diff --git a/src/api-client.mjs b/src/api-client.mjs
index 930b817..116ca02 100644
--- a/src/api-client.mjs
+++ b/src/api-client.mjs
@@ -6,9 +6,14 @@
 // against packages/lua-api source by the M4 contract tests.
 
 import { resolveApiKey } from './auth.mjs';
+import { createRequire } from 'node:module';
+
+const require = createRequire(import.meta.url);
+const { version: PACKAGE_VERSION } = require('../package.json');
 
 const DEFAULT_BASE_URL = 'https://api.heylua.ai';
 const DEFAULT_TIMEOUT_MS = 10_000;
+const CLIENT_IDENTITY = `platform-mcp/${PACKAGE_VERSION}`;
 
 /**
  * @param {string} path - API path (with leading slash)
@@ -35,6 +40,7 @@ export async function apiRequest(path, {
       headers: {
         'Authorization': `Bearer ${apiKey}`,
         'Content-Type': 'application/json',
+        'X-Lua-Client': CLIENT_IDENTITY,
       },
       body: body ? JSON.stringify(body) : undefined,
       signal: controller.signal,
diff --git a/tests/api-client.test.mjs b/tests/api-client.test.mjs
index 3194163..fa7e60e 100644
--- a/tests/api-client.test.mjs
+++ b/tests/api-client.test.mjs
@@ -4,8 +4,58 @@
 // 401 / 403 / generic-error paths, and query-string handling.
 
 import { describe, test, expect, beforeEach, afterEach } from '@jest/globals';
+import { readFileSync, readdirSync } from 'node:fs';
+import { join, relative } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import ts from 'typescript';
 import { apiRequest } from '../src/api-client.mjs';
 
+const SOURCE_DIRECTORY = fileURLToPath(new URL('../src/', import.meta.url));
+const MCP_PACKAGE = JSON.parse(readFileSync(new URL('../package.json', import.meta.url), 'utf8'));
+
+function sourceFiles(directory) {
+  return readdirSync(directory, { withFileTypes: true }).flatMap((entry) => {
+    const path = join(directory, entry.name);
+    return entry.isDirectory() ? sourceFiles(path) : [path];
+  });
+}
+
+const NETWORK_MODULES = new Set([
+  'axios',
+  'got',
+  'ky',
+  'node-fetch',
+  'node:http',
+  'node:https',
+  'undici',
+]);
+
+function directTransportEvidence(path) {
+  const source = readFileSync(path, 'utf8');
+  const file = ts.createSourceFile(path, source, ts.ScriptTarget.Latest, true, ts.ScriptKind.JS);
+  const evidence = [];
+
+  function visit(node) {
+    if (ts.isImportDeclaration(node) && ts.isStringLiteral(node.moduleSpecifier)) {
+      if (NETWORK_MODULES.has(node.moduleSpecifier.text)) {
+        evidence.push(`import:${node.moduleSpecifier.text}`);
+      }
+    }
+    if (ts.isCallExpression(node)) {
+      if (ts.isIdentifier(node.expression) && ['fetch', 'fetchFn'].includes(node.expression.text)) {
+        evidence.push(`call:${node.expression.text}`);
+      }
+      if (ts.isPropertyAccessExpression(node.expression) && node.expression.name.text === 'fetch') {
+        evidence.push(`call:${node.expression.getText(file)}`);
+      }
+    }
+    ts.forEachChild(node, visit);
+  }
+
+  visit(file);
+  return evidence;
+}
+
 function mockFetch(scripted) {
   const calls = [];
   const fn = async (url, init) => {
@@ -61,6 +111,26 @@ describe('apiRequest', () => {
     expect(fetchFn.calls[0].init.headers['Content-Type']).toBe('application/json');
   });
 
+  test('identifies direct requests as the versioned platform MCP client', async () => {
+    const fetchFn = mockFetch(jsonResponse({ ok: true }));
+    await apiRequest('/agents', { fetchFn });
+    expect(fetchFn.calls[0].init.headers).toEqual({
+      'Authorization': 'Bearer lk_test_key',
+      'Content-Type': 'application/json',
+      'X-Lua-Client': `platform-mcp/${MCP_PACKAGE.version}`,
+    });
+  });
+
+  test('keeps every direct Lua API call behind the identified wrapper', () => {
+    const directCallers = sourceFiles(SOURCE_DIRECTORY)
+      .filter((path) => path.endsWith('.mjs'))
+      .filter((path) => directTransportEvidence(path).length > 0)
+      .map((path) => relative(SOURCE_DIRECTORY, path))
+      .sort();
+
+    expect(directCallers).toEqual(['api-client.mjs']);
+  });
+
   test('uses LUA_API_URL env override when set', async () => {
     process.env.LUA_API_URL = 'https://api-staging.heylua.ai';
     const fetchFn = mockFetch(jsonResponse({ ok: true }));