diff --git a/adapter-manifest.json b/adapter-manifest.json
index 3025d0e..8971c13 100644
--- a/adapter-manifest.json
+++ b/adapter-manifest.json
@@ -177,13 +177,14 @@
       "issues": "session"
     },
     { "method": "POST", "path": "/refresh", "credential": "refresh", "issues": "session" },
-    { "method": "POST", "path": "/registration/phone", "credential": "access" },
+    { "method": "POST", "path": "/registration/phone", "credential": "access", "delivery": true },
     { "method": "POST", "path": "/registration/phone/verify", "credential": "access" },
     {
       "method": "POST",
       "path": "/registration/register",
       "credential": "none",
-      "issues": "registration"
+      "issues": "registration",
+      "delivery": true
     },
     { "method": "DELETE", "path": "/sessions", "credential": "access" },
     { "method": "GET", "path": "/sessions", "credential": "access" },
diff --git a/src/lib/adapterManifest.ts b/src/lib/adapterManifest.ts
index d657f7b..484855f 100644
--- a/src/lib/adapterManifest.ts
+++ b/src/lib/adapterManifest.ts
@@ -90,6 +90,23 @@ function successSchemas(response: ZodTypeAny | Record<number, ZodTypeAny> | unde
     .map(([, schema]) => schema);
 }
 
+function successFields(
+  response: ZodTypeAny | Record<number, ZodTypeAny> | undefined,
+  name: string,
+): ZodTypeAny[] {
+  return successSchemas(response)
+    .flatMap(unwrap)
+    .map((schema) => (schema as z.ZodObject).shape[name] as ZodTypeAny | undefined)
+    .filter((field): field is ZodTypeAny => field !== undefined);
+}
+
+/** Whether a success response can carry an external-delivery payload. */
+export function deliveryInResponse(
+  response: ZodTypeAny | Record<number, ZodTypeAny> | undefined,
+): boolean {
+  return successFields(response, 'delivery').length > 0;
+}
+
 /**
  * Whether a success response carries a token, and whether it always does.
  *
@@ -100,10 +117,7 @@ function successSchemas(response: ZodTypeAny | Record<number, ZodTypeAny> | unde
 export function tokenInResponse(
   response: ZodTypeAny | Record<number, ZodTypeAny> | undefined,
 ): 'required' | 'optional' | 'none' {
-  const fields = successSchemas(response)
-    .flatMap(unwrap)
-    .map((schema) => (schema as z.ZodObject).shape.token as ZodTypeAny | undefined)
-    .filter((field): field is ZodTypeAny => field !== undefined);
+  const fields = successFields(response, 'token');
 
   if (fields.some((field) => !(field instanceof z.ZodOptional))) {
     return 'required';
@@ -189,6 +203,14 @@ export function registerAdapterRoute({
     );
   }
 
+  // Only this direction is checked: the shared `MessageSchema` allows a delivery payload
+  // on routes that never send one, so its presence cannot mean a route delivers.
+  if (options.delivery && !deliveryInResponse(response)) {
+    throw new Error(
+      `${label} declares adapter \`delivery\` but no success response has a delivery payload.`,
+    );
+  }
+
   if (options.body && !options.issues) {
     throw new Error(`${label} declares an adapter body \`pick\` but issues nothing.`);
   }
diff --git a/src/routes/registration.routes.ts b/src/routes/registration.routes.ts
index 8e370f9..449778d 100644
--- a/src/routes/registration.routes.ts
+++ b/src/routes/registration.routes.ts
@@ -24,7 +24,7 @@ const registrationRouter = createRouter('/registration');
 registrationRouter.post(
   '/register',
   {
-    adapter: { issues: 'registration' },
+    adapter: { issues: 'registration', delivery: true },
     summary: 'Register a new user',
     tags: ['Registration'],
     middleware: [otpIpLimiter, otpIdentityLimiter],
@@ -46,6 +46,7 @@ registrationRouter.post(
 registrationRouter.post(
   '/phone',
   {
+    adapter: { delivery: true },
     auth: 'access',
     summary: 'Register a phone number for the authenticated user',
     tags: ['Registration'],
diff --git a/tests/unit/lib/adapterManifest.spec.ts b/tests/unit/lib/adapterManifest.spec.ts
index 1b69a28..180fb9f 100644
--- a/tests/unit/lib/adapterManifest.spec.ts
+++ b/tests/unit/lib/adapterManifest.spec.ts
@@ -10,7 +10,11 @@ import {
 
 const Message = z.object({ message: z.string() });
 const Session = z.object({ sub: z.string(), token: z.string(), ttl: z.number() });
-const MaybeToken = z.object({ message: z.string(), token: z.string().optional() });
+const MaybeToken = z.object({
+  message: z.string(),
+  token: z.string().optional(),
+  delivery: z.object({ kind: z.string() }).optional(),
+});
 
 function register(overrides: Partial<Parameters<typeof registerAdapterRoute>[0]>) {
   registerAdapterRoute({
@@ -115,6 +119,12 @@ describe('registerAdapterRoute', () => {
     );
   });
 
+  it('refuses delivery on a route whose response cannot carry a delivery payload', () => {
+    expect(() => register({ auth: 'access', adapter: { delivery: true } })).toThrow(
+      /no success response has a delivery payload/,
+    );
+  });
+
   it('refuses a body pick on a route that issues nothing', () => {
     expect(() => register({ adapter: { body: { pick: ['message'] } } })).toThrow(/issues nothing/);
   });
@@ -135,6 +145,7 @@ describe('registerAdapterRoute', () => {
       path: '/send',
       auth: 'ephemeral',
       adapter: { credential: 'registration', delivery: true },
+      response: { 200: MaybeToken },
     });
 
     expect(getAdapterManifest().routes).toEqual([
diff --git a/tests/unit/routes/adapterManifest.routes.spec.ts b/tests/unit/routes/adapterManifest.routes.spec.ts
index 7f9cda1..fa8aa1a 100644
--- a/tests/unit/routes/adapterManifest.routes.spec.ts
+++ b/tests/unit/routes/adapterManifest.routes.spec.ts
@@ -50,7 +50,7 @@ describe('adapter manifest for the live routes', () => {
 
   // A GET is sent cross-site without a CORS preflight, so a route that sends a message
   // must only reach adapters as POST.
-  it('only exposes message-sending routes as POST', () => {
+  it('marks every message-sending route and exposes each as POST', () => {
     const delivery = manifest.routes.filter((entry) => entry.delivery);
 
     expect(delivery.map((entry) => `${entry.method} ${entry.path}`).sort()).toEqual([
@@ -59,6 +59,8 @@ describe('adapter manifest for the live routes', () => {
       'POST /otp/generate-login-email-otp',
       'POST /otp/generate-login-phone-otp',
       'POST /otp/generate-phone-otp',
+      'POST /registration/phone',
+      'POST /registration/register',
     ]);
   });