diff --git a/src/incoming-requests.ts b/src/incoming-requests.ts
index 7b4f038..e81898a 100644
--- a/src/incoming-requests.ts
+++ b/src/incoming-requests.ts
@@ -19,8 +19,8 @@ export type IncomingRequestsOptions = {
 	maxReassembly?: number | undefined;
 	onRequest?: OnRequest | undefined;
 	reassemblyTimeout?: number | undefined;
-	smsIdFormat?: SmsIdFormat | undefined;
 	session: Session;
+	smsIdFormat?: SmsIdFormat | undefined;
 	systemId?: string | undefined;
 };
 
diff --git a/src/send-sms.ts b/src/send-sms.ts
index 509b8c7..2fb7593 100644
--- a/src/send-sms.ts
+++ b/src/send-sms.ts
@@ -83,7 +83,6 @@ export function submitSmParams(
 	return params;
 }
 
-/** Puts a message on the wire as one submit_sm per segment. */
 /** Nothing goes on the wire until the whole message fits: a half-sent message bills twice. */
 function checkSegments(allowed: number, segments: number): Error | undefined {
 	if (!Number.isInteger(allowed) || allowed < 1 || allowed > maxSegments) {
@@ -125,6 +124,7 @@ function collectSent(
 	return failure ? { err: failure, pduObjs, smsIds } : { pduObjs, smsIds };
 }
 
+/** Puts a message on the wire as one submit_sm per segment. */
 export async function submitSms(deps: SendSmsDeps, sms: SendSmsOptions): Promise<SendSmsResult> {
 	const allowed = sms.maxSegments ?? maxSegments;
 	const encoding = sms.encoding ?? detect(sms.message);
diff --git a/src/sms-id.ts b/src/sms-id.ts
index 202161a..27146ff 100644
--- a/src/sms-id.ts
+++ b/src/sms-id.ts
@@ -11,7 +11,7 @@ export type SmsIdNotation = keyof typeof notations;
 /** The notation per place the peer writes an id. An omitted place is left as it arrived. */
 export type SmsIdFormat = Partial<Record<typeof places[number], SmsIdNotation | undefined>>;
 
-export const smsIdNotations: string[] = Object.keys(notations);
+export const smsIdNotations: readonly string[] = Object.keys(notations);
 
 export const smsIdPlaces: readonly string[] = places;
 
diff --git a/test/readme.test.ts b/test/readme.test.ts
index 886fa9c..44794cb 100644
--- a/test/readme.test.ts
+++ b/test/readme.test.ts
@@ -104,13 +104,15 @@ describe('README: Client', () => {
 		closeAfter(t, session);
 
 		const reported = once<Dlr>(resolve => { session.on('dlr', resolve); });
-		const { smsIds } = await session.sendSms({
+		const { err: sendErr, smsIds } = await session.sendSms({
 			dlr: true,
 			from: '46701113311',
 			message: 'Hello world',
 			to: '46709771337',
 		});
 
+		assert.equal(sendErr, undefined);
+		assert.equal(smsIds.length, 1);
 		// The generated ids the server answers with read as no notation, so they arrive untouched.
 		assert.equal((await reported).smsId, smsIds[0]);
 	});
diff --git a/test/session-extras.test.ts b/test/session-extras.test.ts
index 81c564a..b721965 100644
--- a/test/session-extras.test.ts
+++ b/test/session-extras.test.ts
@@ -878,7 +878,6 @@ describe('message id notation', () => {
 
 		assert.ok(checked.err instanceof Error);
 		assert.match(checked.err.message, /smsIdFormat\.receipt/);
-		// The shape todo.md sketched, which a caller without types would otherwise pass unnoticed.
 		assert.ok(checkSessionOptions({ smsIdFormat: 'hex' }).err instanceof Error);
 		assert.match(
 			checkSessionOptions({ smsIdFormat: { receipts: 'decimal' } }).err?.message ?? '',