From 1e589f06928b3b740d0795f6c112e98fafee5338 Mon Sep 17 00:00:00 2001
From: Christian Gunderman <gundermanc@google.com>
Date: Mon, 9 Feb 2026 16:37:12 -0800
Subject: [PATCH] Ignore notifications that don't match schema.

---
 packages/core/src/code_assist/server.test.ts | 45 ++++++++++++++++++++
 packages/core/src/code_assist/server.ts      | 14 +++++-
 2 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/packages/core/src/code_assist/server.test.ts b/packages/core/src/code_assist/server.test.ts
index 42c1d89922..090fdb5c7c 100644
--- a/packages/core/src/code_assist/server.test.ts
+++ b/packages/core/src/code_assist/server.test.ts
@@ -403,6 +403,51 @@ describe('CodeAssistServer', () => {
     expect(results[1].candidates?.[0].content?.parts?.[0].text).toBe(' World');
   });
 
+  it('should ignore SSE messages that do not match the schema', async () => {
+    const { server, mockRequest } = createTestServer();
+
+    const { Readable } = await import('node:stream');
+    const mockStream = new Readable({
+      read() {},
+    });
+
+    const mockResponseData1 = {
+      response: { candidates: [{ content: { parts: [{ text: 'Hello' }] } }] },
+    };
+    const mockResponseData2 = {
+      somethingElse: 'that does not match schema',
+    };
+    const mockResponseData3 = {
+      response: { candidates: [{ content: { parts: [{ text: ' World' }] } }] },
+    };
+
+    mockRequest.mockResolvedValue({ data: mockStream });
+
+    const stream = await server.generateContentStream(
+      {
+        model: 'test-model',
+        contents: [{ role: 'user', parts: [{ text: 'request' }] }],
+      },
+      'user-prompt-id',
+    );
+
+    setTimeout(() => {
+      mockStream.push('data: ' + JSON.stringify(mockResponseData1) + '\n\n');
+      mockStream.push('data: ' + JSON.stringify(mockResponseData2) + '\n\n');
+      mockStream.push('data: ' + JSON.stringify(mockResponseData3) + '\n\n');
+      mockStream.push(null);
+    }, 0);
+
+    const results = [];
+    for await (const res of stream) {
+      results.push(res);
+    }
+
+    expect(results).toHaveLength(2);
+    expect(results[0].candidates?.[0].content?.parts?.[0].text).toBe('Hello');
+    expect(results[1].candidates?.[0].content?.parts?.[0].text).toBe(' World');
+  });
+
   it('should ignore malformed SSE data', async () => {
     const { server, mockRequest } = createTestServer();
 
diff --git a/packages/core/src/code_assist/server.ts b/packages/core/src/code_assist/server.ts
index c85788e665..1d02840c04 100644
--- a/packages/core/src/code_assist/server.ts
+++ b/packages/core/src/code_assist/server.ts
@@ -65,6 +65,7 @@ import {
   recordConversationOffered,
 } from './telemetry.js';
 import { getClientMetadata } from './experiments/client_metadata.js';
+import { debugLogger } from 'src/utils/debugLogger.js';
 /** HTTP options to be used in each of the requests. */
 export interface HttpOptions {
   /** Additional HTTP headers to be sent with the request. */
@@ -390,6 +391,8 @@ export class CodeAssistServer implements ContentGenerator {
         crlfDelay: Infinity, // Recognizes '\r\n' and '\n' as line breaks
       });
 
+      let seenUnrecognizedNotificationType = false;
+
       let bufferedLines: string[] = [];
       for await (const line of rl) {
         if (line.startsWith('data: ')) {
@@ -398,7 +401,16 @@ export class CodeAssistServer implements ContentGenerator {
           if (bufferedLines.length === 0) {
             continue; // no data to yield
           }
-          yield schema.parse(JSON.parse(bufferedLines.join('\n')));
+          // Ignore notifications that fail to parse.
+          const result = schema.safeParse(JSON.parse(bufferedLines.join('\n')));
+          if (result.success) {
+            yield result.data;
+          } else if (!seenUnrecognizedNotificationType) {
+            seenUnrecognizedNotificationType = true;
+            debugLogger.debug(
+              `[Client] Unrecognized notification type ${result.data}`,
+            );
+          }
           bufferedLines = []; // Reset the buffer after yielding
         }
         // Ignore other lines like comments or id fields