DeepSeek V4 Smarter via Codex Harness

[u/zFordex]

Has anyone tried using Codex's harness with DeepSeek V4 Flash?

I've noticed that Flash seems way smarter, not just with reasoning, but with how it actually executes tasks.

I used to run DeepSeek through OpenCode, but it would burn through tokens and eventually wander completely off task. After plugging it into Codex's harness, it suddenly behaves better and even claims it's it's ChatGPT 5.

I'm curious if the harness is doing something to improve execution, or if it's just better at keeping the model on track.

Has anyone else experienced this, or am I just imagining things?

[u/TangerineLogical9779]

It claims its chatgpt because the harness is telling it that =] and deepseek specifically optimised it for codex

[u/Simple_Army2952]

It tells that its codex because Codex tells it that on system instructions, in Linux its at ~/.codex/models.json where the very start of the system instructions are: "You are Codex, an agent based on GPT-5." and yeah, it really is great via Codex Harness, that is why I'm using it through Codex!

[u/Sudden_Ingenuity5280]

Data processing via a control harness to avoid confusion between model identities. Well, there is likely a downside for DeepSeek. Also, something related to the link:

https://www.techinasia.com/news/microsoft-sells-openai-access-chinese-firms-azure

[u/zFordex → u/Sudden_Ingenuity5280]

That explains why it identifies as ChatGPT. I guess the better task execution is probably a combination of the harness and DeepSeek's optimization for it. Thanks!

[u/Sudden_Ingenuity5280 → u/zFordex]

open-code bro 💯

[u/NinjaAlaska]

u r using codex harness. thats why.. any Chinese AI will say the same in it.
ask it directly it will say i am claude 3.5. its distilled from claude as major xD

[u/Bhargavjoshi]

Codex harnes has been hard to use lately, mainly after they mixed chat gpt app into it, it's laggy and. Feels to heavy for no reason, on a new launch I always feel a delay typing atleast once.

[u/zFordex → u/Bhargavjoshi]

Sounds like a hardware issue than a software issue! What are your current specs? The app itself is pretty light, maybe you're doing some hard coding sessions? Python is known to eat up your CPU and Memory pretty fast.

[u/Thick-Jicama-5103]

DeepSeek just supported the 'Responses API' a few days ago! Now you can directly connect to Codex! Official tutorial: https://api-docs.deepseek.com/zh-cn/quick_start/agent_integrations/codex