What they did
The poster was using a Nokia 110 4G to cut screen time and decided to put an agent on it. Android would not fit in 48 MB of RAM, so he extracted the firmware, worked out how built-in apps use the screen, keypad and network, and got his own C code running in RAM through the Calculator app's entry point. He then replaced the calculator UI with a chat box, traced the firmware's network callbacks until API responses reached the app, and wrote a very small agent loop that sends the typed message to DeepSeek's chat API and dispatches the returned JSON to native phone functions. He says he used Codex to help build it and tested on the handset.
How it went
It works unplugged on mobile data: the agent answers questions over SIM data, reports battery percentage, toggles the torch, starts a call and sets an alarm. Memory was the hard constraint; normal agent code did not fit, so he used smaller builds, compressed the payload and reused buffers. The code is loaded into RAM from a computer and is lost on restart; permanent installation is unsolved. A colour change at one point caused restarts until he found he had written to the wrong style field. The source is not published because secrets are scattered through it.
Worth knowing
This is a prototype that needs a computer to load each time the phone powers off, and the demo is a video rather than code. How much Codex did versus the author is not spelled out; the agent on the phone is a hand-rolled loop around the DeepSeek API with a handful of tools, not a product.
GitHub