diff --git a/apps/web/__tests__/unit/notification-read-state.test.ts b/apps/web/__tests__/unit/notification-read-state.test.ts
new file mode 100644
index 00000000000..3edbf65f1f8
--- /dev/null
+++ b/apps/web/__tests__/unit/notification-read-state.test.ts
@@ -0,0 +1,85 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const mocks = vi.hoisted(() => ({
+	query: vi.fn(),
+	getCurrentUser: vi.fn(),
+	revalidatePath: vi.fn(),
+}));
+
+vi.mock("@cap/database", async () => {
+	const { drizzle } = await import("drizzle-orm/mysql-proxy");
+	const client = drizzle(mocks.query);
+	return { db: () => client };
+});
+vi.mock("@cap/database/auth/session", () => ({
+	getCurrentUser: mocks.getCurrentUser,
+}));
+vi.mock("next/cache", () => ({ revalidatePath: mocks.revalidatePath }));
+
+import { markAsRead } from "@/actions/notifications/mark-as-read";
+
+beforeEach(() => {
+	mocks.getCurrentUser.mockResolvedValue({ id: "user-1" });
+	mocks.query.mockResolvedValue({ rows: [{ affectedRows: 1, insertId: 0 }] });
+});
+
+describe("notification read state", () => {
+	it.each(["own-notification", "another-users-notification"])(
+		"scopes an individual update to the current recipient for %s",
+		async (notificationId) => {
+			await markAsRead(notificationId);
+
+			expect(mocks.query).toHaveBeenCalledExactlyOnceWith(
+				expect.stringContaining(
+					"where (`notifications`.`recipientId` = ? and `notifications`.`id` = ?)",
+				),
+				[expect.any(String), "user-1", notificationId],
+				"execute",
+			);
+			expect(mocks.revalidatePath).toHaveBeenCalledWith("/dashboard");
+		},
+	);
+
+	it("marks all notifications for the current recipient when no ID is supplied", async () => {
+		await markAsRead();
+
+		expect(mocks.query).toHaveBeenCalledExactlyOnceWith(
+			"update `notifications` set `readAt` = ? where `notifications`.`recipientId` = ?",
+			[expect.any(String), "user-1"],
+			"execute",
+		);
+		expect(mocks.revalidatePath).toHaveBeenCalledWith("/dashboard");
+	});
+
+	it("succeeds without exposing whether a notification matched", async () => {
+		mocks.query.mockResolvedValueOnce({
+			rows: [{ affectedRows: 0, insertId: 0 }],
+		});
+
+		await expect(markAsRead("missing-notification")).resolves.toBeUndefined();
+
+		expect(mocks.revalidatePath).toHaveBeenCalledWith("/dashboard");
+	});
+
+	it("does not write when the requester is not authenticated", async () => {
+		mocks.getCurrentUser.mockResolvedValueOnce(null);
+
+		await expect(markAsRead("notification-1")).rejects.toThrow(
+			"User not found",
+		);
+
+		expect(mocks.query).not.toHaveBeenCalled();
+		expect(mocks.revalidatePath).not.toHaveBeenCalled();
+	});
+
+	it("reports a failed write without revalidating the dashboard", async () => {
+		mocks.query.mockRejectedValueOnce(new Error("Database unavailable"));
+		vi.spyOn(console, "log").mockImplementation(() => {});
+
+		await expect(markAsRead("notification-1")).rejects.toThrow(
+			"Error marking notification(s) as read",
+		);
+
+		expect(mocks.revalidatePath).not.toHaveBeenCalled();
+	});
+});
diff --git a/apps/web/actions/notifications/mark-as-read.ts b/apps/web/actions/notifications/mark-as-read.ts
index 0c820c607e3..b3904d54899 100644
--- a/apps/web/actions/notifications/mark-as-read.ts
+++ b/apps/web/actions/notifications/mark-as-read.ts
@@ -3,7 +3,7 @@
 import { db } from "@cap/database";
 import { getCurrentUser } from "@cap/database/auth/session";
 import { notifications } from "@cap/database/schema";
-import { eq } from "drizzle-orm";
+import { and, eq } from "drizzle-orm";
 import { revalidatePath } from "next/cache";
 
 export const markAsRead = async (notificationId?: string) => {
@@ -14,17 +14,15 @@ export const markAsRead = async (notificationId?: string) => {
 
 	try {
 		const now = new Date();
-		if (notificationId) {
-			await db()
-				.update(notifications)
-				.set({ readAt: now })
-				.where(eq(notifications.id, notificationId));
-		} else {
-			await db()
-				.update(notifications)
-				.set({ readAt: now })
-				.where(eq(notifications.recipientId, currentUser.id));
-		}
+		await db()
+			.update(notifications)
+			.set({ readAt: now })
+			.where(
+				and(
+					eq(notifications.recipientId, currentUser.id),
+					notificationId ? eq(notifications.id, notificationId) : undefined,
+				),
+			);
 	} catch (error) {
 		console.log(error);
 		throw new Error("Error marking notification(s) as read");