fix(ai): send only thinking on/off toggle for Xiaomi MiMo models

MiMo Chat Completions rejects reasoning_effort "minimal" with a 400.
Xiaomi documents only thinking.type enabled/disabled and treats all effort
levels identically, so stop sending reasoning_effort and expose only the
off and high thinking levels.

fixes #10818

packages/ai/CHANGELOG.md

@@ -15,6 +15,7 @@
 - Fixed automatic retry not triggering for gateway `Unable to forward upstream stream` errors ([#10920](https://github.com/earendil-works/pi/issues/10920))
 - Fixed OpenAI-compatible responses showing thinking after the answer when a proxy such as LiteLLM sends reasoning and content in the same stream chunk ([#10926](https://github.com/earendil-works/pi/issues/10926))
 - Fixed Gemini 4 Argon requests on Google Vertex failing with "Thinking budget is not supported", and its thinking level being ignored on the Gemini API, by sending `thinkingLevel` for Gemini 4 and later models ([#10890](https://github.com/earendil-works/pi/issues/10890))
+- Fixed Xiaomi MiMo models failing with a 400 at the `minimal` thinking level by sending only the documented thinking on/off toggle and exposing only the `off` and `high` levels ([#10818](https://github.com/earendil-works/pi/issues/10818))
 
 ## [1.2.0] - 2026-10-12
 

packages/ai/scripts/generate-models.ts

@@ -2462,10 +2462,23 @@ async function loadModelsDevData(): Promise<Model<any>[]> {
 		// Built-in `xiaomi` targets the API billing endpoint (single stable URL,
 		// keys from platform.xiaomimimo.com). The three `xiaomi-token-plan-*`
 		// providers cover prepaid Token Plan endpoints in cn / ams / sgp.
+		// MiMo Chat Completions only documents thinking.type enabled/disabled and
+		// rejects some reasoning_effort values (e.g. "minimal"). Xiaomi documents
+		// all effort levels as identical, so expose only off and high.
 		const xiaomiCompat: OpenAICompletionsCompat = {
+			supportsReasoningEffort: false,
 			requiresReasoningContentOnAssistantMessages: true,
 			thinkingFormat: "deepseek",
 		};
+		const xiaomiThinkingLevelMap = {
+			off: "off",
+			minimal: null,
+			low: null,
+			medium: null,
+			high: "high",
+			xhigh: null,
+			max: null,
+		} as const;
 		const xiaomiVariants = [
 			{ source: "xiaomi", provider: "xiaomi", baseUrl: "https://api.xiaomimimo.com/v1" },
 			{
@@ -2502,12 +2515,12 @@ async function loadModelsDevData(): Promise<Model<any>[]> {
 					baseUrl,
 					compat: xiaomiCompat,
 					reasoning: m.reasoning === true,
+					...(m.reasoning === true ? { thinkingLevelMap: xiaomiThinkingLevelMap } : {}),
 					input: m.modalities?.input?.includes("image") ? ["text", "image"] : ["text"],
 					cost: getModelsDevCost(m.cost),
 					contextWindow: m.limit?.context || 4096,
 					maxTokens: m.limit?.output || 4096,
 				});
-				recordModelsDevReasoningOptions(provider, modelId, m);
 			}
 		}
 

packages/ai/test/xiaomi-models.test.ts

@@ -1,5 +1,7 @@
 import { describe, expect, it } from "vitest";
-import { getModels } from "../src/compat.ts";
+import { getModels, streamSimple } from "../src/compat.ts";
+import { getSupportedThinkingLevels } from "../src/models.ts";
+import type { ThinkingLevel } from "../src/types.ts";
 
 const XIAOMI_PROVIDERS = ["xiaomi", "xiaomi-token-plan-cn", "xiaomi-token-plan-ams", "xiaomi-token-plan-sgp"] as const;
 const DEPRECATED_MODEL_IDS = ["mimo-v2-flash", "mimo-v2-omni", "mimo-v2-pro"] as const;
@@ -15,4 +17,39 @@ describe("Xiaomi MiMo models", () => {
 		const modelIds = getModels(provider).map((model) => model.id);
 		for (const modelId of REPLACEMENT_MODEL_IDS) expect(modelIds).toContain(modelId);
 	});
+
+	// #10818: MiMo Chat Completions only supports a thinking on/off toggle.
+	it.each(XIAOMI_PROVIDERS)("models %s reasoning as an off/on toggle", async (provider) => {
+		const models = getModels(provider).filter((model) => model.reasoning);
+		expect(models.length).toBeGreaterThan(0);
+
+		for (const model of models) {
+			expect(getSupportedThinkingLevels(model)).toEqual(["off", "high"]);
+
+			const capturePayload = async (reasoning: ThinkingLevel | undefined) => {
+				let payload: Record<string, unknown> | undefined;
+				await streamSimple(
+					model,
+					{ messages: [{ role: "user", content: "test", timestamp: 0 }] },
+					{
+						apiKey: "test-xiaomi-key",
+						reasoning,
+						onPayload: (value) => {
+							payload = value as Record<string, unknown>;
+							throw new Error("payload captured");
+						},
+					},
+				).result();
+				return payload;
+			};
+
+			const enabled = await capturePayload("high");
+			expect(enabled?.thinking).toEqual({ type: "enabled" });
+			expect(enabled?.reasoning_effort).toBeUndefined();
+
+			const disabled = await capturePayload(undefined);
+			expect(disabled?.thinking).toEqual({ type: "disabled" });
+			expect(disabled?.reasoning_effort).toBeUndefined();
+		}
+	});
 });