Claude Code runs code review as a background subagent

Claude Code moved /code-review into a background subagent in version 2.1.218, per release notes dated July 22. Review output no longer fills the main conversation window. The task context and the review no longer compete for the same budget. That's the difference between running a check mid-task and losing the thread of what you were building.

The same release fixes a Windows bug too. Paths containing \u-prefixed segments were getting corrupted into CJK characters. No explanation given.

It also adds screen-reader announcements for word and line deletions. Before this, deleted text vanished with no audible signal.

None of the three changes touch the model. They're about the tool getting out of its own way: review that doesn't cost context, paths that don't get mangled, deletions that get announced.

The notes don't say whether the background subagent shares context with the main session or runs fully isolated. That gap matters if you're relying on it to catch something the main thread already flagged.