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    Claude in November 2026: every release and what it means

    Published · Last updated

    Abstract cover: a timeline of ten small grey cards along a thin line on a dark background, one of them marked in orange

    Short answer

    Between October 21 and November 10, 2026, Anthropic released Claude Fable 5.2 and Mythos 5.2, opened the Claude Duet preview, launched Claude Whiteboards, Sheets and Data, and donated Agent Skills to the Agentic AI Foundation. Microsoft and Google shipped tools that work with Claude Code.

    Below is one entry per guide on this site, oldest first. Each has the date, one line taken from that guide's own sourced facts, the official page it relies on, and a link to the full guide. This page adds no claims of its own.

    Every release, in date order

    Claude Duet: what it does, who gets it, setup

    · Research preview opened

    Claude Duet is Anthropic's proactive agent app on Opus 5.5. It works on its own cloud computer, asks before sensitive steps, and is on a waitlist for US Pro, Max and Ultra subscribers.

    Source: Introducing Claude Duet (claude.com).

    Agent Skills now belong to the Agentic AI Foundation: what changes for skill authors

    · Agent Skills donated to the AAIF

    Anthropic donated Agent Skills, the SKILL.md format, to the Agentic AI Foundation under the Linux Foundation. None of the sources announces a change you must make to existing SKILL.md files.

    Source: Donating Agent Skills to the Agentic AI Foundation (anthropic.com).

    Claude Code with Claude Fable 5.2: setup, cost and when to switch from Opus 5.5

    · Claude Fable 5.2 released

    Run /model fable in Claude Code to use Claude Fable 5.2. It costs $8 input and $40 output per million tokens, twice Opus 5.5, so keep Opus 5.5 as the default and switch for long, hard agent runs.

    Sources: Claude Fable and Mythos 5.2 (anthropic.com) and Pricing (platform.claude.com).

    Claude Mythos 5.2 vs Fable 5.2: which to use

    · Claude Mythos 5.2 and Fable 5.2 released

    Mythos 5.2 and Fable 5.2 are the same underlying model at the same price. Fable carries cyber and biology safeguards and is open to all users. Mythos is for vetted organizations in Anthropic's verification programs.

    Source: Claude Fable and Mythos 5.2 (anthropic.com).

    Prompting Claude Fable 5.2: Anthropic's rules, with CLAUDE.md before and after

    · Claude Fable 5.2 released, with its prompting docs

    Anthropic's prompting page for Claude Fable 5.2 has 11 sections. Four give text to paste into a system prompt or CLAUDE.md. The rest say to remove old lines, name exact actions or lower effort.

    Source: Prompting Claude Fable 5.2 (platform.claude.com).

    Project Glasswing in numbers: what the VulnCheck audit found

    · VulnCheck published its audit

    On November 2, 2026, Anthropic's disclosure dashboard listed 37,966 candidate findings and a 94.2% true positive rate. VulnCheck counts 442 CVEs it attributes to Anthropic, 2 of them exploited in the wild.

    Sources: Anthropic's disclosure dashboard (red.anthropic.com) and VulnCheck's November update (vulncheck.com).

    Claude Whiteboards, Sheets and Data: what they are, who gets them, setup

    · Whiteboards and Sheets in beta, Data generally available

    Claude Whiteboards and Claude Sheets launched in beta. Claude Data, the new name for Claude Dashboards, is generally available. All three come with every paid Claude plan.

    Source: Claude Sheets, Whiteboards and Data (claude.com).

    Anthropic IPO: the filing facts for teams that use Claude

    · Roadshow launched

    Anthropic launched the roadshow for its proposed initial public offering. Its registration statement is filed with the SEC and is not yet effective.

    Source: Roadshow launch announcement (anthropic.com).

    Build an MCP server in .NET 11 and connect it to Claude

    · .NET 11 SDK 11.0.100 released

    The .NET 11 SDK ships an MCP server template. Run dotnet new mcpserver, build it, then add it to Claude Code with claude mcp add. We ran every step on a fresh Ubuntu machine.

    Source: Announcing .NET 11 (devblogs.microsoft.com).

    Make Claude Code write modern CSS and JS with Chrome's Modern Web Guidance

    · Modern Web Guidance v1.0.0 released

    Modern Web Guidance is Google Chrome's set of agent skills that point Claude Code at current HTML, CSS and JavaScript. Version 1.0.0 covers 250 web platform features in 203 use-case guides.

    Source: v1.0.0 release notes (github.com/GoogleChrome).

    How this page is kept

    The dates and lines above come from each guide, and each guide quotes and links the pages it relies on. Two entries are from late October: Claude Duet and the Agent Skills donation. They are here because their guides went up in November.