> ## Documentation Index
> Fetch the complete documentation index at: https://docs.automate.ax/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Automate.ax automations are TypeScript programs.
> Use Bun for installation and command examples.
> Use Automate.ax for the product name and automate.ax for the package, CLI, and domain.
> Treat documented public APIs as current; do not invent transitional or deprecated names.

# Reply to thread

> Post a reply inside an existing Slack message thread.

`replyToThread` posts beneath a parent message. Use the parent's `timestamp`, not
a reply timestamp, as `threadTimestamp`.

## Example

```ts automations/reply-to-slack-thread.automation.ts theme={null}
import { automation } from "automate.ax"
import { onAppMention, replyToThread } from "automate.ax/slack"

export default automation("Reply to Slack mentions", () => {
  const mention = onAppMention()
  replyToThread({
    conversation: mention.conversationId,
    threadTimestamp: mention.message.timestamp,
    text: "I received your request.",
  })
})
```

## Inputs

| Input                         | Type                                             | Required          | Default         | Description                                                                        |
| ----------------------------- | ------------------------------------------------ | ----------------- | --------------- | ---------------------------------------------------------------------------------- |
| `conversation` / `channel`    | `string`                                         | Yes               | —               | Conversation containing the parent. If both aliases are supplied, they must match. |
| `threadTimestamp`             | `string`                                         | Yes               | —               | Parent message timestamp.                                                          |
| `replyBroadcast`              | `boolean`                                        | No                | `false`         | Also shows the reply in the conversation timeline.                                 |
| `text`                        | `string`                                         | One content field | —               | Plain-text content or fallback.                                                    |
| `blocks`                      | `Record<string, JsonValue>[]`                    | One content field | —               | Up to 50 Block Kit blocks.                                                         |
| `attachments`                 | `Record<string, JsonValue>[]`                    | One content field | —               | Up to 100 legacy attachments.                                                      |
| `unfurlLinks` / `unfurlMedia` | `boolean`                                        | No                | Slack default   | Link and media unfurl behavior.                                                    |
| `account`                     | `string \| IntegrationAccountReference<"slack">` | No                | Project default | Slack binding.                                                                     |

## Output

Returns the reply's `conversationId`, `timestamp`, and normalized `message`.
The result's timestamp identifies the reply; continue using the original parent
timestamp to address the thread.