# DevDay 2026: what it means for plugin builders > Plugin Extensions, MCP Events, Sign in with ChatGPT, dots and new admin controls: the DevDay 2026 announcements that matter if you build or use plugins. Published: 2026-09-30 · Updated: 2026-10-04 · By: Divy Chaurasia · Tags: news, devday For people who build or use ChatGPT plugins, the two DevDay 2026 announcements that matter most are **Plugin Extensions**, which let a plugin add sidebar apps, side panels, file viewers and editors, and richer forms to ChatGPT, and **MCP Events**, which let ChatGPT subscribe to updates from your MCP server and act on them. Around those sit Sign in with ChatGPT, plugins inside Sites, always-on agents called dots, and new workspace controls for admins. OpenAI held DevDay on September 29, 2026 in San Francisco and listed more than 20 announcements ([DevDay 2026 recap](https://openai.com/index/devday-2026-recap)). This post is based on OpenAI's [DevDay 2026 page in the ChatGPT docs](https://learn.chatgpt.com/docs/whats-new/devday-2026), the developer documentation linked from it, and live coverage from [Simon Willison](https://simonwillison.net/2026/Sep/29/openai-devday-2026-live-blog/) and [Latent Space](https://www.latent.space/p/ainews-openai-devday-2026-dots-61). Where coverage and docs disagree, we say so. ## The announcements that affect plugins | Announcement | What it does | Status at launch | Docs | | --- | --- | --- | --- | | Plugin Extensions | Sidebar apps, conversation panels, file viewers/editors, settings, rich forms | Available; Free and Go web support coming soon | [Build extensions](https://developers.openai.com/plugins/build/extensions) | | MCP Events | ChatGPT subscribes to server events via webhooks and acts on them | Requires MCP 2.0; Work chats and dots | [MCP Events](https://developers.openai.com/plugins/build/mcp-events) | | Sign in with ChatGPT | Users sign in to your app with ChatGPT; eligible Plus and Pro users can use their plan for AI requests | Commercial sign-in in limited trial | [Quickstart](https://developers.openai.com/siwc/quickstart) | | Sites with connected data | A Site can use each visitor's own connected plugins | Workspace-private Sites, where enabled | [Sites docs](https://learn.chatgpt.com/docs/sites#load-visitor-data-via-plugins) | | Dots | Always-on agents that work across connected apps | Rolling out gradually | [Dots](https://learn.chatgpt.com/docs/dots) | | Workspace connections, Team Tasks, Agent Security | Company-managed accounts, service-account tasks, tool and network policies | Enterprise features | [Agent Security](https://learn.chatgpt.com/docs/enterprise/agent-security) | | Codex Security Cloud | Scans connected GitHub repos via a plugin | Research preview | [Setup](https://learn.chatgpt.com/docs/security/setup) | ## Plugin Extensions: plugins that look like apps Until DevDay, a plugin's UI lived inside the conversation as a widget under a tool call. Plugin Extensions add new places for that UI. OpenAI's [extension reference](https://developers.openai.com/plugins/build/extensions) lists: - **Sidebar apps:** an entry in the global sidebar that opens your app fullscreen. - **Conversation panels:** your app opens beside a chat. - **File viewers and editors:** your app opens files with supported extensions, with reading, live updates and saving handled together. - **Plugin settings:** product-specific settings inside ChatGPT. - **Rich forms:** structured input, including choosing from images, returned to your tool. - **Composer mentions:** users find and @-mention your content in the composer. Desktop app only. - **Display modes, deep links, Model-App Context and plugin onboarding.** Extensions are declared in tool metadata. A sidebar entry, for example, adds an `"openai/ui"` block with `entrypoints: [{ type: "global" }]` next to the standard `ui.resourceUri`; `{ type: "thread" }` puts it in the conversation side panel, and `{ type: "file", extensions: [...] }` registers a file viewer. OpenAI publishes TypeScript and Python SDKs and a protocol spec in [openai/mcp-extensions](https://github.com/openai/mcp-extensions), plus a sample plugin called Bits & Bolts. The docs point to three early adopters. Canva uses sidebar tabs, Figma uses composer mentions, and Adobe uses file handlers to edit files with Acrobat and Photoshop in ChatGPT. > **app:** [Canva](https://chatgptplugins.directory/apps/canva): Create, resize, edit and review Canva designs from a chat > **app:** [Figma](https://chatgptplugins.directory/apps/figma): Create designs, diagrams and FigJam boards and ship them to code > **app:** [Adobe](https://chatgptplugins.directory/apps/adobe): Edit photos, videos and documents across Creative Cloud and Acrobat **What to keep in mind:** - Extensions build on the open MCP Apps standard. OpenAI's guidance is still to implement the portable standard first and add ChatGPT-specific features with feature detection and fallbacks. - Extensions on the web are not yet available to Free and Go users. If your audience is broad, your plugin must still work without them. - For rich forms, OpenAI-registered MCP servers need to support MCP's multi-round-trip request pattern. ## MCP Events: from request-response to subscriptions Plugins have always waited for the user to ask. With [MCP Events](https://developers.openai.com/plugins/build/mcp-events), a user can tell ChatGPT what to watch ("monitor #product-feedback for bug reports and open draft pull requests") and ChatGPT subscribes through your server. How it works, per OpenAI's docs: 1. Your server advertises an `events` capability and implements `events/list`, `events/subscribe` and `events/unsubscribe` on the same authenticated endpoint as your tools. 2. When a user asks to monitor something, ChatGPT calls `events/subscribe` with filters, a callback URL and a signing secret. 3. Your server verifies the callback with a signed challenge, then delivers matching events by webhook. 4. ChatGPT handles the event in the subscribed chat, following the user's instructions. **Requirements and limits:** - MCP Events in ChatGPT requires **MCP 2.0** (protocol version `2026-07-28`). - ChatGPT supports webhook delivery from the **draft** MCP Events specification. Polling, streaming and some draft control notifications are not supported. - It is available in Work chats on the web, in desktop Work chats with Cloud selected, and with dots. Workspace controls for event-triggered tasks apply. - Your server needs persistent subscription storage and outbound HTTPS to callback URLs, and must check that the user is allowed to see each event before subscribing them. Because the spec is a draft, expect changes. Treat this as something to prototype, not something to bet a launch on. ## Sign in with ChatGPT [Sign in with ChatGPT](https://developers.openai.com/siwc/quickstart) lets users create or link an account in your service with their ChatGPT identity, and lets eligible Plus and Pro users put AI requests in your app on their ChatGPT plan. At launch, commercial sign-in is a limited trial with selected partners, and plan usage is limited to open-source partners and selected private clients. Simon Willison's reaction in his live blog: "I've wanted this one for years!" Inside ChatGPT, the [plugins docs](https://learn.chatgpt.com/docs/plugins) say it is rolling out in beta for plugins including Airtable, GitLab, HubSpot, Notion, Supabase and Vercel. Signing in shares only name, email address and profile picture; it does not grant the plugin access to data or approve actions. For builders, it removes one step (account creation) from plugin onboarding, but you still need your own OAuth scopes for data access. ## Dots and agents that call your tools [Dots](https://learn.chatgpt.com/docs/dots) are always-on agents: you give one a goal and define what it can do on its own, and it works across connected apps on its own computer, reporting back for review. They are rolling out gradually to eligible accounts. For plugin builders, this changes who calls your tools. A dot may run your tools when no one is watching each step. That makes the basics more important: accurate `readOnlyHint` and `destructiveHint` annotations, server-side input validation, and narrow scopes. Our [security checklist](/blog/chatgpt-plugin-security-checklist) covers what users and admins will look for. ## Admin and enterprise controls Several enterprise announcements decide whether a workspace can use your plugin at all: - **Workspace connections** connect company-managed accounts; each connection uses the connected account's permissions. - **Team Tasks** run scheduled or event-triggered work through a team's service account and approved connections. - **Agent Security** lets admins control which tools agents can use and how they access files and the network. - **ChatGPT in Slack and Teams** brings ChatGPT into approved channels with the deployment's connected tools. If you sell to businesses, document which identity your plugin acts as (personal, shared or service account) and which actions are read-only. ## Codex and models - **Codex Security Cloud** scans connected GitHub repositories or monitors new commits through a Security Cloud plugin, in research preview. The existing Codex Security plugin is in our catalog. - **Reusable cloud environments** let Codex prepare and publish a dev setup that new tasks start from. - **GPT-6.1 Sol** offers near-Astra performance at one-fifth of GPT-6 Astra's standard API token prices, according to [OpenAI's launch post](https://openai.com/index/introducing-gpt-6-1-sol). If your plugin or agent backend calls the API, it is worth benchmarking. > **plugin:** [Codex Security](https://chatgptplugins.directory/plugins/codex-security): Security scanning for your codebase ## What was less clear - **"Marketplace."** Simon Willison's live notes record OpenAI launching an "OpenAI Marketplace" with a set of launch partners during the keynote. Other write-ups describe a B2B channel where enterprises can apply part of an existing OpenAI commitment to approved partner products ([Rohit AI](https://rohitai.com/blog/openai-plugin-marketplace-sign-in-chatgpt)), and [Latent Space](https://www.latent.space/p/ainews-openai-devday-2026-dots-61) mentions commitments applied to open models via Baseten. It does not appear on OpenAI's DevDay docs page, and nothing we found ties it to the Plugin Directory. We will update this when OpenAI documents it. - **Plan availability for dots.** Third-party coverage lists specific tiers; OpenAI's page says only "eligible accounts." ## What to do this week 1. **Read the extension reference** and decide if a sidebar app, panel or file viewer fits your product. Most plugins need none. 2. **Check your MCP version.** MCP Events needs MCP 2.0; plan the upgrade if you want event triggers. 3. **Audit tool annotations** before agents like dots call your tools unattended. 4. **Add skills** so ChatGPT and Codex use your tools correctly. See [Write a skill for ChatGPT and Codex](/tutorials/write-a-skill-for-chatgpt-and-codex). 5. **Test locally** with [MCP Inspector](/tutorials/test-mcp-server-with-inspector), then [publish your plugin](/tutorials/publish-a-chatgpt-plugin). New to the platform? Start with [Plugins vs apps vs MCP servers vs skills](/blog/plugins-vs-apps-vs-mcp-servers-vs-skills) and [Build your first ChatGPT app](/tutorials/build-your-first-chatgpt-app). Browse plugins at [/plugins](/plugins). ## Listings in this post - [Canva](https://chatgptplugins.directory/apps/canva.md): Create, resize, edit and review Canva designs from a chat - [Figma](https://chatgptplugins.directory/apps/figma.md): Create designs, diagrams and FigJam boards and ship them to code - [Adobe](https://chatgptplugins.directory/apps/adobe.md): Edit photos, videos and documents across Creative Cloud and Acrobat - [Codex Security](https://chatgptplugins.directory/plugins/codex-security.md): Security scanning for your codebase --- Source: https://chatgptplugins.directory/blog/devday-2026-what-it-means-for-plugin-builders · Index: https://chatgptplugins.directory/llms.txt · Independent and community-run. Not affiliated with or endorsed by OpenAI. ChatGPT is a trademark of OpenAI.