Notification Providers & Resolution

Job arrives for tenantId X, channel = email
  |
  v
resolveEmailProvider("X")
  |
  |-- db.notificationProvider.findFirst({
  |     where: {
  |       tenantId: "X",
  |       channel:  "email",
  |       verifiedAt: { not: null },   // unverified rows are skipped
  |     }
  |   })
  |
  |-- Row found (provider = "smtp")      -> new SmtpProvider(decrypt(row.config))
  |-- Row found (provider = "sendgrid")  -> new SendGridProvider(decrypt(row.config))
  |-- Row found (provider = "ses")       -> new SesProvider(decrypt(row.config))
  +-- No row / not verified              -> new SendGridProvider(platform env vars)

model NotificationProvider {
  id          String    @id @default(cuid())
  tenantId    String
  channel     String    // "email" | "whatsapp" | "telegram"
  provider    String    // "smtp" | "sendgrid" | "ses" | "whatsapp_business_api" | "telegram_bot"
  config      String    // JSON (will be AES-256-GCM encrypted in production)
  verifiedAt  DateTime? // NULL = configured but not tested; unverified = platform default used
  lastError   String?   // shown in Dashboard settings on test failure
  createdAt   DateTime  @default(now())
  updatedAt   DateTime  @updatedAt
 
  tenant      Tenant    @relation(...)
 
  @@unique([tenantId, channel])  // one active provider per channel per tenant
  @@map("notification_provider")
}

interface EmailProvider {
  readonly name: string;
  send(message: EmailMessage): Promise<EmailSendResult>;
}
 
interface EmailMessage {
  to:          { name: string; email: string }[];
  subject:     string;
  html:        string;
  text?:       string;
  replyTo?:    { name: string; email: string };
  attachments?: { filename: string; content: Buffer; contentType: string }[];
}
 
interface EmailSendResult { messageId: string; provider: string; }

interface WhatsAppProvider {
  readonly name: string;
  sendTemplate(message: WhatsAppMessage): Promise<WhatsAppSendResult>;
}
 
interface WhatsAppMessage {
  to:        string;   // E.164
  template:  { name: string; languageCode: string };
  variables: Record<string, string>;
}

interface TelegramProvider {
  readonly name: string;
  send(message: TelegramMessage): Promise<TelegramSendResult>;
}
 
interface TelegramMessage {
  chatId:                 string | number;
  text:                   string;
  parseMode?:             "HTML" | "Markdown" | "MarkdownV2";
  disableWebPagePreview?: boolean;
}

// smtp
{ "host": "smtp.gmail.com", "port": 587, "secure": false,
  "user": "bot@acme.com", "pass": "...", "fromAddress": "noreply@acme.com" }
 
// sendgrid
{ "apiKey": "SG.xxx", "fromAddress": "noreply@acme.com", "fromName": "Acme" }
 
// ses
{ "accessKeyId": "AKIA...", "secretAccessKey": "...", "region": "ap-south-1",
  "fromAddress": "noreply@acme.com" }

{ "apiKey": "EAA...", "phoneNumberId": "123456789", "baseUrl": "https://graph.facebook.com/v19.0" }

{ "botToken": "123456:ABC-...", "defaultChatId": "-100..." }