remove buyer change in web (#290)

### What changes are you making?

It looks like we intentionally removed this from native - so this is aimed at parity. Totally fine to go the otherway and introduce to native though.

---

Removes the `checkout:buyerChange` event (`ec.buyer.change` protocol message) from the web platform. This includes removing the event class (`ShopifyCheckoutBuyerChangeEvent`), its associated detail interface (`ShopifyCheckoutBuyerChangeEventDetail`), the typed `addEventListener` overload, the protocol message handler, and all related type definitions (`CheckoutBuyerChangeEvent`, `CheckoutProtocolMessageMap["ec.buyer.change"]`). The event is also removed from the public exports, the sample app event list, and the README documentation.

The test suite is updated to verify that `ec.buyer.change` is now treated as an unsupported/ignored notification alongside other unknown methods.

### How to test

1. Run the existing test suite: `pnpm test` in `platforms/web`.
2. Confirm that the `"ignores unsupported notification"` test now covers both `"customMethod"` and `"ec.buyer.change"`.
3. Confirm that no `checkout:buyerChange` events are dispatched or exported by the package.
4. Verify the sample app no longer lists `checkout:buyerChange` as a subscribable event type.

---

### Before you merge

> [!IMPORTANT]
> - [ ] I've added tests to support my implementation
> - [ ] I have read and agree with the [Contribution Guidelines](./CONTRIBUTING.md)
> - [ ] I have read and agree with the [Code of Conduct](./CODE_OF_CONDUCT.md)
> - [ ] I've updated the relevant platform README (`platforms/swift/README.md` and/or `platforms/android/README.md`)

---

<details>
<summary>Releasing a new Swift version?</summary>

- [ ] I have bumped the version in `ShopifyCheckoutKit.podspec`
- [ ] I have bumped the version in `platforms/swift/Sources/ShopifyCheckoutKit/ShopifyCheckoutKit.swift`
- [ ] I have updated `platforms/swift/CHANGELOG.md`
- [ ] I have updated the SwiftPM/CocoaPods version snippets in `platforms/swift/README.md` (major version only)

</details>

<details>
<summary>Releasing a new Android version?</summary>

- [ ] I have bumped the `versionName` in `platforms/android/lib/build.gradle`
- [ ] I have updated `platforms/android/CHANGELOG.md`
- [ ] I have updated the Gradle/Maven version snippets in `platforms/android/README.md`

</details>

> [!TIP]
> See the [Contributing documentation](./CONTRIBUTING.md) for the full release process per platform.

Author: kiftio

platforms/android/lib/src/test/java/com/shopify/checkoutkit/CheckoutProtocolTest.kt

@@ -60,6 +60,7 @@ class CheckoutProtocolTest {
     @Test
     fun `supported protocol methods exclude internal or unsupported methods`() {
         assertThat(CheckoutProtocol.supportedProtocolMethods).doesNotContain(
+            "ec.buyer.change",
             "ec.payment.credential_request",
             "ep.cart.ready",
         )

platforms/web/README.md

@@ -388,16 +388,15 @@ DOM — including a single delegated listener at `document` if you have many
 elements on the page. Each event carries a typed `event.detail` payload with
 exactly the fields relevant to that moment.
 
-| Event                | `event.detail`          | When it fires                                                              |
-| -------------------- | ----------------------- | -------------------------------------------------------------------------- |
-| `ec.start`           | `{checkout}`            | Checkout has loaded and is interactive.                                    |
-| `ec.complete`        | `{checkout, order}`     | The buyer completed the order successfully.                                |
-| `ec.close`           | _(none)_                | The popup was dismissed (by the buyer, by `close()`, or by `focus` loss).  |
-| `ec.error`           | `{error}`               | Session-level fatal error — tear down the embedded context.                |
+| Event                  | `event.detail`          | When it fires                                                              |
+| ---------------------- | ----------------------- | -------------------------------------------------------------------------- |
+| `ec.start`             | `{checkout}`            | Checkout has loaded and is interactive.                                    |
+| `ec.complete`          | `{checkout, order}`     | The buyer completed the order successfully.                                |
+| `ec.close`             | _(none)_                | The popup was dismissed (by the buyer, by `close()`, or by `focus` loss).  |
+| `ec.error`             | `{error}`               | Session-level fatal error — tear down the embedded context.                |
 | `ec.line_items.change` | `{checkout, lineItems}` | The cart's line items changed (item added/removed/quantity updated).       |
-| `ec.buyer.change`    | `{checkout, buyer}`     | The buyer's information changed (email, address, etc.).                    |
-| `ec.totals.change`   | `{checkout, totals}`    | The cart totals changed (subtotal, tax, shipping, discounts, total).       |
-| `ec.messages.change` | `{checkout, messages}`  | Checkout-level warnings/errors/info shown inside the checkout changed.     |
+| `ec.totals.change`     | `{checkout, totals}`    | The cart totals changed (subtotal, tax, shipping, discounts, total).       |
+| `ec.messages.change`   | `{checkout, messages}`  | Checkout-level warnings/errors/info shown inside the checkout changed.     |
 
 The `checkout` field on every change event is the full UCP `Checkout`
 snapshot, included for handlers that want broader context. Most handlers only

platforms/web/sample/main.ts

@@ -134,7 +134,6 @@ const EVENT_TYPES = [
   "ec.close",
   "ec.error",
   "ec.line_items.change",
-  "ec.buyer.change",
   "ec.totals.change",
   "ec.messages.change",
 ] as const;

platforms/web/src/checkout.test.ts

@@ -821,21 +821,24 @@ describe("<shopify-checkout>", () => {
         expect(mockCheckoutWindow.postMessage).not.toHaveBeenCalled();
       });
 
-      it("ignores unsupported notifications", () => {
-        const { checkout, mockCheckoutWindow } = openPopupCheckout();
+      it.each(["customMethod", "ec.buyer.change"])(
+        "ignores unsupported notification %s",
+        (method) => {
+          const { checkout, mockCheckoutWindow } = openPopupCheckout();
 
-        simulateRawMessageEvent(
-          checkout,
-          {
-            jsonrpc: "2.0",
-            method: "customMethod",
-            params: {},
-          },
-          { source: mockCheckoutWindow },
-        );
+          simulateRawMessageEvent(
+            checkout,
+            {
+              jsonrpc: "2.0",
+              method,
+              params: {},
+            },
+            { source: mockCheckoutWindow },
+          );
 
-        expect(mockCheckoutWindow.postMessage).not.toHaveBeenCalled();
-      });
+          expect(mockCheckoutWindow.postMessage).not.toHaveBeenCalled();
+        },
+      );
     });
 
     describe("ec.start", () => {
@@ -967,23 +970,6 @@ describe("<shopify-checkout>", () => {
       });
     });
 
-    describe("ec.buyer.change", () => {
-      it("updates the checkout property and dispatches an ec.buyer.change event", async () => {
-        const { checkout, mockCheckoutWindow } = openPopupCheckout();
-        const onBuyerChangeSpy = vi.fn();
-        const listenForEvent = waitForEvent(checkout, "ec.buyer.change", onBuyerChangeSpy);
-
-        const payload = makeCheckoutPayload();
-        simulateProtocolMessageEvent(checkout, "ec.buyer.change", payload, {
-          source: mockCheckoutWindow,
-        });
-        await listenForEvent;
-
-        expect(checkout.checkout).toBe(payload.checkout);
-        expect(onBuyerChangeSpy).toHaveBeenCalledOnce();
-      });
-    });
-
     describe("ec.totals.change", () => {
       it("updates the checkout property and dispatches an ec.totals.change event", async () => {
         const { checkout, mockCheckoutWindow } = openPopupCheckout();
@@ -1084,22 +1070,6 @@ describe("<shopify-checkout>", () => {
         expect(event.detail.checkout).toBe(payload.checkout);
       });
 
-      it("ec.buyer.change carries {buyer, checkout}", async () => {
-        const { checkout, mockCheckoutWindow } = openPopupCheckout();
-        const spy = vi.fn();
-        const wait = waitForEvent(checkout, "ec.buyer.change", spy);
-
-        const payload = makeCheckoutPayload();
-        simulateProtocolMessageEvent(checkout, "ec.buyer.change", payload, {
-          source: mockCheckoutWindow,
-        });
-        await wait;
-
-        const event = spy.mock.calls[0]![0] as CustomEvent;
-        expect(event.detail.buyer).toBe(payload.checkout.buyer);
-        expect(event.detail.checkout).toBe(payload.checkout);
-      });
-
       it("ec.totals.change carries {totals, checkout}", async () => {
         const { checkout, mockCheckoutWindow } = openPopupCheckout();
         const spy = vi.fn();

platforms/web/src/checkout.ts

@@ -11,7 +11,6 @@ import type {
   CheckoutLineItem,
   CheckoutMessage,
   Total,
-  Buyer,
   OrderConfirmation,
   UcpErrorResponse,
 } from "./checkout.types";
@@ -66,7 +65,6 @@ const SHADOW_TEMPLATE = createTemplate(html`
  * @event ec.complete - Dispatched when the checkout was successfully completed
  * @event ec.error - Dispatched on a session-level fatal error
  * @event ec.line_items.change - Dispatched when cart line items change
- * @event ec.buyer.change - Dispatched when buyer information changes
  * @event ec.totals.change - Dispatched when totals change
  * @event ec.messages.change - Dispatched when checkout messages change
  * @event ec.close - Dispatched when the checkout overlay is closed (synthetic, not part of ECP)
@@ -580,16 +578,6 @@ export class ShopifyCheckout
         );
         break;
       }
-      case "ec.buyer.change": {
-        const checkout = (message.body as CheckoutProtocolMessageMap["ec.buyer.change"]).checkout;
-        this.dispatchEvent(
-          new ShopifyCheckoutBuyerChangeEvent({
-            checkout,
-            buyer: checkout.buyer,
-          }),
-        );
-        break;
-      }
       case "ec.totals.change": {
         const checkout = (message.body as CheckoutProtocolMessageMap["ec.totals.change"]).checkout;
         this.dispatchEvent(
@@ -761,12 +749,6 @@ export class ShopifyCheckout
     options?: boolean | AddEventListenerOptions,
   ): void;
 
-  override addEventListener(
-    type: "ec.buyer.change",
-    listener: TypedEventListener<ShopifyCheckoutBuyerChangeEvent> | null,
-    options?: boolean | AddEventListenerOptions,
-  ): void;
-
   override addEventListener(
     type: "ec.totals.change",
     listener: TypedEventListener<ShopifyCheckoutTotalsChangeEvent> | null,
@@ -818,13 +800,6 @@ export interface ShopifyCheckoutLineItemsChangeEventDetail {
   checkout: Checkout;
 }
 
-export interface ShopifyCheckoutBuyerChangeEventDetail {
-  /** Updated buyer (may be undefined when buyer information is cleared). */
-  buyer: Buyer | undefined;
-  /** Full checkout snapshot for handlers that want broader context. */
-  checkout: Checkout;
-}
-
 export interface ShopifyCheckoutTotalsChangeEventDetail {
   /** Updated totals. */
   totals: readonly Total[];
@@ -884,14 +859,6 @@ export class ShopifyCheckoutLineItemsChangeEvent extends CustomEvent<ShopifyChec
   }
 }
 
-export class ShopifyCheckoutBuyerChangeEvent extends CustomEvent<ShopifyCheckoutBuyerChangeEventDetail> {
-  declare type: "ec.buyer.change";
-
-  constructor(detail: ShopifyCheckoutBuyerChangeEventDetail) {
-    super("ec.buyer.change", { detail, bubbles: true });
-  }
-}
-
 export class ShopifyCheckoutTotalsChangeEvent extends CustomEvent<ShopifyCheckoutTotalsChangeEventDetail> {
   declare type: "ec.totals.change";
 
@@ -918,7 +885,6 @@ const CHECKOUT_PROTOCOL_MESSAGES: (keyof CheckoutProtocolMessageMap)[] = [
   "ec.complete",
   "ec.error",
   "ec.line_items.change",
-  "ec.buyer.change",
   "ec.totals.change",
   "ec.messages.change",
   "ec.window.open_request",

platforms/web/src/checkout.types.ts

@@ -2,7 +2,6 @@
 // checkout protocol. Embed payload shapes live in `./ucp-embed-types.ts`.
 
 import type {
-  Buyer,
   Checkout,
   CheckoutLineItem,
   CheckoutMessage,
@@ -118,11 +117,6 @@ export interface CheckoutEvents {
    */
   "ec.line_items.change": CheckoutLineItemsChangeEvent;
 
-  /**
-   * Dispatched when the buyer information changes.
-   */
-  "ec.buyer.change": CheckoutBuyerChangeEvent;
-
   /**
    * Dispatched when the totals change.
    */
@@ -175,16 +169,6 @@ export interface CheckoutLineItemsChangeEvent {
   };
 }
 
-export interface CheckoutBuyerChangeEvent {
-  type: "ec.buyer.change";
-  detail: {
-    /** Updated buyer (may be undefined when buyer information is cleared). */
-    buyer: Buyer | undefined;
-    /** Full checkout snapshot for handlers that want broader context. */
-    checkout: Checkout;
-  };
-}
-
 export interface CheckoutTotalsChangeEvent {
   type: "ec.totals.change";
   detail: {
@@ -252,7 +236,6 @@ export interface CheckoutProtocolMessageMap {
   "ec.complete": CheckoutPayload;
   "ec.error": EcErrorParams;
   "ec.line_items.change": CheckoutPayload;
-  "ec.buyer.change": CheckoutPayload;
   "ec.totals.change": CheckoutPayload;
   "ec.messages.change": CheckoutPayload;
   "ec.window.open_request": { url: string };

platforms/web/src/index.test.ts

@@ -15,7 +15,6 @@ describe("@shopify/checkout-kit public entry", () => {
       pkg.ShopifyCheckoutCloseEvent,
       pkg.ShopifyCheckoutErrorEvent,
       pkg.ShopifyCheckoutLineItemsChangeEvent,
-      pkg.ShopifyCheckoutBuyerChangeEvent,
       pkg.ShopifyCheckoutTotalsChangeEvent,
       pkg.ShopifyCheckoutMessagesChangeEvent,
     ];

platforms/web/src/index.ts

@@ -11,7 +11,6 @@ export {
   ShopifyCheckoutCloseEvent,
   ShopifyCheckoutErrorEvent,
   ShopifyCheckoutLineItemsChangeEvent,
-  ShopifyCheckoutBuyerChangeEvent,
   ShopifyCheckoutTotalsChangeEvent,
   ShopifyCheckoutMessagesChangeEvent,
 } from "./checkout";
@@ -22,7 +21,6 @@ export type {
   ShopifyCheckoutCompleteEventDetail,
   ShopifyCheckoutErrorEventDetail,
   ShopifyCheckoutLineItemsChangeEventDetail,
-  ShopifyCheckoutBuyerChangeEventDetail,
   ShopifyCheckoutTotalsChangeEventDetail,
   ShopifyCheckoutMessagesChangeEventDetail,
 } from "./checkout";

protocol/languages/swift/Tests/ShopifyCheckoutProtocolTests/DescriptorTests.swift

@@ -54,6 +54,7 @@ struct DescriptorTests {
         }
 
         @Test func excludesInternalOrUnsupportedMethods() {
+            #expect(!CheckoutProtocol.supportedProtocolMethods.contains("ec.buyer.change"))
             #expect(!CheckoutProtocol.supportedProtocolMethods.contains("ec.payment.credential_request"))
             #expect(!CheckoutProtocol.supportedProtocolMethods.contains("ep.cart.ready"))
         }