Neosaipien  |  Issue 1  |  16 Sep to 16 Oct 2026

What changed: October 2026

Changes in Claude, ChatGPT and Gemini over the last month that alter how a team works, each with one thing to do.

 
 

Top 3 this month

26 Oct and 11 Dec. Custom GPTs retire on 11 Dec. On Enterprise, no new ones after 26 Oct (planned). [15]

Do: List your GPTs and who made them.

Now. Claude: chat and Cowork become one, Pro and Max first. No way back. [2]

Do: Try one real task in a chat.

Now. ChatGPT plugins now reach personal and work accounts in one chat. [10, 14]

Do: Set plugins to “Always ask”.

 
Claude  Anthropic

Cowork is now part of every chat  16 Sep 2026  |  Pro, Max first

“Claude Cowork and chat are merging into one Claude”. Quick questions and handed-over tasks happen in one conversation, with projects, connectors and skills carried over.

Do: Keep the default: Claude asks before it acts.

[1, 2] Claude release notes and Anthropic’s article, 16 Sep

Claude Opus 5.5, a new model  22 Sep 2026  |  Pro and up

For long tasks, coding and knowledge work; Anthropic says it “performs at the level of Claude Fable 5.1 on most work”. Sonnet 5.5 and Haiku 5.5, for everyday and quick jobs, are on every plan.

Do: Start on Sonnet 5.5; use Opus 5.5 for careful work.

[1, 3, 4] Claude release notes; Opus 5.5 page, 22 Sep; plans page

Docs and decks from any chat  16 Sep 2026  |  All plans

Claude Docs, Claude Slides and Claude Design arrive in the conversation with one shareable link, and download as PowerPoint or PDF, Free plan included.

Do: Check a made deck’s facts before it goes out.

[2] Anthropic’s article, 16 Sep

Claude in Google Docs and Sheets  6 Oct 2026  |  Paid plans, beta

Claude for Google Workspace puts a sidebar in Google Docs, Sheets and Slides, in public beta, with “Ask before edits” as the default.

Do: Keep “Ask before edits” on for shared files.

[6] Anthropic’s post, 6 Oct

 
ChatGPT  OpenAI

GPT-6 comes to Chat  7 Oct 2026  |  All plans

Choose GPT-6, then Instant, Medium or High on the Thinking slider; Pro, Business and Enterprise also get Extra High and Pro. Free and Go get GPT-6 Luna, with a Think button for harder questions.

Do: Use Medium day to day, High for careful work.

[10, 12] OpenAI release notes, 7 Oct; GPT-6 help page

GPT-6.1 Sol for Work  29 Sep 2026  |  Plus and up

A new model for Work and Codex, close to GPT-6 Astra on agent work and computer use; “not yet available in Chat”. In Work, the Default setting mixes models for you.

Do: Start Work on Default. Pick a model only if it misses.

[12, 13] OpenAI, 29 Sep; GPT-6 help page

ChatGPT inside Word  17 Sep 2026  |  All plans

ChatGPT for Word drafts, summarises and revises from a sidebar, Free plan included. It joins Excel and PowerPoint in the same add-in.

Do: Decide if work files may go through the add-in.

[10] OpenAI release notes, 17 Sep

Voice can now act  23 Sep 2026  |  All plans

Voice can use plugins and connected apps, and works in ChatGPT Work on web and mobile. On web and mobile, “Spoken approval is not supported”.

Do: Approve on screen. Set plugin permissions first.

[10, 11] OpenAI release notes, 23 Sep; Work help page

 
Gemini  Google

Gemini 4 Argon arrives  13 Oct 2026  |  Google AI Pro, Ultra

Google’s newest frontier model, for complex work from start to finish. Pick it at the bottom of the chat box, then a thinking level.

Do: Save Argon for the hardest work.

[16, 17] Gemini release notes, 13 Oct; models help page

Skills in, Gems out  30 Sep, 13 Oct 2026  |  Personal 18+, Workspace

Saved how-tos you can reuse. Personal accounts since 30 Sep; Workspace from 13 Oct, “with expected completion by mid-November”.

Do: List your Gems and who made them.

[16, 18, 19] Gemini release notes, 30 Sep; Workspace Updates, 30 Sep, updated 13 Oct

Apps and skills in one menu  13 Oct 2026  |  All user tiers

A new Customize menu holds connected apps and skills, on web, mobile and desktop. “Most connected apps are available in English in the US”.

Do: Remove apps you no longer use.

[16] Gemini release notes, 13 Oct

 

My recommendation

Claude first, ChatGPT second, Gemini third.

Claude for the simplest start to finish and finished files on every plan. ChatGPT for Work and routines that start on a new email. Gemini where your company runs on Google’s apps. For company data, your company’s approved tool comes first. [2, 11]

 

Which model when

New this month: Opus 5.5, GPT-6.1 Sol, Gemini 4 Argon. Pick a model next to the send button (Claude), in the model menu (ChatGPT) or at the bottom of the chat box (Gemini). Start on the default; move up only when the answer misses something. [4, 5, 8, 12, 13, 17]

Quick question, short rewrite. Claude: Haiku 5.5 or Sonnet 5.5. ChatGPT: GPT-6 at Instant. Gemini: Auto, or Flash-Lite.

Everyday writing, a summary. Claude: Sonnet 5.5. ChatGPT: GPT-6 at Medium. Gemini: Flash.

Careful report, messy spreadsheet. Claude: Opus 5.5. ChatGPT: GPT-6 at High. Gemini: Pro, thinking High.

Hand over a multi-step task. Claude: Opus 5.5, in a chat. ChatGPT: Work on Default, or GPT-6.1 Sol. Gemini: Task with Argon (personal accounts).

The hardest, high-stakes work. Claude: Fable 5.1 (uses limits fastest). ChatGPT: GPT-6 Pro, or Astra in Work. Gemini: Argon, thinking High.

 

Settings that changed

New this month, and the standing defaults they meet.

ChatGPT plugins. Plugins can now connect several accounts, personal and work, in one chat (17 Sep, all plans). The standing default on personal accounts, stated on 14 Sep, is “Allow low-risk actions”. [10, 14]

Do: Set Settings, Plugins, Permissions to “Always ask” or “Allow read actions”. In a managed workspace, ask your admin.

Claude connectors. With chat and Cowork merged, connectors work in any conversation. Each connector’s tools can be set to Always allow, Needs approval or Blocked; in a chat you choose Allow once or Always allow. [2, 7]

Do: Set new connectors to “Needs approval”. Choose “Allow once” until you trust it.

 

Retired or retiring

Custom GPTs (ChatGPT). Scheduled to retire on 11 Dec 2026, replaced by plugins: a GPT’s instructions become a skill inside a plugin. Custom actions and sharing settings do not carry over. [15]

Do: List the GPTs you rely on. On Enterprise, publish any drafts you need to migrate before 26 Oct.

Gems (Gemini). Being replaced by skills: personal accounts from November 2026, business accounts no sooner than 1 Mar 2027. Remaining Gems become draft skills automatically, Google says. [18, 19]

Do: Rebuild key Gems as skills, personal accounts first.

In all three tools, saved instructions are moving to skills (as of Oct 2026). [2, 15, 17]

 

Coming up

26 Oct 2026ChatGPT Enterprise: no new custom GPTs after this (planned). [15]
12 Nov 2026Claude: Anthropic’s updated Usage Policy takes effect. [9]
17 Nov 2026Gemini, Workspace accounts: Gems move to Settings, still usable. [18]
2 Dec 2026EU AI Act: new bans, with conditions, on AI that makes realistic intimate or sexual images, video or audio of an identifiable person without explicit consent, or child sexual abuse material. [20]
2 Dec 2026EU AI Act: makers of AI that generates audio, images, video or text, on the market before 2 Aug 2026, must mark its outputs as AI-made, in a machine-readable way. [20, 21]
11 Dec 2026ChatGPT: custom GPTs retire (approved Enterprise deferrals: 11 Feb 2027). [15]
1 Mar 2027Gemini: Gems end for Workspace business, no sooner than this (education: 1 Jun 2027). [18]
2 Dec 2027EU AI Act: high-risk duties apply to the uses in Annex III, including AI in hiring, promotion or termination, allocating tasks by behaviour or traits, and monitoring performance. [20, 21]

Not legal advice. Read in the official texts on EUR-Lex on 16 Oct 2026: Regulation (EU) 2024/1689 and the amending Regulation (EU) 2026/1744.

 
 One habit this month

Read the steps, not just the result.

Check it. Agents now work inside ordinary chat. Before you share what one made, read the steps it took and open what it changed.

 

Rechecked this month

The Agent Playbook’s dated pages. Rechecked on 16 Oct 2026.

 

What gets in

■  Three tools: Claude, ChatGPT and Gemini.

■  Only changes that alter how a team works, its settings or its risks.

■  No developer API news, no rumours and no third-party dates.

■  Nothing from before the window, except standing defaults, the model menus and Coming up.

■  No prices: the vendor’s page is linked instead.

 

More, free

neosaipien.com/library/

Every Neosaipien kit, free to download.

 

Next step: The Agent Playbook: brief cards, ready briefs and the five checks.

Learn: Field Guide level 3, Power features: neosaipien.com/learn/

For leaders: I’m Samson Mathew. I run the Leadership briefing for leadership teams.

Book a call: neosaipien.com

 

Checked against

Every vendor fact and law line in this issue was read on the vendor’s own page, or in the official text of the law, on 16 Oct 2026.

[1] Anthropic. Claude release notes (entries of 16 Sep to 7 Oct 2026). support.claude.com/en/articles/12138966-release-notes

[2] Anthropic. Claude Cowork and chat are now one Claude (16 Sep 2026). claude.com/resources/articles/cowork-is-now-claude

[3] Anthropic. Introducing Claude Opus 5.5 (22 Sep 2026). www.anthropic.com/news/claude-opus-5-5

[4] Anthropic. Claude plans: which models each plan has. claude.com/pricing

[5] Anthropic. Change the model, effort, and thinking settings. support.claude.com/en/articles/8664678-change-the-model-effort-and-thinking-settings

[6] Anthropic. Claude now works with Google Docs, Sheets, and Slides (6 Oct 2026). claude.com/blog/claude-now-works-in-google-docs-sheets-and-slides

[7] Anthropic. Get started with connectors. claude.com/docs/connectors/overview

[8] Anthropic. Choosing the right Claude model (Claude Academy). academy.claude.com/tutorials/choosing-the-right-claude-model

[9] Anthropic. Usage Policy, the version headed “Effective November 12, 2026”. www.anthropic.com/legal/aup

[10] OpenAI. ChatGPT release notes (entries of 14 Sep to 7 Oct 2026). help.openai.com/en/articles/6825453-chatgpt-release-notes

[11] OpenAI. ChatGPT Work and Codex. help.openai.com/en/articles/20001275-chatgpt-work-and-codex

[12] OpenAI. GPT-6 and other models in ChatGPT. help.openai.com/en/articles/20001354-gpt-6-and-other-models-in-chatgpt

[13] OpenAI. Introducing GPT-6.1 Sol (29 Sep 2026). openai.com/index/introducing-gpt-6-1-sol/

[14] OpenAI. Managing app permissions in ChatGPT. help.openai.com/en/articles/20001495-managing-app-permissions-in-chatgpt

[15] OpenAI. Custom GPT retirement and migration FAQ. help.openai.com/en/articles/20001519-custom-gpt-retirement-and-migration-faq

[16] Google. Gemini Apps release notes (entries of 30 Sep and 13 Oct 2026). gemini.google/release-notes/

[17] Google. About Gemini models (Gemini Apps Help). support.google.com/gemini/answer/18648722

[18] Google. Workspace Updates: skills in the Gemini app and Workspace, and what’s next for Gems (30 Sep 2026, updated 13 Oct 2026). workspaceupdates.googleblog.com/2026/09/skills-gemini-app-workspace.html

[19] Google. About the transition from Gems to skills (Gemini Apps Help). support.google.com/gemini/answer/18560919

[20] European Union. Regulation (EU) 2026/1744, the Digital Omnibus on AI: Article 5 points (ba) and (bb), paragraphs 1a and 1b; Article 111(4); Article 113 (OJ 24 Jul 2026). eur-lex.europa.eu/eli/reg/2026/1744/oj/eng

[21] European Union. Regulation (EU) 2024/1689, the AI Act: Article 50(2) and Annex III, point 4. eur-lex.europa.eu/eli/reg/2024/1689/oj/eng

Left out this month: Automatic switching to Thinking retired for Plus and Pro (14 Sep 2026: before this window); Dots, ChatGPT’s always-on agents (29 Sep) (Pro and Business Premium only, still rolling out; most office workers will not need them yet); Developer news: Codex Cloud, Claude Code updates, Antigravity in the Gemini Mac app (Developer tools, not team settings); Plan and allowance changes in ChatGPT (29 Sep) and Claude (7 Oct) (Prices and allowances: see the vendor’s page); Personal features: shopping, finances, health (Not team work); The Meetings plugin (29 Sep, beta), audio uploads (6 Oct), Dashboards and Motion in Claude (8 Oct, beta) (Real, but cut for space).

 

Every item as of Oct 2026, read on the vendor’s own page on 16 Oct 2026. Sources: Checked against, above. These products change monthly: check the settings in your own tool. Neosaipien is not affiliated with Anthropic, OpenAI or Google. Not legal advice.

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Neosaipien is AI training and consulting for leaders and teams: the Leadership briefing, Executive coaching, the Team workshop, Workflow automation and AI implementation. neosaipien.com  |  samson@neosaipien.com