If you're using a custom statusline script, you can add cache health monitoring to catch when your prompt cache is getting thrashed. Here's what to add and what it means.
What it tracks: The ratio between cache_read_input_tokens (cheap, reused from cache) and cache_creation_input_tokens (expensive, rebuilding cache). When cache reads drop to zero while creation stays high, you're paying full price every turn instead of getting the ~90% cache discount.
Add this near the top where you parse the statusline JSON input: