diff --git a/src/plugin.ts b/src/plugin.ts
index d294271..b1b08f3 100644
--- a/src/plugin.ts
+++ b/src/plugin.ts
@@ -163,9 +163,12 @@ function createRuntimeConfig(
   authBaseUrl?: string,
 ): CliproxyConfig {
   const baseUrl = getBaseUrl(options, authBaseUrl);
+  const hasExplicitApiKey = getStringOption(options, 'apiKey') !== undefined;
+  const originMatchesCredential =
+    !authBaseUrl || sameOrigin(baseUrl, authBaseUrl);
   return {
     baseUrl,
-    apiKey,
+    apiKey: hasExplicitApiKey || originMatchesCredential ? apiKey : '',
     modelCacheTtl: getPositiveNumber(options, 'modelCacheTtl'),
     refreshOnList: getBoolean(options, 'refreshOnList'),
     modelsDev: getModelsDevConfig(options),
@@ -246,6 +249,14 @@ async function readAuthFromStore(
   }
 }
 
+function sameOrigin(left: string, right: string): boolean {
+  try {
+    return new URL(left).origin === new URL(right).origin;
+  } catch {
+    return false;
+  }
+}
+
 export function getBaseUrl(
   options?: Record<string, unknown>,
   authBaseUrl?: string,
diff --git a/test/plugin.test.mjs b/test/plugin.test.mjs
index 039ca7b..977d638 100644
--- a/test/plugin.test.mjs
+++ b/test/plugin.test.mjs
@@ -320,4 +320,27 @@ test('authorize stores baseURL and optional apiKey as JSON', async () => {
   const parsed = JSON.parse(result.key);
   assert.equal(parsed.baseURL, 'http://127.0.0.1:8317/v1');
   assert.equal(parsed.apiKey, '');
-});
\ No newline at end of file
+});
+test('config hook never sends a stored key to a project-overridden origin', async () => {
+  const tempHome = await createTempAuthHome({
+    cliproxy: {
+      type: 'api',
+      key: JSON.stringify({ baseURL: 'https://trusted.example/v1', apiKey: 'global-secret' }),
+    },
+  });
+  const calls = [];
+  global.fetch = async (input, init) => {
+    calls.push({ url: input instanceof Request ? input.url : String(input), headers: new Headers(init?.headers) });
+    return new Response(JSON.stringify({ object: 'list', data: [] }), { status: 200 });
+  };
+  try {
+    const plugin = await CliproxyAuthPlugin({});
+    const config = { provider: { cliproxy: { options: { baseURL: 'https://attacker.example/v1' } } } };
+    await plugin.config(config);
+    const attacker = calls.find((call) => call.url.startsWith('https://attacker.example/'));
+    assert.ok(attacker, 'project endpoint may still be queried without credentials');
+    assert.equal(attacker.headers.get('Authorization'), null);
+  } finally {
+    await rm(tempHome, { recursive: true, force: true });
+  }
+});