CodexOpenAICodex keeps going until it’s done.
When python wasn’t on PATH, Codex noticed, switched to python3, and finished the job — that’s the real session on this page, captured on a zipbox sandbox in YOLO mode. One click boots a fresh microVM where Codex installs and launches itself at first boot.
⊞ Dashboardzesty-lynx
zesty-lynx>_ OpenAI Codex (v0.142.5)
model: gpt-5.5 /model to change
directory: ~
permissions: YOLO mode
Tip: GPT-5.5 is now available in Codex. It's our strongest agentic coding model yet, built to reason through large codebases, check assumptions with tools, and keep going until the work is done.
find the bug: def median(xs): return sorted(xs)[len(xs)//2] — fix it, write a quick test for odd and even lists, run it, show the result. be brief.
• I don't see an existing median definition in the workspace, so I'm checking the project shape before creating the smallest useful file and test.
• Explored
└ List ls -la
List rg --files
• I'm going to add a tiny median.py plus a standard-library unittest file so the bug and fix are explicit without adding dependencies.
• Edited 2 files (+26 -0)
└ median.py (+11 -0)
1 +def median(xs):
2 + if not xs:
3 + raise ValueError("median() arg is an empty sequence")
4 +
5 + values = sorted(xs)
6 + mid = len(values) // 2
7 +
8 + if len(values) % 2:
9 + return values[mid]
10 +
11 + return (values[mid - 1] + values[mid]) / 2
test_median.py (+15 -0)
1 +import unittest
3 +from median import median
6 +class MedianTest(unittest.TestCase):
7 + def test_odd_list(self):
8 + self.assertEqual(median([3, 1, 2]), 2)
10 + def test_even_list(self):
11 + self.assertEqual(median([4, 1, 2, 3]), 2.5)
14 +if __name__ == "__main__":
15 + unittest.main()
• The fix is in place: odd lists return the middle element, even lists return the average of the two middle elements. I'm running the tests now.
• Ran python -m unittest -v
└ /bin/bash: line 1: python: command not found
• python isn't installed as a command here, so I'm rerunning with python3.
• Ran python3 -m unittest -v
└ test_even_list (test_median.MedianTest.test_even_list) ... ok
test_odd_list (test_median.MedianTest.test_odd_list) ... ok
… +3 lines (ctrl + t to view transcript)
OK
• Fixed in median.py and added tests in test_median.py.
Result from python3 -m unittest -v:
test_even_list ... ok
test_odd_list ... ok
Ran 2 tests in 0.000s
OK
gpt-5.5 default · ~
Codex · zesty-lynx.zbox.sh⚙ 0%▤ 4%⛁ 8%⌘K to askPop outDelete
real session · captured live on zipbox.ai · sandbox deleted afterCodex source ↗
time to a live terminalseconds
your URLcodex.zbox.sh
price$0.0342/hr · $25/mo
How you set up Codex in the cloud
01
Sign in
Email if you want it simple, a crypto key if you want anonymity. No passwords — every session is cryptographically signed.
02
Boot Codex
A fresh Firecracker microVM boots and Codex installs and launches itself at first boot. On pay-per-use a metered key is injected; or paste your own key at boot.
03
It’s live in your browser
A full-root terminal opens in the browser and the box answers at its own zbox.sh subdomain. Pause parks it for free, delete wipes it for good, SSH is optional.
Questions, answered straight
- Do I need an OpenAI API key to run Codex?
- No. On pay-per-use, a metered key is injected when the sandbox boots and tokens are billed to your prepaid balance at cost plus 3% — Codex works immediately. Prefer your own billing? Paste your OpenAI key at boot and pay them direct.
- What does running Codex in the cloud cost?
- $0.0342 per hour while the sandbox runs — about $25 a month left on 24/7 — and $0 while it’s paused. You start with free credit — no card. Codex’s default machine is 2 vCPU · 4 GB RAM · 80 GB disk, and other sizes start at $10/mo.
- What happens when I pause or delete a Codex sandbox?
- Two buttons, honestly: Pause shuts the machine down and parks its disk for free — restore it later and pick up where the agent left off. Delete wipes the whole VM — disk, memory, network — permanently. You only ever pay while it runs.
- Is it safe to let Codex run unattended with full permissions?
- In a sandbox, yes — that’s the point. The box is a hardware-isolated Firecracker microVM with its own kernel and none of your files, keys, or cookies. Close the tab and it keeps working; the blast radius is one disposable machine.
- Can I SSH into the sandbox?
- Optionally. The browser terminal is the default and needs no setup. Add an SSH public key when you boot and you can also connect from your own terminal — same machine, same session.
every agent zipbox boots
Pi
Claude Code
Grok
Hermes
OpenClaw
opencode
Cline
Cursor CLICodex, on a machine you can throw away.
One click boots OpenAI’s open-source coding agent on a disposable cloud machine — and you pay only while it runs.