diff --git a/packages/ai/CHANGELOG.md b/packages/ai/CHANGELOG.md
index ae883f27d..f1154cc7d 100644
--- a/packages/ai/CHANGELOG.md
+++ b/packages/ai/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed Xiaomi MiMo standard API-key validation to use the supported `mimo-v2.5` model. ([#4063](https://github.com/can1357/oh-my-pi/issues/4063))
+
 ## [16.2.12] - 2026-07-01
 
 ### Changed
diff --git a/packages/ai/src/registry/oauth/xiaomi.ts b/packages/ai/src/registry/oauth/xiaomi.ts
index ca84c82d1..a2ae7c1f1 100644
--- a/packages/ai/src/registry/oauth/xiaomi.ts
+++ b/packages/ai/src/registry/oauth/xiaomi.ts
@@ -18,7 +18,7 @@ const STANDARD_AUTH_URL = "https://platform.xiaomimimo.com/#/console/api-keys";
 const TOKEN_PLAN_AUTH_URL = "https://platform.xiaomimimo.com/console/plan-manage";
 const STANDARD_API_BASE_URL = "https://api.xiaomimimo.com/v1";
 const TOKEN_PLAN_KEY_PREFIX = "tp-";
-const STANDARD_VALIDATION_MODEL = "mimo-v2-flash";
+const STANDARD_VALIDATION_MODEL = "mimo-v2.5";
 const TOKEN_PLAN_VALIDATION_MODEL = "mimo-v2.5";
 const TOKEN_PLAN_SGP_API_BASE_URL = "https://token-plan-sgp.xiaomimimo.com/v1";
 const TOKEN_PLAN_AMS_API_BASE_URL = "https://token-plan-ams.xiaomimimo.com/v1";
diff --git a/packages/ai/test/xiaomi-oauth.test.ts b/packages/ai/test/xiaomi-oauth.test.ts
index 2e7c8329a..50dd8273c 100644
--- a/packages/ai/test/xiaomi-oauth.test.ts
+++ b/packages/ai/test/xiaomi-oauth.test.ts
@@ -55,9 +55,11 @@ describe("xiaomi oauth validation", () => {
 	it("sends Authorization: Bearer for standard sk- keys as well", async () => {
 		const capturedHeaders: Record<string, string>[] = [];
 		const capturedUrls: string[] = [];
+		const capturedBodies: string[] = [];
 		const fetchMock: FetchImpl = vi.fn(async (input, init) => {
 			capturedUrls.push(typeof input === "string" ? input : input.toString());
 			capturedHeaders.push((init?.headers ?? {}) as Record<string, string>);
+			capturedBodies.push(String(init?.body));
 			return new Response("{}", { status: 200, headers: { "Content-Type": "application/json" } });
 		});
 
@@ -69,6 +71,7 @@ describe("xiaomi oauth validation", () => {
 
 		expect(fetchMock).toHaveBeenCalledTimes(1);
 		expect(capturedUrls[0]).toBe("https://api.xiaomimimo.com/v1/chat/completions");
+		expect(JSON.parse(capturedBodies[0]).model).toBe("mimo-v2.5");
 		const headers = capturedHeaders[0];
 		expect(headers.Authorization).toBe("Bearer sk-test-key");
 		expect(headers["x-api-key"]).toBeUndefined();
diff --git a/packages/catalog/CHANGELOG.md b/packages/catalog/CHANGELOG.md
index 912cca759..1ac776840 100644
--- a/packages/catalog/CHANGELOG.md
+++ b/packages/catalog/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed the Xiaomi provider default model to use the supported `mimo-v2.5` model. ([#4063](https://github.com/can1357/oh-my-pi/issues/4063))
+
 ## [16.2.12] - 2026-07-01
 
 ### Breaking Changes
diff --git a/packages/catalog/src/provider-models/descriptors.ts b/packages/catalog/src/provider-models/descriptors.ts
index 70e79edf3..587422c7f 100644
--- a/packages/catalog/src/provider-models/descriptors.ts
+++ b/packages/catalog/src/provider-models/descriptors.ts
@@ -415,7 +415,7 @@ export const CATALOG_PROVIDERS = [
 	},
 	{
 		id: "xiaomi",
-		defaultModel: "mimo-v2-flash",
+		defaultModel: "mimo-v2.5",
 		envVars: ["XIAOMI_API_KEY"],
 		createModelManagerOptions: (config: ModelManagerConfig) => xiaomiModelManagerOptions(config),
 		catalogDiscovery: { label: "Xiaomi" },
diff --git a/packages/catalog/test/descriptors.test.ts b/packages/catalog/test/descriptors.test.ts
index feb85b5d1..66a244b06 100644
--- a/packages/catalog/test/descriptors.test.ts
+++ b/packages/catalog/test/descriptors.test.ts
@@ -16,6 +16,7 @@ describe("catalog provider descriptors", () => {
 		expect(DEFAULT_MODEL_PER_PROVIDER.minimax).toBe("MiniMax-M3");
 		expect(DEFAULT_MODEL_PER_PROVIDER["minimax-code"]).toBe("MiniMax-M3");
 		expect(DEFAULT_MODEL_PER_PROVIDER["minimax-code-cn"]).toBe("MiniMax-M3");
+		expect(DEFAULT_MODEL_PER_PROVIDER.xiaomi).toBe("mimo-v2.5");
 		// Login-only tools have no default model.
 		expect(DEFAULT_MODEL_PER_PROVIDER).not.toHaveProperty("kagi");
 	});