Reasoning Stream

Agent reasoning trickling through a two-line window, collapsing to a summary that expands into the transcript.

• Category: Transitions
• Licence: Charcoal UI Pro
• Built with: React 19, Tailwind CSS 4, Motion
• Dependencies: motion, clsx, tailwind-merge

Examples

Reasoning Stream

API reference

About Reasoning Stream

Reasoning Stream trickles agent reasoning through a two-line window, then collapses to a summary that expands into the full transcript.

Reasoning Stream is an UI transition for React 19, styled with Tailwind CSS 4 and animated with Motion. It drops into Next.js, Vite, Remix or Astro through the shadcn CLI as a single file you own.

When to use Reasoning Stream

• AI agent interfaces.
• Chain-of-thought displays.
• Research assistants.
• Debugging tools.

How it works

Text scrolls inside a masked window and the summary expands with layout animation.

The change it animates is also announced to assistive tech, and the motion is short enough never to block what the user wants to do. With prefers-reduced-motion on, it holds still or settles instantly instead of animating.

Customizing Reasoning Stream

Every prop is documented in the API reference above with its type and default. The ones you will reach for first are listed here.

The Customize panel next to the preview lets you change summary, speed live, and the Code tab updates to match, so the snippet you copy already carries your values.

• thoughts (string[]).
• streaming (boolean).
• summary (string, default "Thought it through").
• speed (number, default 30): Words per second.

Goes well with Reasoning Stream

These transitions pieces share its tokens and motion language, so they sit together on one page without clashing.

• Card Resize: A React box that springs to the size of its content
• Notification Badge: A React notification badge that pops in and slides new counts in
• Page Transition: React page transitions: native-feeling push and pop between views
• Error Shake: A React error shake: a decaying head shake for wrong input
• Arrow Link: A React arrow link whose chevron grows a stem on hover, CSS only

Install Reasoning Stream

npx shadcn@latest add @charcoal/reasoning-stream

Reasoning Stream is part of Charcoal UI Pro. One seat unlocks all 300 Pro components, 107 landing-page sections and 100 full templates, for every personal and client project, with updates included. Add the @charcoal registry once with your access token, then the command above copies reasoning-stream.tsx into components/ui and installs clsx, tailwind-merge.

You own the file you install: no runtime package, no lock-in, nothing to keep in sync. Change it however your product needs.

See Charcoal UI Pro pricing · Pro setup

Frequently asked questions

How do I show an AI model's reasoning?

Feed the reasoning text into Reasoning Stream as it arrives. It trickles through a two-line window while the model works, then collapses to a one-line summary that expands into the full transcript.

How do I install Reasoning Stream?

Reasoning Stream is part of Charcoal UI Pro. Add the @charcoal registry to components.json with your access token, then run npx shadcn@latest add @charcoal/reasoning-stream. It copies reasoning-stream.tsx into components/ui and installs motion, clsx, tailwind-merge.

Is Reasoning Stream free for commercial use?

Reasoning Stream needs a Charcoal UI Pro seat, monthly or a one-time lifetime price. A seat covers unlimited personal and commercial projects, including client work, and every future Pro component.

Does Reasoning Stream work with Next.js?

Yes. It is a client component for React 19 styled with Tailwind CSS 4, so it works in the Next.js App Router and Pages Router, Vite, Remix and Astro.

Can an AI coding agent install Reasoning Stream?

Yes. Connect the Charcoal UI MCP server (https://charcoalui.com/mcp) to Claude Code, Cursor or any MCP client; get_component returns Reasoning Stream's props and get_install_command returns the exact command.

Reasoning Stream as Markdown · llms.txt