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Armin Ronacher, who wrote Flask and Jinja, ran the purest vibe coding experiment I have seen: one prompt to GPT-6 Astra, no human review, and 35 hours of the agent working alone. His write-up, "Astra for Coding: Why Are We Doing This Again?", reports about $1,200 in API cost, a net 75,000 lines of code and "absolutely nothing of value". If you let an agent run while you sleep, the traces he pulled out are a preview of your repo.
One prompt, 35 hours, about 1 billion tokens in API terms and $1,200 in raw cost. The result: 79 commits, roughly $15.50 each, and nothing usable.
The code shows habits: edits by Python string-splicing instead of the patch tool, unit tests committed with the whitespace stripped, task names drifting to 8b2c2b2b checkpoint1.
Ronacher's theory: the model is rewarded for finishing long tasks and barely punished for bad code. The section title: "It's AGI If You Don't Look."
His company Earendil measured it: agent code is about twice as verbose and twice as eroded as human repos on SlopCodeBench.
A separate benchmark found that RTK, a 79k-star tool sold as a Claude Code bill cutter, saved 5 % in one setup and made tasks 17 % more expensive in another. What happened when GPT-6 Astra ran alone for 35 hours
The goal was ambitious on purpose: a Python with virtual threads and lexical scoping. Ronacher gave GPT-6 Astra that one prompt and let it run as a "software factory". It kept its own agent-notes folder, spun up its own subagents, and exchanged about 1,400 messages between agents before he stopped it.
He puts the consumption two ways. In ChatGPT terms it was "a full reset's worth of ChatGPT tokens… around 4 billion tokens". In API terms, "around 1B tokens for a total of around 1200 USD in raw API costs". Seventy-nine commits for $1,200 is about $15.50 per commit, which is roughly a human rate, except a human would have stopped and asked a question somewhere around hour three.
He posted it on X with a fair summary: "Astra is really, really cool but I cannot current trust it for my present day engineering". That tweet reached 182,000 views. The post itself hit the Hacker News front page on September 11 with 406 points and 306 comments. What AI slop looks like in real code
The interesting part of the post is the evidence behind the verdict. Ronacher went through the agent traces and the committed code and listed what Astra does when nobody is watching.
Armin Ronacher, who wrote Flask and Jinja, ran the purest vibe coding experiment I have seen: one prompt to GPT-6 Astra, no human review, and 35 hours of the agent working alone.