FE-1776: Remove the built-in AI chat and the aiAssistant prop

[kube]

Important

Removes the aiAssistant prop. Hosts provide the AI assistant with a plugin.

Summary

Before this PR, @hashintel/petrinaut shipped a built-in AI chat behind the aiAssistant prop, with its PetrinautAi* types and helpers. Demo site renders its assistants from plugins with its own chat, so nothing uses the built-in chat.

This PR removes the built-in chat. Assistant panel shows only a plugin's content, and an editor without an assistant plugin shows no assistant entry points. Library drops ai, @ai-sdk/react and react-markdown from its dependencies.

Links

• Ticket FE-1776
• Docs Writing a plugin › Provide the AI assistant
• Docs Plugin API reference
• Docs Embedding in a host application
• Docs Experiments in AI chat
• Docs The demo site's plugins

Changes

• aiAssistant prop removed from <Petrinaut>
• Built-in chat and its exports removed

  PetrinautAi* types, definePetrinautAiInteractiveTool, executePetrinautAiMutation, ExperimentExecutionCard and DefaultChatTransport leave /ui and the package root.
  Voice session store, voice components and the Storybook AI transport go with the chat.

• Editor shows an assistant only from a plugin

  Bottom bar button, toggle shortcut and empty-canvas prompt appear only while a plugin provides one.

• Empty-canvas prompt's built-in Voice button goes with the chat

  Prompt offers the assistant's start action alone.

• ai, @ai-sdk/react and react-markdown leave the library's dependencies

  Library build no longer keeps the AI SDK's declaration files out of its types.

• Petrinaut / With Assistant Plugin story renders an Echo assistant plugin

  It replaces the stories that ran the built-in chat against a scripted transport.

• README and architecture docs describe the assistant as a plugin

  Experiments in AI chat attaches to the website's chat.

• createPetrinautAiWritableCallbacks in @hashintel/petrinaut-core is deprecated

  Only core's own tests call it.

Next steps

• Remove createPetrinautAiWritableCallbacks from @hashintel/petrinaut-core

  Only its own tests call it after this PR.

Test coverage

• editor-assistant.test.tsx:

  Plugin content and title bar in the panel, Close handler order, start request until consumed, and a failing content that keeps the panel's frame.

• editor-view.test.tsx, ai-cta-modal.test.tsx, walkthrough/plugin.test.tsx:

  Adapted to an editor whose assistant comes from a plugin.

• Existing @hashintel/petrinaut and website unit suites

How to test

Petrinaut AI

• Open Petrinaut preview on Vercel
• Menu > New
• Submit Build an SIR model in prompt

  Expect panel titled AI and net built

Brunch

• Press ⌘K > Use Brunch
• Bottom bar > Show AI assistant

  Expect Chat and Ledger tabs in title bar

• Send Add a place called Queue

  Expect Brunch's reply and the place on the canvas

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Project	Deployment	Actions	Updated
hash	Ready	Preview	Oct 20, 2026 5:13pm UTC
petrinaut	Ready	Preview	Oct 20, 2026 5:13pm UTC
petrinaut-docs	Ready	Preview	Oct 20, 2026 5:13pm UTC

1 Skipped Deployment

Project	Deployment	Actions	Updated
hashdotdesign-tokens	Ignored	Preview	Oct 20, 2026 5:13pm UTC