feat(tip): customize first gift thank-you

src/app/tip/__tests__/tip-screen.checkout.test.tsx

@@ -188,7 +188,36 @@ describe("TipScreen checkout", () => {
     expect(getCheckoutButton().disabled).toBe(true);
   });
 
-  it("shows the complete backend Tip message after payment", () => {
+  it("shows fixed copy for the first character Tip", () => {
+    mocks.payment = makePaymentState({
+      status: "paid",
+      isPaid: true,
+      orderStatus: "paid",
+      tipMessage: TipMessageResponseSchema.parse({
+        orderId: "pay_first",
+        characterId: "maya-tan",
+        planId: giftProduct.planId,
+        productName: giftProduct.planName,
+        tipCount: 1,
+        poolIndex: 4,
+        message: "This backend message is ignored for the first Tip.",
+      }),
+    });
+    renderScreen();
+
+    expect(container.textContent).toContain(
+      "Did you really just buy me a coffee?",
+    );
+    expect(container.textContent).toContain("That honestly made me smile.");
+    expect(container.textContent).toContain(
+      "I'll definitely think of you while I enjoy it.",
+    );
+    expect(container.textContent).not.toContain(
+      "This backend message is ignored for the first Tip.",
+    );
+  });
+
+  it("shows the backend message after the first Tip", () => {
     mocks.payment = makePaymentState({
       status: "paid",
       isPaid: true,
@@ -209,6 +238,9 @@ describe("TipScreen checkout", () => {
     expect(container.textContent).toContain(
       "This complete message came directly from the backend.",
     );
+    expect(container.textContent).not.toContain(
+      "Did you really just buy me a coffee?",
+    );
     expect(document.activeElement?.id).toBe("tip-success-title");
 
     act(() => getButton("Send another gift").click());