fix(mistral): pass through reasoning effort (#42164)

Co-authored-by: Aiden Cline <rekram1-node@users.noreply.github.com>

packages/core/test/provider-mistral.test.ts

@@ -27,6 +27,32 @@ test("Mistral sends promptCacheKey as prompt_cache_key", async () => {
   expect(body?.prompt_cache_key).toBe("session-123")
 })
 
+test("Mistral passes through unknown reasoning effort", async () => {
+  let body: Record<string, unknown> | undefined
+  const mockFetch = Object.assign(
+    async (_input: Parameters<typeof fetch>[0], init?: RequestInit) => {
+      body = JSON.parse(String(init?.body))
+      return Response.json({
+        id: "response-1",
+        created: 0,
+        model: "mistral-large-latest",
+        object: "chat.completion",
+        choices: [{ index: 0, message: { role: "assistant", content: "Hello" }, finish_reason: "stop" }],
+        usage: { prompt_tokens: 1, completion_tokens: 1, total_tokens: 2 },
+      })
+    },
+    { preconnect: fetch.preconnect },
+  )
+  const model = createMistral({ apiKey: "test", fetch: mockFetch })("mistral-large-latest")
+
+  await model.doGenerate({
+    prompt: [{ role: "user", content: [{ type: "text", text: "Hello" }] }],
+    providerOptions: { mistral: { reasoningEffort: "custom" } },
+  })
+
+  expect(body?.reasoning_effort).toBe("custom")
+})
+
 test("Mistral round-trips native reasoning in assistant history", async () => {
   let body: { messages?: unknown[] } | undefined
   const mockFetch = Object.assign(

patches/@ai-sdk%2Fmistral@3.0.51.patch

@@ -2,10 +2,12 @@ diff --git a/dist/index.d.mts b/dist/index.d.mts
 index 1bde0b9f8cbe6771a52c1041095c9dddfe8e5b6c..0ca2ffb2a0c9327aed5ddcf0004500dc8b42569f 100644
 --- a/dist/index.d.mts
 +++ b/dist/index.d.mts
-@@ -14,6 +14,7 @@ declare const mistralLanguageModelOptions: z.ZodObject<{
-         none: "none";
-         high: "high";
-     }>>;
+@@ -13,7 +13,5 @@ declare const mistralLanguageModelOptions: z.ZodObject<{
+-    reasoningEffort: z.ZodOptional<z.ZodEnum<{
+-        none: "none";
+-        high: "high";
+-    }>>;
++    reasoningEffort: z.ZodOptional<z.ZodString>;
 +    promptCacheKey: z.ZodOptional<z.ZodString>;
  }, z.core.$strip>;
  type MistralLanguageModelOptions = z.infer<typeof mistralLanguageModelOptions>;
@@ -14,10 +16,12 @@ diff --git a/dist/index.d.ts b/dist/index.d.ts
 index 1bde0b9f8cbe6771a52c1041095c9dddfe8e5b6c..0ca2ffb2a0c9327aed5ddcf0004500dc8b42569f 100644
 --- a/dist/index.d.ts
 +++ b/dist/index.d.ts
-@@ -14,6 +14,7 @@ declare const mistralLanguageModelOptions: z.ZodObject<{
-         none: "none";
-         high: "high";
-     }>>;
+@@ -13,7 +13,5 @@ declare const mistralLanguageModelOptions: z.ZodObject<{
+-    reasoningEffort: z.ZodOptional<z.ZodEnum<{
+-        none: "none";
+-        high: "high";
+-    }>>;
++    reasoningEffort: z.ZodOptional<z.ZodString>;
 +    promptCacheKey: z.ZodOptional<z.ZodString>;
  }, z.core.$strip>;
  type MistralLanguageModelOptions = z.infer<typeof mistralLanguageModelOptions>;
@@ -69,7 +73,7 @@ index d3f904c12a1d582cc7b9e9a2d30273e1a8505b28..267f34e20ea392b7a85ad5259d72d506
     * - `'none'`: Disable reasoning
     */
 -  reasoningEffort: import_v4.z.enum(["high", "none"]).optional()
-+  reasoningEffort: import_v4.z.enum(["high", "none"]).optional(),
++  reasoningEffort: import_v4.z.string().optional(),
 +  promptCacheKey: import_v4.z.string().optional()
  });
  
@@ -268,7 +272,7 @@ index d2eff622c1b84a96bdeb4012cb0206a33012a04d..3bff11ddd6136ada45809568828cbc8f
     * - `'none'`: Disable reasoning
     */
 -  reasoningEffort: z.enum(["high", "none"]).optional()
-+  reasoningEffort: z.enum(["high", "none"]).optional(),
++  reasoningEffort: z.string().optional(),
 +  promptCacheKey: z.string().optional()
  });
  
@@ -655,7 +659,8 @@ index 54b29c08517d348995b6ca093b11160e453d5c8b..de30c3e7d924889339e38b1067cb26e9
 @@ -64,6 +64,11 @@ export const mistralLanguageModelOptions = z.object({
     * - `'none'`: Disable reasoning
     */
-   reasoningEffort: z.enum(['high', 'none']).optional(),
+-  reasoningEffort: z.enum(['high', 'none']).optional(),
++  reasoningEffort: z.string().optional(),
 +
 +  /**
 +   * A stable identifier used to route requests with shared prompt prefixes.