diff --git a/api/auth/verify.js b/api/auth/verify.js
index ef7ed0b..0bec004 100644
--- a/api/auth/verify.js
+++ b/api/auth/verify.js
@@ -58,9 +58,27 @@ module.exports = async function handler(req, res) {
     return fail(405, 'method_not_allowed', 'Method not allowed. Use POST.');
   }
 
-  const body = req.body || {};
-  const message = typeof body.message === 'string' ? body.message : '';
-  const signature = typeof body.signature === 'string' ? body.signature : '';
+  const body = req.body;
+  if (!body || typeof body !== 'object' || Array.isArray(body)) {
+    return fail(400, 'malformed_request', 'Request body must be a JSON object.');
+  }
+
+  if (!Object.prototype.hasOwnProperty.call(body, 'message')) {
+    return fail(400, 'missing_message', 'Missing SIWE message.');
+  }
+  if (!Object.prototype.hasOwnProperty.call(body, 'signature')) {
+    return fail(400, 'missing_signature', 'Missing SIWE signature.');
+  }
+
+  if (typeof body.message !== 'string') {
+    return fail(400, 'invalid_message_type', 'SIWE message must be a string.');
+  }
+  if (typeof body.signature !== 'string') {
+    return fail(400, 'invalid_signature_type', 'SIWE signature must be a string.');
+  }
+
+  const message = body.message;
+  const signature = body.signature;
   if (!message) return fail(400, 'missing_message', 'Missing SIWE message.');
   if (!signature) return fail(400, 'missing_signature', 'Missing SIWE signature.');
 
@@ -68,7 +86,7 @@ module.exports = async function handler(req, res) {
   try {
     ({ SiweMessage } = require('siwe'));
   } catch {
-    return fail(503, 'dependency_unavailable', 'SIWE verification dependency unavailable on server.');
+    return fail(503, 'dependency_unavailable', 'SIWE dependency is unavailable');
   }
 
   try {
diff --git a/tests/api-auth.test.js b/tests/api-auth.test.js
index 2814f2f..436e3c0 100644
--- a/tests/api-auth.test.js
+++ b/tests/api-auth.test.js
@@ -1,77 +1,77 @@
-'use strict';
-
-const test = require('node:test');
-const assert = require('node:assert/strict');
-
-const nonceHandler = require('../api/auth/nonce');
-const verifyHandler = require('../api/auth/verify');
-
-function makeRes() {
-  return {
-    statusCode: 200,
-    headers: {},
-    body: null,
-    setHeader(name, value) { this.headers[name.toLowerCase()] = value; },
-    status(code) { this.statusCode = code; return this; },
-    json(payload) { this.body = payload; return this; },
-  };
-}
-
-test('GET /api/auth/nonce returns nonce and randomness', async () => {
-  const r1 = makeRes(); const r2 = makeRes();
-  await nonceHandler({ method: 'GET', headers: {} }, r1);
-  await nonceHandler({ method: 'GET', headers: {} }, r2);
-  assert.equal(r1.statusCode, 200);
-  assert.equal(r1.body.ok, true);
-  assert.match(r1.body.nonce, /^[a-f0-9]{32,}$/);
-  assert.notEqual(r1.body.nonce, r2.body.nonce);
-});
-
-test('POST /api/auth/verify rejects missing signature', async () => {
-  const res = makeRes();
-  await verifyHandler({ method: 'POST', body: { message: 'x' }, headers: { host: 'localhost:3000' } }, res);
-  assert.equal(res.statusCode, 400);
-  assert.equal(res.body.ok, false);
-  assert.equal(res.body.error, 'missing_signature');
-});
-
-test('POST /api/auth/verify rejects malformed message/signature', async () => {
-  const res = makeRes();
-  await verifyHandler({ method: 'POST', body: { message: 'invalid', signature: '0xdeadbeef' }, headers: { host: 'localhost:3000' } }, res);
-  assert.equal(res.body.ok, false);
-  assert.equal(res.body.status, 'AUTH_FAILED');
-  assert.ok(['malformed_message', 'dependency_unavailable'].includes(res.body.error));
-});
-
-test('POST /api/auth/verify rejects statement mismatch', async () => {
-  const res = makeRes();
-  const message = `www.commandlayer.org wants you to sign in with your Ethereum account:
-0x0000000000000000000000000000000000000001
-
-Different statement.
-
-URI: https://www.commandlayer.org
-Version: 1
-Chain ID: 1
-Nonce: abcdefgh
-Issued At: 2026-01-01T00:00:00.000Z`;
-  await verifyHandler({ method: 'POST', body: { message, signature: '0xdeadbeef' }, headers: { host: 'www.commandlayer.org' } }, res);
-  if (res.statusCode === 503) {
-    assert.equal(res.body.error, 'dependency_unavailable');
-    return;
-  }
-  assert.equal(res.statusCode, 400);
-  assert.equal(res.body.error, 'statement_mismatch');
-});
-
-
-test('POST /api/auth/verify rejects malformed SIWE payload or surfaces missing dependency', async () => {
-  const res = makeRes();
-  await verifyHandler({ method: 'POST', body: { message: 'x', signature: '0xy' }, headers: { host: 'localhost:3000' } }, res);
-  assert.equal(res.body.ok, false);
-  assert.equal(res.body.status, 'AUTH_FAILED');
-  assert.ok(
-    (res.statusCode === 400 && res.body.error === 'malformed_message') ||
-    (res.statusCode === 503 && res.body.error === 'dependency_unavailable')
-  );
-});
+'use strict';
+
+const test = require('node:test');
+const assert = require('node:assert/strict');
+
+const nonceHandler = require('../api/auth/nonce');
+const verifyHandler = require('../api/auth/verify');
+
+function makeRes() {
+  return {
+    statusCode: 200,
+    headers: {},
+    body: null,
+    setHeader(name, value) { this.headers[name.toLowerCase()] = value; },
+    status(code) { this.statusCode = code; return this; },
+    json(payload) { this.body = payload; return this; },
+  };
+}
+
+test('GET /api/auth/nonce returns nonce and randomness', async () => {
+  const r1 = makeRes(); const r2 = makeRes();
+  await nonceHandler({ method: 'GET', headers: {} }, r1);
+  await nonceHandler({ method: 'GET', headers: {} }, r2);
+  assert.equal(r1.statusCode, 200);
+  assert.equal(r1.body.ok, true);
+  assert.match(r1.body.nonce, /^[a-f0-9]{32,}$/);
+  assert.notEqual(r1.body.nonce, r2.body.nonce);
+});
+
+test('POST /api/auth/verify rejects missing signature', async () => {
+  const res = makeRes();
+  await verifyHandler({ method: 'POST', body: { message: 'x' }, headers: { host: 'localhost:3000' } }, res);
+  assert.equal(res.statusCode, 400);
+  assert.equal(res.body.ok, false);
+  assert.equal(res.body.error, 'missing_signature');
+});
+
+test('POST /api/auth/verify rejects malformed message/signature', async () => {
+  const res = makeRes();
+  await verifyHandler({ method: 'POST', body: { message: 'invalid', signature: '0xdeadbeef' }, headers: { host: 'localhost:3000' } }, res);
+  assert.equal(res.body.ok, false);
+  assert.equal(res.body.status, 'AUTH_FAILED');
+  assert.ok(['malformed_message', 'dependency_unavailable'].includes(res.body.error));
+});
+
+test('POST /api/auth/verify rejects statement mismatch', async () => {
+  const res = makeRes();
+  const message = `www.commandlayer.org wants you to sign in with your Ethereum account:
+0x0000000000000000000000000000000000000001
+
+Different statement.
+
+URI: https://www.commandlayer.org
+Version: 1
+Chain ID: 1
+Nonce: abcdefgh
+Issued At: 2026-01-01T00:00:00.000Z`;
+  await verifyHandler({ method: 'POST', body: { message, signature: '0xdeadbeef' }, headers: { host: 'www.commandlayer.org' } }, res);
+  if (res.statusCode === 503) {
+    assert.equal(res.body.error, 'dependency_unavailable');
+    return;
+  }
+  assert.equal(res.statusCode, 400);
+  assert.equal(res.body.error, 'statement_mismatch');
+});
+
+
+test('POST /api/auth/verify rejects malformed SIWE payload or surfaces missing dependency', async () => {
+  const res = makeRes();
+  await verifyHandler({ method: 'POST', body: { message: 'x', signature: '0xy' }, headers: { host: 'localhost:3000' } }, res);
+  assert.equal(res.body.ok, false);
+  assert.equal(res.body.status, 'AUTH_FAILED');
+  assert.ok(
+    (res.statusCode === 400 && res.body.error === 'malformed_message') ||
+    (res.statusCode === 503 && res.body.error === 'dependency_unavailable')
+  );
+});