Module cache 

Binary scene cache: TOML stays source of truth; _cache/ holds content-hash-keyed, version-stamped binaries.

Pure logic lives here (hash, paths, encode/decode, stale matching); lib.rs owns the filesystem flow (load_cached).

Structs

CacheHeader

Header carried by every cache file: which container and scene versions it was written with, plus the exact source it came from.

Enums

CacheStatus

How a scene load resolved: cache hit, clean miss (no usable cache), or rebuild (cache existed but was stale/corrupt/mismatched).

Constants

CACHE_DIR_NAME

Sibling directory next to each scene file holding its binaries.

CACHE_EXT

Extension for cache files: <stem>.<content-hash>.bin.

CACHE_VERSION

Cache container version. A bump rebuilds every cache from TOML instead of misreading it.

Functions

cache_path_for

Cache path for a scene file + hex content hash: <scene_dir>/_cache/<stem>.<hash>.bin. The hash keys the cache, so any source change is a different file (old ones get pruned).

content_hash

Lowercase hex content hash used in cache filenames.

decode

Decode a cache payload. Bad magic, truncation, trailing bytes, or a version stamp that is not the live one all fail loudly — the caller falls back to TOML and says so, never silently reinterprets.

encode

Encode a scene document as a cache payload stamped with the live CACHE_VERSION and FORMAT_VERSION.

encode_with

Encode with explicit stamps (test hook: simulates version bumps without touching the live constants).

fnv1a_u64

FNV-1a 64-bit over bytes (same function as pite-assets, zero deps).

prune_stale

Remove sibling caches for scene_path whose hash differs from keep_hash_hex; returns removed paths. Best-effort: unreadable dirs or failed removals are ignored, never errors.