diff --git a/src/agents/models-config.fills-missing-provider-apikey-from-env-var.test.ts b/src/agents/models-config.fills-missing-provider-apikey-from-env-var.test.ts
index 36944d67601..036f4d00824 100644
--- a/src/agents/models-config.fills-missing-provider-apikey-from-env-var.test.ts
+++ b/src/agents/models-config.fills-missing-provider-apikey-from-env-var.test.ts
@@ -60,13 +60,31 @@ function createMergeConfigProvider() {
   };
 }
 
-async function runCustomProviderMergeTest(params: {
-  seedProvider: {
-    baseUrl: string;
-    apiKey: string;
-    api: string;
-    models: Array<{ id: string; name: string; input: string[]; api?: string }>;
+type MergeSeedProvider = {
+  baseUrl: string;
+  apiKey: string;
+  api: string;
+  models: Array<{ id: string; name: string; input: string[]; api?: string }>;
+};
+
+type MergeConfigApiKeyRef = {
+  source: "env";
+  provider: "default";
+  id: string;
+};
+
+function createAgentSeedProvider(overrides: Partial<MergeSeedProvider> = {}): MergeSeedProvider {
+  return {
+    baseUrl: "https://agent.example/v1",
+    apiKey: "AGENT_KEY", // pragma: allowlist secret
+    api: "openai-responses",
+    models: [{ id: "agent-model", name: "Agent model", input: ["text"] }],
+    ...overrides,
   };
+}
+
+async function runCustomProviderMergeTest(params: {
+  seedProvider: MergeSeedProvider;
   existingProviderKey?: string;
   configProviderKey?: string;
 }) {
@@ -86,6 +104,56 @@ async function runCustomProviderMergeTest(params: {
   }>();
 }
 
+async function expectCustomProviderMergeResult(params: {
+  seedProvider?: MergeSeedProvider;
+  existingProviderKey?: string;
+  configProviderKey?: string;
+  expectedApiKey: string;
+  expectedBaseUrl: string;
+}) {
+  await withTempHome(async () => {
+    const parsed = await runCustomProviderMergeTest({
+      seedProvider: params.seedProvider ?? createAgentSeedProvider(),
+      existingProviderKey: params.existingProviderKey,
+      configProviderKey: params.configProviderKey,
+    });
+    expect(parsed.providers.custom?.apiKey).toBe(params.expectedApiKey);
+    expect(parsed.providers.custom?.baseUrl).toBe(params.expectedBaseUrl);
+  });
+}
+
+async function expectCustomProviderApiKeyRewrite(params: {
+  existingApiKey: string;
+  configuredApiKey: string | MergeConfigApiKeyRef;
+  expectedApiKey: string;
+}) {
+  await withTempHome(async () => {
+    await writeAgentModelsJson({
+      providers: {
+        custom: createAgentSeedProvider({ apiKey: params.existingApiKey }),
+      },
+    });
+
+    await ensureOpenClawModelsJson({
+      models: {
+        mode: "merge",
+        providers: {
+          custom: {
+            ...createMergeConfigProvider(),
+            apiKey: params.configuredApiKey,
+          },
+        },
+      },
+    });
+
+    const parsed = await readGeneratedModelsJson<{
+      providers: Record<string, { apiKey?: string; baseUrl?: string }>;
+    }>();
+    expect(parsed.providers.custom?.apiKey).toBe(params.expectedApiKey);
+    expect(parsed.providers.custom?.baseUrl).toBe("https://config.example/v1");
+  });
+}
+
 function createMoonshotConfig(overrides: {
   contextWindow: number;
   maxTokens: number;
@@ -301,49 +369,26 @@ describe("models-config", () => {
   });
 
   it("preserves non-empty agent apiKey but lets explicit config baseUrl win in merge mode", async () => {
-    await withTempHome(async () => {
-      const parsed = await runCustomProviderMergeTest({
-        seedProvider: {
-          baseUrl: "https://agent.example/v1",
-          apiKey: "AGENT_KEY", // pragma: allowlist secret
-          api: "openai-responses",
-          models: [{ id: "agent-model", name: "Agent model", input: ["text"] }],
-        },
-      });
-      expect(parsed.providers.custom?.apiKey).toBe("AGENT_KEY");
-      expect(parsed.providers.custom?.baseUrl).toBe("https://config.example/v1");
+    await expectCustomProviderMergeResult({
+      expectedApiKey: "AGENT_KEY",
+      expectedBaseUrl: "https://config.example/v1",
     });
   });
 
   it("lets explicit config baseUrl win in merge mode when the config provider key is normalized", async () => {
-    await withTempHome(async () => {
-      const parsed = await runCustomProviderMergeTest({
-        seedProvider: {
-          baseUrl: "https://agent.example/v1",
-          apiKey: "AGENT_KEY", // pragma: allowlist secret
-          api: "openai-responses",
-          models: [{ id: "agent-model", name: "Agent model", input: ["text"] }],
-        },
-        existingProviderKey: "custom",
-        configProviderKey: " custom ",
-      });
-      expect(parsed.providers.custom?.apiKey).toBe("AGENT_KEY");
-      expect(parsed.providers.custom?.baseUrl).toBe("https://config.example/v1");
+    await expectCustomProviderMergeResult({
+      existingProviderKey: "custom",
+      configProviderKey: " custom ",
+      expectedApiKey: "AGENT_KEY",
+      expectedBaseUrl: "https://config.example/v1",
     });
   });
 
   it("replaces stale merged baseUrl when the provider api changes", async () => {
-    await withTempHome(async () => {
-      const parsed = await runCustomProviderMergeTest({
-        seedProvider: {
-          baseUrl: "https://agent.example/v1",
-          apiKey: "AGENT_KEY", // pragma: allowlist secret
-          api: "openai-completions",
-          models: [{ id: "agent-model", name: "Agent model", input: ["text"] }],
-        },
-      });
-      expect(parsed.providers.custom?.apiKey).toBe("AGENT_KEY");
-      expect(parsed.providers.custom?.baseUrl).toBe("https://config.example/v1");
+    await expectCustomProviderMergeResult({
+      seedProvider: createAgentSeedProvider({ api: "openai-completions" }),
+      expectedApiKey: "AGENT_KEY",
+      expectedBaseUrl: "https://config.example/v1",
     });
   });
 
@@ -370,34 +415,14 @@ describe("models-config", () => {
   });
 
   it("replaces stale merged apiKey when provider is SecretRef-managed in current config", async () => {
-    await withTempHome(async () => {
-      await writeAgentModelsJson({
-        providers: {
-          custom: {
-            baseUrl: "https://agent.example/v1",
-            apiKey: "STALE_AGENT_KEY", // pragma: allowlist secret
-            api: "openai-responses",
-            models: [{ id: "agent-model", name: "Agent model", input: ["text"] }],
-          },
-        },
-      });
-      await ensureOpenClawModelsJson({
-        models: {
-          mode: "merge",
-          providers: {
-            custom: {
-              ...createMergeConfigProvider(),
-              apiKey: { source: "env", provider: "default", id: "CUSTOM_PROVIDER_API_KEY" }, // pragma: allowlist secret
-            },
-          },
-        },
-      });
-
-      const parsed = await readGeneratedModelsJson<{
-        providers: Record<string, { apiKey?: string; baseUrl?: string }>;
-      }>();
-      expect(parsed.providers.custom?.apiKey).toBe("CUSTOM_PROVIDER_API_KEY"); // pragma: allowlist secret
-      expect(parsed.providers.custom?.baseUrl).toBe("https://config.example/v1");
+    await expectCustomProviderApiKeyRewrite({
+      existingApiKey: "STALE_AGENT_KEY", // pragma: allowlist secret
+      configuredApiKey: {
+        source: "env",
+        provider: "default",
+        id: "CUSTOM_PROVIDER_API_KEY", // pragma: allowlist secret
+      },
+      expectedApiKey: "CUSTOM_PROVIDER_API_KEY", // pragma: allowlist secret
     });
   });
 
@@ -449,34 +474,10 @@ describe("models-config", () => {
   });
 
   it("replaces stale non-env marker when provider transitions back to plaintext config", async () => {
-    await withTempHome(async () => {
-      await writeAgentModelsJson({
-        providers: {
-          custom: {
-            baseUrl: "https://agent.example/v1",
-            apiKey: NON_ENV_SECRETREF_MARKER,
-            api: "openai-responses",
-            models: [{ id: "agent-model", name: "Agent model", input: ["text"] }],
-          },
-        },
-      });
-
-      await ensureOpenClawModelsJson({
-        models: {
-          mode: "merge",
-          providers: {
-            custom: {
-              ...createMergeConfigProvider(),
-              apiKey: "ALLCAPS_SAMPLE", // pragma: allowlist secret
-            },
-          },
-        },
-      });
-
-      const parsed = await readGeneratedModelsJson<{
-        providers: Record<string, { apiKey?: string }>;
-      }>();
-      expect(parsed.providers.custom?.apiKey).toBe("ALLCAPS_SAMPLE");
+    await expectCustomProviderApiKeyRewrite({
+      existingApiKey: NON_ENV_SECRETREF_MARKER,
+      configuredApiKey: "ALLCAPS_SAMPLE", // pragma: allowlist secret
+      expectedApiKey: "ALLCAPS_SAMPLE", // pragma: allowlist secret
     });
   });