observability-anthropic-cache-cont-anthropic-messages-api-top-level-cache-control-fie-567c157a

THEN Add a CacheControl field to the AnthropicMessageRequest struct in types.go and ensure it is carried through the ToAnthropicChatRequest() conversion path. This preserves automatic prompt caching functionality without modification to content blocks.

type AnthropicMessageRequest struct {
    // ... existing fields
    CacheControl *schemas.CacheControl `json:"cache_control,omitempty"`
}