fix(client): broadcast session updates to other tabs on sign-out and user update (#8177)

Co-authored-by: Abhinav-kodes <183825080+Abhinav-kodes@users.noreply.github.com>

packages/better-auth/src/client/config.ts

@@ -61,7 +61,10 @@ export const getClientConfig = (
 			...pluginsFetchPlugins,
 		],
 	});
-	const { $sessionSignal, session } = getSessionAtom($fetch, options);
+	const { $sessionSignal, session, broadcastSessionUpdate } = getSessionAtom(
+		$fetch,
+		options,
+	);
 	const plugins = options?.plugins || [];
 	let pluginsActions = {} as Record<string, any>;
 	const pluginsAtoms = {
@@ -92,6 +95,13 @@ export const getClientConfig = (
 
 				return matchesCommonPaths;
 			},
+			callback(path) {
+				if (path === "/sign-out") {
+					broadcastSessionUpdate("signout");
+				} else if (path === "/update-user" || path === "/update-session") {
+					broadcastSessionUpdate("updateUser");
+				}
+			},
 		},
 	];
 

packages/better-auth/src/client/proxy.ts

@@ -118,6 +118,8 @@ export function createDynamicPathProxy<T extends Record<string, any>>(
 								//@ts-expect-error
 								signal.set(!val);
 							}, 10);
+							// we also call the callback if it exists
+							match.callback?.(routePath);
 						}
 					},
 				});

packages/better-auth/src/client/session-atom.ts

@@ -23,6 +23,10 @@ export function getSessionAtom(
 		method: "GET",
 	});
 
+	let broadcastSessionUpdate: (
+		trigger: "signout" | "getSession" | "updateUser",
+	) => void = () => {};
+
 	onMount(session, () => {
 		const refreshManager = createSessionRefreshManager({
 			sessionAtom: session,
@@ -32,6 +36,7 @@ export function getSessionAtom(
 		});
 
 		refreshManager.init();
+		broadcastSessionUpdate = refreshManager.broadcastSessionUpdate;
 
 		return () => {
 			refreshManager.cleanup();
@@ -41,5 +46,8 @@ export function getSessionAtom(
 	return {
 		session,
 		$sessionSignal: $signal,
+		broadcastSessionUpdate: (
+			trigger: "signout" | "getSession" | "updateUser",
+		) => broadcastSessionUpdate(trigger),
 	};
 }

packages/better-auth/src/client/session-refresh.test.ts

@@ -2,6 +2,7 @@
 
 import { atom } from "nanostores";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { getGlobalBroadcastChannel } from "./broadcast-channel";
 import { getGlobalOnlineManager } from "./online-manager";
 import type { SessionAtom } from "./session-atom";
 import { createSessionRefreshManager } from "./session-refresh";
@@ -15,6 +16,8 @@ describe("session-refresh", () => {
 
 	afterEach(() => {
 		vi.useRealTimers();
+		vi.restoreAllMocks();
+		delete (globalThis as any)[Symbol.for("better-auth:broadcast-channel")];
 	});
 
 	it("should trigger network fetch and update session when refetchInterval fires", async () => {
@@ -618,4 +621,68 @@ describe("session-refresh", () => {
 		manager.cleanup();
 		vi.useRealTimers();
 	});
+
+	it("should broadcast session update when broadcastSessionUpdate is called with signout", () => {
+		const channel = getGlobalBroadcastChannel();
+		const postSpy = vi.spyOn(channel, "post");
+
+		const sessionAtom: SessionAtom = atom({
+			data: {
+				user: { id: "1", email: "test@test.com" },
+				session: { id: "session-1" },
+			},
+			error: null,
+			isPending: false,
+		});
+		const sessionSignal = atom(false);
+		const mockFetch = vi.fn(async () => ({ data: null, error: null }));
+
+		const manager = createSessionRefreshManager({
+			sessionAtom,
+			sessionSignal,
+			$fetch: mockFetch as any,
+			options: {},
+		});
+
+		manager.init();
+		manager.broadcastSessionUpdate("signout");
+
+		expect(postSpy).toHaveBeenCalledWith(
+			expect.objectContaining({ data: { trigger: "signout" } }),
+		);
+
+		manager.cleanup();
+	});
+
+	it("should broadcast session update when broadcastSessionUpdate is called with updateUser", () => {
+		const channel = getGlobalBroadcastChannel();
+		const postSpy = vi.spyOn(channel, "post");
+
+		const sessionAtom: SessionAtom = atom({
+			data: {
+				user: { id: "1", email: "test@test.com" },
+				session: { id: "session-1" },
+			},
+			error: null,
+			isPending: false,
+		});
+		const sessionSignal = atom(false);
+		const mockFetch = vi.fn(async () => ({ data: null, error: null }));
+
+		const manager = createSessionRefreshManager({
+			sessionAtom,
+			sessionSignal,
+			$fetch: mockFetch as any,
+			options: {},
+		});
+
+		manager.init();
+		manager.broadcastSessionUpdate("updateUser");
+
+		expect(postSpy).toHaveBeenCalledWith(
+			expect.objectContaining({ data: { trigger: "updateUser" } }),
+		);
+
+		manager.cleanup();
+	});
 });

packages/core/src/types/plugin-client.ts

@@ -17,6 +17,7 @@ export interface ClientStore {
 export type ClientAtomListener = {
 	matcher: (path: string) => boolean;
 	signal: "$sessionSignal" | Omit<string, "$sessionSignal">;
+	callback?: (path: string) => void;
 };
 
 /**