diff --git a/extensions/litellm/onboard.test.ts b/extensions/litellm/onboard.test.ts
index d0283a7ea03..37ac2527fc1 100644
--- a/extensions/litellm/onboard.test.ts
+++ b/extensions/litellm/onboard.test.ts
@@ -1,26 +1,21 @@
 import { describe, expect, it } from "vitest";
-import { createLegacyProviderConfig } from "../../test/helpers/plugins/onboard-config.js";
+import { expectProviderOnboardMergedLegacyConfig } from "../../test/helpers/plugins/provider-onboard.js";
 import { applyLitellmProviderConfig } from "./onboard.js";
 
 describe("litellm onboard", () => {
   it("preserves existing baseUrl and api key while adding the default model", () => {
-    const cfg = applyLitellmProviderConfig(
-      createLegacyProviderConfig({
-        providerId: "litellm",
-        api: "anthropic-messages",
-        modelId: "custom-model",
-        modelName: "Custom",
-        baseUrl: "https://litellm.example/v1",
-        apiKey: "  old-key  ",
-      }),
-    );
+    const provider = expectProviderOnboardMergedLegacyConfig({
+      applyProviderConfig: applyLitellmProviderConfig,
+      providerId: "litellm",
+      providerApi: "openai-completions",
+      baseUrl: "https://litellm.example/v1",
+      legacyApi: "anthropic-messages",
+      legacyModelId: "custom-model",
+      legacyModelName: "Custom",
+      legacyBaseUrl: "https://litellm.example/v1",
+      legacyApiKey: "  old-key  ",
+    });
 
-    expect(cfg.models?.providers?.litellm?.baseUrl).toBe("https://litellm.example/v1");
-    expect(cfg.models?.providers?.litellm?.api).toBe("openai-completions");
-    expect(cfg.models?.providers?.litellm?.apiKey).toBe("old-key");
-    expect(cfg.models?.providers?.litellm?.models.map((m) => m.id)).toEqual([
-      "custom-model",
-      "claude-opus-4-6",
-    ]);
+    expect(provider?.models.map((m) => m.id)).toEqual(["custom-model", "claude-opus-4-6"]);
   });
 });
diff --git a/extensions/synthetic/onboard.test.ts b/extensions/synthetic/onboard.test.ts
index 1172567e231..f71ffa9fbbe 100644
--- a/extensions/synthetic/onboard.test.ts
+++ b/extensions/synthetic/onboard.test.ts
@@ -1,6 +1,6 @@
 import { resolveAgentModelPrimaryValue } from "openclaw/plugin-sdk/provider-onboard";
 import { describe, expect, it } from "vitest";
-import { createLegacyProviderConfig } from "../../test/helpers/plugins/onboard-config.js";
+import { expectProviderOnboardMergedLegacyConfig } from "../../test/helpers/plugins/provider-onboard.js";
 import { SYNTHETIC_DEFAULT_MODEL_REF as SYNTHETIC_DEFAULT_MODEL_REF_PUBLIC } from "./api.js";
 import {
   applySyntheticConfig,
@@ -21,16 +21,14 @@ describe("synthetic onboard", () => {
   });
 
   it("merges existing synthetic provider models", () => {
-    const cfg = applySyntheticProviderConfig(
-      createLegacyProviderConfig({
-        providerId: "synthetic",
-        api: "openai-completions",
-      }),
-    );
-    expect(cfg.models?.providers?.synthetic?.baseUrl).toBe("https://api.synthetic.new/anthropic");
-    expect(cfg.models?.providers?.synthetic?.api).toBe("anthropic-messages");
-    expect(cfg.models?.providers?.synthetic?.apiKey).toBe("old-key");
-    const ids = cfg.models?.providers?.synthetic?.models.map((m) => m.id);
+    const provider = expectProviderOnboardMergedLegacyConfig({
+      applyProviderConfig: applySyntheticProviderConfig,
+      providerId: "synthetic",
+      providerApi: "anthropic-messages",
+      baseUrl: "https://api.synthetic.new/anthropic",
+      legacyApi: "openai-completions",
+    });
+    const ids = provider?.models.map((m) => m.id);
     expect(ids).toContain("old-model");
     expect(ids).toContain(SYNTHETIC_DEFAULT_MODEL_REF.replace(/^synthetic\//, ""));
   });
diff --git a/extensions/xiaomi/onboard.test.ts b/extensions/xiaomi/onboard.test.ts
index 89f8529592f..f45af114055 100644
--- a/extensions/xiaomi/onboard.test.ts
+++ b/extensions/xiaomi/onboard.test.ts
@@ -1,6 +1,6 @@
 import { resolveAgentModelPrimaryValue } from "openclaw/plugin-sdk/provider-onboard";
 import { describe, expect, it } from "vitest";
-import { createLegacyProviderConfig } from "../../test/helpers/plugins/onboard-config.js";
+import { expectProviderOnboardMergedLegacyConfig } from "../../test/helpers/plugins/provider-onboard.js";
 import { applyXiaomiConfig, applyXiaomiProviderConfig } from "./onboard.js";
 
 describe("xiaomi onboard", () => {
@@ -19,19 +19,16 @@ describe("xiaomi onboard", () => {
   });
 
   it("merges Xiaomi models and keeps existing provider overrides", () => {
-    const cfg = applyXiaomiProviderConfig(
-      createLegacyProviderConfig({
-        providerId: "xiaomi",
-        api: "openai-completions",
-        modelId: "custom-model",
-        modelName: "Custom",
-      }),
-    );
-
-    expect(cfg.models?.providers?.xiaomi?.baseUrl).toBe("https://api.xiaomimimo.com/v1");
-    expect(cfg.models?.providers?.xiaomi?.api).toBe("openai-completions");
-    expect(cfg.models?.providers?.xiaomi?.apiKey).toBe("old-key");
-    expect(cfg.models?.providers?.xiaomi?.models.map((m) => m.id)).toEqual([
+    const provider = expectProviderOnboardMergedLegacyConfig({
+      applyProviderConfig: applyXiaomiProviderConfig,
+      providerId: "xiaomi",
+      providerApi: "openai-completions",
+      baseUrl: "https://api.xiaomimimo.com/v1",
+      legacyApi: "openai-completions",
+      legacyModelId: "custom-model",
+      legacyModelName: "Custom",
+    });
+    expect(provider?.models.map((m) => m.id)).toEqual([
       "custom-model",
       "mimo-v2-flash",
       "mimo-v2-pro",
diff --git a/test/helpers/plugins/provider-onboard.ts b/test/helpers/plugins/provider-onboard.ts
index befd5a62b6c..22ce672eb3a 100644
--- a/test/helpers/plugins/provider-onboard.ts
+++ b/test/helpers/plugins/provider-onboard.ts
@@ -4,7 +4,11 @@ import {
 } from "openclaw/plugin-sdk/provider-onboard";
 import { expect } from "vitest";
 import type { OpenClawConfig } from "../../../src/config/config.js";
-import { createConfigWithFallbacks, EXPECTED_FALLBACKS } from "./onboard-config.js";
+import {
+  createConfigWithFallbacks,
+  createLegacyProviderConfig,
+  EXPECTED_FALLBACKS,
+} from "./onboard-config.js";
 
 export function expectProviderOnboardAllowlistAlias(params: {
   applyProviderConfig: (config: OpenClawConfig) => OpenClawConfig;
@@ -38,3 +42,38 @@ export function expectProviderOnboardPrimaryAndFallbacks(params: {
     ...EXPECTED_FALLBACKS,
   ]);
 }
+
+export function expectProviderOnboardMergedLegacyConfig(params: {
+  applyProviderConfig: (config: OpenClawConfig) => OpenClawConfig;
+  providerId: string;
+  providerApi: OpenClawConfig["models"] extends { providers?: infer P }
+    ? P extends Record<string, infer Provider>
+      ? Provider extends { api?: infer Api }
+        ? Api
+        : never
+      : never
+    : never;
+  baseUrl: string;
+  legacyApi: Parameters<typeof createLegacyProviderConfig>[0]["api"];
+  legacyModelId?: string;
+  legacyModelName?: string;
+  legacyBaseUrl?: string;
+  legacyApiKey?: string;
+}) {
+  const cfg = params.applyProviderConfig(
+    createLegacyProviderConfig({
+      providerId: params.providerId,
+      api: params.legacyApi,
+      modelId: params.legacyModelId,
+      modelName: params.legacyModelName,
+      baseUrl: params.legacyBaseUrl,
+      apiKey: params.legacyApiKey,
+    }),
+  );
+
+  const provider = cfg.models?.providers?.[params.providerId];
+  expect(provider?.baseUrl).toBe(params.baseUrl);
+  expect(provider?.api).toBe(params.providerApi);
+  expect(provider?.apiKey).toBe((params.legacyApiKey ?? "old-key").trim());
+  return provider;
+}