subagent/sendMessage

Queue a user note into a running child; admission-only ack, the note settles on the child session’s view stream.

Parameters

Type: SubagentInputParams

Params for subagent/sendMessage and subagent/followupTask: a child target plus the input body.

Field	Type	Stability	Presence	Description
body	string		required	The note/task text: trimmed with Unicode-whitespace semantics, rejected when empty after trimming, delivered trimmed with multibyte content byte-for-byte intact.
commandId	string		required	Client-minted UUIDv7 command id.
sessionId	string		required	Target session (UUIDv7 string; preamble).
subagentId	string		required	Durable child id (the item’s subagentId; opaque string).

Source

schema/msp/experimental/msp.schema.json#/methods/subagent~2FsendMessage

{
  "description": "Queue a user note into a running child; admission-only ack, the note settles on the child session's view stream.",
  "params": {
    "$ref": "#/$defs/SubagentInputParams"
  },
  "result": {
    "$ref": "#/$defs/CommandAcceptedResult"
  }
}