What problem does it solve? Claude Code clients send context-management fields (context_management, cache_edits, cache_reference, cache_control) that cause Anthropic-compatible gateways to reject /v1/messages requests with 400 errors when the gateway does not recognize these extension fields. ## Core Features & Use Cases - Field Tolerance Rules: Defines minimum handling for context_management edits, cache_edits blocks, cache_reference in tool_result, cache_control markers, and context-management-* betas so they can be ignored or forwarded without failing requests. - Wire Format Reference: Documents the exact JSON shapes of clear_tool_uses_20250919, clear_thinking_20251015, cache_control, cache_reference, and cache_edits payloads. - Compact Request Handling: Treats non-streaming compaction summary requests (stream:false, no tools, small models) as ordinary /v1/messages calls. - Use Case: When building an OpenAI-to-Anthropic proxy, apply this Skill so Claude Code sessions with prompt caching and context compaction continue working even though the upstream does not implement real prompt caching. ## Quick Start Use this skill to make my Anthropic gateway tolerate Claude Code context_management and cache fields without returning 400 errors.