C# library selection

Same include/exclude rule as Python: measure local handoff. Brokers are category N. Job runners are not queues.

Decision

Decision	Libraries
Already in	Queue+lock, ConcurrentQueue, Channel, steal-deque, opt-in P/S/D
Added	BlockingCollection
Out — not a put/get queue	TPL Dataflow BufferBlock / ActionBlock (pipeline), Disruptor-net (event framework)
Out — not FIFO	ConcurrentStack, ConcurrentBag
Out — job / worker frameworks	Hangfire, Quartz.NET, MassTransit, Rebus, NServiceBus
Out — category N	RabbitMQ.Client, StackExchange.Redis, NATS.Client, Confluent.Kafka

BufferBlock was listed out of scope in DESIGN.md. It is a dataflow block, not a handoff primitive. Channel already covers async. Disruptor-net is a publish/handle framework, not Add/Take.

In this lab

Log name	Category	Why
Queue+lock	T / locked	Locked Queue<T> baseline. Already present.
ConcurrentQueue	T / concurrent	Lock-free-ish MPMC, non-blocking take. Already present.
BlockingCollection	T / concurrent	Stdlib blocking + bounding wrapper (default backing: ConcurrentQueue). The analog of Python queue.Queue. Added.
Channel	A	Async channel. Already present.