Under the hood
Prompt-cache miss telemetry now records the specific reason for the miss.
Prompt-cache telemetry now records why a cache miss happened. The tracking data gains last_miss_cause (with tools_added, tools_removed, and system_char_delta detail) and miss_causes, backed by a lookup table mapping internal cause codes such as system_prompt_changed, betas_changed, and ttl_expired_5m to human-readable strings.