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Claude Code weekly updates
Every week, what changed in Claude Code: new features, changed behavior and documentation updates, written from the official changelog and docs.
- Haiku 5.5 becomes the default Haiku, and sub-agents get their own effort and compaction window
Claude Haiku 5.5 is now the default Haiku model on the Anthropic API, with a 1M context window. The week also brings sub-agent effort and compaction controls, fail-closed hooks, and a new default MCP protocol version.