# Reasoning

A React component in [Beamline](https://beamline.io/)'s [AI & agents](https://beamline.io/components/ai) category. Live demo: https://beamline.io/components/reasoning

The agent's trace, fed by your stream: a shimmering label and the seconds so far while it works, then "Thought for N seconds"; steps that check off, prose thoughts, search sources or tool calls, open while running and folded when done.

## Use it for

- Showing what an agent did while thinking: steps, searches, code, collapsible afterwards.

## Not for

- The answer itself ([response](https://beamline.io/components/response)).
- Tool calls with inputs and outputs to inspect ([tool-call](https://beamline.io/components/tool-call)).
- A plan that needs approval ([plan](https://beamline.io/components/plan)).

## Anatomy

- header button: glyph, label (shimmer while running), seconds, chevron
- trace (ordered list with a guide line)
- query row (search)
- rows: step check or spinner / source glyph and link / prose / tool with +/− lines
- +N more
- polite announcement when a run finishes

## Variants

- **variant**: steps, reasoning, search, coding

## States

- running (open, shimmer, elapsed seconds)
- done (folded, "Thought for N seconds" or doneLabel)
- opened or closed by the person (kept until a new run)
- controlled (open / onOpenChange)

## Keyboard

- Enter/Space on the header toggles the trace (aria-expanded)
- Closed traces are out of the Tab order
- Search rows are links

## Motion

The label shimmers while running (still under reduced motion); the trace opens on --motion-in and folds on --motion-out (disclosure-panel); a step that arrives while it runs grows to its height (enter-grow, --duration-morph) and rises in once (enter-rise), so the content below glides; the label eases to each new width (useWidthMorph) so the chevron glides instead of jumping.

## Props

| Prop | Type | Default | Description |
| --- | --- | --- | --- |
| `rows` (required) | `ReasoningRow[]` | — | { id?, primary, secondary?, mono?, add?, del?, href? } |
| `variant` | `"steps" \| "reasoning" \| "search" \| "coding"` | — |  |
| `status` | `"running" \| "done"` | — |  |
| `activeLabel / doneLabel / startedAt` | `string / string / number` | — |  |
| `query / more / icon` | `string / number / ReactNode` | — |  |
| `open / defaultOpen / onOpenChange` | `boolean` | — |  |
| `style / ref` | `CSSProperties / native Ref` | — |  |
| `classNames` | `ReasoningClassNames` | — |  |

## Built from

- [text-shimmer](https://beamline.io/components/text-shimmer)
- spinner

## Dependencies

`lucide-react`

## Import

```tsx
import { Reasoning } from "@/components/reasoning/reasoning";
```

## Get it

Reasoning is part of Beamline: 190 React components and screens your coding agent (Claude Code, Codex, Cursor or any MCP client) installs into your app through Beamline's MCP server, as a ready-built package or as plain React source you can change. $49 one payment (regular $200), no subscription, a year of updates, one licence for your whole team. [Get Beamline](https://beamline.io/checkout?pack=complete) · [Connect your agent](https://beamline.io/connect)

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