ANTHROPIC

Anthropic's Frontier Red Team says GLM-5.3 builds working exploits at rates close to Claude Mythos Preview, and that its safeguards can be stripped in days. Here are the verified numbers, the community backlash, and the practical read for developers.

Claude Code is Anthropic's agent for software engineering; Claude Cowork is the same agent loop pointed at documents, spreadsheets, and research. Both come with every paid Claude plan from $17/month. Here is how to pick, with a verified September 2026 pricing table.

Claude Sonnet 5.5 (claude-sonnet-5-5) is Anthropic's new mid-tier model: $2/$10 per million tokens, 70.6% on Terminal-Bench 4.0, 1M context, now GA in GitHub Copilot and on Vercel AI Gateway. The pricing math, the five breaking API changes, and where it fits next to Opus 5.5 and Sonnet 5.

Claude Opus 5.5 (claude-opus-5-5) is Anthropic's new default Opus: $4/$20 per million tokens, $0.20 cache reads, 1M context, thinking always on with medium default effort. Runnable TypeScript and Python SDK examples, Claude Code setup, before/after prompts, and a decision guide vs Sonnet 5, Haiku 4.5, and Fable 5.1.

Anthropic says Claude worked largely autonomously for 11 days to formalize Fermat's Last Theorem in Lean. The developer lesson is less about one theorem and more about verified repo-scale research artifacts.

Anthropic confirms that every Claude model released after August 2, 2026 embeds a machine-readable watermark in generated text and attaches C2PA provenance metadata to generated files, across the API, Claude Code, Cowork, and Tag. Detection tooling for third parties is coming, but details are not published yet.

Anthropic retuned Claude Fable 5's biology classifiers on August 7, cutting biology-related fallbacks by about 85% while keeping dual-use domains like virology, toxicology, and molecular design routed to Opus 5. Here is what changed, what stays blocked, and what it means for Claude Code and API users.

How much of an AI session can you actually take with you? Store defaults, encrypted reasoning, opaque compaction, hidden search, and subagent ciphertext compared across OpenAI, Anthropic, and Gemini - all verified against live docs.

Claude Mythos Preview is the model that found thousands of zero-days, and you could not buy it. Here is what it is, who got access through Project Glasswing, what it actually found, and where the model line went after it retired.

Effort levels and model choice both cost more for more capability, but they are not interchangeable. Here is when to move the effort dial and when to switch models instead.

Dario Amodei published Anthropic's stance on open-weights models this week - no total ban, but support for chip export controls, distillation crackdowns, and mandatory safety testing. HN responded with 800+ comments calling it regulatory capture. Here is what the CEO said, what the thread argued, and why the debate matters for every developer deploying AI.

Anthropic's Claude Mythos Preview found novel attacks on the HAWK post-quantum signature scheme and reduced-round AES. The HN community debates the real significance, the $100K price tag, and what it means for prompt engineering.

Anthropic cut 80% of Claude Code's system prompt for Opus 5 and Fable 5 with zero regression on coding evals. The post landed on HN with 197 points and 133 comments. Here is what the article says, what HN thinks, and what it means for your agent harness.

Anthropic released Opus 5 on July 24, 2026 - same price as Opus 4.8, within 0.5% of Fable 5 on CursorBench, and the new #1 on Artificial Analysis. We break down the benchmarks, HN reaction, and what it means for every developer choosing a daily-driver model.

Claude Opus 5 launched July 24, 2026 at $5/$25 per MTok - matching Opus 4.8 pricing while delivering near-Fable 5 intelligence. Full benchmark comparison across 7 evals, pricing breakdown, and decision guide.

Anthropic launched the Claude Cookbook - 80+ practical guides from their engineers covering tool use, agent patterns, evals, and production deployment. The HN discussion debates whether cookbook resources still matter when you can just ask the AI.

Claude Opus 5 ships today with Frontier-Bench SOTA, near-Fable-5 coding at half the price, and self-verification that catches its own bugs. Here is what changed, what to migrate, and when the price-performance curve makes Opus 5 the right default.

Terence Tao published a deep mathematical digestion of the Jacobian conjecture counterexample discovered by Claude Fable 5. Here is what happened, what HN is saying, and what it means for AI-assisted research.

Andrew Kelley's blunt response to Anthropic's AI-assisted Bun rewrite sparked debate about AI marketing, language choices, and what makes engineering decisions honest.

A companion guide to the Claude Fable 5 video: what the first general-use Mythos class model is, the walkthrough beats from the review, hands-on developer takeaways, and the pricing and context specs from primary sources.