The session thread object

⚠️

Preview — this feature is being built; the design below is the spec.

The session_thread object as the API returns it. Every field below appears in every response that returns this object; fields with no value are null rather than missing.

Example

{
  "id": "thr_01JCC2E4G6J8L0N2Q4S6",
  "type": "session_thread",
  "session_id": "sesn_01JC7M2K4P6R8T0V2X4Z",
  "role": "delegate",
  "parent_thread_id": "thr_01JCC1D3F5H7K9M1P3R5",
  "agent_id": "agt_01JCC0B2D4F6H8K0M2P4",
  "agent_version": 2,
  "title": "Check carrier tracking for order 88123",
  "status": "interrupted",
  "usage": {
    "input_tokens": 6120,
    "cached_input_tokens": 4096,
    "output_tokens": 388,
    "cost_usd": "0.0112"
  },
  "created_at": "2026-11-05T10:02:10Z",
  "ended_at": "2026-11-05T10:02:30Z"
}

Fields

Field	Type	Description
`id`	string	Starts with `thr_`.
`type`	string	The object type, always `session_thread`.
`session_id`	string	The related session.
`role`	string	`primary` for the session’s main conversation, `delegate` for a sub-agent the primary handed work to.
`parent_thread_id`	string or null	The thread that started this one; `null` for the primary thread.
`agent_id`	string	The agent running in this thread. Delegates run the agent named in the parent’s `delegates` list.
`agent_version`	integer	See the endpoint pages below.
`title`	string	Display title.
`status`	string	`running`, `idle`, `completed`, `failed` or `interrupted`.
`usage`	object	Tokens and cost for this thread alone. The session’s `usage` is the sum of all threads.
`created_at`	string	When it was created, RFC 3339 UTC (some older objects use Unix seconds).
`ended_at`	string	See the endpoint pages below.

Returned by

session_resource skill

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