diff --git a/server/jest.config.ts b/server/jest.config.ts
index be7d359b1..1faf98181 100644
--- a/server/jest.config.ts
+++ b/server/jest.config.ts
@@ -13,6 +13,7 @@ const config: Config = {
 		"^@/(.*)\\.ts$": "<rootDir>/src/$1.ts",
 		"^@/(.*)\\.js$": "<rootDir>/src/$1.ts",
 		"^@/(.*)$": "<rootDir>/src/$1",
+		"^(\\.{1,2}/.*)\\.js$": "$1",
 	},
 	testMatch: ["<rootDir>/test/**/*.test.ts"],
 	setupFilesAfterEnv: [],
diff --git a/server/test/unit/validation/maintenanceWindowValidation.test.ts b/server/test/unit/validation/maintenanceWindowValidation.test.ts
new file mode 100644
index 000000000..dfede3670
--- /dev/null
+++ b/server/test/unit/validation/maintenanceWindowValidation.test.ts
@@ -0,0 +1,171 @@
+import { describe, expect, it, jest, afterEach } from "@jest/globals";
+import {
+	createMaintenanceWindowBodyValidation,
+	editMaintenanceByIdWindowBodyValidation,
+} from "../../../src/validation/maintenanceWindowValidation.ts";
+
+const FROZEN_NOW = new Date("2026-05-07T12:00:00Z").getTime();
+
+const baseCreateBody = (overrides: Record<string, unknown> = {}) => ({
+	monitors: ["mon-1"],
+	name: "Scheduled Maintenance",
+	duration: 60,
+	durationUnit: "minutes",
+	start: new Date(FROZEN_NOW + 60 * 60 * 1000).toISOString(),
+	end: new Date(FROZEN_NOW + 2 * 60 * 60 * 1000).toISOString(),
+	repeat: 0,
+	...overrides,
+});
+
+afterEach(() => {
+	jest.useRealTimers();
+});
+
+describe("createMaintenanceWindowBodyValidation", () => {
+	it("accepts a valid one-time window with end in the future", () => {
+		jest.useFakeTimers().setSystemTime(FROZEN_NOW);
+		const result = createMaintenanceWindowBodyValidation.safeParse(baseCreateBody());
+		expect(result.success).toBe(true);
+	});
+
+	it("accepts a recurring window even when end is in the past", () => {
+		jest.useFakeTimers().setSystemTime(FROZEN_NOW);
+		const result = createMaintenanceWindowBodyValidation.safeParse(
+			baseCreateBody({
+				repeat: 1,
+				start: new Date(FROZEN_NOW - 2 * 60 * 60 * 1000).toISOString(),
+				end: new Date(FROZEN_NOW - 60 * 60 * 1000).toISOString(),
+			})
+		);
+		expect(result.success).toBe(true);
+	});
+
+	it("rejects when end is before start", () => {
+		jest.useFakeTimers().setSystemTime(FROZEN_NOW);
+		const result = createMaintenanceWindowBodyValidation.safeParse(
+			baseCreateBody({
+				start: new Date(FROZEN_NOW + 2 * 60 * 60 * 1000).toISOString(),
+				end: new Date(FROZEN_NOW + 60 * 60 * 1000).toISOString(),
+			})
+		);
+		expect(result.success).toBe(false);
+		if (!result.success) {
+			expect(result.error.issues).toEqual(expect.arrayContaining([expect.objectContaining({ message: "End must be after start", path: ["end"] })]));
+		}
+	});
+
+	it("rejects when end equals start", () => {
+		jest.useFakeTimers().setSystemTime(FROZEN_NOW);
+		const sameInstant = new Date(FROZEN_NOW + 60 * 60 * 1000).toISOString();
+		const result = createMaintenanceWindowBodyValidation.safeParse(baseCreateBody({ start: sameInstant, end: sameInstant }));
+		expect(result.success).toBe(false);
+		if (!result.success) {
+			expect(result.error.issues).toEqual(expect.arrayContaining([expect.objectContaining({ message: "End must be after start", path: ["end"] })]));
+		}
+	});
+
+	it("rejects a one-time window with end in the past", () => {
+		jest.useFakeTimers().setSystemTime(FROZEN_NOW);
+		const result = createMaintenanceWindowBodyValidation.safeParse(
+			baseCreateBody({
+				start: new Date(FROZEN_NOW - 2 * 60 * 60 * 1000).toISOString(),
+				end: new Date(FROZEN_NOW - 60 * 60 * 1000).toISOString(),
+			})
+		);
+		expect(result.success).toBe(false);
+		if (!result.success) {
+			expect(result.error.issues).toEqual(
+				expect.arrayContaining([
+					expect.objectContaining({
+						message: "End must be in the future for one-time maintenance windows",
+						path: ["end"],
+					}),
+				])
+			);
+		}
+	});
+
+	it("rejects a one-time window with end exactly equal to now", () => {
+		jest.useFakeTimers().setSystemTime(FROZEN_NOW);
+		const result = createMaintenanceWindowBodyValidation.safeParse(
+			baseCreateBody({
+				start: new Date(FROZEN_NOW - 60 * 60 * 1000).toISOString(),
+				end: new Date(FROZEN_NOW).toISOString(),
+			})
+		);
+		expect(result.success).toBe(false);
+		if (!result.success) {
+			expect(result.error.issues).toEqual(
+				expect.arrayContaining([
+					expect.objectContaining({
+						message: "End must be in the future for one-time maintenance windows",
+						path: ["end"],
+					}),
+				])
+			);
+		}
+	});
+
+	it("rejects unknown fields under .strict()", () => {
+		jest.useFakeTimers().setSystemTime(FROZEN_NOW);
+		const result = createMaintenanceWindowBodyValidation.safeParse(baseCreateBody({ teamId: "team-1" }));
+		expect(result.success).toBe(false);
+	});
+
+	it("rejects an invalid durationUnit value", () => {
+		jest.useFakeTimers().setSystemTime(FROZEN_NOW);
+		const result = createMaintenanceWindowBodyValidation.safeParse(baseCreateBody({ durationUnit: "weeks" }));
+		expect(result.success).toBe(false);
+	});
+
+	it("rejects a missing required field", () => {
+		jest.useFakeTimers().setSystemTime(FROZEN_NOW);
+		const { name: _name, ...withoutName } = baseCreateBody();
+		const result = createMaintenanceWindowBodyValidation.safeParse(withoutName);
+		expect(result.success).toBe(false);
+	});
+});
+
+describe("editMaintenanceByIdWindowBodyValidation", () => {
+	it("accepts an empty body (all fields optional)", () => {
+		const result = editMaintenanceByIdWindowBodyValidation.safeParse({});
+		expect(result.success).toBe(true);
+	});
+
+	it("accepts a partial update with only active toggled", () => {
+		const result = editMaintenanceByIdWindowBodyValidation.safeParse({ active: false });
+		expect(result.success).toBe(true);
+	});
+
+	it("rejects unknown fields under .strict()", () => {
+		const result = editMaintenanceByIdWindowBodyValidation.safeParse({
+			active: false,
+			id: "mw-1",
+		});
+		expect(result.success).toBe(false);
+	});
+
+	it("rejects when start and end are both present and end <= start", () => {
+		const start = new Date("2026-05-08T10:00:00Z").toISOString();
+		const end = new Date("2026-05-08T09:00:00Z").toISOString();
+		const result = editMaintenanceByIdWindowBodyValidation.safeParse({ start, end });
+		expect(result.success).toBe(false);
+		if (!result.success) {
+			expect(result.error.issues).toEqual(expect.arrayContaining([expect.objectContaining({ message: "End must be after start", path: ["end"] })]));
+		}
+	});
+
+	it("does not apply the start/end ordering rule when only end is provided", () => {
+		const result = editMaintenanceByIdWindowBodyValidation.safeParse({
+			end: new Date("2020-01-01T00:00:00Z").toISOString(),
+		});
+		expect(result.success).toBe(true);
+	});
+
+	it("does not apply the start/end ordering rule when only start is provided", () => {
+		const result = editMaintenanceByIdWindowBodyValidation.safeParse({
+			start: new Date("2099-01-01T00:00:00Z").toISOString(),
+		});
+		expect(result.success).toBe(true);
+	});
+});