defaultBaseUrl,
+            )
+            // Use createDeepSeek to properly handle reasoning_content for Kimi
+            // thinking models (e.g., kimi-k2.6). Kimi's API uses the same
+            // reasoning_content field as DeepSeek, so this provider correctly
+            // captures and replays reasoning in multi-turn conversations.
+            const customProvider = createDeepSeek({ apiKey, baseURL })
+            model = customProvider(modelId)
+            break
+        }
+
         default:
             throw new Error(
                 `Unknown AI provider: ${provider}. Supported providers: bedrock, openai, anthropic, google, azure, ollama, openrouter, deepseek, siliconflow, sglang, gateway, edgeone, doubao, modelscope, glm, qwen, qiniu, kimi, minimax, novita`,

tests/unit/ai-providers.test.ts

@@ -245,6 +245,67 @@ vi.mock("ollama-ai-provider-v2", () => {
     return { createOllama: mockCreateOllama, ollama: mockOllama }
 })
 
+vi.mock("@ai-sdk/deepseek", () => {
+    const mockModel = { modelId: "test-model" }
+    const mockProviderFn = vi.fn(() => mockModel)
+    const mockCreateDeepSeek = vi.fn(() => mockProviderFn)
+    const mockDeepseek = vi.fn(() => mockModel)
+    return { createDeepSeek: mockCreateDeepSeek, deepseek: mockDeepseek }
+})
+
+describe("Kimi provider uses createDeepSeek for reasoning_content support", () => {
+    let createDeepSeekMock: ReturnType<typeof vi.fn>
+    const savedEnv: Record<string, string | undefined> = {}
+
+    beforeEach(async () => {
+        savedEnv.KIMI_API_KEY = process.env.KIMI_API_KEY
+        savedEnv.KIMI_BASE_URL = process.env.KIMI_BASE_URL
+        delete process.env.KIMI_BASE_URL
+
+        const mod = await import("@ai-sdk/deepseek")
+        createDeepSeekMock = mod.createDeepSeek as ReturnType<typeof vi.fn>
+        createDeepSeekMock.mockClear()
+    })
+
+    afterEach(() => {
+        process.env.KIMI_API_KEY = savedEnv.KIMI_API_KEY
+        process.env.KIMI_BASE_URL = savedEnv.KIMI_BASE_URL
+    })
+
+    it("uses createDeepSeek with Kimi default base URL for reasoning_content support", () => {
+        process.env.KIMI_API_KEY = "test-kimi-key"
+
+        getAIModel({
+            provider: "kimi",
+            apiKey: "test-kimi-key",
+            modelId: "moonshot-v1-8k",
+        })
+
+        expect(createDeepSeekMock).toHaveBeenCalledWith(
+            expect.objectContaining({
+                baseURL: "https://api.moonshot.cn/v1",
+            }),
+        )
+    })
+
+    it("uses custom base URL when provided for kimi provider", () => {
+        process.env.KIMI_API_KEY = "test-kimi-key"
+
+        getAIModel({
+            provider: "kimi",
+            apiKey: "test-kimi-key",
+            baseUrl: "https://custom-kimi-endpoint.com/v1",
+            modelId: "kimi-k2.6",
+        })
+
+        expect(createDeepSeekMock).toHaveBeenCalledWith(
+            expect.objectContaining({
+                baseURL: "https://custom-kimi-endpoint.com/v1",
+            }),
+        )
+    })
+})
+
 describe("Ollama API key security", () => {
     let createOllamaMock: ReturnType<typeof vi.fn>
     const savedEnv: Record<string, string | undefined> = {}