`class TaskStore`

In-memory task registry with pub/sub for streaming and webhook delivery. Swap for a DB-backed implementation in production -- if the server crashes, in-memory tasks vanish and the client never gets notified.

Definitions

`def subscribe(task_id)`

Subscribe to task updates. Returns a Queue that will receive events. Each event is a Hash: type: :status|:artifact, data: Hash A nil sentinel signals stream end.

Implementation

def subscribe(task_id)
  queue = Thread::Queue.new
  @mutex.synchronize do
    task = @tasks[task_id]
    return nil unless task
    task.subscribers << queue
  end
  queue
end