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

# Agent freeze (kill switch)

> In-place irreversible freeze via POST /v1/me/freeze — D178 Part 1, API v1.

## What it is

**Agent freeze** is an in-place **kill switch** for a registered agent: it sets `agents.frozen_at` (UTC) and blocks normal API use without rotating keys or transferring custody.

Shipped in **D178 Part 1** (free on all tiers). Discoverable under **`GET /v1/capabilities`** → `security.freeze` and MCP `lithtrix_freeze`.

## Request

```http theme={null}
POST /v1/me/freeze
Authorization: Bearer ltx_...   # root key only
```

* **Root `ltx_*` required** — scoped sub-keys cannot freeze the parent.
* **Idempotent** — repeat calls return the same `frozen_at` timestamp.
* **Irreversible via API v1** — there is no self-service unfreeze; operator recovery is out of scope for this route.

## What freeze does

| Effect         | Detail                                                            |
| -------------- | ----------------------------------------------------------------- |
| Bearer auth    | Blocked for most routes after freeze                              |
| Still allowed  | `GET /v1/capabilities`, `GET /v1/me`, `POST /v1/me/freeze`        |
| Swarm children | Scoped sub-keys get **403** `PARENT_AGENT_FROZEN` at auth         |
| Delegations    | Active delegations where this agent is **parent** are invalidated |
| Task trace     | Append denied for frozen agents                                   |

Enforcement applies to **Lithtrix API calls** authenticated with Lithtrix keys — not to local model runtime or off-platform actions.

## Not the same as

| Mechanism              | Difference                                                          |
| ---------------------- | ------------------------------------------------------------------- |
| **Custody transfer**   | Changes holder / epoch; freeze keeps the DID in place               |
| **Recovery / rebirth** | Rotates root key and opens a new epoch; freeze does not rotate keys |
| **Key revoke**         | Revokes one key material; freeze blocks the agent identity          |

See [Custody and recovery](/custody-and-recovery).

## MCP

Tool definition: `GET /mcp/v1/lithtrix-freeze.json` — same semantics as the HTTP route.