feat(api): support scheduled message delivery

src/api-surface.spec.ts

@@ -136,6 +136,26 @@ describe('public SDK surface', () => {
       expect.objectContaining({ method: 'PUT', body: JSON.stringify(assignment) })
     );
   });
+
+  it('reschedules and cancels scheduled messages', async () => {
+    const api = Lettermint.api('api-token');
+    await api.messages.reschedule('message/id', { scheduled_at: '2026-08-27T09:00:00Z' });
+    await api.messages.cancel('message/id');
+
+    expect(mockFetch).toHaveBeenNthCalledWith(
+      1,
+      'https://api.lettermint.co/v1/messages/message%2Fid',
+      expect.objectContaining({
+        method: 'PATCH',
+        body: JSON.stringify({ scheduled_at: '2026-08-27T09:00:00Z' }),
+      })
+    );
+    expect(mockFetch).toHaveBeenNthCalledWith(
+      2,
+      'https://api.lettermint.co/v1/messages/message%2Fid/cancel',
+      expect.objectContaining({ method: 'POST' })
+    );
+  });
 });
 
 describe('api endpoint coverage', () => {
@@ -151,6 +171,8 @@ describe('api endpoint coverage', () => {
     'v1.blockedFileTypes': 'blockedFileTypes',
     'message.index': 'messages.list',
     'message.show': 'messages.retrieve',
+    rescheduleMessage: 'messages.reschedule',
+    cancelScheduledMessage: 'messages.cancel',
     'message.events': 'messages.events',
     'message.source': 'messages.source',
     'message.html': 'messages.html',
@@ -208,7 +230,7 @@ describe('api endpoint coverage', () => {
 
 describe('generated api types', () => {
   it('matches current Team API schema additions', () => {
-    const messageEvent: Types.MessageEventType = 'auto_replied';
+    const messageEvent: Types.MessageEventType = 'scheduled';
     const webhookEvent: Types.WebhookEvent = 'message.auto_replied';
     const builtInRole: Types.BuiltInTeamRole = 'admin';
     const suppression: Types.StoreSuppressionData = {
@@ -279,6 +301,7 @@ describe('generated api types', () => {
       created_at: '2026-08-12T00:00:00Z',
     };
     const spamScore: Types.MessageListData['spam_score'] = 2.5;
+    const scheduledAt: Types.SendMailRequest['scheduled_at'] = '2026-08-27T09:00:00Z';
 
     expect({
       messageEvent,
@@ -295,6 +318,7 @@ describe('generated api types', () => {
       domain,
       sourceMessage,
       spamScore,
+      scheduledAt,
     }).toBeDefined();
   });
 });

src/client.ts

@@ -246,6 +246,19 @@ export class LettermintClient {
     return response.json();
   }
 
+  /** Make a PATCH request to the API. */
+  public async patch<T>(path: string, data?: unknown, config?: RequestConfig): Promise<T> {
+    const url = this.buildUrl(path, config?.params);
+    const headers = this.buildHeaders(config?.headers);
+    const response = await this.fetchWithTimeout(url, {
+      method: 'PATCH',
+      headers,
+      body: data ? JSON.stringify(data) : undefined,
+    });
+
+    return response.json();
+  }
+
   /**
    * Make a DELETE request to the API
    *

src/endpoints/api.ts

@@ -50,6 +50,17 @@ export class MessagesEndpoint extends Endpoint {
     return this.httpClient.get(`/messages/${this.pathSegment(messageId)}`);
   }
 
+  public reschedule(
+    messageId: string,
+    payload: Types.RescheduleMessageRequest
+  ): Promise<Types.RescheduleMessageResponse> {
+    return this.httpClient.patch(`/messages/${this.pathSegment(messageId)}`, payload);
+  }
+
+  public cancel(messageId: string): Promise<Types.RescheduleMessageResponse> {
+    return this.httpClient.post(`/messages/${this.pathSegment(messageId)}/cancel`);
+  }
+
   public events(messageId: string): Promise<Types.MessageEventsResponse> {
     return this.httpClient.get(`/messages/${this.pathSegment(messageId)}/events`);
   }

src/endpoints/email.ts

@@ -93,6 +93,12 @@ export class EmailEndpoint extends Endpoint {
     return this;
   }
 
+  /** Set the requested delivery time for the email. */
+  public scheduledAt(scheduledAt: string): this {
+    this.payload.scheduled_at = scheduledAt;
+    return this;
+  }
+
   /**
    * Set the HTML body of the email
    *

src/types.ts

@@ -2,7 +2,7 @@
 // biome-ignore-all lint: generated OpenAPI types use schema-shaped names.
 // This file is generated by sdk-generator/node/generate-types.mjs.
 
-export type MessageStatus = "pending" | "queued" | "suppressed" | "processed" | "delivered" | "opened" | "clicked" | "soft_bounced" | "hard_bounced" | "spam_complaint" | "failed" | "blocked" | "policy_rejected" | "unsubscribed";
+export type MessageStatus = "scheduled" | "pending" | "queued" | "suppressed" | "processed" | "delivered" | "opened" | "clicked" | "soft_bounced" | "hard_bounced" | "spam_complaint" | "failed" | "blocked" | "policy_rejected" | "unsubscribed" | "canceled";
 
 export interface SendMailRequest {
   "route"?: string;
@@ -12,6 +12,7 @@ export interface SendMailRequest {
   "bcc"?: string[];
   "reply_to"?: string[];
   "subject": string;
+  "scheduled_at"?: string;
   "headers"?: Record<string, string>;
   "metadata"?: Record<string, string>;
   "tag"?: string | null;
@@ -42,6 +43,7 @@ export type SendBatchMailRequest = {
   "bcc"?: string[];
   "reply_to"?: string[];
   "subject": string;
+  "scheduled_at"?: string;
   "headers"?: Record<string, string>;
   "metadata"?: Record<string, string>;
   "tag"?: string | null;
@@ -141,6 +143,7 @@ export interface MessageData {
   "type": MessageType;
   "status": MessageStatus;
   "status_changed_at": string | null;
+  "scheduled_at": string | null;
   "tag": string | null;
   "tags": {
   "name": string;
@@ -173,12 +176,13 @@ export interface MessageEventData {
   "timestamp": string;
 }
 
-export type MessageEventType = "queued" | "processed" | "suppressed" | "delivered" | "auto_replied" | "soft_bounced" | "hard_bounced" | "spam_complaint" | "failed" | "blocked" | "policy_rejected" | "unsubscribed" | "opened" | "clicked" | "inbound_received" | "inbound_queued" | "inbound_spam_blocked" | "inbound_processed" | "inbound_retry";
+export type MessageEventType = "scheduled" | "rescheduled" | "canceled" | "released" | "queued" | "processed" | "suppressed" | "delivered" | "auto_replied" | "soft_bounced" | "hard_bounced" | "spam_complaint" | "failed" | "blocked" | "policy_rejected" | "unsubscribed" | "opened" | "clicked" | "inbound_received" | "inbound_queued" | "inbound_spam_blocked" | "inbound_processed" | "inbound_retry";
 
 export interface MessageListData {
   "id": string;
   "type": MessageType;
   "status": MessageStatus;
+  "scheduled_at": string | null;
   "spam_score"?: number | null;
   "from_email": string;
   "from_name": string | null;
@@ -622,11 +626,21 @@ export type SendBatchEmailResponse = SendBatchMailResponse;
 export type SendMailResponse = {
   "message_id": string;
   "status": MessageStatus;
+  "scheduled_at"?: string;
 };
 export type SendBatchMailResponse = {
   "message_id": string;
   "status": MessageStatus;
+  "scheduled_at"?: string;
 }[];
+export interface RescheduleMessageRequest {
+  "scheduled_at": string;
+}
+export type RescheduleMessageResponse = {
+  "message_id": string;
+  "status": MessageStatus | null;
+  "scheduled_at": string | null;
+};
 export type PingResponse = 200;
 export type DomainIndexResponse = {
   "data": DomainListData[];