Recognize exchange-only promotions in the swap settings

CHANGELOG.md

@@ -26,6 +26,7 @@
 - fixed: Password reminder no longer stops reappearing after unlocking Account Settings
 - fixed: Show the password recovery reminder at every balance milestone, including for funds that arrived while the app was closed or before the exchange rates loaded.
 - fixed: Hide the send scene's MAX button once a send has more than one recipient, and hide "Add another address" once MAX has been applied, so the two can no longer combine into an insufficient-funds transaction.
+- fixed: Recognize promotions that only set a preferred exchange in the exchange settings, which now say the promotion is choosing it and offer to remove it, instead of showing a list whose taps were saved but silently overridden for the promotion's whole window
 
 ## 4.51.1 (2026-09-23)
 

src/__tests__/util/ReferralHelpers.test.ts

@@ -0,0 +1,110 @@
+import { describe, expect, it } from '@jest/globals'
+
+import type { AccountReferral, Promotion } from '../../types/ReferralTypes'
+import type { PluginTweak } from '../../types/TweakTypes'
+import { bestOfPlugins } from '../../util/ReferralHelpers'
+
+const now = new Date('2026-09-24T12:00:00Z')
+
+const tweak = (
+  pluginId: string,
+  extra: Partial<PluginTweak> = {}
+): PluginTweak => ({
+  pluginId,
+  disabled: false,
+  startDate: new Date('2026-09-20T00:00:00Z'),
+  durationDays: 14,
+  ...extra
+})
+
+const promo = (installerId: string, plugins: PluginTweak[]): Promotion => ({
+  installerId,
+  hiddenMessages: {},
+  messages: [],
+  plugins
+})
+
+const referral = (promotions: Promotion[]): AccountReferral => ({
+  promotions,
+  ignoreAccountSwap: false,
+  hiddenAccountMessages: {},
+  activePromotions: []
+})
+
+describe('bestOfPlugins', () => {
+  it('lets a promotion outrank the preferred exchange from the settings', () => {
+    const out = bestOfPlugins(
+      [],
+      referral([
+        promo('nexchange_test', [tweak('nexchange', { preferredSwap: true })])
+      ]),
+      'changenow',
+      now
+    )
+    expect(out.preferredSwapPluginId).toBe('nexchange')
+  })
+
+  it('reports the promotion as the source when it only sets an exchange preference', () => {
+    const out = bestOfPlugins(
+      [],
+      referral([
+        promo('nexchange_test', [tweak('nexchange', { preferredSwap: true })])
+      ]),
+      'changenow',
+      now
+    )
+    expect(out.swapSource).toEqual({
+      type: 'promotion',
+      installerId: 'nexchange_test'
+    })
+  })
+
+  it('still reports the promotion when it sets both preferences', () => {
+    const out = bestOfPlugins(
+      [],
+      referral([
+        promo('nexchange_test', [
+          tweak('nexchange', { preferredSwap: true, preferredFiat: true })
+        ])
+      ]),
+      undefined,
+      now
+    )
+    expect(out.preferredSwapPluginId).toBe('nexchange')
+    expect(out.swapSource).toEqual({
+      type: 'promotion',
+      installerId: 'nexchange_test'
+    })
+  })
+
+  it('does not blame a promotion that sets no exchange preference', () => {
+    // A buy/sell-only promotion, with nothing else preferring an exchange:
+    // undefined equals undefined, so the gate needs its second test.
+    const out = bestOfPlugins(
+      [],
+      referral([
+        promo('moonpay_promo', [tweak('moonpay', { preferredFiat: true })])
+      ]),
+      undefined,
+      now
+    )
+    expect(out.preferredSwapPluginId).toBeUndefined()
+    expect(out.swapSource.type).not.toBe('promotion')
+  })
+
+  it('ignores an expired promotion entirely', () => {
+    const stale = tweak('nexchange', {
+      preferredSwap: true,
+      startDate: new Date('2026-08-01T00:00:00Z'),
+      durationDays: 7
+    })
+    const out = bestOfPlugins(
+      [],
+      referral([promo('old_promo', [stale])]),
+      'changenow',
+      now
+    )
+    expect(out.preferredSwapPluginId).toBe('changenow')
+    expect(out.swapSource.type).not.toBe('promotion')
+  })
+})

src/util/ReferralHelpers.ts

@@ -99,9 +99,13 @@ export function bestOfPlugins(
   for (const promo of accountReferral.promotions) {
     const fromPromo = summarizePlugins(promo.plugins, now)
     out = mergePluginSummaries(out, fromPromo)
+    // This promotion is the source when it names the swap plugin that won.
+    // The second test keeps a promotion with no swap preference from claiming
+    // the source when nothing else has one either, since undefined equals
+    // undefined:
     if (
       out.preferredSwapPluginId === fromPromo.preferredSwapPluginId &&
-      fromPromo.preferredFiatPluginId != null
+      fromPromo.preferredSwapPluginId != null
     ) {
       swapSource = { type: 'promotion', installerId: promo.installerId }
     }