agent_session_current_id()

Return the innermost active agent session id for the currently executing VM thread.

Signature

agent_session_current_id() -> string | nil

The builtin returns:

• the active session_id while code is running inside an agent_loop(...) turn, subscriber callback, or other session-scoped callback
• nil when no agent session is active

Why it exists

Session management builtins like agent_session_snapshot(id), agent_session_fork(id, dst?), and agent_session_trim(id, keep_last) operate on explicit ids. agent_session_current_id() lets nested handlers discover "the session I am currently executing under" without threading that id through every layer manually.

Example

let session = "support-thread"

agent_subscribe(
  session,
  { ev ->
  if ev?.type == "iteration_end" {
    let current = agent_session_current_id()
    if current != nil {
      agent_inject_feedback(current, "iteration_marker", "just finished an iteration")
    }
  }
},
)

Use Sessions for the broader storage and lifecycle model.