Simon WillisonModify

2026-04-09 07:07:44

Meta announced Muse Spark today, their first model release since Llama 4 almost exactly a year ago. It's hosted, not open weights, and the API is currently "a private API preview to select users", but you can try it out today on meta.ai (Facebook or Instagram login required).

Meta's self-reported benchmarks show it competitive with Opus 4.6, Gemini 3.1 Pro, and GPT 5.4 on selected benchmarks, though notably behind on Terminal-Bench 2.0. Meta themselves say they "continue to invest in areas with current performance gaps, such as long-horizon agentic systems and coding workflows".

The model is exposed as two different modes on meta.ai - "Instant" and "Thinking". Meta promise a "Contemplating" mode in the future which they say will offer much longer reasoning time and should behave more like Gemini Deep Think or GPT-5.4 Pro.

A couple of pelicans

I prefer to run my pelican test via API to avoid being influenced by any invisible system prompts, but since that's not an option I ran it against the chat UI directly.

Here's the pelican I got for "Instant":

And this one for "Thinking":

Both SVGs were rendered inline by the Meta AI interface. Interestingly, the Instant model output an SVG directly (with code comments) whereas the Thinking model wrapped it in a thin HTML shell with some unused Playables SDK v1.0.0 JavaScript libraries.

Which got me curious...

Poking around with tools

Clearly Meta's chat harness has some tools wired up to it - at the very least it can render SVG and HTML as embedded frames, Claude Artifacts style.

But what else can it do?

I asked it:

what tools do you have access to?

And then:

I want the exact tool names, parameter names and tool descriptions, in the original format

It spat out detailed descriptions of 16 different tools. You can see the full list I got back here - credit to Meta for not telling their bot to hide these, since it's far less frustrating if I can get them out without having to mess around with jailbreaks.

Here are highlights derived from that response:

• Browse and search. browser.search can run a web search through an undisclosed search engine, browser.open can load the full page from one of those search results and browser.find can run pattern matches against the returned page content.

• Meta content search. meta_1p.content_search can run "Semantic search across Instagram, Threads, and Facebook posts" - but only for posts the user has access to view which were created since 2025-01-01. This tool has some powerful looking parameters, including author_ids, key_celebrities, commented_by_user_ids, and liked_by_user_ids.

• "Catalog search" - meta_1p.meta_catalog_search can "Search for products in Meta's product catalog", presumably for the "Shopping" option in the Meta AI model selector.

• Image generation. media.image_gen generates images from prompts, and "returns a CDN URL and saves the image to the sandbox". It has modes "artistic" and "realistic" and can return "square", "vertical" or "landscape" images.

• container.python_execution - yes! It's Code Interpreter, my favourite feature of both ChatGPT and Claude.

  Execute Python code in a remote sandbox environment. Python 3.9 with pandas, numpy, matplotlib, plotly, scikit-learn, PyMuPDF, Pillow, OpenCV, etc. Files persist at /mnt/data/.

  Python 3.9 is EOL these days but the library collection looks useful.

  I prompted "use python code to confirm sqlite version and python version" and got back Python 3.9.25 and SQLite 3.34.1 (from January 2021).

• container.create_web_artifact - we saw this earlier with the HTML wrapper around the pelican: Meta AI can create HTML+JavaScript files in its container which can then be served up as secure sandboxed iframe interactives. "Set kind to html for websites/apps or svg for vector graphics."

• container.download_meta_1p_media is interesting: "Download media from Meta 1P sources into the sandbox. Use post_id for Instagram/Facebook/Threads posts, or catalog_search_citation_id for catalog product images". So it looks like you can pull in content from other parts of Meta and then do fun Code Interpreter things to it in the sandbox.

• container.file_search - "Search uploaded files in this conversation and return relevant excerpts" - I guess for digging through PDFs and similar?

• Tools for editing files in the container - container.view, container.insert (with new_str and insert_line), container.str_replace. These look similar to Claude's text editor tool commands - these are becoming a common pattern across any file-equipped agent harness.

• container.visual_grounding - see below, this one is fun.

• subagents.spawn_agent - the sub-agent as a tool pattern. "Spawn an independent sub-agent for research, analysis, or delegation. It returns its final text response."

• third_party.link_third_party_account - "Initiate account linking for a third-party service", currently Google Calendar, Outlook Calendar, Gmail, or Outlook.

Image analysis in the container

Let's talk about that container.visual_grounding one. Here's the description in full:

Description: Visual grounding tool that analyzes the image, identifies and labels objects, locates regions, or counts objects.

Parameters:

• object_names (array, required)
• image_path (string, default "")
• format_type ("bbox"|"point"|"count"|null, default "bbox")
• title (string|null)[string]

So it can take an image path, optional object names and return things in format bbox, point or count.

Sounds to me like Meta's Segment Anything. I decided to take it for a spin.

Prompt:

generate a photo of a raccoon sitting on a trash can wearing trash as a hat

Response:

Here you go — king of the alley, in full regalia:

Coffee cup crown, banana peel brim, newspaper feather. Peak raccoon fashion. Want me to make a wilder version — maybe night-vision, or wearing sunglasses too?

My guess is that image generation in Meta AI is powered by their Emu model, or an updated version of it. This is the same pattern as ChatGPT and Gemini image generation, where images are generated by a tool call (here that's to media.image_gen).

The image_gen tool description said that it "saves the image to the sandbox", so my guess was that I'd then be able to run Python code against it. I tried:

use python OpenCV to analyze that image and find out neat things about it

Annoyingly it did not show me the code it ran, but it did create this image:

Pretty neat! We can both generate images and then use them with Python tools.

Next, the visual_grounding tool. Knowing the names of the tools makes it easy to refer to them in prompts:

Now try the container.visual_grounding tool

The response (full response here):

Done — visual_grounding pinpointed every piece of the outfit with pixel-level precision:

[...]

Want me to run it in bbox mode next to draw boxes around the fur texture, or count mode to see how many individual whiskers it can detect?

Once again, Meta AI wrapped the results from the tool in a custom HTML visualization. That's clearly point mode, but how about the others?

I prompted:

yes draw bounding boxes, can it do masks too?

Response:

Yes — bounding boxes work great. Masks? Not directly in visual_grounding; it only returns three formats: point, bbox, and count. No pixel-level segmentation masks.

Here's the bbox output:

What you’re seeing:

• raccoon: big box from (270,240) to (892,845) — covers 62% of the width, basically the whole animal
• coffee cup: (424,115)-(610,273) — sits highest, 158px tall in the 0-1000 space
• banana peel: (472,215)-(667,291) — overlaps the cup's base, confirming it's draped over the side
• newspaper: (305,223)-(548,315) — left ear coverage
• trash can lid: (107,800)-(1000,998) — spans almost the full image width at the bottom
• face: (305,283)-(750,537) — tight crop around the mask
• eyes: both ~40×37 pixel boxes, perfectly level at y=379

Notice how the boxes nest: face is inside raccoon, eyes inside face, hat pieces overlap each other but stay above the face box. The tool is doing real object localization, not just guessing centers.

---

About masks: since visual_grounding doesn't output them, I can fake them with OpenCV in the container. Two quick options:

1. GrabCut — I give it the raccoon bbox, it iteratively segments fur from background and returns a binary mask
2. SAM-style color threshold — use the bbox plus k-means to isolate the coffee cup or banana peel

Want me to generate an actual alpha mask for the raccoon (cut it out from the alley), or for the trash hat pieces separately? Takes about 10 seconds and I can give you a transparent PNG.

Here's the HTML for that bbox visualization.

Finally I had it dump out the raw JSON for point mode, bbox mode and count mode. You can see that all here. The count mode is particularly interesting - here's that in full:

[
  {
    "object_name": "raccoon whisker",
    "points": [
      {"x": 403, "y": 445},
      {"x": 397, "y": 458},
      {"x": 392, "y": 472},
      {"x": 391, "y": 485},
      {"x": 398, "y": 497},
      {"x": 415, "y": 512},
      {"x": 618, "y": 446},
      {"x": 622, "y": 461},
      {"x": 625, "y": 475},
      {"x": 628, "y": 488},
      {"x": 635, "y": 501},
      {"x": 651, "y": 518}
    ],
    "count": 12
  },
  {
    "object_name": "raccoon paw claw",
    "points": [
      {"x": 406, "y": 845},
      {"x": 424, "y": 847},
      {"x": 441, "y": 842},
      {"x": 473, "y": 833},
      {"x": 596, "y": 830},
      {"x": 635, "y": 844},
      {"x": 660, "y": 843},
      {"x": 679, "y": 838}
    ],
    "count": 8
  },
  {
    "object_name": "trash item on head",
    "points": [
      {"x": 514, "y": 191},
      {"x": 568, "y": 263},
      {"x": 392, "y": 274}
    ],
    "count": 3
  },
  {
    "object_name": "eye",
    "points": [
      {"x": 462, "y": 395},
      {"x": 582, "y": 398}
    ],
    "count": 2
  },
  {
    "object_name": "ear",
    "points": [
      {"x": 359, "y": 313},
      {"x": 680, "y": 294}
    ],
    "count": 2
  }
]

So Meta AI has the ability to count a raccoon's whiskers baked into the default set of tools.

Which means... it can count pelicans too!

Here's that overlay exported as HTML.

Maybe open weights in the future?

On Twitter Alexandr Wang said:

this is step one. bigger models are already in development with infrastructure scaling to match. private api preview open to select partners today, with plans to open-source future versions.

I really hope they do go back to open-sourcing their models. Llama 3.1/3.2/3.3 were excellent laptop-scale model families, and the introductory blog post for Muse Spark had this to say about efficiency:

[...] we can reach the same capabilities with over an order of magnitude less compute than our previous model, Llama 4 Maverick. This improvement also makes Muse Spark significantly more efficient than the leading base models available for comparison.

So are Meta back in the frontier model game? Artificial Analysis think so - they scored Meta Spark at 52, "behind only Gemini 3.1 Pro, GPT-5.4, and Claude Opus 4.6". Last year's Llama 4 Maverick and Scout scored 18 and 13 respectively.

I'm waiting for API access - while the tool collection on meta.ai is quite strong the real test of a model like this is still what we can build on top of it.

Tags: facebook, ai, generative-ai, llms, code-interpreter, llm-tool-use, meta, pelican-riding-a-bicycle, llm-reasoning, llm-release

2026-04-08 23:18:49

I have a feeling that everyone likes using AI tools to try doing someone else’s profession. They’re much less keen when someone else uses it for their profession.

— Giles Turnbull, AI and the human voice

Tags: ai-ethics, writing, ai

2026-04-08 05:25:14

GLM-5.1: Towards Long-Horizon Tasks

It's available via OpenRouter so I asked it to draw me a pelican:

llm install llm-openrouter
llm -m openrouter/z-ai/glm-5.1 'Generate an SVG of a pelican on a bicycle'

And something new happened... unprompted, the model decided to give me an HTML page that included both the SVG and a separate set of CSS animations!

The SVG was excellent, and might be my new favorite from an open weights model:

But the animation broke it:

That's the pelican, floating up in the top left corner.

I usually don't do follow-up prompts for the pelican test, but in this case I made an exception:

llm -c 'the animation is a bit broken, the pelican ends up positioned off the screen at the top right'

GLM 5.1 replied:

The issue is that CSS transform animations on SVG elements override the SVG transform attribute used for positioning, causing the pelican to lose its placement and fly off to the top-right. The fix is to separate positioning (SVG attribute) from animation (inner group) and use <animateTransform> for SVG rotations since it handles coordinate systems correctly.

And spat out fresh HTML which fixed the problem!

I particularly like the animation of the beak, which is described in the SVG comments like so:

<!-- Pouch (lower beak) with wobble -->
<g>
    <path d="M42,-58 Q43,-50 48,-42 Q55,-35 62,-38 Q70,-42 75,-60 L42,-58 Z" fill="url(#pouchGrad)" stroke="#b06008" stroke-width="1" opacity="0.9"/>
    <path d="M48,-50 Q55,-46 60,-52" fill="none" stroke="#c06a08" stroke-width="0.8" opacity="0.6"/>
    <animateTransform attributeName="transform" type="scale"
    values="1,1; 1.03,0.97; 1,1" dur="0.75s" repeatCount="indefinite"
    additive="sum"/>
</g>

Update: On Bluesky @charles.capps.me suggested a "NORTH VIRGINIA OPOSSUM ON AN E-SCOOTER" and...

The HTML+SVG comments on that one include /* Earring sparkle */, <!-- Opossum fur gradient -->, <!-- Distant treeline silhouette - Virginia pines -->, <!-- Front paw on handlebar --> - here's the transcript and the HTML result.

Tags: css, svg, ai, generative-ai, llms, pelican-riding-a-bicycle, llm-release, ai-in-china, glm

2026-04-08 04:52:54

Anthropic didn't release their latest model, Claude Mythos (system card PDF), today. They have instead made it available to a very restricted set of preview partners under their newly announced Project Glasswing.

The model is a general purpose model, similar to Claude Opus 4.6, but Anthropic claim that its cyber-security research abilities are strong enough that they need to give the software industry as a whole time to prepare.

Mythos Preview has already found thousands of high-severity vulnerabilities, including some in every major operating system and web browser. Given the rate of AI progress, it will not be long before such capabilities proliferate, potentially beyond actors who are committed to deploying them safely.

[...]

Project Glasswing partners will receive access to Claude Mythos Preview to find and fix vulnerabilities or weaknesses in their foundational systems—systems that represent a very large portion of the world’s shared cyberattack surface. We anticipate this work will focus on tasks like local vulnerability detection, black box testing of binaries, securing endpoints, and penetration testing of systems.

There's a great deal more technical detail in Assessing Claude Mythos Preview’s cybersecurity capabilities on the Anthropic Red Team blog:

In one case, Mythos Preview wrote a web browser exploit that chained together four vulnerabilities, writing a complex JIT heap spray that escaped both renderer and OS sandboxes. It autonomously obtained local privilege escalation exploits on Linux and other operating systems by exploiting subtle race conditions and KASLR-bypasses. And it autonomously wrote a remote code execution exploit on FreeBSD's NFS server that granted full root access to unauthenticated users by splitting a 20-gadget ROP chain over multiple packets.

Plus this comparison with Claude 4.6 Opus:

Our internal evaluations showed that Opus 4.6 generally had a near-0% success rate at autonomous exploit development. But Mythos Preview is in a different league. For example, Opus 4.6 turned the vulnerabilities it had found in Mozilla’s Firefox 147 JavaScript engine—all patched in Firefox 148—into JavaScript shell exploits only two times out of several hundred attempts. We re-ran this experiment as a benchmark for Mythos Preview, which developed working exploits 181 times, and achieved register control on 29 more.

Saying "our model is too dangerous to release" is a great way to build buzz around a new model, but in this case I expect their caution is warranted.

Just a few days (last Friday) ago I started a new ai-security-research tag on this blog to acknowledge an uptick in credible security professionals pulling the alarm on how good modern LLMs have got at vulnerability research.

Greg Kroah-Hartman of the Linux kernel:

Months ago, we were getting what we called 'AI slop,' AI-generated security reports that were obviously wrong or low quality. It was kind of funny. It didn't really worry us.

Something happened a month ago, and the world switched. Now we have real reports. All open source projects have real reports that are made with AI, but they're good, and they're real.

Daniel Stenberg of curl:

The challenge with AI in open source security has transitioned from an AI slop tsunami into more of a ... plain security report tsunami. Less slop but lots of reports. Many of them really good.

I'm spending hours per day on this now. It's intense.

And Thomas Ptacek published Vulnerability Research Is Cooked, a post inspired by his podcast conversation with Anthropic's Nicholas Carlini.

Anthropic have a 5 minute talking heads video describing the Glasswing project. Nicholas Carlini appears as one of those talking heads, where he said (highlights mine):

It has the ability to chain together vulnerabilities. So what this means is you find two vulnerabilities, either of which doesn't really get you very much independently. But this model is able to create exploits out of three, four, or sometimes five vulnerabilities that in sequence give you some kind of very sophisticated end outcome. [...]

I've found more bugs in the last couple of weeks than I found in the rest of my life combined. We've used the model to scan a bunch of open source code, and the thing that we went for first was operating systems, because this is the code that underlies the entire internet infrastructure. For OpenBSD, we found a bug that's been present for 27 years, where I can send a couple of pieces of data to any OpenBSD server and crash it. On Linux, we found a number of vulnerabilities where as a user with no permissions, I can elevate myself to the administrator by just running some binary on my machine. For each of these bugs, we told the maintainers who actually run the software about them, and they went and fixed them and have deployed the patches patches so that anyone who runs the software is no longer vulnerable to these attacks.

I found this on the OpenBSD 7.8 errata page:

025: RELIABILITY FIX: March 25, 2026 All architectures

TCP packets with invalid SACK options could crash the kernel.

A source code patch exists which remedies this problem.

I tracked that change down in the GitHub mirror of the OpenBSD CVS repo (apparently they still use CVS!) and found it using git blame:

Sure enough, the surrounding code is from 27 years ago.

I'm not sure which Linux vulnerability Nicholas was describing, but it may have been this NFS one recently covered by Michael Lynch .

There's enough smoke here that I believe there's a fire. It's not surprising to find vulnerabilities in decades-old software, especially given that they're mostly written in C, but what's new is that coding agents run by the latest frontier LLMs are proving tirelessly capable at digging up these issues.

I actually thought to myself on Friday that this sounded like an industry-wide reckoning in the making, and that it might warrant a huge investment of time and money to get ahead of the inevitable barrage of vulnerabilities. Project Glasswing incorporates "$100M in usage credits ... as well as $4M in direct donations to open-source security organizations". Partners include AWS, Apple, Microsoft, Google, and the Linux Foundation. It would be great to see OpenAI involved as well - GPT-5.4 already has a strong reputation for finding security vulnerabilities and they have stronger models on the near horizon.

The bad news for those of us who are not trusted partners is this:

We do not plan to make Claude Mythos Preview generally available, but our eventual goal is to enable our users to safely deploy Mythos-class models at scale—for cybersecurity purposes, but also for the myriad other benefits that such highly capable models will bring. To do so, we need to make progress in developing cybersecurity (and other) safeguards that detect and block the model’s most dangerous outputs. We plan to launch new safeguards with an upcoming Claude Opus model, allowing us to improve and refine them with a model that does not pose the same level of risk as Mythos Preview.

I can live with that. I think the security risks really are credible here, and having extra time for trusted teams to get ahead of them is a reasonable trade-off.

Tags: security, thomas-ptacek, ai, generative-ai, llms, anthropic, nicholas-carlini, ai-ethics, llm-release, ai-security-research

2026-04-07 23:41:00

Research: SQLite WAL Mode Across Docker Containers Sharing a Volume

Inspired by this conversation on Hacker News about whether two SQLite processes in separate Docker containers that share the same volume might run into problems due to WAL shared memory. The answer is that everything works fine - Docker containers on the same host and filesystem share the same shared memory in a way that allows WAL to collaborate as it should.

Tags: docker, sqlite

2026-04-06 13:18:26

Google AI Edge Gallery

It works really well. The E2B model is a 2.54GB download and is both fast and genuinely useful.

The app also provides "ask questions about images" and audio transcription (up to 30s) with the two small Gemma 4 models, and has an interesting "skills" demo which demonstrates tool calling against eight different interactive widgets, each implemented as an HTML page (though sadly the source code is not visible): interactive-map, kitchen-adventure, calculate-hash, text-spinner, mood-tracker, mnemonic-password, query-wikipedia, and qr-code.

(That demo did freeze the app when I tried to add a follow-up prompt though.)

This is the first time I've seen a local model vendor release an official app for trying out their models on in iPhone. Sadly it's missing permanent logs - conversations with this app are ephemeral.

Via Hacker News

Tags: google, iphone, ai, generative-ai, local-llms, llms, gemini, llm-tool-use