find org context from loginname

apps/login/src/app/api/loginname/route.ts

@@ -2,6 +2,7 @@ import { idpTypeToSlug } from "@/lib/idp";
 import {
   getActiveIdentityProviders,
   getLoginSettings,
+  getOrgsByDomainSuffix,
   listAuthenticationMethodTypes,
   listUsers,
   startIdentityProviderFlow,
@@ -9,6 +10,8 @@ import {
 import { createSessionForUserIdAndUpdateCookie } from "@/utils/session";
 import { NextRequest, NextResponse } from "next/server";
 
+const ORG_SUFFIX_REGEX = /(?<=@)(.+)/;
+
 export async function POST(request: NextRequest) {
   const body = await request.json();
   if (body) {
@@ -104,14 +107,37 @@ export async function POST(request: NextRequest) {
           loginSettings?.allowRegister &&
           loginSettings?.allowUsernamePassword
         ) {
-          const params: any = { organization };
+          let orgToRegisterOn: string | undefined = organization;
+
+          if (
+            !orgToRegisterOn &&
+            loginName &&
+            ORG_SUFFIX_REGEX.test(loginName)
+          ) {
+            const matched = ORG_SUFFIX_REGEX.exec(loginName);
+            const suffix = matched?.[1] ?? "";
+
+            const orgs = await getOrgsByDomainSuffix(suffix);
+            orgToRegisterOn =
+              orgs.result && orgs.result.length === 1
+                ? orgs.result[0].id
+                : undefined;
+          }
+
+          const params: any = {};
+
           if (authRequestId) {
             params.authRequestId = authRequestId;
           }
+
           if (loginName) {
             params.email = loginName;
           }
 
+          if (orgToRegisterOn) {
+            params.organization = orgToRegisterOn;
+          }
+
           const registerUrl = new URL(
             "/register?" + new URLSearchParams(params),
             request.url,

apps/login/src/lib/zitadel.ts

@@ -5,6 +5,7 @@ import {
   createUserServiceClient,
   createIdpServiceClient,
   makeReqCtx,
+  createOrganizationServiceClient,
 } from "@zitadel/client/v2";
 import { createManagementServiceClient } from "@zitadel/client/v1";
 import { createServerTransport } from "@zitadel/node";
@@ -36,10 +37,10 @@ const transport = createServerTransport(
 );
 
 export const sessionService = createSessionServiceClient(transport);
-export const managementService = createManagementServiceClient(transport);
 export const userService = createUserServiceClient(transport);
 export const oidcService = createOIDCServiceClient(transport);
 export const idpService = createIdpServiceClient(transport);
+export const orgService = createOrganizationServiceClient(transport);
 
 export const settingsService = createSettingsServiceClient(transport);
 
@@ -292,8 +293,11 @@ export async function listUsers({
   );
 }
 
-export async function getOrgByDomain(domain: string) {
+export async function getOrgsByDomainSuffix(domain: string) {
-  return managementService.getOrgByDomainGlobal({ domain }, {});
+  return orgService.listOrganizations(
+    { queries: [{ query: { case: "domainQuery", value: { domain } } }] },
+    {},
+  );
 }
 
 export async function startIdentityProviderFlow({