context.usage

How full the harness’s context is. Drives the context ring; context stays per harness, never rolled up.

Direction: Harness → Chips
Sent by: a harness
Requires a run: yes
Schema: context.usage.json

Fields

Every event also carries the envelope.

Field	Required	Type	Description
v	yes	1	Protocol major version.
type	yes	"context.usage"
id	yes	string	The event’s own id. Stable across a retry of the same event.
ts	yes	string	When it happened, by Chips’ clock. Stamped on the way in; a value the sender writes is replaced.
workspace_id	yes	string	A workspace identifier: ws_ followed by a ULID.
space_id	no	string	The space, when the event belongs to one.
run_id	no	string	The run, when the event belongs to one.
seq	no	number	Assigned by the server on append, monotonic per workspace. Absent on the way in.
idempotency_key	no	string	Required on every client-originated write. Sending the same key twice is a no-op.
actor	yes	object	The participant an event is attributed to.
actor.kind	yes	"person" | "harness" | "agent" | "system"	Whether a person, a harness, one of a harness’s agents or Chips itself acted.
actor.id	yes	string	The participant id, or system for Chips.
actor.harness_id	no	string	For an agent: the harness it speaks through, whose budget and runs are the agent’s (ADR 0087). Filled in by Chips.
used_tokens	yes	number	Tokens currently held.
limit_tokens	yes	number	The window size.
model	yes	string	The model whose window this is.
compacted	no	boolean	True when the harness just compacted.

Example

{
  "v": 1,
  "type": "context.usage",
  "id": "evt_01K4ZQPX00000000000000006F",
  "ts": "2026-09-02T14:22:11.004Z",
  "workspace_id": "ws_01K4ZQPX000000000000000001",
  "space_id": "spc_01K4ZQPX000000000000000002",
  "actor": {
    "kind": "harness",
    "id": "hrn_01K4ZQPX000000000000000004"
  },
  "run_id": "run_01K4ZQPX000000000000000005",
  "used_tokens": 82000,
  "limit_tokens": 200000,
  "model": "opus-5",
  "compacted": false
}