Yet another Hacker News

Microsoft agentically ports Copilot runtime to Rust for $120K

23 points pjmlp 2 hours ago 15 comments

tecoholic 45 minutes ago | parent

    One of the thorniest conversions was the session.ts file, which was over 30,000 lines of TypeScript that touched all aspects of the runtime.

This can’t be real. Single file with 30K lines? Which human being is working on it and how much RAM does it take for a code editor to load that with full symbol tree? I am genuinely curious. Is this common? I think most files I come across stretch to maybe 2-3k lines max.

smitty1e 42 minutes ago | parent

Was the documentation for each function a full-on essay?

formerly_proven 39 minutes ago | parent

> Which human being is working on it

If you've ever used that tool you wouldn't ask this question, since it's obviously fully vibecoded.

wayvey 38 minutes ago | parent

I recently saw a ~60k lines / 3mb .cpp file in one vibe coded project (and yes I was a bit horrified) Surprised it works at all but it apparently does. Not really for a human though and even for an LLM it would be more beneficial for it to be split up.

NewsaHackO 29 minutes ago | parent

This has to be 1) early LLM vibe coding or 2) “hand” vibe codingwhere the user asked the LLM to code sections and stitches them together manually, and the programmer is a novice. The second part I speak from experience; got to ~2k before realizing this is out of the script range and started to break it up. Regardless, it would be almost impossible to get an SOTA LLM agent to ever do this.

Rexxar 26 minutes ago | parent

30000 is not that big in very old projects with many contributors. There are always one or two files that no one wants to take the time and responsibility to clean up. And 30000 is not a big number for RAM. The fact that you find it choking is more and of an indication of how bad our tools have become than anything else.

For example, until recently the main file for donet runtime GC was more than 50000 lines (it has since been split).

Rexxar 42 minutes ago | parent

They don't have to tell us they are vibe coding everything.

- there are now ridiculous vibe coded localisation in VS2026

- task manager started to not report cpu usage correctly recently (the number becomes stalled)

- file explorer display the "loading" icon infinitely on some directories

- and many other things!

chrischen 4 minutes ago | parent

The line between vibe coding and just coding has now moved. Vibe coding is specifically when the output is not understood by the prompter. Even in the back in the days of the earlier models i used the models to do my basic typing because it was easier than me typing it out…

amelius 32 minutes ago | parent

Still hoping for a company to agentically port the python ecosystem to GIL-free python.

andrewstuart 30 minutes ago | parent

I did a lot of benchmarking of Gil free python.

Greenlets were much faster.

Gil free python gets stuck on all sorts of python locks. It’s slow.

rienbdj 9 minutes ago | parent

If runtime performance is the goal it’s easier to port the required libraries to another language at this point.

andrewstuart 29 minutes ago | parent

Can we not say “agentically” please?

perching_aix 22 minutes ago | parent

Is that why session compaction stopped working for me in VS Code at the end of last week, or is that just the integrated extension itself having a normal one?

Though it's the same extension that can't keep its session timestamps straight, randomly hides sessions I was just in (then suddenly remembers them after going in and out of a session), and completely shits itself visually when using OpenAI's models, so maybe it really is the latter.

dmix 18 minutes ago | parent

> agents converted 430,000 lines of TypeScript into 800,000 lines of production Rust

The +400k new lines were probably code comments the agents added to everything