---
title: <Signal>
description: "A typed wrapper around <WaitForEvent> for external signals keyed by node id."
---

`<Signal>` is the ergonomic form of [`<WaitForEvent>`](/components/wait-for-event) when the signal name should match the node id and the payload should be typed by a Zod schema.

## Import

```tsx
import { Signal } from "smithers-orchestrator";
```

## Props

| Prop | Type | Default | Description |
| --- | --- | --- | --- |
| `id` | `string` | **(required)** | Signal name and node id. |
| `schema` | `z.ZodObject` | **(required)** | Typed payload schema and output target. |
| `correlationId` | `string` | `undefined` | Correlation key for matching a specific signal instance. |
| `timeoutMs` | `number` | `undefined` | Max wait time in ms. |
| `onTimeout` | `"fail" \| "skip" \| "continue"` | `"fail"` | Timeout behavior. |
| `async` | `boolean` | `false` | When `true`, unrelated downstream flow can continue while the signal is still pending. Explicit dependencies still wait for the payload. |
| `skipIf` | `boolean` | `false` | Skip this node entirely. |
| `dependsOn` | `string[]` | `undefined` | Task IDs that must complete first. |
| `needs` | `Record<string, string>` | `undefined` | Named deps. Keys become context keys, values are task IDs. |
| `label` | `string` | `signal:<id>` | Display label override. |
| `meta` | `Record<string, unknown>` | `undefined` | Extra metadata. |
| `children` | `(data) => ReactNode` | `undefined` | Optional typed render callback that mounts only after the signal payload exists. |

## Example

```tsx
import { Signal, Task, Workflow, createSmithers } from "smithers-orchestrator";
import { z } from "zod";

const { smithers, outputs } = createSmithers({
  feedback: z.object({
    rating: z.number(),
    comment: z.string(),
  }),
  summary: z.object({
    upper: z.string(),
  }),
});

export default smithers(() => (
  <Workflow name="signal-demo">
    <Signal id="user-feedback" schema={outputs.feedback} async>
      {(feedback) => (
        <Task id="summarize" output={outputs.summary}>
          {{ upper: feedback.comment.toUpperCase() }}
        </Task>
      )}
    </Signal>
  </Workflow>
));
```

## Behavior

- `<Signal>` renders a [`<WaitForEvent>`](/components/wait-for-event) internally with `event={id}` and `output={schema}`.
- Without `children`, it behaves like a plain typed [`<WaitForEvent>`](/components/wait-for-event).
- With `children`, the callback runs only after the payload has been received and validated.
- Async signal waits contribute to `smithers_external_wait_async_pending{kind="event"}` while unresolved.