diff --git a/client/src/Types/Notification.ts b/client/src/Types/Notification.ts
index 5b9645c9da..610f73547d 100644
--- a/client/src/Types/Notification.ts
+++ b/client/src/Types/Notification.ts
@@ -5,6 +5,7 @@ export const NotificationChannels = [
 	"webhook",
 	"pager_duty",
 	"matrix",
+	"teams",
 ] as const;
 export type NotificationChannel = (typeof NotificationChannels)[number];
 
diff --git a/client/src/Validation/notifications.ts b/client/src/Validation/notifications.ts
index e505c695fd..2bbb871c94 100644
--- a/client/src/Validation/notifications.ts
+++ b/client/src/Validation/notifications.ts
@@ -45,6 +45,11 @@ const matrixSchema = baseSchema.extend({
 	accessToken: z.string().min(1, "Access token is required"),
 });
 
+const teamsSchema = baseSchema.extend({
+	type: z.literal("teams"),
+	address: z.string().min(1, "Webhook URL is required").url("Please enter a valid URL"),
+});
+
 export const notificationSchema = z.discriminatedUnion("type", [
 	emailSchema,
 	slackSchema,
@@ -52,6 +57,7 @@ export const notificationSchema = z.discriminatedUnion("type", [
 	webhookSchema,
 	pagerDutySchema,
 	matrixSchema,
+	teamsSchema,
 ]);
 
 export type NotificationFormData = z.infer<typeof notificationSchema>;
diff --git a/server/src/config/services.ts b/server/src/config/services.ts
index 65377eeb4b..9434b3ae55 100644
--- a/server/src/config/services.ts
+++ b/server/src/config/services.ts
@@ -27,6 +27,7 @@ import {
 	DiscordProvider,
 	PagerDutyProvider,
 	MatrixProvider,
+	TeamsProvider,
 	// Interfaces
 	INetworkService,
 	IEmailService,
@@ -228,6 +229,7 @@ export const initializeServices = async ({
 	const discordProvider = new DiscordProvider(logger);
 	const pagerDutyProvider = new PagerDutyProvider(logger);
 	const matrixProvider = new MatrixProvider(logger);
+	const teamsProvider = new TeamsProvider(logger);
 
 	const notificationsService = new NotificationsService(
 		notificationsRepository,
@@ -238,6 +240,7 @@ export const initializeServices = async ({
 		discordProvider,
 		pagerDutyProvider,
 		matrixProvider,
+		teamsProvider,
 		settingsService,
 		logger,
 		notificationMessageBuilder
diff --git a/server/src/db/models/Notification.ts b/server/src/db/models/Notification.ts
index 97e2d43fb0..9ea3f17bdd 100755
--- a/server/src/db/models/Notification.ts
+++ b/server/src/db/models/Notification.ts
@@ -25,7 +25,7 @@ const NotificationSchema = new Schema<NotificationDocument>(
 		},
 		type: {
 			type: String,
-			enum: ["email", "slack", "discord", "webhook", "pager_duty", "matrix"] as NotificationChannel[],
+			enum: ["email", "slack", "discord", "webhook", "pager_duty", "matrix", "teams"] as NotificationChannel[],
 			required: true,
 		},
 		notificationName: {
diff --git a/server/src/service/business/userService.ts b/server/src/service/business/userService.ts
index 48f3a51cf4..f224e9ba4b 100644
--- a/server/src/service/business/userService.ts
+++ b/server/src/service/business/userService.ts
@@ -273,8 +273,8 @@ export class UserService implements IUserService {
 		await this.recoveryTokensRepository.deleteManyByEmail(email);
 		const recoveryToken = await this.recoveryTokensRepository.create(email);
 		const name = user.firstName;
-		const { clientHost } = this.settingsService.getSettings();
-		const url = `${clientHost}/set-new-password/${recoveryToken.token}`;
+		const settings = this.settingsService.getSettings();
+		const url = `${settings.clientHost!}/set-new-password/${recoveryToken.token}`;
 
 		const html = await this.emailService.buildEmail("passwordResetTemplate", {
 			name,
diff --git a/server/src/service/index.ts b/server/src/service/index.ts
index 464866e091..9686d2a135 100644
--- a/server/src/service/index.ts
+++ b/server/src/service/index.ts
@@ -27,6 +27,7 @@ export * from "@/service/infrastructure/notificationProviders/INotificationProvi
 export * from "@/service/infrastructure/notificationProviders/matrix.js";
 export * from "@/service/infrastructure/notificationProviders/pagerduty.js";
 export * from "@/service/infrastructure/notificationProviders/slack.js";
+export * from "@/service/infrastructure/notificationProviders/teams.js";
 export * from "@/service/infrastructure/notificationProviders/webhook.js";
 
 // System services
diff --git a/server/src/service/infrastructure/notificationProviders/teams.ts b/server/src/service/infrastructure/notificationProviders/teams.ts
new file mode 100644
index 0000000000..2a44768075
--- /dev/null
+++ b/server/src/service/infrastructure/notificationProviders/teams.ts
@@ -0,0 +1,274 @@
+const SERVICE_NAME = "TeamsProvider";
+import type { Notification } from "@/types/index.js";
+import { INotificationProvider } from "@/service/index.js";
+import type { NotificationMessage } from "@/types/notificationMessage.js";
+import { getTestMessage } from "@/service/infrastructure/notificationProviders/utils.js";
+import type { ILogger } from "@/utils/logger.js";
+import got, { HTTPError } from "got";
+
+// Types for Adaptive Card elements
+type TextBlock = {
+	type: "TextBlock";
+	text: string;
+	weight?: "Bolder" | "Normal" | "Lighter";
+	size?: "Small" | "Medium" | "Large" | "ExtraLarge";
+	color?: "Default" | "Dark" | "Light" | "Accent" | "Good" | "Warning" | "Attention";
+	wrap?: boolean;
+	spacing?: "None" | "Small" | "Medium" | "Large" | "ExtraLarge" | "Auto";
+	isSubtle?: boolean;
+};
+
+type ColumnSet = {
+	type: "ColumnSet";
+	separator?: boolean;
+	spacing?: "None" | "Small" | "Medium" | "Large" | "ExtraLarge" | "Auto";
+	columns: unknown[];
+};
+
+type Fact = {
+	title: string;
+	value: string;
+};
+
+type FactSet = {
+	type: "FactSet";
+	facts: Fact[];
+};
+
+type Action = {
+	type: string;
+	title: string;
+	url?: string;
+};
+
+type AdaptiveCard = {
+	type: "AdaptiveCard";
+	$schema: "http://adaptivecards.io/schemas/adaptive-card.json";
+	version: "1.4";
+	body: (TextBlock | ColumnSet | FactSet)[];
+	actions?: Action[];
+};
+
+type TeamsMessage = {
+	type: "message";
+	attachments: Array<{
+		contentType: "application/vnd.microsoft.card.adaptive";
+		contentUrl: null;
+		content: AdaptiveCard;
+	}>;
+};
+
+export class TeamsProvider implements INotificationProvider {
+	private logger: ILogger;
+
+	constructor(logger: ILogger) {
+		this.logger = logger;
+	}
+
+	async sendTestAlert(notification: Notification): Promise<boolean> {
+		if (!notification.address) {
+			return false;
+		}
+
+		try {
+			const payload = this.wrapAdaptiveCard({
+				type: "AdaptiveCard",
+				$schema: "http://adaptivecards.io/schemas/adaptive-card.json",
+				version: "1.4",
+				body: [
+					{
+						type: "TextBlock",
+						text: getTestMessage(),
+						weight: "Bolder",
+						size: "Medium",
+					},
+				],
+			});
+
+			await got.post(notification.address, {
+				json: payload,
+				headers: {
+					"Content-Type": "application/json",
+				},
+			});
+			return true;
+		} catch (error) {
+			const err = error as HTTPError;
+			this.logger.warn({
+				message: "Teams test alert failed",
+				service: SERVICE_NAME,
+				method: "sendTestAlert",
+				stack: err?.stack,
+			});
+			return false;
+		}
+	}
+
+	async sendMessage(notification: Notification, message: NotificationMessage): Promise<boolean> {
+		if (!notification.address) {
+			return false;
+		}
+
+		const payload = this.wrapAdaptiveCard(this.buildAdaptiveCard(message));
+
+		try {
+			await got.post(notification.address, {
+				json: payload,
+				headers: {
+					"Content-Type": "application/json",
+				},
+			});
+			this.logger.info({
+				message: "Teams notification sent via sendMessage",
+				service: SERVICE_NAME,
+				method: "sendMessage",
+			});
+			return true;
+		} catch (error) {
+			const err = error as HTTPError;
+			this.logger.warn({
+				message: "Teams alert failed via sendMessage",
+				service: SERVICE_NAME,
+				method: "sendMessage",
+				stack: err?.stack,
+			});
+			return false;
+		}
+	}
+
+	/**
+	 * Wrap an Adaptive Card in the Teams webhook envelope format
+	 */
+	private wrapAdaptiveCard(card: AdaptiveCard): TeamsMessage {
+		return {
+			type: "message",
+			attachments: [
+				{
+					contentType: "application/vnd.microsoft.card.adaptive",
+					contentUrl: null,
+					content: card,
+				},
+			],
+		};
+	}
+
+	/**
+	 * Build an Adaptive Card from NotificationMessage
+	 */
+	private buildAdaptiveCard(message: NotificationMessage): AdaptiveCard {
+		const colorMap: Record<string, string> = {
+			critical: "attention",
+			warning: "warning",
+			success: "good",
+			info: "accent",
+		};
+		const color = (colorMap[message.severity] || "default") as "Default" | "Dark" | "Light" | "Accent" | "Good" | "Warning" | "Attention" | undefined;
+
+		const body: (TextBlock | ColumnSet | FactSet)[] = [];
+
+		// Header with colored status indicator
+		body.push({
+			type: "TextBlock",
+			text: message.content.title,
+			weight: "Bolder",
+			size: "Large",
+			color,
+			wrap: true,
+		});
+
+		// Summary
+		body.push({
+			type: "TextBlock",
+			text: message.content.summary,
+			wrap: true,
+			spacing: "Small",
+		});
+
+		// Separator
+		body.push({
+			type: "ColumnSet",
+			separator: true,
+			spacing: "Medium",
+			columns: [],
+		});
+
+		// Monitor details as a FactSet
+		body.push({
+			type: "FactSet",
+			facts: [
+				{ title: "Name", value: message.monitor.name },
+				{ title: "Type", value: message.monitor.type },
+				{ title: "Status", value: message.monitor.status },
+				{ title: "URL", value: message.monitor.url },
+			],
+		});
+
+		// Threshold breaches
+		if (message.content.thresholds && message.content.thresholds.length > 0) {
+			body.push({
+				type: "TextBlock",
+				text: "**Threshold Breaches**",
+				weight: "Bolder",
+				spacing: "Medium",
+				wrap: true,
+			});
+
+			for (const breach of message.content.thresholds) {
+				body.push({
+					type: "TextBlock",
+					text: `• **${breach.metric.toUpperCase()}**: ${breach.formattedValue} (threshold: ${breach.threshold}${breach.unit})`,
+					wrap: true,
+					spacing: "Small",
+				});
+			}
+		}
+
+		// Additional details
+		if (message.content.details && message.content.details.length > 0) {
+			body.push({
+				type: "TextBlock",
+				text: "**Additional Information**",
+				weight: "Bolder",
+				spacing: "Medium",
+				wrap: true,
+			});
+
+			for (const detail of message.content.details) {
+				body.push({
+					type: "TextBlock",
+					text: `• ${detail}`,
+					wrap: true,
+					spacing: "Small",
+				});
+			}
+		}
+
+		// Timestamp footer
+		body.push({
+			type: "TextBlock",
+			text: `Checkmate | ${new Date(message.content.timestamp).toUTCString()}`,
+			size: "Small",
+			isSubtle: true,
+			spacing: "Medium",
+			wrap: true,
+		});
+
+		// Actions (incident link)
+		const actions: Action[] = [];
+		if (message.content.incident) {
+			actions.push({
+				type: "Action.OpenUrl",
+				title: "View Incident",
+				url: `${message.clientHost}/incidents/${message.content.incident.id}`,
+			});
+		}
+
+		return {
+			type: "AdaptiveCard",
+			$schema: "http://adaptivecards.io/schemas/adaptive-card.json",
+			version: "1.4",
+			body,
+			...(actions.length > 0 ? { actions } : {}),
+		};
+	}
+}
diff --git a/server/src/service/infrastructure/notificationsService.ts b/server/src/service/infrastructure/notificationsService.ts
index 1da308678b..ea7b78a4ff 100644
--- a/server/src/service/infrastructure/notificationsService.ts
+++ b/server/src/service/infrastructure/notificationsService.ts
@@ -32,6 +32,7 @@ export class NotificationsService implements INotificationsService {
 	private discordProvider: INotificationProvider;
 	private pagerDutyProvider: INotificationProvider;
 	private matrixProvider: INotificationProvider;
+	private teamsProvider: INotificationProvider;
 	private logger: ILogger;
 	private settingsService: ISettingsService;
 	private notificationMessageBuilder: INotificationMessageBuilder;
@@ -45,6 +46,7 @@ export class NotificationsService implements INotificationsService {
 		discordProvider: INotificationProvider,
 		pagerDutyProvider: INotificationProvider,
 		matrixProvider: INotificationProvider,
+		teamsProvider: INotificationProvider,
 		settingsService: ISettingsService,
 		logger: ILogger,
 		notificationMessageBuilder: INotificationMessageBuilder
@@ -57,6 +59,7 @@ export class NotificationsService implements INotificationsService {
 		this.discordProvider = discordProvider;
 		this.pagerDutyProvider = pagerDutyProvider;
 		this.matrixProvider = matrixProvider;
+		this.teamsProvider = teamsProvider;
 		this.settingsService = settingsService;
 		this.logger = logger;
 		this.notificationMessageBuilder = notificationMessageBuilder;
@@ -92,6 +95,8 @@ export class NotificationsService implements INotificationsService {
 				return await this.discordProvider.sendMessage!(notification, notificationMessage);
 			case "email":
 				return await this.emailProvider.sendMessage!(notification, notificationMessage);
+			case "teams":
+				return await this.teamsProvider.sendMessage!(notification, notificationMessage);
 			default:
 				this.logger.warn({
 					message: `Unknown notification type: ${notification.type}`,
@@ -150,6 +155,8 @@ export class NotificationsService implements INotificationsService {
 				return await this.matrixProvider.sendTestAlert(notification);
 			case "webhook":
 				return await this.webhookProvider.sendTestAlert(notification);
+			case "teams":
+				return await this.teamsProvider.sendTestAlert(notification);
 			default:
 				return false;
 		}
diff --git a/server/src/types/notification.ts b/server/src/types/notification.ts
index 669c840ca1..a121cd8e0c 100644
--- a/server/src/types/notification.ts
+++ b/server/src/types/notification.ts
@@ -1,4 +1,4 @@
-export const NotificationChannels = ["email", "slack", "discord", "webhook", "pager_duty", "matrix"] as const;
+export const NotificationChannels = ["email", "slack", "discord", "webhook", "pager_duty", "matrix", "teams"] as const;
 export type NotificationChannel = (typeof NotificationChannels)[number];
 
 export interface Notification {
diff --git a/server/src/validation/notificationValidation.ts b/server/src/validation/notificationValidation.ts
index d974d873ff..5aa0b976eb 100644
--- a/server/src/validation/notificationValidation.ts
+++ b/server/src/validation/notificationValidation.ts
@@ -18,7 +18,7 @@ export const createNotificationBodyValidation = z.discriminatedUnion("type", [
 	z.object({
 		notificationName: z.string().min(1, "Notification name is required"),
 		type: z.literal("webhook"),
-		address: z.string().url("Please enter a valid Webhook URL"),
+		address: z.url({ message: "Please enter a valid Webhook URL" }),
 		homeserverUrl: z.union([z.string(), z.literal("")]).optional(),
 		roomId: z.union([z.string(), z.literal("")]).optional(),
 		accessToken: z.union([z.string(), z.literal("")]).optional(),
@@ -27,7 +27,7 @@ export const createNotificationBodyValidation = z.discriminatedUnion("type", [
 	z.object({
 		notificationName: z.string().min(1, "Notification name is required"),
 		type: z.literal("slack"),
-		address: z.string().url("Please enter a valid Webhook URL"),
+		address: z.url({ message: "Please enter a valid Webhook URL" }),
 		homeserverUrl: z.union([z.string(), z.literal("")]).optional(),
 		roomId: z.union([z.string(), z.literal("")]).optional(),
 		accessToken: z.union([z.string(), z.literal("")]).optional(),
@@ -36,7 +36,7 @@ export const createNotificationBodyValidation = z.discriminatedUnion("type", [
 	z.object({
 		notificationName: z.string().min(1, "Notification name is required"),
 		type: z.literal("discord"),
-		address: z.string().url("Please enter a valid Webhook URL"),
+		address: z.url({ message: "Please enter a valid Webhook URL" }),
 		homeserverUrl: z.union([z.string(), z.literal("")]).optional(),
 		roomId: z.union([z.string(), z.literal("")]).optional(),
 		accessToken: z.union([z.string(), z.literal("")]).optional(),
@@ -55,10 +55,16 @@ export const createNotificationBodyValidation = z.discriminatedUnion("type", [
 		notificationName: z.string().min(1, "Notification name is required"),
 		type: z.literal("matrix"),
 		address: z.union([z.string(), z.literal("")]).optional(),
-		homeserverUrl: z.string().url("Please enter a valid Homeserver URL"),
+		homeserverUrl: z.url({ message: "Please enter a valid Homeserver URL" }),
 		roomId: z.string().min(1, "Room ID is required"),
 		accessToken: z.string().min(1, "Access Token is required"),
 	}),
+	// Teams notification
+	z.object({
+		notificationName: z.string().min(1, "Notification name is required"),
+		type: z.literal("teams"),
+		address: z.url({ message: "Please enter a valid Webhook URL" }),
+	}),
 ]);
 
 export const sendTestEmailBodyValidation = z.object({
diff --git a/server/test/teamsProvider.test.ts b/server/test/teamsProvider.test.ts
new file mode 100644
index 0000000000..e6104f5687
--- /dev/null
+++ b/server/test/teamsProvider.test.ts
@@ -0,0 +1,267 @@
+import { describe, expect, it, jest, beforeEach } from "@jest/globals";
+import { TeamsProvider } from "../src/service/infrastructure/notificationProviders/teams.ts";
+import type { Notification } from "../src/types/notification.ts";
+import type { NotificationMessage } from "../src/types/notificationMessage.ts";
+
+// Mock got
+jest.unstable_mockModule("got", () => ({
+	default: { post: jest.fn() },
+}));
+
+const createLogger = () => ({
+	info: jest.fn(),
+	warn: jest.fn(),
+	error: jest.fn(),
+	debug: jest.fn(),
+});
+
+const createNotification = (overrides?: Partial<Notification>): Notification => ({
+	id: "notif-1",
+	userId: "user-1",
+	teamId: "team-1",
+	type: "teams",
+	notificationName: "Teams Alert",
+	address: "https://xxxxx.webhook.office.com/webhookb2/test",
+	createdAt: new Date().toISOString(),
+	updatedAt: new Date().toISOString(),
+	...overrides,
+});
+
+const createMessage = (overrides?: Partial<NotificationMessage>): NotificationMessage => ({
+	type: "monitor_down",
+	severity: "critical",
+	monitor: {
+		id: "mon-1",
+		name: "API Server",
+		url: "https://api.example.com",
+		type: "http",
+		status: "down",
+	},
+	content: {
+		title: "🔴 Monitor Down",
+		summary: "API Server is not responding",
+		details: ["Response timeout after 30s"],
+		thresholds: [],
+		incident: {
+			id: "inc-1",
+			url: "https://app.example.com/incidents/inc-1",
+			createdAt: new Date(),
+		},
+		timestamp: new Date("2026-01-15T12:00:00Z"),
+	},
+	clientHost: "https://app.example.com",
+	metadata: {
+		teamId: "team-1",
+		notificationReason: "monitor_down",
+	},
+	...overrides,
+});
+
+describe("TeamsProvider", () => {
+	let provider: TeamsProvider;
+	let logger: ReturnType<typeof createLogger>;
+	let gotPost: jest.Mock;
+
+	beforeEach(async () => {
+		logger = createLogger();
+		provider = new TeamsProvider(logger);
+		const got = await import("got");
+		gotPost = got.default.post as jest.Mock;
+		gotPost.mockReset();
+		gotPost.mockResolvedValue({});
+	});
+
+	describe("sendTestAlert", () => {
+		it("returns false when address is missing", async () => {
+			const notification = createNotification({ address: undefined });
+			const result = await provider.sendTestAlert(notification);
+			expect(result).toBe(false);
+			expect(gotPost).not.toHaveBeenCalled();
+		});
+
+		it("sends an Adaptive Card test message and returns true on success", async () => {
+			const notification = createNotification();
+			const result = await provider.sendTestAlert(notification);
+			expect(result).toBe(true);
+			expect(gotPost).toHaveBeenCalledTimes(1);
+
+			const [url, options] = gotPost.mock.calls[0] as [string, { json: any; headers: any }];
+			expect(url).toBe(notification.address);
+			expect(options.headers["Content-Type"]).toBe("application/json");
+
+			// Verify Teams webhook envelope
+			const payload = options.json;
+			expect(payload.type).toBe("message");
+			expect(payload.attachments).toHaveLength(1);
+			expect(payload.attachments[0].contentType).toBe("application/vnd.microsoft.card.adaptive");
+
+			// Verify Adaptive Card structure
+			const card = payload.attachments[0].content;
+			expect(card.type).toBe("AdaptiveCard");
+			expect(card.version).toBe("1.4");
+			expect(card.body[0].type).toBe("TextBlock");
+			expect(card.body[0].text).toContain("test notification");
+		});
+
+		it("returns false and logs warning on HTTP error", async () => {
+			gotPost.mockRejectedValue(new Error("Network error"));
+			const notification = createNotification();
+			const result = await provider.sendTestAlert(notification);
+			expect(result).toBe(false);
+			expect(logger.warn).toHaveBeenCalledWith(
+				expect.objectContaining({
+					message: "Teams test alert failed",
+					service: "TeamsProvider",
+				})
+			);
+		});
+	});
+
+	describe("sendMessage", () => {
+		it("returns false when address is missing", async () => {
+			const notification = createNotification({ address: undefined });
+			const result = await provider.sendMessage(notification, createMessage());
+			expect(result).toBe(false);
+			expect(gotPost).not.toHaveBeenCalled();
+		});
+
+		it("sends a well-formed Adaptive Card and returns true", async () => {
+			const notification = createNotification();
+			const message = createMessage();
+			const result = await provider.sendMessage(notification, message);
+
+			expect(result).toBe(true);
+			expect(gotPost).toHaveBeenCalledTimes(1);
+
+			const [url, options] = gotPost.mock.calls[0] as [string, { json: any }];
+			expect(url).toBe(notification.address);
+
+			const payload = options.json;
+			expect(payload.type).toBe("message");
+
+			const card = payload.attachments[0].content;
+			expect(card.type).toBe("AdaptiveCard");
+			expect(card.version).toBe("1.4");
+
+			// Verify body contains expected elements
+			const textBlocks = card.body.filter((b: any) => b.type === "TextBlock");
+			const factSets = card.body.filter((b: any) => b.type === "FactSet");
+
+			// Title block
+			expect(textBlocks[0].text).toBe(message.content.title);
+			expect(textBlocks[0].color).toBe("attention"); // critical -> attention
+
+			// Summary block
+			expect(textBlocks[1].text).toBe(message.content.summary);
+
+			// FactSet with monitor details
+			expect(factSets).toHaveLength(1);
+			const facts = factSets[0].facts;
+			expect(facts).toEqual(
+				expect.arrayContaining([
+					expect.objectContaining({ title: "Name", value: "API Server" }),
+					expect.objectContaining({ title: "URL", value: "https://api.example.com" }),
+					expect.objectContaining({ title: "Status", value: "down" }),
+				])
+			);
+
+			// Incident action button
+			expect(card.actions).toHaveLength(1);
+			expect(card.actions[0].type).toBe("Action.OpenUrl");
+			expect(card.actions[0].title).toBe("View Incident");
+			expect(card.actions[0].url).toContain("/infrastructure/mon-1");
+		});
+
+		it("omits actions when no incident is present", async () => {
+			const notification = createNotification();
+			const message = createMessage({
+				content: {
+					title: "Test",
+					summary: "Summary",
+					timestamp: new Date(),
+				},
+			});
+			const result = await provider.sendMessage(notification, message);
+			expect(result).toBe(true);
+
+			const [, options] = gotPost.mock.calls[0] as [string, { json: any }];
+			const card = options.json.attachments[0].content;
+			expect(card.actions).toBeUndefined();
+		});
+
+		it("includes threshold breaches when present", async () => {
+			const notification = createNotification();
+			const message = createMessage({
+				type: "threshold_breach",
+				severity: "warning",
+				content: {
+					title: "Threshold Breach",
+					summary: "CPU usage exceeded",
+					thresholds: [
+						{
+							metric: "cpu",
+							currentValue: 95,
+							threshold: 80,
+							unit: "%",
+							formattedValue: "95%",
+						},
+					],
+					timestamp: new Date(),
+				},
+			});
+
+			await provider.sendMessage(notification, message);
+
+			const [, options] = gotPost.mock.calls[0] as [string, { json: any }];
+			const card = options.json.attachments[0].content;
+
+			// Title should use "warning" color
+			expect(card.body[0].color).toBe("warning");
+
+			// Find threshold text blocks
+			const thresholdHeader = card.body.find((b: any) => b.type === "TextBlock" && b.text === "**Threshold Breaches**");
+			expect(thresholdHeader).toBeDefined();
+
+			const cpuBlock = card.body.find((b: any) => b.type === "TextBlock" && b.text?.includes("CPU"));
+			expect(cpuBlock).toBeDefined();
+			expect(cpuBlock.text).toContain("95%");
+			expect(cpuBlock.text).toContain("threshold: 80%");
+		});
+
+		it("maps severity to correct Adaptive Card colors", async () => {
+			const notification = createNotification();
+
+			const severityMap = [
+				{ severity: "critical", expected: "attention" },
+				{ severity: "warning", expected: "warning" },
+				{ severity: "success", expected: "good" },
+				{ severity: "info", expected: "accent" },
+			] as const;
+
+			for (const { severity, expected } of severityMap) {
+				gotPost.mockReset();
+				gotPost.mockResolvedValue({});
+
+				const message = createMessage({ severity });
+				await provider.sendMessage(notification, message);
+
+				const [, options] = gotPost.mock.calls[0] as [string, { json: any }];
+				const card = options.json.attachments[0].content;
+				expect(card.body[0].color).toBe(expected);
+			}
+		});
+
+		it("returns false and logs warning on HTTP error", async () => {
+			gotPost.mockRejectedValue(new Error("502 Bad Gateway"));
+			const notification = createNotification();
+			const result = await provider.sendMessage(notification, createMessage());
+			expect(result).toBe(false);
+			expect(logger.warn).toHaveBeenCalledWith(
+				expect.objectContaining({
+					message: "Teams alert failed via sendMessage",
+					service: "TeamsProvider",
+				})
+			);
+		});
+	});
+});