When Claude Code routes through OmniRoute (Claude → OmniRoute → Claude),
OmniRoute was stripping all cache_control markers and replacing them with
its own generic caching strategy. This broke Claude Code's carefully
placed cache breakpoints for plans and other features.
Changes:
- Add preserveCacheControl parameter to prepareClaudeRequest()
- Detect Claude passthrough mode (sourceFormat === targetFormat === CLAUDE)
- Skip cache_control normalization when preserveCacheControl=true
- Preserve client's cache_control markers in system, messages, and tools
This ensures Claude Code's prompt caching optimization works correctly
while maintaining OmniRoute's caching strategy for translation scenarios.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
