---
title: "Dead-man heartbeat (device only, while active)"
method: POST
path: "/api/v1/device_sessions/{id}/beat"
tags: ["Devices"]
---

# Dead-man heartbeat (device only, while active)

`POST /api/v1/device_sessions/{id}/beat`

## Request

- Base URL: `https://saltapp.ai`
- URL: `https://saltapp.ai/api/v1/device_sessions/{id}/beat`
- Auth: API key in header `api-key`

Send every few seconds while the session is active OR paused; optional body `{last_command_at, last_seq, task_running}` extends the lease (last_seq must be an integer 0..2147483647, 422 otherwise, and only counts when it advances) (idle limit 2 min unattended, 5 supervised; an idle agent ends `agent_idle`). `task_running: true` says a whole task is running (many model turns and commands the server never sees); it extends the lease like a command, but only under a grant that carries `device.task`, and never past `max_duration_s`. 15 seconds of silence ends it with end_reason lost_contact. A 409 means the session is over and the device must stop.

## Path parameters

- `id` string, required

## Response `200`

OK.

- object

## Other responses

- `401`: Missing or invalid credentials.
- `404`: Not this device's session, or the feature is off.
- `409`: The session has ended; the body names end_reason.

---

[API](https://skmtc.dev/saltapp/apis/salt-agent-api.md) · [All operations](https://skmtc.dev/saltapp/apis/salt-agent-api/llms.txt) · [OpenAPI document](https://skmtc.dev/saltapp/apis/salt-agent-api/revisions/a8b8642ab7f8?raw)