Claude Code v2.0.15 → v2.0.17: Haiku 4.5 + Explore subagent

[claude-yolo]

WHY users should care: New model selector with hybrid approach and efficient codebase search

Key Features:

• 🚀 Haiku 4.5 added to model selector
• 🧠 SonnetPlan mode - Sonnet for planning, Haiku for execution (automatic with Haiku 4.5)
• 🔍 Explore subagent - Haiku-powered efficient codebase search to save context

Note: 3P providers (Bedrock/Vertex) not auto-upgraded yet, manual via ANTHROPIC_DEFAULT_HAIKU_MODEL

Related PR: #389

[claude-yolo]

💤 Ancient version tracking - well established features