oh-my-opencode/src/hooks/atlas/session-last-agent.ts

import { findNearestMessageWithFields } from "../../features/hook-message-injector"
import { getMessageDir } from "../../shared"

export function getLastAgentFromSession(sessionID: string): string | null {
  const messageDir = getMessageDir(sessionID)
  if (!messageDir) return null
  const nearest = findNearestMessageWithFields(messageDir)
  return nearest?.agent?.toLowerCase() ?? null
}