refactor: unify outbound result envelopes

src/infra/outbound/envelope.ts

@@ -0,0 +1,52 @@
+import type { ReplyPayload } from "../../auto-reply/types.js";
+import type { OutboundDeliveryJson } from "./format.js";
+import {
+  normalizeOutboundPayloadsForJson,
+  type OutboundPayloadJson,
+} from "./payloads.js";
+
+export type OutboundResultEnvelope = {
+  payloads?: OutboundPayloadJson[];
+  meta?: unknown;
+  delivery?: OutboundDeliveryJson;
+};
+
+type BuildEnvelopeParams = {
+  payloads?: ReplyPayload[] | OutboundPayloadJson[];
+  meta?: unknown;
+  delivery?: OutboundDeliveryJson;
+  flattenDelivery?: boolean;
+};
+
+const isOutboundPayloadJson = (
+  payload: ReplyPayload | OutboundPayloadJson,
+): payload is OutboundPayloadJson => "mediaUrl" in payload;
+
+export function buildOutboundResultEnvelope(
+  params: BuildEnvelopeParams,
+): OutboundResultEnvelope | OutboundDeliveryJson {
+  const hasPayloads = params.payloads !== undefined;
+  const payloads =
+    params.payloads === undefined
+      ? undefined
+      : params.payloads.length === 0
+        ? []
+        : isOutboundPayloadJson(params.payloads[0])
+          ? (params.payloads as OutboundPayloadJson[])
+          : normalizeOutboundPayloadsForJson(params.payloads as ReplyPayload[]);
+
+  if (
+    params.flattenDelivery !== false &&
+    params.delivery &&
+    !params.meta &&
+    !hasPayloads
+  ) {
+    return params.delivery;
+  }
+
+  return {
+    ...(hasPayloads ? { payloads } : {}),
+    ...(params.meta ? { meta: params.meta } : {}),
+    ...(params.delivery ? { delivery: params.delivery } : {}),
+  };
+}