Function claimTask

src/utils/tasks.ts:541–612

(
  taskListId: string,
  taskId: string,
  claimantAgentId: string,
  options: ClaimTaskOptions = {},
)

 * if the agent owns any other open tasks before claiming.
 */
export async function claimTask(
  taskListId: string,
  taskId: string,
  claimantAgentId: string,
  options: ClaimTaskOptions = {},
): Promise<ClaimTaskResult> {
  const taskPath = getTaskPath(taskListId, taskId)

  // Check existence before locking — proper-lockfile.lock throws if the
  // target file doesn't exist, and we want a clean task_not_found result.
  const taskBeforeLock = await getTask(taskListId, taskId)
  if (!taskBeforeLock) {
    return { success: false, reason: 'task_not_found' }
  }

  // If we need to check agent busy status, use task-list-level lock
  // to prevent TOCTOU race conditions
  if (options.checkAgentBusy) {
    return claimTaskWithBusyCheck(taskListId, taskId, claimantAgentId)
  }

  // Otherwise, use task-level lock (original behavior)
  let release: (() => Promise<void>) | undefined
  try {
    // Acquire exclusive lock on the task file
    release = await lockfile.lock(taskPath, LOCK_OPTIONS)

    // Read current task state
    const task = await getTask(taskListId, taskId)
    if (!task) {
      return { success: false, reason: 'task_not_found' }
    }

    // Check if already claimed by another agent
    if (task.owner && task.owner !== claimantAgentId) {
      return { success: false, reason: 'already_claimed', task }
    }

    // Check if already resolved
    if (task.status === 'completed') {
      return { success: false, reason: 'already_resolved', task }
    }

    // Check for unresolved blockers (open or in_progress tasks block)
    const allTasks = await listTasks(taskListId)
    const unresolvedTaskIds = new Set(
      allTasks.filter(t => t.status !== 'completed').map(t => t.id),
    )
    const blockedByTasks = task.blockedBy.filter(id =>
      unresolvedTaskIds.has(id),
    )
    if (blockedByTasks.length > 0) {
      return { success: false, reason: 'blocked', task, blockedByTasks }
    }

    // Claim the task (already holding taskPath lock — use unsafe variant)
    const updated = await updateTaskUnsafe(taskListId, taskId, {
      owner: claimantAgentId,