fix(webapp): revalidate cached regions after setting a default

The org layout caches regions for useRegions(); the set-default action
redirects to the same URL, so add a shouldRevalidate hook (mirroring the
pause/resume pattern) to refresh the default shown in Test/Replay.

Author: myftija

apps/webapp/app/routes/_app.orgs.$organizationSlug.projects.$projectParam.env.$envParam.regions/route.tsx

@@ -101,6 +101,20 @@ const FormSchema = z.object({
   regionId: z.string(),
 });
 
+// Lets the parent layout route revalidate its cached regions after a new
+// default is set — the action redirects to the same URL, so a pathname check
+// alone wouldn't refresh the default shown by useRegions().
+export function isSetDefaultRegionFormSubmission(
+  formMethod: string | undefined,
+  formData: FormData | undefined
+) {
+  if (!formMethod || !formData) {
+    return false;
+  }
+
+  return formMethod.toLowerCase() === "post" && formData.has("regionId");
+}
+
 export const action = async ({ request, params }: ActionFunctionArgs) => {
   const user = await requireUser(request);
   const { organizationSlug, projectParam, envParam } = EnvironmentParamSchema.parse(params);

apps/webapp/app/routes/_app.orgs.$organizationSlug/route.tsx

@@ -14,6 +14,7 @@ import { requireUser } from "~/services/session.server";
 import { telemetry } from "~/services/telemetry.server";
 import { organizationPath } from "~/utils/pathBuilder";
 import { isEnvironmentPauseResumeFormSubmission } from "../_app.orgs.$organizationSlug.projects.$projectParam.env.$envParam.queues/route";
+import { isSetDefaultRegionFormSubmission } from "../_app.orgs.$organizationSlug.projects.$projectParam.env.$envParam.regions/route";
 
 const ParamsSchema = z.object({
   organizationSlug: z.string(),
@@ -53,6 +54,11 @@ export const shouldRevalidate: ShouldRevalidateFunction = (params) => {
     return true;
   }
 
+  // Invalidate so useRegions() reflects a newly set default region
+  if (isSetDefaultRegionFormSubmission(params.formMethod, params.formData)) {
+    return true;
+  }
+
   // This prevents revalidation when there are search params changes
   // IMPORTANT: If the loader function depends on search params, this should be updated
   return params.currentUrl.pathname !== params.nextUrl.pathname;