Release a message's hold when the response goes out, or when its listener failed

src/sms.ts

@@ -77,8 +77,7 @@ export function createSms(input: SmsInput, handlers: SmsHandlers): Sms {
 		message: input.message,
 		pduObjs: input.pduObjs,
 		sendDlr: status => sendDlr(sms, handlers.send, status),
-		sendResp: options => sendResp(sms, answered, options ?? {}, handlers.lostLink)
-			.finally(handlers.onAnswered),
+		sendResp: options => sendResp(sms, answered, options ?? {}, handlers),
 		session: input.session,
 		get smsId(): string {
 			return answered.smsId;
@@ -94,7 +93,7 @@ async function sendResp(
 	sms: Sms,
 	answered: { smsId: string },
 	options: SendRespOptions,
-	lostLink: () => boolean,
+	handlers: SmsHandlers,
 ): Promise<VoidResult> {
 	const total = sms.pduObjs.length;
 
@@ -109,7 +108,7 @@ async function sendResp(
 	if (options.smsId !== undefined) answered.smsId = options.smsId;
 
 	// A response carries the sequence number it was asked on, which the next link knows nothing about.
-	if (lostLink()) {
+	if (handlers.lostLink()) {
 		return { err: new Error('The link this message arrived on is gone, so nothing would correlate the response') };
 	}
 
@@ -119,6 +118,9 @@ async function sendResp(
 		{ message_id: segmentId(answered.smsId, index, total) },
 	)));
 
+	// Only here: a refusal above put nothing on the wire, so the peer is still owed its response.
+	handlers.onAnswered();
+
 	return results.find(result => result.err) ?? {};
 }