Side Questions Stay Out of the History, Not Off the Bill

In a long agent session, every turn you add stays in the context the agent reasons from for the rest of the run. In a dark software factory, where agents run long tasks unattended, keeping that context clean is part of keeping the output checkable. A side question should not join it, and it is not quite free either.

You are two hours into debugging why a fine-tuning run diverges at step 4,000. You want to recall which warmup schedule the session settled on an hour ago, without adding another turn to an already crowded context. Claude Code's /btw is built for that:

/btw which warmup schedule did we settle on?

The documented behavior is specific. The question and answer never enter the conversation history. A side question is described as low cost while the conversation's prompt cache is warm, costing little beyond the answer itself. Low cost is not free.

It also has no tools. A side question answers only from what is already in context: your messages, Claude's replies and the tool results gathered so far. It cannot open a config the session has not read, or check a library's current documentation. When you need that, press f in the overlay to fork the question into a subagent with full tool access, or ask in the main thread.

A check you can run in two minutes.

1. Run /context and note the size of the conversation.
2. Ask a /btw question and dismiss the answer.
3. Run /context again. The conversation should not have grown by the side exchange.
4. Ask /btw about a file the session has never opened. Expect an answer that says it cannot see it, or one that invents contents. If it invents, you have learned where not to trust it.

If the answer changes what you will do, bring the decision back into the main task, where it is recorded. Chapter 21 covers why what stays in context shapes every later answer.