diff --git a/src/lib/router.js b/src/lib/router.js
index bb65144..258b0d9 100644
--- a/src/lib/router.js
+++ b/src/lib/router.js
@@ -13,7 +13,10 @@ export async function chat({ routerUrl, model, messages, agentId, sessionId, ten
     // and return non-review text. The domain preflight (agent_mismatch 400)
     // still applies per agent tier; the pipeline's attempt-2 fallback agent
     // covers that.
-    body: JSON.stringify({ model, messages, agentId, sessionId, tenantId, stream: false, tools: false, raw: true }),
+    body: JSON.stringify({
+      model, messages, agentId, sessionId, tenantId,
+      stream: false, tools: false, raw: true, fallbackModels: []
+    }),
     signal: AbortSignal.timeout(timeoutMs)
   });
   if (!res.ok) {
diff --git a/test/routerClient.test.js b/test/routerClient.test.js
new file mode 100644
index 0000000..7ada51f
--- /dev/null
+++ b/test/routerClient.test.js
@@ -0,0 +1,34 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { chat } from '../src/lib/router.js';
+
+test('review router client disables model fallbacks explicitly', async () => {
+  const originalFetch = globalThis.fetch;
+  let body;
+  globalThis.fetch = async (_url, init) => {
+    body = JSON.parse(init.body);
+    return Response.json({
+      message: { content: '{"axes":{},"overall":90,"grade":"A","findings":[]}' },
+      _shre: { model: 'ollama-remote/qwen2.5-coder:7b' }
+    });
+  };
+
+  try {
+    await chat({
+      routerUrl: 'http://router.test',
+      model: 'ollama-remote/qwen2.5-coder:7b',
+      messages: [{ role: 'user', content: 'review' }],
+      agentId: 'code-reviewer',
+      sessionId: 'review-test',
+      tenantId: 'nirlab',
+      timeoutMs: 1000
+    });
+  } finally {
+    globalThis.fetch = originalFetch;
+  }
+
+  assert.deepEqual(body.fallbackModels, []);
+  assert.equal(body.tools, false);
+  assert.equal(body.raw, true);
+  assert.equal(body.stream, false);
+});