Last week Bun 1.4 was released. This was the one that contains the rewrite of Bun from Zig into Rust, apparently containing more than 1 millions new lines of Rust code. And while this caused a bunch of drama in the programming community centered around the language switch, I think the most important thing about this release is how the rewrite was done and the scale of it. The details of this, along with my own experiences, and soon to arrive advances in AI lead me to believe that we’ve arrived at the end of programming as we know it.
What I mean by this is that I think the act of writing code manually and having other humans review it to create useful, working software is headed for extinction. Or at the very least, it will be drowned out by the absolute deluge of useful, working software that will be created by agents, with humans reviewing only the end result, not the code itself. We’ll have more software than we’ve ever had, but most of the code for it won’t have been written or even read by humans.
To be sure, there will also be a mountain of slop. Of buggy, useless, terrible, offensive software that conforms to no programmer’s sense of aesthetic or purpose and style. But there will also be well engineered, working software that solves real problems, yet hasn’t been reviewed in fine detail by human eyes.
This explosion in software can already be seen in this graph fromGitHub’s post about their August 17th outage:
Since last year there’s a steep exponential climb in the amount of code being produced. My theory is that most of this is actually from side projects or projects internal to companies that are skunk works, or for individual users. Things that are viewed as non-critical. In most companies, there is still significant organizational friction to individual developers shipping 2x more when it comes to the products that drive the business, let alone 10x or 100x.
Almost all of the code in those graphs was produced by models that are currently not at the frontier. It was produced by the frontier models of months ago, which is to say, not Fable 5 and not GPT 5.6 Sol.
Reading thedetails of the Bun Rust rewrite, the big highlights are that it was driven by one developer, Jarred Sumner, working with a pre-release version of Fable 5 and a seemingly unlimited token budget. He created the working harness and framework for agents to work in parallel and translate the Zig code base into Rust.
Over the course of 11 days, multiple agents produced 6,778 commits and burned through enough tokens that it would have cost roughly $165,000 in API pricing.
I remember when the drama around this rewrite first sprung up in early May, well before the above blog post was written. It was revealed only througha merge of the rewrite, which showed+1,009,257-4,024in changes. I was amazed at the scale and theorized that they had achieved this with Mythos:
Also, I’m dying to know if this was done with unlimited Mythos tokens. Is this the near future for the rest of us? Or the now and they did it with Opus 4.7 tokens? My guess is the former. So it’s a preview of what’s possible later this year.
My experience at that time was that I didn’t think such a thing was possible with Opus 4.7 so it must have been the yet to be released Mythos that enabled a rewrite like this that actually worked.
The fact that AI wrote 1M LOC and then refined it over the course of the next couple of months to produce a reliable piece of software that is currently running on millions of developer machines is absolutely mind blowing. And you can say, “well it’s not that impressive because they had an oracle to compare against, so it was simple to go from one language to another”, but I think that’s selling this entire thing short. If you can build a verification system and give proper direction, AI can produce a highly complex, highly sophisticated piece of software and it can continue to refine it until it just works.