diff --git a/docs/INTEGRATION-TESTS.md b/docs/INTEGRATION-TESTS.md
index c8ed80eee..185270176 100644
--- a/docs/INTEGRATION-TESTS.md
+++ b/docs/INTEGRATION-TESTS.md
@@ -104,6 +104,15 @@ A separate false-by-default `run_environment_probe` dispatch runs only the
 script-only public environment probe through the same release-attested public
 MCP route, without an agent executor, API proxy, or Copilot secret; see
 [the probe dispatch](cloud-hypervisor-foundation.md#public-enclave-environment-probe-dispatch).
+The public gateway fixture preserves the MCP server's empty HTTP 202
+acknowledgment for JSON-RPC notifications, including `notifications/initialized`
+and cancellation. It still requires bounded JSON responses for requests with
+an ID and rejects malformed, truncated, or oversized backend responses.
+Deterministic fixture tests cover this distinction: release v0.28.70's probe
+and live acceptance both passed `initialize` but failed the initialized
+notification because the fixture tried to parse its empty acknowledgment as
+JSON and returned HTTP 502. This fixture regression does not establish a guest
+or provider failure, and its mocked fix does not prove live KVM acceptance.
 The live job also runs scripts/ci-only startup-failure probes for both roles
 after real VM creation and boot, using the production host executor service,
 authenticated broker protocol v2 client, storage provider, and VM manager.
diff --git a/scripts/ci/cloud-hypervisor-enclave-gateway.js b/scripts/ci/cloud-hypervisor-enclave-gateway.js
index 982841025..689e4656f 100644
--- a/scripts/ci/cloud-hypervisor-enclave-gateway.js
+++ b/scripts/ci/cloud-hypervisor-enclave-gateway.js
@@ -109,6 +109,15 @@ const server = http.createServer((request, response) => {
         let forwarded;
         try {
           parsed = JSON.parse(payload.toString('utf8'));
+          // MCP notifications are acknowledged without a JSON-RPC response body.
+          if (upstreamResponse.statusCode === 202 && responseBytes === 0
+              && parsed && typeof parsed === 'object' && !Array.isArray(parsed)
+              && parsed.jsonrpc === '2.0' && typeof parsed.method === 'string'
+              && !Object.prototype.hasOwnProperty.call(parsed, 'id')) {
+            response.writeHead(202, { 'cache-control': 'no-store', 'content-length': '0' });
+            response.end();
+            return;
+          }
           forwarded = transformResponse(parsed, JSON.parse(Buffer.concat(responseChunks).toString('utf8')));
         } catch {
           sendJson(response, 502, { error: 'invalid upstream response' });
diff --git a/scripts/ci/cloud-hypervisor-enclave-gateway.test.ts b/scripts/ci/cloud-hypervisor-enclave-gateway.test.ts
index caba314ae..dfd9c6eab 100644
--- a/scripts/ci/cloud-hypervisor-enclave-gateway.test.ts
+++ b/scripts/ci/cloud-hypervisor-enclave-gateway.test.ts
@@ -31,7 +31,7 @@ async function post(port: number, body: unknown): Promise<{ status: number; body
           response.on('data', (chunk: Buffer) => chunks.push(chunk));
           response.on('end', () => resolve({
             status: response.statusCode ?? 0,
-            body: JSON.parse(Buffer.concat(chunks).toString('utf8')),
+            body: chunks.length === 0 ? undefined : JSON.parse(Buffer.concat(chunks).toString('utf8')),
           }));
         });
         request.on('error', reject);
@@ -77,12 +77,25 @@ describe('Cloud Hypervisor enclave gateway fixture', () => {
     });
   });
 
-  it('forwards a reachable backend and rewrites the initialize server identity', async () => {
+  it('completes initialize, the empty initialized acknowledgment, and routed tool discovery', async () => {
+    const methods: string[] = [];
     upstream = http.createServer((request, response) => {
-      request.resume();
+      const chunks: Buffer[] = [];
+      request.on('data', (chunk: Buffer) => chunks.push(chunk));
       request.on('end', () => {
+        const message = JSON.parse(Buffer.concat(chunks).toString('utf8'));
+        methods.push(message.method);
+        if (message.method === 'notifications/initialized') {
+          response.writeHead(202, { 'content-length': '0' });
+          response.end();
+          return;
+        }
         response.writeHead(200, { 'content-type': 'application/json' });
-        response.end(JSON.stringify({ jsonrpc: '2.0', id: 1, result: { serverInfo: { name: 'inner' } } }));
+        response.end(JSON.stringify({
+          jsonrpc: '2.0', id: message.id,
+          result: message.method === 'initialize' ? { serverInfo: { name: 'inner' } }
+            : { tools: [{ name: 'enclave_run_script', description: 'bounded script', inputSchema: {} }] },
+        }));
       });
     });
     await new Promise<void>((resolve) => upstream?.listen(0, '127.0.0.1', resolve));
@@ -91,6 +104,16 @@ describe('Cloud Hypervisor enclave gateway fixture', () => {
       status: 200,
       body: { jsonrpc: '2.0', id: 1, result: { serverInfo: { name: 'awmg-awf-enclave', version: 'live-test' } } },
     });
+    await expect(post(port, { jsonrpc: '2.0', method: 'notifications/initialized' })).resolves.toEqual({
+      status: 202, body: undefined,
+    });
+    await expect(post(port, { jsonrpc: '2.0', id: 2, method: 'tools/list' })).resolves.toEqual({
+      status: 200,
+      body: { jsonrpc: '2.0', id: 2, result: { tools: [{
+        name: 'enclave_run_script', description: '[awf-enclave] bounded script', inputSchema: {},
+      }] } },
+    });
+    expect(methods).toEqual(['initialize', 'notifications/initialized', 'tools/list']);
   });
 
   it('keeps an invalid backend response permanent', async () => {
@@ -105,6 +128,51 @@ describe('Cloud Hypervisor enclave gateway fixture', () => {
     });
   });
 
+  it.each([
+    { jsonrpc: '2.0', method: 'notifications/initialized' },
+    { jsonrpc: '2.0', method: 'notifications/cancelled', params: { requestId: 3 } },
+  ])('preserves empty notification acknowledgments for $method', async (notification) => {
+    const received: unknown[] = [];
+    upstream = http.createServer((request, response) => {
+      const chunks: Buffer[] = [];
+      request.on('data', (chunk: Buffer) => chunks.push(chunk));
+      request.on('end', () => {
+        expect(request.headers.authorization).toBe(`Bearer ${capability}`);
+        received.push(JSON.parse(Buffer.concat(chunks).toString('utf8')));
+        response.writeHead(202, { 'content-length': '0' });
+        response.end();
+      });
+    });
+    await new Promise<void>((resolve) => upstream?.listen(0, '127.0.0.1', resolve));
+    const port = await startGateway((upstream.address() as AddressInfo).port);
+    await expect(post(port, notification)).resolves.toEqual({ status: 202, body: undefined });
+    expect(received).toEqual([notification]);
+    expect(gateway?.exitCode).toBeNull();
+  });
+
+  it.each([
+    { status: 202, request: { jsonrpc: '2.0', id: 1, method: 'initialize' } },
+    { status: 202, request: { jsonrpc: '2.0', id: null, method: 'initialize' } },
+    { status: 202, request: { method: 'notifications/initialized' } },
+    { status: 202, request: { jsonrpc: '2.0' } },
+    { status: 200, request: { jsonrpc: '2.0', method: 'notifications/initialized' } },
+    { status: 401, request: { jsonrpc: '2.0', method: 'notifications/initialized' } },
+    { status: 503, request: { jsonrpc: '2.0', method: 'notifications/initialized' } },
+  ])('does not accept an empty $status response for $request', async ({ status, request }) => {
+    upstream = http.createServer((incoming, response) => {
+      incoming.resume();
+      incoming.on('end', () => {
+        response.writeHead(status, { 'content-length': '0' });
+        response.end();
+      });
+    });
+    await new Promise<void>((resolve) => upstream?.listen(0, '127.0.0.1', resolve));
+    const port = await startGateway((upstream.address() as AddressInfo).port);
+    await expect(post(port, request)).resolves.toEqual({
+      status: 502, body: { error: 'invalid upstream response' },
+    });
+  });
+
   it('returns permanent failures for truncated backend responses without terminating the gateway', async () => {
     upstream = http.createServer((request, response) => {
       request.resume();