diff --git a/src/consts.ts b/src/consts.ts
index 18e7793..059e9d7 100644
--- a/src/consts.ts
+++ b/src/consts.ts
@@ -1,4 +1,8 @@
 export const NEW_API_BASE_URL = "https://recoup-api.vercel.app";
 export const RECOUP_API_KEY = process.env.RECOUP_API_KEY;
 export const CODING_AGENT_ACCOUNT_ID = "ccbed42f-4d91-4834-b954-2a64a77d8665";
-export const OPENCLAW_DEFAULT_MODEL = "vercel-ai-gateway/anthropic/claude-sonnet-4.6";
\ No newline at end of file
+export const OPENCLAW_DEFAULT_MODEL = "vercel-ai-gateway/anthropic/claude-sonnet-4.6";
+// Scheduled customer tasks run headless with no user to catch a hallucinated report.
+// Sonnet 5 respects the data-grounding rule (refuses to fabricate) where the prior
+// default (haiku-4.5) did not — verified on the OneRPM/Apache benchmark (recoupable/chat#1833).
+export const DEFAULT_TASK_MODEL = "anthropic/claude-sonnet-5";
diff --git a/src/tasks/__tests__/customerPromptTask.test.ts b/src/tasks/__tests__/customerPromptTask.test.ts
new file mode 100644
index 0000000..677aa30
--- /dev/null
+++ b/src/tasks/__tests__/customerPromptTask.test.ts
@@ -0,0 +1,49 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+
+const mockRun = vi.hoisted(() => vi.fn());
+vi.mock("@trigger.dev/sdk/v3", () => ({
+  logger: { log: vi.fn(), warn: vi.fn(), error: vi.fn() },
+  tags: { add: vi.fn() },
+  schedules: {
+    task: (config: { run: unknown }) => {
+      mockRun.mockImplementation(config.run as (...args: unknown[]) => unknown);
+      return config;
+    },
+  },
+}));
+
+const mockFetchTask = vi.fn();
+vi.mock("../../recoup/fetchTask", () => ({ fetchTask: (...a: unknown[]) => mockFetchTask(...a) }));
+const mockGetTaskRoomId = vi.fn();
+vi.mock("../../chats/getTaskRoomId", () => ({ getTaskRoomId: (...a: unknown[]) => mockGetTaskRoomId(...a) }));
+const mockGenerateChat = vi.fn();
+vi.mock("../../recoup/generateChat", () => ({ generateChat: (...a: unknown[]) => mockGenerateChat(...a) }));
+
+// real chatSchema is used
+import "../customerPromptTask";
+
+const payload = { timestamp: new Date(0), timezone: "UTC", externalId: "ext-1" };
+
+beforeEach(() => {
+  vi.clearAllMocks();
+  mockGetTaskRoomId.mockResolvedValue("room-1");
+  mockGenerateChat.mockResolvedValue(undefined);
+});
+
+describe("customerPromptTask model default", () => {
+  it("defaults the model to anthropic/claude-sonnet-5 when the task config omits it", async () => {
+    mockFetchTask.mockResolvedValue({ accountId: "acc-1", artistId: "art-1", prompt: "do a thing" });
+    await mockRun(payload);
+    expect(mockGenerateChat).toHaveBeenCalledWith(
+      expect.objectContaining({ model: "anthropic/claude-sonnet-5", accountId: "acc-1" }),
+    );
+  });
+
+  it("forwards an explicit task model unchanged", async () => {
+    mockFetchTask.mockResolvedValue({ accountId: "acc-1", model: "anthropic/claude-opus-4-8", prompt: "x" });
+    await mockRun(payload);
+    expect(mockGenerateChat).toHaveBeenCalledWith(
+      expect.objectContaining({ model: "anthropic/claude-opus-4-8" }),
+    );
+  });
+});
diff --git a/src/tasks/customerPromptTask.ts b/src/tasks/customerPromptTask.ts
index 3768930..6f7e387 100644
--- a/src/tasks/customerPromptTask.ts
+++ b/src/tasks/customerPromptTask.ts
@@ -3,6 +3,7 @@ import { getTaskRoomId } from "../chats/getTaskRoomId";
 import { fetchTask } from "../recoup/fetchTask";
 import { generateChat } from "../recoup/generateChat";
 import { chatSchema, type ChatConfig } from "../schemas/chatSchema";
+import { DEFAULT_TASK_MODEL } from "../consts";
 
 type TaskPayload = {
   // Provided automatically by Trigger.dev schedules
@@ -47,7 +48,7 @@ export const customerPromptTask = schedules.task({
 
     const accountId = taskConfig?.accountId;
     const artistId = taskConfig?.artistId;
-    const model = taskConfig?.model;
+    const model = taskConfig?.model ?? DEFAULT_TASK_MODEL;
     const prompt =
       taskConfig?.prompt ??
       "Draft a friendly check-in message for our customers.";