/** Unified webhook event schema that every provider verifier normalizes
*  into. Consumers get one shape regardless of which SDK the upstream
*  vendor ships. */
export type WebhookEventType = "sent" | "delivered" | "bounced" | "complained" | "opened" | "clicked" | "unsubscribed" | "rejected" | "failed" | "other";
export interface WebhookEvent {
	type: WebhookEventType;
	id: string;
	at: Date;
	recipient: string;
	provider: string;
	/** Provider-native payload, preserved for drivers that surface extra
	*  fields (bounce diagnostics, click URLs, etc.). */
	raw: unknown;
	/** For \`clicked\` events — the URL the recipient clicked. */
	url?: string;
	/** For \`bounced\` events — bounce classification (\`"hard"\` / \`"soft"\`
	*  / \`"unknown"\`). */
	bounce?: "hard" | "soft" | "unknown";
}
/** A provider-specific verifier that can normalize one webhook request
*  into one or more \`WebhookEvent\`s. */
export interface WebhookProvider {
	readonly name: string;
	verify: (request: Request) => Promise<WebhookEvent[] | null> | WebhookEvent[] | null;
}
/** Handler returned by \`defineWebhookHandler\`. */
export type WebhookHandler = (request: Request) => Promise<Response>;
export interface DefineWebhookHandlerOptions {
	providers: ReadonlyArray<WebhookProvider>;
	onEvent: (event: WebhookEvent, context: {
		provider: string;
		request: Request;
	}) => void | Promise<void>;
	onUnknown?: (request: Request) => Promise<Response> | Response;
	onVerificationFailure?: (request: Request, provider: string) => Promise<Response> | Response;
}
/** Build a fetch-compatible handler that accepts webhook payloads from
*  any registered provider, verifies signatures, and yields unified
*  \`WebhookEvent\`s via \`onEvent\`. */
export declare function defineWebhookHandler(options: DefineWebhookHandlerOptions): WebhookHandler;