fix(kakao): use comma-separated consent scopes

.changeset/kakao-profile-types.md

@@ -2,4 +2,4 @@
 "@better-auth/core": minor
 ---
 
-Kakao profile callbacks now accept responses without account information. Profile mappings must handle an omitted `kakao_account`.
+Kakao profile mappings now accept profiles without account information. Authorization requests separate consent scopes with commas as documented by Kakao.

packages/core/src/social-providers/kakao.test.ts

@@ -1,4 +1,4 @@
-import { assertType, it } from "vitest";
+import { assertType, expect, it } from "vitest";
 import type { KakaoProfile } from "./kakao";
 
 /**
@@ -7,3 +7,29 @@ import type { KakaoProfile } from "./kakao";
 it("accepts a Kakao profile without account information", () => {
 	assertType<KakaoProfile>({ id: 123 });
 });
+
+import { kakao } from "./kakao";
+
+/** @see https://developers.kakao.com/docs/ko/kakaologin/rest-api#req-auth-code */
+it("joins authorization scopes with commas", async () => {
+	const provider = kakao({ clientId: "app", scope: ["openid"] });
+	const url = await provider.createAuthorizationURL({
+		state: "state",
+		redirectURI: "https://example.com/callback",
+		codeVerifier: "",
+		scopes: ["gender"],
+	});
+	expect(url.searchParams.get("scope")).toBe(
+		"account_email,profile_image,profile_nickname,openid,gender",
+	);
+	const custom = await kakao({
+		clientId: "app",
+		disableDefaultScope: true,
+		scope: ["account_email", "gender"],
+	}).createAuthorizationURL({
+		state: "state",
+		redirectURI: "https://example.com/callback",
+		codeVerifier: "",
+	});
+	expect(custom.searchParams.get("scope")).toBe("account_email,gender");
+});

packages/core/src/social-providers/kakao.ts

@@ -118,6 +118,7 @@ export const kakao = (options: KakaoOptions) => {
 				options,
 				authorizationEndpoint: "https://kauth.kakao.com/oauth/authorize",
 				scopes: _scopes,
+				scopeJoiner: ",",
 				state,
 				redirectURI,
 				additionalParams,