Vol. I · No. 157WED, SEP 23, 2026
Topic

Claude

Every story matching this topic across titles and summaries, newest first.

Anthropic launches Claude Opus 5.5 with stricter safeguards for cybersecurity

Anthropic says its new Claude Opus 5.5 model comes with stronger safeguards in the wake of recent rogue AI hacking incidents. In an announcement on Tuesday, Anthropic says Opus 5.5 comes with improvements to certain risky behaviors, including attempts to escape the company's testing sandbox. It's the first model released by Anthropic after CEO Dario Amodei announced plans to "pace the frontier," or slow down AI development. In recent weeks, several AI companies, including Anthropic, Google, and OpenAI, have reported that their AI models escaped containment and hacked third-party companies dur...

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Don’t be fooled by this summer of AI hype

It’s been a busy few months for AI hype. At the end of April, Anthropic claimed that its model Claude Mythos is better at finding software vulnerabilities than most security experts. Then we had the OpenAI–Hugging Face hacking incident, after which Anthropic (proudly) and Meta (reluctantly) disclosed similar incidents involving their models. This was followed…

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Quoting voxium

Anecdote: large company relying heavily on Claude Code for artifact generation creates workflow dysfunction despite high throughput expectations.

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Quoting Thariq Shihipar

Anthropic adds AGENTS.md support to Claude Code v2.1.277 for project instruction customization via modular architecture.

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Claude Code relaunches Projects to manage multiple AI agents in the cloud

The revamped projects feature in Claude Code allows users to run multiple agents under the same roof, with a shared memory, goals, and library of files and artifacts. Similar to Grok Bot and other tools that manage groups of AI agents, each project has "threads" running different tasks in parallel, with a "coordinator" directing everything: Under the hood, each thread is a Claude Code cloud session working on its own branch and copy of the repo. The coordinator keeps work organized, but if any threads work on the same code, the overlap is resolved as a merge conflict just like any other PR. E...

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Google will now let any AI agent run your smart home

Google is inviting third-party agents, including Claude and Open Claw, into Google Home. | Photo by Jennifer Pattison Tuohy / The Verge Google is opening up its smart home to AI agents, letting tools like Claude and Open Claw access and control your connected devices and analyze your home's data using the standardized Model Context Protocol. Google Home MCP is a new integration that lets third-party AI agents control and monitor your smart home and act on your behalf. It "allows any AI agents that support MCP, including Google Antigravity, Claude, Hermes or Open Claw, to securely work with al...

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Claude comes for Gemini with its own take on Docs and Slides

Claude is getting a pair of new tools today: Docs and Slides. They'll let you create documents and presentations through Claude chats, which you can export, edit, and share with other users. As part of the announcement, Anthropic is also simplifying how Claude chats work, merging regular chats and Cowork into "one Claude," with all of its AI productivity tools available from any chat. Artifacts and Claude Design capabilities will be available through the new single interface as well. According to Anthropic, Claude "can now figure out what a task needs, so what Cowork and Design can do is avai...

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Quoting Boris Cherny

Boris Cherny outlines Anthropic's production guardrails for Claude-generated code: linting, testing, fuzzers, automated review, and refactoring.

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A new class action lawsuit questions whether Anthropic broke the law by misleading power users

Anthropic says power users are key to its business - it's prioritized them even when it means cutting off other popular applications, like OpenClaw. But some of these same customers say Anthropic misled them into believing they'd get more out of a top-tier pricing subscription than they did. In an expanded class-action lawsuit filed today, a group of Claude subscribers say the company deceptively advertised the limits of its Max subscription tier. The lawsuit was brought by attorneys Monica Vaca and Kati Daffan, who both formerly worked at the Federal Trade Commission under Lina Khan. It's a ...

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Video compressor

Simon Willison used Claude Fable 5.1 to build a WebAssembly-based video compressor tool via Claude Code.

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August newsletter is out

Simon Willison's August newsletter covers OpenAI security incidents, game-playing agents (Fable 5, Sol 5.6), and Claude auto mode with model releases roundup.

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GPT‑6 Astra

OpenAI launches GPT-6 Astra, a Claude Fable competitor priced at $10/$50 per million tokens, rolling out to ChatGPT Plus/Pro/Business/Enterprise and via API.

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ChatGPT, Grok, and Claude all went down at the same time

OpenAI's ChatGPT, xAI's Grok, and Anthropic's Claude are all experiencing issues. At around 11AM ET, ChatGPT started returning error messages for users trying to use the chatbot, with its status page saying there are currently "elevated errors across ChatGPT and Codex." In addition to preventing users from having conversations with ChatGPT, the outage is also affecting logins, file uploads, voice mode, search, deep research, image generation, and more. OpenAI says it has "applied a mitigation" and is "monitoring recovery," though its AI tools are still experiencing "degraded performance." The...

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llm-anthropic 0.28

llm-anthropic 0.28 displays Claude reasoning traces by default and adds refusal exception handling.

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Quoting Rick Brewster

Paint.NET developer credits Claude AI for reverse-engineering Direct2D wrapper to run on WINE; demonstrates LLM utility for systems programming.

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Anthropic launches Claude Fable 5.1 and says it’s up to 45 percent cheaper for agentic work

Anthropic says its newest AI models, Fable 5.1 and Mythos 5.1, address criticisms from customers about price, data retention, and overzealous safeguards. The company claims Claude Fable 5.1 offers stronger performance than Fable 5, but costs around 25 percent less typically and up to 45 percent less for complex agentic tasks, thanks to reduced pricing on cached data that was already processed and stored. Along with the announcement, a slew of early impressions popped up, including from Every CEO Dan Shipper, who claims, "It's the strongest coding model we've used, but now it's fast, token-eff...

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GeoJSON Map Viewer

Simon Willison built a GeoJSON map viewer tool using Claude Code and GPT-5.6-Sol for visualizing and exporting local political boundary maps.

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Run NVIDIA BioNeMo NIM Microservices for Protein Structure Prediction in Claude Science

Agentic AI is changing how research is done. AI scientists can read papers, propose hypotheses, call models, and determine which experiments to prioritize next.... Agentic AI is changing how research is done. AI scientists can read papers, propose hypotheses, call models, and determine which experiments to prioritize next. First proving their value in software engineering, coding agents now write, test, and ship production code. Scientific research can be more demanding and iterative. Researchers continually evaluate evidence, refine hypotheses… Source

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Breaking Claude Code Opus 5 Auto Mode

Johann Rehberger demonstrates 80% success rate prompt injection attack against Claude Code's auto mode default, bypassing Anthropic's claimed protections via zip extraction and base64 import.

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Quoting Drew Breunig

Drew Breunig argues frontier model improvements now require careful cost-benefit analysis for coding tasks, as cheaper alternatives (Claude 3.5, K3, GLM) remain sufficient for most use cases.

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Anthropic’s Opus 4.6 is a smut-machine

Anthropic forbids its Claude models from generating sexually explicit content. But a series of tests conducted by TechCrunch found that it didn't take much to get past the restriction.

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Slack is launching collaborative vibe coding channels

Slack is introducing dedicated channels where teams can vibe code together with AI agents instead of jumping between different tools and conversations. The Slack Code launch includes open, project-specific code channels with dedicated user tabs, alongside features that compare coding changes and preview HTML output before the project is shipped. "With Slack Code, when you have an idea or need to build a new feature, update a web page, or fix a bug, you simply tag in a coding agent like Anthropic's Claude or Cognition's Devin, and that agent then spins up a code channel to tackle the task," Sl...

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We still don’t know how people are really using AI

AI companies like Anthropic and OpenAI regularly publish reports on how people are using products like Claude and ChatGPT, but they only release the data they want us to see, AI researchers say. “There is no independent source to corroborate it,” says Anka Reuel, a Computer Science PhD candidate at the Stanford Trustworthy AI Research…

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Anthropic explains how Claude’s invisible text watermarks will work

Anthropic has clarified how it's planning to apply invisible watermarks to Claude-generated text in order to comply with Europe's AI transparency rules. On Friday, Anthropic announced that Claude's text marking system is "a version of the SynthID-Text approach" - an open-source watermarking technology developed by Google DeepMind that creates detectable patterns using wording probabilities. This watermarking feature, alongside C2PA support for Claude-processed images, is being introduced to meet Anthropic's obligations under the European Union's AI Act, which requires synthetic audio, image, ...

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Quoting Florian Herrengt

But then users start to report a weird bug. It's the 4th time your team has been trying to fix it. I mean... asking AI to fix it. Unfortunately, it seems like not even Fable can figure it out. You go talk to the person who worked on this feature. "So where does the data come from?" "Hmm... actually I don't know. Let me ask Claude." You sit next to each other watching an endless wall of text appear on the screen. Neither of you has any idea whether any of it is true but Claude seems very confident. [...] This project has become so convoluted, with so many layers and services, that no one on yo...

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Why Does CLAUDE.md Keep Growing? Catastrophic Remembering in Agentic Coding

Agentic coding READMEs like CLAUDE.md grow without bound in real repositories, stopping only when the repository retires or someone rewrites the file wholesale. We trace this to imperfect recall: appending an instruction is always cheap, but once an instruction's rationale is gone, deleting it without risking a correctness regression costs O(2^|D|) in a prompt of |D| instructions. We name the resulting divergence catastrophic remembering, the inverse of catastrophic forgetting around which continual learning is organized. First, we characterize this phenomenon across 247,694 instruction lifet...

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Claude will apply invisible watermarks to AI text and images

Anthropic has pledged to start marking Claude-generated text and images with machine-readable data, in an effort to comply with European rules for AI transparency. "Generated text will carry embedded watermarks, and generated files will include digitally signed provenance metadata where supported," Anthropic says on a new Claude support page. The changes are invisible to human eyes, but will make it easier for people and online platforms to detect if content was generated by Claude models. These updates are a future commitment rather than something that will go into effect immediately. New AI...

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Quoting Claude Opus 5 system prompt

Claude Fable 5 and Claude Mythos 5 were first released on June 9, 2026. On June 12, 2026, Anthropic suspended access to both models to comply with U.S. Department of Commerce export controls; the Department lifted those controls on June 30, 2026, and Anthropic restored access on July 1, 2026 (Anthropic's statement: https://www.anthropic.com/news/fable-mythos-access ). These events are after Claude's training-data cutoff, so Claude knows about them only from this notice. If asked, Claude confirms them accurately and matter-of-factly — it doesn't deny the suspension happened — and otherwise tre...

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Auto mode is now the default in Claude Code for Pro, Max, and Team plans

Auto mode is now the default in Claude Code for Pro, Max, and Team plans Anthropic are really confident in Claude Code's auto mode , to the point that they are making it the default setting for new sessions in most Claude Code plans starting on August 14th. This was one of the topics discussed in our Fireside Chat with Cat Wu and Thariq Shihipar at the AI Engineer World’s Fair last month. I asked them how they run Claude Code safely within Anthropic (given the threat of prompt injection) and they replied that "Broadly within Anthropic, almost every single person uses auto mode". Cat Wu then s...

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Moonlight & Mayhem (Raccoon Heist by Codex + GPT-5.6 Sol Ultra)

Moonlight & Mayhem (Raccoon Heist by Codex + GPT-5.6 Sol Ultra) On Wednesday I wrote about One-shotting a Raccoon Heist game using Claude Fable 5 , where I had Claude Fable 5 build a full working game from a premise I generated with GPT-3 and DALL-E four years ago . I decided to pose the exact same prompt to Codex Desktop running GPT-5.6 Sol Ultra - the mode where Sol makes aggressive use of sub-agents - to see how it would do. It produced a much better game! Here's Moonlight & Mayhem - GitHub repository here , including the textures and prompts it generated using gpt-image-2 . Your browser d...

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Jill Lepore on the ‘Artificial State’ and why Silicon Valley’s leaders are bad sci-fi readers

Historian Jill Lepore has a theory about why tech companies often use soaring language to describe their products — almost as if they’re forming a new government. And whether you’re thinking of Twitter’s old “town hall in your pocket” or Anthropic’s Claude constitution, it’s a theory that doesn’t paint Silicon Valley in a very flattering light. In Lepore’s upcoming book, The Rise and Fall of the Artificial State, the Pulitzer […]

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One-shotting a Raccoon Heist game using Claude Fable 5

Back in 2022 I tweeted screenshots of a game concept generated by GPT-3 and some concept "art" created using DALL-E. Today, on the fourth anniversary of that tweet, I decided to see if Claude Fable 5 (running in Claude Code for web ) could build the entire game from the content of that tweet. It did a pretty good job of it! You can play the game here . Here's the GitHub repo , and a short video demo: Your browser does not support HTML5 video. How I built this This is the August 5th, 2022 tweet : My GPT-3 prompt back then was: Write a detailed product description of a computer game where a tea...

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Anthropic is hiring an AI chip design team

Anthropic is building a team for designing its own custom AI chips. The Claude-maker said it would co-design hardware and models to help its technology run faster and more efficiently.

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llm-anthropic 0.26

Release: llm-anthropic 0.26 Includes new features enabled by LLM 0.32 : New models: claude-fable-5 , claude-sonnet-5 , and claude-opus-5 . #75 , #76 Added server-side tools for WebSearch , WebFetch , CodeExecution , and AnthropicMCP , available through LLM's -T interface or Python tools= . The previous -o web_search* options have been removed in favor of -T WebSearch . #79 Upgraded to llm>=0.32 . Reasoning, tool calls, tool results, and server-side tool results now stream as typed events. Reasoning for llm CLI prompts now displays to standard error unless you pass --hide-reasoning/-R . Simpli...

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July 2026 newsletter

Simon Willison's June 2026 newsletter roundup covering model releases (GPT-5.6, Claude Opus 5, DeepSeek-V4), open letters, and accidental cyberattacks by OpenAI and Anthropic test models.

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Anthropic says Claude accidentally hacked real companies too

Anthropic just realized several of its Claude AI models hacked into the systems of three different organizations during testing, acting on their own and without the company noticing. The revelation comes days after rival OpenAI said one of its own models had breached developer platform Hugging Face, adding to growing unease over whether frontier AI labs are doing enough to control the increasingly capable systems they are building. In a blog post describing the incidents, Anthropic said Claude gained unauthorized access to the systems during cybersecurity evaluations. All of the attacks happe...

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APEX-Accounting

APEX-Accounting benchmark from Mercor and Ramp tests frontier models on real accounting tasks; Claude-Fable-5 Max achieves 56.4% accuracy.

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Quoting Boris Cherny

Claude Opus 5 achieves lowest prompt injection vulnerability rate across evals and red team testing, per Anthropic's system card.

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Introducing Claude Opus 5

Anthropic releases Claude Opus 5, matching Fable 5 frontier performance at half the cost, now leading Artificial Analysis leaderboard.

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Introducing Claude Opus 5

Anthropic releases Claude Opus 5 with improvements in agent execution, coding, and professional tasks.

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Anthropic releases Opus 5 with ‘close’ to Fable 5’s capabilities

Weeks after Anthropic's latest toe-to-toe with the US government, and days after an OpenAI security incident that dominated tech industry discussions, Anthropic on Thursday released its newest model, Claude Opus 5. The company said in a release that Opus 5 "comes close to the capabilities of Claude Fable 5 in many domains" and is much better at complex coding tasks. (Fable 5 is the public-facing Mythos-class model that drew the government's ire, was taken offline for a few weeks along with Mythos 5, and then brought back with even stronger cyber safeguards than before.) The Fable 5 concerns -...

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Meta is making its AI chatbot more like an assistant

Meta says its AI chatbot is going beyond just answering questions and generating images. | Image: Meta Meta is upgrading its AI chatbot with new productivity features in a bid to compete with rivals like Gemini, ChatGPT, and Claude. The update will allow Meta AI to tap into your calendar to help you plan events and generate daily briefings, as well as perform in-depth research that you can steer as it progresses. In a blog post, Meta says this update marks its "next step toward personal superintelligence," something CEO Mark Zuckerberg has touted as the future of AI. Meta is powering the upda...

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Claude’s voice mode is now available for Opus and Sonnet

Until now, voice mode has only been available on Claude Haiku, Anthropic's faster but less powerful model. Now the company is making its Opus and Sonnet models available in voice mode, and extending its reach into apps like Gmail, Slack, and Canva. When Anthropic launched voice mode last year, it was primarily focused on delivering answers to quick questions with minimal delay. But in a blog post, the company said people immediately started using voice mode for far more than casual queries. They were using it to work "through real business problems," which Haiku was not really designed for. T...

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