CachePolicy

One per-content cache policy with two independent facets, threaded into every TileStore / FeatureStore. Defaults are unbounded — callers opt in to each axis.

1. Eviction (capacity) — maxEntries deletes data to keep the cache within bounds. Eviction sweeps on bind (a freshly-opened content is brought into bounds immediately) and via explicit evict(). There is no per-write trigger — high-frequency writers must call evict() themselves on a schedule that fits their workload.

2. Revalidation (freshness) — staleAfter is the stale-while-revalidate threshold. It never deletes; it only decides when an already-served tile is re-checked against the network in the background (see CachedTileSource / CachedTiledFeatureSource / CachedElevationSourceFactory).

staleAfter lives in the same bundle as the capacity cap because the store is the single component that owns both a cache's size and its age — but note it is a revalidation knob, not an evictor: it began as a TTL-eviction setting and was repurposed as the SWR trigger when the cache moved to stale-while-revalidate, so it never deletes despite sitting beside maxEntries.

• maxEntries caps the number of cached rows / tiles. Evicts. This is the only capacity cap — a byte budget was removed because the byte-accounting paths needed SUM(size) scans, couldn't be kept transactional under concurrent writes, and dominated startup time when the cache was even mildly over-budget. Entry count is a close-enough proxy for raster tiles (~50 KB each, fairly uniform) and 3D-Tiles content (~5–50 KB, ~10× variance). Pick a row cap that matches your target footprint at the dataset's typical row size.

• staleAfter revalidation staleness threshold, by write time. Never evicts. A missing freshness stamp is treated as epoch 0 (immediately stale) so the first read kicks one revalidation pass that stamps it, rather than freezing the tile as un-refreshable.

Bulk-refresh sources (WFS, Shapefile) only meaningfully honor staleAfter — the snapshot is atomic, so capping by entries would corrupt it. Tile-pyramid sources honor both.