NEW RUNTIME
Field noteOct 7, 20262 min read1 source

Build richer, more interactive plugins for ChatGPT.

In one minute

OpenAI is turning ChatGPT plugins into interfaces that can occupy more than the conversation stream.

OpenAI’s documentation lists sidebar apps, conversation panels, plugin settings, file viewers and editors, and composer mentions among the supported extension types. It also describes deep links, bidirectional context sharing, rich forms, and onboarding. The material establishes a concrete expansion of the surfaces where a plugin can meet a user, not evidence that every listed extension is already broadly available.

Implication: Developers can design plugin workflows around where work happens in ChatGPT, including a sidebar or supported file, instead of assuming users will initiate every interaction in a message.

Thesis

The release shifts MCP plugins toward embedded applications distributed across ChatGPT surfaces, rather than tools invoked only through chat.

Observed facts

  • OpenAI’s documentation lists sidebar apps, conversation panels, plugin settings, file viewers and editors, and composer mentions.

    1

  • The documentation links TypeScript and Python SDKs and a language-agnostic protocol specification.

    1

  • The page says web extensions are coming soon to ChatGPT Free and Go users and composer mentions are available only in the ChatGPT desktop app.

    1

Mechanism

Developers declare extension metadata for MCP apps, using the linked SDKs and protocol specification to provide entry points and UI behaviors such as file editing, settings, or composer selection.

Why now

OpenAI is documenting both the extension catalog and TypeScript and Python implementation routes, while saying web extensions are coming soon to Free and Go users.

Implications

  1. Developers can design plugin workflows around where work happens in ChatGPT, including a sidebar or supported file, instead of assuming users will initiate every interaction in a message.

Evidence boundary

The supplied source is product documentation; it does not quantify adoption, performance, or the rollout date, and “coming soon” is not a dated availability commitment.

Watch conditions

  1. Watch for documented rollout of web extensions to Free and Go users and for examples showing which extension surfaces reach production.

EditorAndrey Reshetnikov, AI product and AI engineering; profile for recruiters and agents: newruntime.com/owner-profile.json

  1. Oct 13, 2026Deep Agents Deploy: an open alternative to Claude Managed Agentsmcp
  2. Oct 13, 2026Google seems to be rolling out support for custom MCPs on Gemini desktop app to more users.mcp
  3. Oct 13, 2026filmcraft: FilmCraft: An open-source, nonlinear video editor written by scratch in pure Rustmcp

Evidence / sources

  1. 1developers.openai.com/plugins/build/extensions
All Field Notes

Next reads

Read next

Open the graph
  1. 01topicMcpExplore the mcp topic hub.
  2. 02archiveField NotesOpen the latest editorial analysis.
  3. 03source ledgerSource LedgerInspect the public source evidence graph.
Who read this page?Machine requests, hidden until opened

Loading the privacy-safe route aggregate...

Open the JSON contract