fix(webapp): tidy promo landing copy and bust credits cache on redeem

- omit the expiry clause on the promo page when a code has no expiry, so it
  no longer renders a dangling "The credits expire on ."
- invalidate the promo-credits cache after a successful redeem so the usage
  page shows the new credits immediately instead of a stale value
- align stale comment wording with redeem-at-plan-selection

Author: matt-aitken

apps/webapp/app/routes/promo.tsx

@@ -44,8 +44,8 @@ export async function loader({ request }: LoaderFunctionArgs) {
     return typedjson({ view: "invalid" as const, ...authMethods });
   }
 
-  // Stash the code so it survives the OAuth round-trip and can be applied when
-  // the new org is created.
+  // Stash the code so it survives the OAuth round-trip and can be applied once
+  // the new org selects a plan.
   return typedjson(
     {
       view: "valid" as const,
@@ -152,16 +152,20 @@ export default function PromoPage() {
         ) : (
           <>
             <Header2 className="sm:text-2xl md:text-3xl lg:text-4xl" spacing>
-              {data.view === "valid" ? `Claim ${formatDollars(data.amountInCents)} credits` : "Create your account"}
+              {data.view === "valid"
+                ? `Claim ${formatDollars(data.amountInCents)} credits`
+                : "Create your account"}
             </Header2>
             {data.view === "valid" ? (
               <Paragraph variant="base" spacing>
-              These are only available for new accounts. The credits expire on {formatExpiry(data.expiresAt)}.
-            </Paragraph>
+                These are only available for new accounts.
+                {formatExpiry(data.expiresAt)
+                  ? ` The credits expire on ${formatExpiry(data.expiresAt)}.`
+                  : ""}
+              </Paragraph>
             ) : (
               <Callout variant="warning" className="mb-6 w-full">
-                That promo code isn't valid. You can still sign up below but credits won't be
-                added.
+                That promo code isn't valid. You can still sign up below but credits won't be added.
               </Callout>
             )}
             <SignInForm showGithubAuth={data.showGithubAuth} showGoogleAuth={data.showGoogleAuth} />

apps/webapp/app/routes/resources.orgs.$organizationSlug.select-plan.tsx

@@ -34,7 +34,7 @@ import { prisma } from "~/db.server";
 import { redirectWithErrorMessage } from "~/models/message.server";
 import { resolveOrgIdFromSlug } from "~/models/organization.server";
 import { logger } from "~/services/logger.server";
-import { applyPromoCode, setPlan } from "~/services/platform.v3.server";
+import { applyPromoCode, bustPromoCreditsCache, setPlan } from "~/services/platform.v3.server";
 import { clearPromoCodeCookie, getPromoCodeFromCookie } from "~/services/promoCode.server";
 import { dashboardAction } from "~/services/routeBuilders/dashboardBuilder";
 import { engine } from "~/v3/runEngine.server";
@@ -166,6 +166,7 @@ export const action = dashboardAction(
       if (promoCode) {
         const applied = await applyPromoCode(organization.id, user.id, promoCode);
         if (applied?.applied) {
+          bustPromoCreditsCache(organization.id);
           result.headers.append("Set-Cookie", await clearPromoCodeCookie());
         }
       }

apps/webapp/app/services/platform.v3.server.ts

@@ -212,6 +212,12 @@ export function bustBillingLimitCaches(organizationId: string) {
   invalidateBillingLimitCaches(organizationId);
 }
 
+// Clear the cached promo-credits read so a just-granted code shows on the usage
+// page immediately rather than after the stale TTL.
+export function bustPromoCreditsCache(organizationId: string) {
+  platformCache.promoCredits.remove(organizationId).catch(() => {});
+}
+
 type Machines = typeof machinesFromPlatform;
 
 const MachineOverrideValues = z.object({