namespace AcDream.Content;

/// <summary>
/// Hit/miss/eviction counters for one bounded content cache. 2026-07-24
/// measurement-tooling review: the canonical checkpoint JSON tracked cache
/// residency (entry/byte counts) but never hit/miss traffic, so "does a
/// revisit portal hit or miss the caches" was unanswerable from the
/// artifact alone. Each cache accumulates its own counts via
/// <see cref="System.Threading.Interlocked"/> — mesh preparation runs on up
/// to four concurrent workers — and exposes them through this public,
/// cross-assembly-safe struct so <c>AcDream.App</c> diagnostics can read
/// them without taking the cache's internal lock.
/// </summary>
public readonly record struct CacheStats(long Hits, long Misses, long Evictions)
{
    public static CacheStats operator +(CacheStats a, CacheStats b) =>
        new(a.Hits + b.Hits, a.Misses + b.Misses, a.Evictions + b.Evictions);
}