models
Reflection Beam: 501B open-weight model, weights later in October 2026
Reflection Beam is a 501B sparse MoE with 23B active parameters for coding and agent tasks; Reflection plans Apache 2.0 weights later in October 2026.
What changed in Claude Code during September 2026?
September 2026 added Opus 5.5, Sonnet 5.5, server-side auto-mode checks, AGENTS.md fallback, and tighter subagent controls.