fix(payment): synthesise empty payload on paymentComplete auto-submit (DF-832)

src/server/plugins/engine/components/PaymentField.ts

@@ -113,9 +113,6 @@ export class PaymentField extends FormComponent {
       ? (payload[this.name] as unknown as PaymentState)
       : undefined
 
-    // Use payment state amount if pre-authorized, otherwise use default.
-    // The page controller overrides this with the resolved conditional amount
-    // using the full form state (which getViewModel doesn't have access to).
     const amount = paymentState?.amount ?? this.options.amount
 
     return {
@@ -258,7 +255,6 @@ export class PaymentField extends FormComponent {
     const reference = state.$$__referenceNumber as string
     const resolvedAmount = PaymentField.resolveAmount(options, model, state)
 
-    // Zero-amount safety net (page skip should prevent this, but defensive)
     if (resolvedAmount === 0) {
       return h.redirect(summaryUrl).code(StatusCodes.SEE_OTHER)
     }
@@ -270,9 +266,6 @@ export class PaymentField extends FormComponent {
     const payCallbackUrl = `${baseUrl}/payment-callback?uuid=${uuid}`
     const paymentPageUrl = args.sourceUrl
 
-    // Prepopulate GOV.UK Pay email if emailField is configured.
-    // The referenced EmailAddressField validates with joi.string().email()
-    // at input time, so the value in state is already validated.
     let prefilledEmail: string | undefined
     if (options.emailField) {
       const emailValue = state[options.emailField]
@@ -330,7 +323,6 @@ export class PaymentField extends FormComponent {
     _metadata: FormMetadata,
     context: FormContext
   ): Promise<void> {
-    // Zero-amount bypass — no capture needed
     const resolvedAmount = PaymentField.resolveAmount(
       this.options,
       this.model,

src/server/plugins/engine/pageControllers/QuestionPageController.ts

@@ -185,9 +185,6 @@ export class QuestionPageController extends PageController {
       }
     }
 
-    // Override payment amount display with resolved conditional amount
-    // getViewModel() only has the current page's payload, not full form state.
-    // The full state is available via context.evaluationState.
     for (const comp of components) {
       if ('amount' in comp.model && 'paymentState' in comp.model) {
         const paymentField = this.collection.fields.find(
@@ -270,9 +267,6 @@ export class QuestionPageController extends PageController {
             }
           }
 
-          // Skip payment pages in the normal page walk.
-          // Users reach the payment page via "Pay and submit" on CYA,
-          // not by navigating forward through the form.
           if (isPaymentPage(page.pageDef)) {
             return false
           }

src/server/plugins/engine/pageControllers/SummaryPageController.test.ts

@@ -153,6 +153,16 @@ describe('SummaryPageController - Payment (DF-832)', () => {
       expect(handleFormSubmitSpy).toHaveBeenCalledTimes(1)
       // The GET handler should short-circuit before rendering the view
       expect(h.view).not.toHaveBeenCalled()
+
+      // GOV.UK Pay callback is a GET so request.payload is undefined.
+      // Downstream submit code (e.g. outputService) reads
+      // request.payload.* fields, so the controller must synthesise an
+      // empty payload before calling handleFormSubmit, otherwise
+      // request.payload.userConfirmationEmailAddress crashes with
+      // "Cannot read properties of undefined".
+      const passedRequest = handleFormSubmitSpy.mock.calls[0][0]
+      expect(passedRequest.payload).toBeDefined()
+      expect(passedRequest.payload).toEqual({})
     })
 
     it('follows the normal CYA render path when paymentComplete is absent', async () => {

src/server/plugins/engine/pageControllers/SummaryPageController.ts

@@ -62,14 +62,6 @@ export class SummaryPageController extends QuestionPageController {
   declare pageDef: Page
   allowSaveAndExit = true
 
-  /**
-   * The controller which is used when Page["controller"] is defined as "./pages/summary.js"
-   */
-
-  /**
-   * Finds the PaymentField component across all pages in the model.
-   * Payment pages are skipped in the normal page walk
-   */
   private findPaymentField(): PaymentField | undefined {
     return this.model.pages
       .flatMap((page) => page.collection.fields)
@@ -183,9 +175,11 @@ export class SummaryPageController extends QuestionPageController {
     ) => {
       const { viewName } = this
 
-      // After GOV.UK Pay callback, auto-submit the form instead of
-      // showing CYA again. The payment is already pre-authorized.
       if (request.query.paymentComplete === 'true') {
+        const requestWithPayload = request as unknown as {
+          payload: FormRequestPayload['payload']
+        }
+        requestWithPayload.payload = {} as FormRequestPayload['payload']
         return this.handleFormSubmit(
           request as unknown as FormRequestPayload,
           context,
@@ -204,10 +198,6 @@ export class SummaryPageController extends QuestionPageController {
     }
   }
 
-  /**
-   * Checks if the resolved payment amount has changed since pre-auth
-   * and invalidates stale payment state if so.
-   */
   private async reconcilePaymentState(
     request: FormRequest,
     context: FormContext
@@ -358,9 +348,6 @@ export class SummaryPageController extends QuestionPageController {
       }
     }
 
-    // Payment page is skipped in the page walk, so proceed() would redirect
-    // to an earlier page. For PaymentIncomplete, redirect directly to the
-    // payment page using its href.
     if (
       error.errorType === PaymentErrorTypes.PaymentIncomplete &&
       error.component.page
@@ -502,8 +489,6 @@ async function finaliseComponents(
   context: FormContext,
   model: FormModel
 ) {
-  // Get fields from relevant pages (normal components)
-  // plus PaymentField from all pages (payment page is skipped in the page walk)
   const allFields = new Set([
     ...context.relevantPages.flatMap((page) => page.collection.fields),
     ...model.pages

src/server/plugins/engine/routes/index.ts

@@ -103,9 +103,6 @@ export async function redirectOrMakeHandler(
     return proceed(request, h, resumeInRepeaterUrl)
   }
 
-  // Return handler for relevant pages, payment pages, or preview URL direct access.
-  // Payment pages are skipped in the normal page walk but must render when the user
-  // is redirected there from CYA "Pay and submit".
   if (
     relevantPath.startsWith(page.path) ||
     isPaymentPage(page.pageDef) ||

src/server/plugins/engine/routes/payment.js

@@ -104,8 +104,6 @@ function handlePaymentSuccess(request, h, session, sessionKey, paymentStatus) {
   flashComponentState(request, session, paymentStatus)
   request.yar.clear(sessionKey)
 
-  // Append paymentComplete flag so the summary page auto-submits
-  // instead of showing CYA again
   const separator = session.returnUrl.includes('?') ? '&' : '?'
   const returnUrl = `${session.returnUrl}${separator}paymentComplete=true`
 

src/server/plugins/payment/service.js

@@ -63,7 +63,6 @@ export class PaymentService {
         delayed_capture: true
       }
 
-      // Prepopulate email on GOV.UK Pay if provided
       if (email) {
         payload.email = email
       }