Claude Code 2.1.218 moves `/code-review` and every `context: fork` skill to background subagents by default

anthropics/claude-code·high signal

Shipped July 22: `/code-review` now runs as a background subagent so review output no longer floods the main conversation, and any skill declaring `context: fork` in frontmatter runs in the background by default, with `background: false` as the per-skill opt-out. This is the natural pairing for the 2.1.215 change that stopped `/verify` and `/code-review` from firing automatically — you now invoke them explicitly, but they cost you no main-thread context when you do. If you wrote fork skills expecting inline blocking behavior, they will now return control immediately; audit any skill whose output the next step depends on.