Agent freeze (kill switch) - Lithtrix

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

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.

MCP

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