From 45ae4f2457e68741717dbc198fb4958d18d67c3f Mon Sep 17 00:00:00 2001
From: lemonzoey <25550414+lemonzoey@users.noreply.github.com>
Date: Tue, 20 Oct 2026 10:11:23 +0800
Subject: [PATCH] fix(code-interpreter): use backend timestamp in JS
 OutputMessage

parseOutput set OutputMessage.timestamp to new Date().getTime() * 1000
(client clock, microseconds), ignoring the timestamp the kernel sends with
each stdout/stderr message. Read msg.timestamp instead, matching the
documented 'Unix epoch in nanoseconds' contract and the Python SDK (which
passes data["timestamp"] straight through). Type unchanged (number).

Closes #1969.
---
 .changeset/js-output-backend-timestamp.md     |  5 ++
 packages/code-interpreter-js/src/messaging.ts |  4 +-
 .../tests/messaging.test.ts                   | 50 ++++++++++++++++++-
 3 files changed, 56 insertions(+), 3 deletions(-)
 create mode 100644 .changeset/js-output-backend-timestamp.md

diff --git a/.changeset/js-output-backend-timestamp.md b/.changeset/js-output-backend-timestamp.md
new file mode 100644
index 0000000000..fb6b6180cd
--- /dev/null
+++ b/.changeset/js-output-backend-timestamp.md
@@ -0,0 +1,5 @@
+---
+'@e2b/code-interpreter': patch
+---
+
+Fix `OutputMessage.timestamp` in the JS Code Interpreter to use the backend timestamp (Unix epoch in nanoseconds) sent with each stdout/stderr message, instead of the client clock (`new Date().getTime() * 1000`). The type is unchanged (`number`); this aligns the value with the documented contract and the Python SDK.
diff --git a/packages/code-interpreter-js/src/messaging.ts b/packages/code-interpreter-js/src/messaging.ts
index c145f5b46f..4a887edc01 100644
--- a/packages/code-interpreter-js/src/messaging.ts
+++ b/packages/code-interpreter-js/src/messaging.ts
@@ -352,7 +352,7 @@ export async function parseOutput(
         await onStdout({
           error: false,
           line: msg.text,
-          timestamp: new Date().getTime() * 1000,
+          timestamp: msg.timestamp,
         })
       }
       break
@@ -362,7 +362,7 @@ export async function parseOutput(
         await onStderr({
           error: true,
           line: msg.text,
-          timestamp: new Date().getTime() * 1000,
+          timestamp: msg.timestamp,
         })
       }
       break
diff --git a/packages/code-interpreter-js/tests/messaging.test.ts b/packages/code-interpreter-js/tests/messaging.test.ts
index c0add5149c..8256696b22 100644
--- a/packages/code-interpreter-js/tests/messaging.test.ts
+++ b/packages/code-interpreter-js/tests/messaging.test.ts
@@ -1,7 +1,12 @@
 import { expect, test } from 'vitest'
 
 import { SandboxError } from '../src'
-import { extractError } from '../src/messaging'
+import {
+  Execution,
+  OutputMessage,
+  extractError,
+  parseOutput,
+} from '../src/messaging'
 
 test('includes the response body in server errors', async () => {
   const error = await extractError(
@@ -25,3 +30,46 @@ test('falls back to the status text for an empty body', async () => {
 
   expect(error).toEqual(new SandboxError('500 Internal Server Error'))
 })
+
+test('stdout output carries the backend timestamp, not the client clock', async () => {
+  const backendTimestamp = 1700000000000000000
+  const execution = new Execution()
+  let received: OutputMessage | undefined
+
+  await parseOutput(
+    execution,
+    JSON.stringify({
+      type: 'stdout',
+      text: 'hello',
+      timestamp: backendTimestamp,
+    }),
+    (msg) => {
+      received = msg
+    }
+  )
+
+  expect(received?.timestamp).toBe(backendTimestamp)
+  expect(received?.error).toBe(false)
+})
+
+test('stderr output carries the backend timestamp, not the client clock', async () => {
+  const backendTimestamp = 1700000000000000000
+  const execution = new Execution()
+  let received: OutputMessage | undefined
+
+  await parseOutput(
+    execution,
+    JSON.stringify({
+      type: 'stderr',
+      text: 'boom',
+      timestamp: backendTimestamp,
+    }),
+    undefined,
+    (msg) => {
+      received = msg
+    }
+  )
+
+  expect(received?.timestamp).toBe(backendTimestamp)
+  expect(received?.error).toBe(true)
+})