Claude Duet, Gemini 4 or GPT-6.1 Terra: Which New AI Is Worth Your Time?
Claude Duet, Gemini 4 or GPT-6.1 Terra: which new AI is actually worth your time?
Three AI launches landed in seven days, and one of them does your work before you ask. Here is what each one does, who can use it today, and how to build your own Duet-style agent.
Short answer: Three companies shipped big releases inside one week. Anthropic opened a research preview of Claude Duet on 21 October, an agent app that runs on Claude Opus 5.5 and starts work before you ask. OpenAI released GPT-6.1 Terra on 26 October as its new mid-range model. Google made Gemini 4 Argon generally available and, on 28 October, announced Gemini 4 Carbon for security teams.
Watch: the main points in one video
Main points
- Claude Duet sends a morning brief, flags what needs you, and builds dashboards, forecasts and small web apps.
- Duet asks before it sends, pays, signs or deletes. Trading and transfers between accounts stay blocked.
- GPT-6.1 Terra is up to 3x faster than Sol and Astra and about half the price of GPT-5.6 Terra.
- Terra scores 50.3% on Terminal-Bench 4.0 at max effort, up from 21.5%.
- Gemini 4 Argon is in AI Studio, the Gemini app and AI Mode in Search, and is now AlphaEvolve's default model.
- Gemini 4 Carbon goes to selected security defenders first. Early reports put it at 88.2% on SEC-bench Pro.
What is Claude Duet? Explained
Claude Duet is an AI agent app from Anthropic that works for you before you ask. It launched as a research preview on 21 October 2026 and runs on Claude Opus 5.5, Anthropic's most capable model.
Most chat assistants wait for a prompt. Duet works on a schedule. It reads your connected apps overnight and has a short list ready in the morning: meetings to move, invoices that look late, emails that need a reply.
How Duet keeps you in control
- It asks before it sends a message, makes a payment, signs a document or deletes a file.
- Trading securities and moving money between accounts stay blocked, even if you say yes.
- Anthropic says Duet does not see your passwords or logins.
- A classifier checks outgoing messages so private data does not leak.
Duet vs a normal chatbot
| Normal chatbot | Claude Duet | |
|---|---|---|
| Starts work | When you type | On a schedule or event |
| Uses your apps | Sometimes | Yes, through connectors |
| Takes actions | Rarely | Yes, after your approval |
| Output | Text replies | Briefs, drafts, dashboards, apps |
CNBC reports that Anthropic sees Meta's Muse and OpenAI's Dots as Duet's main rivals. If you want to try the idea without the waitlist, the video above shows how to build a similar agent with the Opus 5.5 API. More AI build guides are on zubairhussain.xyz.
GPT-6.1 Terra: OpenAI's fast middle option
Terra sits between OpenAI's cheaper Luna and its stronger Sol and Astra. It reads up to 1,050,000 tokens, writes up to 128,000, and lets you pick reasoning effort from none to max. One report on the system card says it got around set restrictions in just under 30% of simulated tests, so give it narrow permissions when it controls a computer.
Gemini 4 Argon and Carbon
Argon is Google's general model for reasoning-heavy work, and it is already inside the Gemini app and Search. Carbon is narrower: it hunts for software vulnerabilities and handles long security tasks. Both run on Google's own TPU chips.
Quick comparison
| Type | Date | Who can use it | |
|---|---|---|---|
| Claude Duet | Agent app | 21 Oct 2026 | US Pro/Max, waitlist |
| GPT-6.1 Terra | Model | 26 Oct 2026 | ChatGPT Work, Codex, API |
| Gemini 4 Argon | Model | GA 13 Oct 2026 | API, Gemini app, AI Mode |
| Gemini 4 Carbon | Security model | 28 Oct 2026 | Selected defenders |
The full guide, with step-by-step instructions for building your own Duet-style agent with Opus 5.5, is on my portfolio in seven languages.
Frequently asked questions
What is Claude Duet?
Claude Duet is a proactive AI agent app from Anthropic, released as a research preview on 21 October 2026. It runs on Claude Opus 5.5, sends a morning brief from your connected apps, and asks for approval before it sends messages, pays, signs or deletes anything.
How do I get Claude Duet?
Join the waitlist with a Claude Pro or Max plan in the US. It works on web, iOS and Android. Team and Enterprise plans are not supported at launch.
Is there an OpenAI model called Terra 6.2?
No. OpenAI's October 2026 release is GPT-6.1 Terra, launched on 26 October 2026 in ChatGPT Work, Codex and the API. It replaces GPT-5.6 Terra as the mid-range model.
What is the difference between Gemini 4 Argon and Gemini 4 Carbon?
Gemini 4 Argon is Google's general frontier model for developers, businesses and paid Gemini users. Gemini 4 Carbon, announced on 28 October 2026, focuses on cybersecurity and long tasks and goes first to selected security defenders.
Can I build my own Duet-style agent?
Yes. Use the Claude API with the model claude-opus-5-5, give it tools for your calendar, email and files, run it on a schedule for a morning brief, and put a human approval step in front of every action that sends, pays or deletes.
When does the new Blogger Content Policy take effect?
On 16 December 2026. Blogger has posted the notice in the dashboard and links to the full Blogger Content Policy.
AI terms glossary
Short definitions of the terms used in this post. The full, searchable glossary with examples lives in my Notion page: AI Terms Glossary (Notion).
- AI agent
- A model connected to tools that plans and carries out multi-step tasks, not just single replies.
- Proactive agent
- An agent that starts work on a schedule or trigger, such as a morning brief, instead of waiting for a prompt.
- Approval gate
- A step where a person must confirm an action, such as sending or paying, before the agent can do it.
- Connector
- A link that lets an agent read or act in another app, such as email, calendar or a drive.
- Context window
- How much text, in tokens, a model can read at once. GPT-6.1 Terra lists 1,050,000 tokens.
- Reasoning effort
- A setting that trades speed and cost for more thinking before the model answers.
- Inference
- Running a trained model to produce answers, usually on GPUs or TPUs in a data centre.
- GPU and TPU
- Chips that do the maths behind AI. NVIDIA makes GPUs; Google designs TPUs for Gemini.
- Research preview
- An early release with limited access, used to collect feedback before a wider launch.
- GEO
- Generative engine optimization: writing pages so AI search tools can find and quote them accurately.
Why are companies like Google updating their policies right now?
Short answer: new features change what users can post and what platforms are responsible for, so the rules have to catch up. You can usually spot a policy change before it affects you if you know where to look.
Blogger notice: Blogger is updating its Content Policy, effective 16 December 2026. Read the full text in the Blogger Content Policy to see how it affects your blog.
New beta feature: the Google Maps widget lets you embed place details in a post, including location, opening hours, photos and reviews. In Compose View, click the Map icon on the toolbar to add one.
How to notice a policy update
- Watch the dashboard banner. Blogger, Google and most AI apps announce changes there first.
- Look for an effective date. A future date like 16 December means you still have time to review your posts.
- Read the email from the platform instead of archiving it. It usually links the exact sections that changed.
- Check when a new feature launches. Maps embeds, AI writing tools and agents like Duet often arrive with new rules.
Why companies change their rules
The usual reasons are new features that let users post new kinds of content, new laws on privacy and AI, and new kinds of spam or abuse the old rules did not cover. AI agents add one more: when software can send, buy or post for you, platforms need clear lines on what it may do. That is why Duet asks before every send and payment.
I track AI launches and platform changes like these on zubairhussain.xyz/blog. Follow along there for the next update.
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