session/contextUsage

A provider-reported context-occupancy fact folded to a changed (windowTokens, usedTokens, pressure) triple.

Parameters

Type: SessionContextUsageParams

session/contextUsage params: context-window pressure — the counted-once occupancy at the latest provider-reported durable fact, joined with the host’s pressure basis. Replace wholesale; emitted only when the (windowTokens, usedTokens, pressure) triple changes value (identical adoptions emit nothing).

Field	Type	Stability	Presence	Description
pressure	ContextPressureLevel		required	Server-computed pressure level over the basis thresholds.
sessionId	string		required	The owning session.
sourceRange	SourceRange		required	The durable records this event folded from.
usedTokens	integer		required	Counted-once prompt tokens plus output tokens of the driving record, saturating — the honest occupancy floor.
viewCursor	string		required	Opaque, strictly monotonic view cursor.
windowTokens	integer		optional	The effective context-window size from the host’s pressure basis; absent when the basis has no limit — the limit part is omitted, never invented.

Source

schema/msp/experimental/msp.schema.json#/notifications/session~2FcontextUsage

{
  "description": "A provider-reported context-occupancy fact folded to a changed (windowTokens, usedTokens, pressure) triple.",
  "params": {
    "$ref": "#/$defs/SessionContextUsageParams"
  }
}