Simon Willison's Weblog: Blogmarks

dbreunig/nesformer

2026-10-30T21:59:22+00:00

Inspired by qwenputer by Divyansh Agrawal, Drew Breunig baked a working emulator for a Nintendo Entertainment System 6502 CPU into the weights of Qwen3.5-4B. You can now play NES ROMs such as Super Mario Bros (very slowly) running inside Qwen!

In a comment on Hacker News Drew reveals the Opus 5.5 prompts he used to build this system:

Read this article and any relevant source code: https://divagr.com/blog/qwenputer. Then explore if you could emulate the chip and ram in a Nintendo Entertainment System (as people do today with FPGAs in MISTRs) using this technique. If so, what size model would you have to build and if you could use smaller faster ones, could you get it to be at the standard clockspeed.

Followed by:

I think we should build it! Just for fun. It's okay if it's not fast. We want to be able to have the weights, and a cli to run them that we can point at a ROM.

Apparently Opus found and then used this collection of conformance tests for the NES CPU released 15 years ago by Christopher Pow.

Via Hacker News

Tags: games, ai, generative-ai, llms, drew-breunig, qwen, conformance-suites

API credits benefit for eligible ChatGPT subscriptions

2026-10-29T22:48:29+00:00

API credits benefit for eligible ChatGPT subscriptions

Earlier this month Anthropic announced a generous new benefit for their Max and Team subscriptions: $100, $200, and $500 per month subscribers would get the equivalent quantity of (expiring) credits to use with the Anthropic API.

OpenAI have now launched pretty much exactly the same deal: if you have a $100, $200, or $500 subscription plan with them you now get that same quantity of credits to apply to one of your API organizations.

I maintain subscriptions with both companies, so this is great news for me! I may even ship some public-facing demos now that the credits are already covered by my existing subscriptions.

Tags: ai, openai, generative-ai, llms, anthropic, llm-pricing

Building a multiplayer game world with autonomous Fable-class models

2026-10-29T17:00:26+00:00

How I Built the Most AI-Pilled Company in the World

Don't be put off by the clickbait headline, this piece by Jacob Sansbury describing how they are building Spawn is a fascinating exploration of the bleeding edge of what's possible with agentic engineering against frontier models.

Spawn is a massively multiplayer gaming environment where players can use prompts (to the in-game agent, Savi) to modify the game world.

I fired it up on my phone for a few minutes and was able to prompt a castle into existence, then a dragon, then ride the dragon to fly around that castle.

By Jacob's telling, Spawn is now being developed autonomously by a swarm of Fable-powered agents costing over $3 million in tokens per month ("we spend 30x payroll on AI tokens").

Our agents change the live code directly and ship to production hourly, so they read every error, bug report and metric themselves. About 60% of our work starts from a production error, a Savi bug report (Savi is the AI you build games with in Spawn), something odd in our logs, or a feature request.

Savi files bugs herself. When a user hits one, or Savi hits one in the product, she files it. It goes straight to an agent that decides whether it's a real bug to fix, something we won't fix, or intentional design that needs a decision. Usually it becomes a change, delivered to that user within an hour, with a message in the same chat.

This is continuous deployment turned up to 11:

A loop this tight only works if it never stops, so we treat an hour without a ship as a SEV-0, our most severe kind of incident. Unshipped changes pile up, and every problem already in production lasts longer. The feedback slows down too. An agent can only keep a few hours of work in its head, so shipping faster than that actually helps it stay coherent. [...]

We can roll back a broken change in 30 seconds, exactly where it's broken and nowhere else. When a monitor or a log alert fires, it starts or wakes an agent that owns the incident, and we break things on purpose to test that those recovery paths work.

My eyebrows raised at least a dozen times reading this. I have trouble imagining this style of development working on software with higher stakes for when something goes wrong, but for a game this appears to be working surprisingly well.

Jacob says that Fable 5 (and then 5.1) was the model that made this level of autonomy possible. Opus 5.5 doesn't quite hack it for them, and when they tried GPT-6 Astra to apply fixes from a security review everything stopped working:

Every feature had been disabled and marked to be turned on again once the security fixes were done. Astra had gone through our whole product and made the insecure things secure by turning them off.

These kinds of extreme experiments are why I'm excited about game development as a substrate for exploring the edges of what today's coding agents can do.

Tags: game-design, ai, generative-ai, llms, claude, coding-agents, agentic-engineering, claude-mythos-fable

GitHub Octoverse 2026

2026-10-28T16:45:23+00:00

GitHub Octoverse 2026

I'm at GitHub Universe today (GitHub gave me a free ticket through their "GitHub Stars" program). EVP Jay Parikh just announced this year's Octoverse report, and highlighted these numbers in particular:

This is a pretty stark representation of the impact of agentic engineering on GitHub. In 2026, merged pull requests tripled in less than a year to 220 million per month. Commits more than tripled to 7.38 billion per month, with most of that increase in the second half of this year. New repository rate doubled this year, to 30.3 million per month.

The report includes new numbers by industry, and breaks out numbers for repositories that involve "interoperability or reverse engineering". The methodology section includes notes about how they did this:

Top countries by pushes to public repositories, adjusted by profile location. Pushes from each country were summed across the Octoverse year. To adjust for biases caused by VPN usage, LLM classification was used to extract the ISO 3166-1 alpha-2 code from the profiles of GitHub users who contributed pushes during this period [...]

Industry. Public repositories created 2022 to 2026 were sorted into NAICS sectors by a fine-tuned multilingual embedding model using name, description, topics, and README, from random samples per year. [...]

Interoperability. Counts public repositories created each year whose name, description, topics, or README mention interoperability or reverse engineering, or related terms, such as clean room implementation, drop-in replacement, or protocol re-implementation.

Tags: github, ai, generative-ai, llms, coding-agents, disclosures, agentic-engineering

Game Boy Color on My Conference Badge

2026-10-27T19:34:18+00:00

Game Boy Color on My Conference Badge

I'm at GitHub Universe this week and, similar to last year, the conference badge is a full-blown color screen computer.

I've been hacking around with it again, and then I ran into with Steve Francia... who worked with Gemini to get a full NES emulator working on it, and then went a step further and deployed an emulator for both the Game Boy and the Game Boy Color.

Which means, if you can obtain the ROM, you can run The Legend of Zelda: Link's Awakening on your conference badge!

A neat feature of the badge is that you can turn it upside down and then use game controller touch buttons that are built into the badge body.

Tags: games, github, hardware-hacking, ai, generative-ai, llms, gemini, steve-francia

GPT-6.1 Terra

2026-10-26T23:53:07+00:00

GPT-6.1 Terra

It's always interesting to note which aspects of a new model are emphasized in the release announcement.

In the case of GPT-6.1 Terra, OpenAI went with visual reasoning and computer use:

We’re introducing GPT-6.1 Terra, a fast, efficient model that combines detailed visual reasoning and precise computer use alongside clearer, more natural writing. A significant step up from GPT‑5.6 Terra, it excels at the communication and computer-based tasks that fill the workday, from drafting proposals and interpreting technical drawings to filling out forms and editing videos.

Terra sits in the same position as Sonnet in the Anthropic model collection - not the cheapest or the most expensive, making it harder to decide when to use it.

Computer use is a good example of a task that benefits from a less expensive model, since you might put it to work on automated, repetitive tasks.

OpenAI's Ted Sanders provided some useful advice in a comment on Hacker News:

In the case of GPT-6.1 Terra, I'd say Terra is probably better than Astra and Sol at technical communication, similar on vision and computer use (but much faster!), and a bit worse on most other things. For API developers, it's a nice midrange option if you want something cheaper than Sol but a lot smarter than Luna (especially for vision / computer use / communication). For subscribers, it's not a bombshell release - if you're hitting usage limits, maybe it helps you go a bit further, and if you want clearer communication or faster computer use, it can be a nice option to select.

Here are the pelicans for the different reasoning levels. This pelican for "max" cost 11.3161 cents and took 4 minutes and 11 seconds:

Here's a new comparison grid showing pelicans for every reasoning level of OpenAI's current frontier lineup: GPT-6 Astra, GPT-6.1 Sol, GPT-6.1 Terra, and GPT-6 Luna.

GPT-6.1 Terra is priced at $1/million input tokens and $5/million output - almost half the price of GPT-5.6 Terra and GPT-6.1 Sol, and around 10x the price of GPT-6 Luna.

Via Hacker News

Tags: ai, openai, generative-ai, llms, llm-pricing, pelican-riding-a-bicycle, llm-release, gpt, ted-sanders

Introducing Kimi K3.1 Pro

2026-10-23T19:40:54+00:00

Introducing Kimi K3.1 Pro

Kimi K3.1 Pro landed on the Kimi API today - it's not yet open weights, but Moonshot promise "Full model weights will be released by Nov 4, 2026".

They're also offering a "Highspeed" version that's 2-3x faster, at twice the price (except for input token cache hits, which are priced the same).

The US dollar pricing is $2.00/million tokens for input and $10/million for output - the same as GPT-6.1 Sol and half the price of Claude Opus 5.5.

Moonshot's own benchmarks show Kimi as approximately level with Opus 5.5 and GPT-6 Astra - beating them on a few benchmarks, coming close on others.

Artificial Analysis scored Kimi at 55 - ahead of Claude Fable 5.1, GPT-6 Astra, and Gemini 4 Argon (all at 53) and behind only Claude Opus 5.5 (58).

This is the first time a (soon-to-be) open weight model has scored this highly against the frontier.

I tried it out via the Moonshot API using the llm openai endpoint command I added to LLM 0.32 back in August:

llm openai endpoint \
  https://api.moonshot.ai/v1 \
  --key kimi \
  -m kimi-k3.1-pro \
  "Generate an SVG of a pelican riding a bicycle" \
  --responses \
  -o reasoning_effort low \
  > kimi-k3.1-pro-pelican-low.stdout.txt \
  2> kimi-k3.1-pro-pelican-low.stderr.txt

llm openai endpoint can run prompts against any OpenAI-compatible endpoint but doesn't log the results, hence the extra options to save stdout and stderr (the reasoning trace).

Here are the pelicans I got for Kimi K3.1 Pro on the three reasoning levels it supports - low, medium, and max. This is max:

For comparison, I ran fresh pelicans against Kimi K3 on those three reasoning levels.

Via Hacker News

Tags: ai, generative-ai, llms, llm, llm-pricing, pelican-riding-a-bicycle, llm-release, ai-in-china, moonshot, kimi

DE STAAT - FREEDOM (Official Music Video)

2026-10-22T19:42:26+00:00

DE STAAT - FREEDOM (Official Music Video)

OK well this is a first for me... at 00:44 in this new music video by Dutch alternative rock band De Staat:

The visual effects are credited to Matties Grooten of Fake it or Leave it.

Via flir on Hacker News

Tags: music, ai, generative-ai, pelican-riding-a-bicycle

Donating Agent Skills to the Agentic AI Foundation

2026-10-22T18:09:56+00:00

Donating Agent Skills to the Agentic AI Foundation

News today from Anthropic:

We’re committed to keeping Agent Skills open, community-driven, and vendor-neutral. Today, we are donating the standard to the Agentic AI Foundation (AAIF) under the Linux Foundation, which we co-founded with Block and OpenAI last year, and to which we donated the Model Context Protocol (MCP).

I'm pleased to note I called this one last December, when Anthropic first declared skills to be an "open standard":

I wouldn't be surprised to see this end up in the AAIF, recently the new home of the MCP specification.

Fun side note: since my blog content is available to Claude via the datasette-mcp plugin I found that post by prompting Claude to "Use simonwillison.net MCP to find if I ever talked about how I want skills to be donated to a standards body".

Tags: standards, ai, generative-ai, llms, anthropic, model-context-protocol, skills

Today's PHP Security Release, and How We're Strengthening PHP Security

2026-10-21T18:41:53+00:00

Today's PHP Security Release, and How We're Strengthening PHP Security

If you're running anything on PHP it's vital you upgrade - today's updates (across the entire PHP 8.x line) address two remote code execution holes, and there have been exploits circulating since last night, thanks to a leak in the coordinated disclosure process.

This post from the PHP Foundation explain what went so wrong:

On Tuesday, October 20th, at around 15:00 UTC, the two CVE IDs began circulating on online forums and social media. They came with a wrong release time and a wrong CVSS score of 10.0 (the actual score is 9.2). No technical details leaked. In response, the PHP project brought its pre-announcement forward and published it at 19:30 UTC. It also moved the release from October 22nd, 14:00 UTC, to October 21st, 14:00 UTC [...]

As a result of the leak and pre-announcement around 20:00 UTC, Calif, one of the security firms that had reported the issues mistakenly published a video. It showed their proof of concept working against a number of targets and revealed a few additional, though limited, details about the vulnerabilities. Copies of the deleted video started circulating on social media soon after. The video contributed to accelerated development of various PoCs (exploitation proof of concepts), which then increased circulation on October 21st.

This article from the team that discovered the original vulnerability includes a more detailed timeline of the original intended responsible disclosure:

August 19, 2026: Wiz Research discovers the first PHP vulnerability using Wiz Atlas, Gemini 4 Argon, and GPT-5.6 Sol.

August 20, 2026: Unauthenticated RCE is confirmed against Drupal.

August 21, 2026: Unauthenticated RCE is confirmed against WordPress.

August 24, 2026: Wiz Research reports the vulnerabilities to the PHP security team.

September 21, 2026: PHP acknowledges the reports and begins developing a coordinated fix.

October 21, 2026: Patched PHP releases become available.

October 21, 2026: Public disclosure.

Via Hacker News

Tags: open-source, php, security, ai, ai-security-research

Panache — RTS Belle Époque pour mobile

2026-10-21T16:25:16+00:00

Panache — RTS Belle Époque pour mobile

Well this is delightful: I released Battle Drones yesterday under an Apache 2.0 License and there's already a French language fork by Gabriel Turpin which reskins the game to take place in steampunk 1900s France and adds an animated intro!

Panache est un jeu de stratégie en temps réel pour mobile et navigateur, dans la France de la Belle Époque (vers 1900) : dirigeables, Fardiers à vapeur, Creusot cuirassés, automates en képi, Gargantua la forteresse marchante — et beaucoup de panache.

You can play Panache here - it's worth clicking that link just to experience the new intro video.

So far it's mostly just aesthetic updates as opposed to gameplay changes. The music has had a French twist added to it as well.

The new steampunk models are so cool!

Here's a page with the original Battle Drones models and that same page with the new Panache alternatives.

This is a comparison of the original and the new design for the Goliath:

Via @Meffysto69

Tags: game-design, open-source

eMudhra Intermediate CA Compromise

2026-10-20T23:50:25+00:00

eMudhra Intermediate CA Compromise

This is very, very bad news:

The private keys of eight eMudhra intermediate CA certificates have been compromised. They chain to roots trusted by the Mozilla, Microsoft, Apple and Chrome root programs and by many downstream trust stores.

Any software that bundles a list of trusted certificates needs to be updated. This site is tracking software updates via this GitHub repository - Linux distros need to update their ca-certificates packages.

In Python world uv 0.13.4 and pip 26.2.2 and certifi 2026.10.19 have been released with upgraded certificate lists.

There's a very informative thread about this on the official Python forum.

Tags: encryption, https, pip, python, security, uv

My obituary for programming

2026-10-19T23:58:25+00:00

My obituary for programming

Jeremy Scheff poignantly captures the key loss caused by coding agents for career programmers who enjoyed the puzzle of developing code:

Programming turned into one of the greatest jobs you could imagine. You got paid to work on tricky little logic puzzles. The trickier the puzzle, the more you got paid. But even pretty simple puzzles were worth a lot of money because regular people just couldn't do it! No, they needed us. They would give us a problem and we would solve it the way we wanted. We set the strategy, we made the timeline, we defined what was and was not possible.

If you're a programmer who thrives on building working systems and doesn't care too deeply about the problems solved along the way, LLMs are the gift that keeps on giving.

If directly solving those problems was a big part of your enjoyment, the loss is very real.

Via lobste.rs

Tags: programming, careers, ai, generative-ai, llms, coding-agents, deep-blue

Inline rendering with document.currentScript

2026-10-17T21:11:12+00:00

Inline rendering with document.currentScript

Lean Rada describes a neat trick that takes advantage of the document.currentScript property. You can use that to drop in a tiny inline <script> element that replaces itself when the page loads:

The year is <script>
document.currentScript.replaceWith(
  new Date().getFullYear())</script>

If you define a shortcut function like this:

$=(...n)=>document.currentScript.replaceWith(...n)

You get a tiny template language:

The year is <script>$(new Date().getFullYear())</script>

Tags: javascript

Anthropic tells investors quarterly revenue up nearly 50% to $16.8bn ahead of IPO

2026-10-15T13:04:03+00:00

Anthropic tells investors quarterly revenue up nearly 50% to $16.8bn ahead of IPO

The phrase "told investors" appears four times in this FT article, which reports on Anthropic's day of hosting investors on Wednesday. Lots of details in here from "people with knowledge of the matter".

Key things I learned from the article:

Q1 revenue (Jan/Feb/Mar) was "about $4.8bn"
Q2 (Apr/May/Jun) was $11.5bn
Q3 (Jul/Aug/Sep) was $16.8bn
In Q3: $1.70 in revenue for every $1 spent on "computing power"
Adjusted operating margins (excluding stock-based compensation) were 11%

This point about distillation is worth quoting in full (highlight mine):

The start-up has also clamped down on “distillation” — a controversial practice whereby rival AI labs train their models on the outputs of more advanced ones.

When rival companies “distil” their models from Anthropic’s models, that involves heavy usage and spending.

Anthropic told investors on Wednesday distillation accounted for 5 per cent to 7 per cent of revenue and that they had cut it back “materially” in the third quarter of the year, said four people with direct knowledge of the matter.

Napkin maths says that if distillation was 5% of their Q2 revenue (before they cut it back in Q3) then unnamed "other labs" spent over half a billion dollars distilling Anthropic's models in that quarter!

Also notable: Anthropic appear to no longer be leaning on "annualized run-rate revenue" (previously) in these communications to their investors.

Tags: ai, generative-ai, llms, anthropic

Simon Willison's Weblog: Blogmarks

dbreunig/nesformer

API credits benefit for eligible ChatGPT subscriptions

Building a multiplayer game world with autonomous Fable-class models

GitHub Octoverse 2026

Game Boy Color on My Conference Badge

GPT-6.1 Terra

Introducing Kimi K3.1 Pro

DE STAAT - FREEDOM (Official Music Video)

Donating Agent Skills to the Agentic AI Foundation

Today's PHP Security Release, and How We're Strengthening PHP Security

Panache — RTS Belle Époque pour mobile

eMudhra Intermediate CA Compromise

My obituary for programming

Inline rendering with document​.currentScript

Anthropic tells investors quarterly revenue up nearly 50% to $16.8bn ahead of IPO

Inline rendering with document.currentScript