diff --git a/platforms/web/src/checkout.test.ts b/platforms/web/src/checkout.test.ts
index 0fbbfa23..71d5f402 100644
--- a/platforms/web/src/checkout.test.ts
+++ b/platforms/web/src/checkout.test.ts
@@ -1204,10 +1204,10 @@ describe("<shopify-checkout>", () => {
         await wait;
 
         const event = spy.mock.calls[0]![0] as CustomEvent;
-        expect(event.detail).toEqual({ checkout: decodeCheckout(payload) });
+        expect(event.detail).toStrictEqual({ checkout: decodeCheckout(payload) });
       });
 
-      it("ec.complete carries {checkout, order} with order derived from checkout", async () => {
+      it("ec.complete carries {checkout} with order nested in checkout", async () => {
         const { checkout, mockCheckoutWindow } = openPopupCheckout();
         const spy = vi.fn();
         const wait = waitForEvent(checkout, "ec.complete", spy);
@@ -1224,11 +1224,11 @@ describe("<shopify-checkout>", () => {
 
         const event = spy.mock.calls[0]![0] as CustomEvent;
         const decoded = decodeCheckout(payload);
-        expect(event.detail).toEqual({ checkout: decoded, order: decoded.order });
-        expect(event.detail.order).toEqual(event.detail.checkout.order);
+        expect(event.detail).toStrictEqual({ checkout: decoded });
+        expect(event.detail.checkout.order).toEqual(decoded.order);
       });
 
-      it("ec.complete leaves order undefined when the checkout has no order", async () => {
+      it("ec.complete keeps an absent order nested in checkout", async () => {
         const { checkout, mockCheckoutWindow } = openPopupCheckout();
         const spy = vi.fn();
         const wait = waitForEvent(checkout, "ec.complete", spy);
@@ -1240,7 +1240,9 @@ describe("<shopify-checkout>", () => {
         await wait;
 
         const event = spy.mock.calls[0]![0] as CustomEvent;
-        expect(event.detail.order).toBeUndefined();
+        const decoded = decodeCheckout(payload);
+        expect(event.detail).toStrictEqual({ checkout: decoded });
+        expect(event.detail.checkout.order).toBeUndefined();
       });
 
       it("ec.error carries {error}", async () => {
@@ -1255,10 +1257,10 @@ describe("<shopify-checkout>", () => {
         await wait;
 
         const event = spy.mock.calls[0]![0] as CustomEvent;
-        expect(event.detail).toEqual({ error: decodeError(errorParams) });
+        expect(event.detail).toStrictEqual({ error: decodeError(errorParams) });
       });
 
-      it("ec.line_items.change carries {lineItems, checkout}", async () => {
+      it("ec.line_items.change carries {checkout} with lineItems nested in checkout", async () => {
         const { checkout, mockCheckoutWindow } = openPopupCheckout();
         const spy = vi.fn();
         const wait = waitForEvent(checkout, "ec.line_items.change", spy);
@@ -1271,11 +1273,11 @@ describe("<shopify-checkout>", () => {
 
         const event = spy.mock.calls[0]![0] as CustomEvent;
         const decoded = decodeCheckout(payload);
-        expect(event.detail.lineItems).toEqual(decoded.lineItems);
-        expect(event.detail.checkout).toEqual(decoded);
+        expect(event.detail).toStrictEqual({ checkout: decoded });
+        expect(event.detail.checkout.lineItems).toEqual(decoded.lineItems);
       });
 
-      it("ec.totals.change carries {totals, checkout}", async () => {
+      it("ec.totals.change carries {checkout} with totals nested in checkout", async () => {
         const { checkout, mockCheckoutWindow } = openPopupCheckout();
         const spy = vi.fn();
         const wait = waitForEvent(checkout, "ec.totals.change", spy);
@@ -1288,11 +1290,11 @@ describe("<shopify-checkout>", () => {
 
         const event = spy.mock.calls[0]![0] as CustomEvent;
         const decoded = decodeCheckout(payload);
-        expect(event.detail.totals).toEqual(decoded.totals);
-        expect(event.detail.checkout).toEqual(decoded);
+        expect(event.detail).toStrictEqual({ checkout: decoded });
+        expect(event.detail.checkout.totals).toEqual(decoded.totals);
       });
 
-      it("ec.messages.change carries {messages, checkout}", async () => {
+      it("ec.messages.change carries {checkout} with messages nested in checkout", async () => {
         const { checkout, mockCheckoutWindow } = openPopupCheckout();
         const spy = vi.fn();
         const wait = waitForEvent(checkout, "ec.messages.change", spy);
@@ -1305,8 +1307,8 @@ describe("<shopify-checkout>", () => {
 
         const event = spy.mock.calls[0]![0] as CustomEvent;
         const decoded = decodeCheckout(payload);
-        expect(event.detail.messages).toEqual(decoded.messages ?? []);
-        expect(event.detail.checkout).toEqual(decoded);
+        expect(event.detail).toStrictEqual({ checkout: decoded });
+        expect(event.detail.checkout.messages).toEqual(decoded.messages);
       });
 
       it("ec.close carries no detail", () => {
diff --git a/platforms/web/src/checkout.ts b/platforms/web/src/checkout.ts
index a6b2fb9e..dc7d106a 100644
--- a/platforms/web/src/checkout.ts
+++ b/platforms/web/src/checkout.ts
@@ -17,10 +17,7 @@ import type {
   CheckoutTarget,
   TypedEventListener,
   Checkout,
-  LineItem,
-  Message,
   CheckoutAppearance,
-  CheckoutTotal,
   ErrorResponse,
 } from "./checkout.types";
 
@@ -232,7 +229,7 @@ export class ShopifyCheckout
    * @returns The current Checkout, or undefined before the first notification.
    * @example
    * checkout.addEventListener('ec.start', (event) => {
-   *   const {line_items, totals, buyer} = event.detail.checkout;
+   *   const {lineItems, totals, buyer} = event.detail.checkout;
    * });
    */
   get checkout(): Checkout | undefined {
@@ -587,7 +584,7 @@ export class ShopifyCheckout
       })
       .on(Event.complete, (checkout) => {
         this.#checkout = checkout;
-        this.dispatchEvent(new ShopifyCheckoutCompleteEvent({ checkout, order: checkout.order }));
+        this.dispatchEvent(new ShopifyCheckoutCompleteEvent({ checkout }));
       })
       .on(Event.error, (error) => {
         this.#error = error;
@@ -603,30 +600,15 @@ export class ShopifyCheckout
       })
       .on(Event.lineItemsChange, (checkout) => {
         this.#checkout = checkout;
-        this.dispatchEvent(
-          new ShopifyCheckoutLineItemsChangeEvent({
-            checkout,
-            lineItems: checkout.lineItems,
-          }),
-        );
+        this.dispatchEvent(new ShopifyCheckoutLineItemsChangeEvent({ checkout }));
       })
       .on(Event.totalsChange, (checkout) => {
         this.#checkout = checkout;
-        this.dispatchEvent(
-          new ShopifyCheckoutTotalsChangeEvent({
-            checkout,
-            totals: checkout.totals,
-          }),
-        );
+        this.dispatchEvent(new ShopifyCheckoutTotalsChangeEvent({ checkout }));
       })
       .on(Event.messagesChange, (checkout) => {
         this.#checkout = checkout;
-        this.dispatchEvent(
-          new ShopifyCheckoutMessagesChangeEvent({
-            checkout,
-            messages: checkout.messages ?? [],
-          }),
-        );
+        this.dispatchEvent(new ShopifyCheckoutMessagesChangeEvent({ checkout }));
       })
       .on(Event.windowOpen, (request) => this.#handleWindowOpen(request));
   }
@@ -801,7 +783,6 @@ export interface ShopifyCheckoutStartEventDetail {
 export interface ShopifyCheckoutCompleteEventDetail {
   /** Final checkout snapshot from the ECP `ec.complete` notification. */
   checkout: Checkout;
-  order?: Checkout["order"];
 }
 
 export interface ShopifyCheckoutErrorEventDetail {
@@ -810,23 +791,17 @@ export interface ShopifyCheckoutErrorEventDetail {
 }
 
 export interface ShopifyCheckoutLineItemsChangeEventDetail {
-  /** Updated cart line items. */
-  lineItems: readonly LineItem[];
-  /** Full checkout snapshot for handlers that want broader context. */
+  /** Checkout snapshot with updated cart line items. */
   checkout: Checkout;
 }
 
 export interface ShopifyCheckoutTotalsChangeEventDetail {
-  /** Updated totals. */
-  totals: readonly CheckoutTotal[];
-  /** Full checkout snapshot for handlers that want broader context. */
+  /** Checkout snapshot with updated totals. */
   checkout: Checkout;
 }
 
 export interface ShopifyCheckoutMessagesChangeEventDetail {
-  /** Updated checkout-level messages (warnings, errors, info). */
-  messages: readonly Message[];
-  /** Full checkout snapshot for handlers that want broader context. */
+  /** Checkout snapshot with updated warnings, errors, and informational messages. */
   checkout: Checkout;
 }