Module cache 

XDG content-addressable cache with the cache-id integrity-check mechanism.

A snapdir cache is just a local content-addressable store (the same sharded layout as a file:// store): objects live under <cache_dir>/.objects/<h[0..3]>/<h[3..6]>/<h[6..9]>/<h[9..]> and manifests under <cache_dir>/.manifests/<id…>. This module mirrors the cache-side integrity machinery of the Bash oracle:

• check_snapshot_integrity mirrors _snapdir_check_integrity (snapdir ~L1691): given a snapshot id and a cache directory, assert the manifest is present locally, then verify every file object referenced by the manifest hashes (BLAKE3) to the checksum it is filed under. This is the “verify a cached snapshot by its id” check at the heart of checkout/verify.
• verify_cache mirrors verify-cache (snapdir ~L1011): enumerate every object under .objects/*/*/*/*, recompute its hash, and compare the actual hash to the expected hash encoded by the object’s own sharded path (the path is the content address). Collect mismatches; when purge is set, delete the corrupt objects.
• flush_cache mirrors flush-cache (snapdir ~L1061): empty the cache directory, idempotent on a missing dir.

Per the library-purity principle this module performs no terminal I/O and reads no $HOME/XDG/environment for behavior. The cache directory is a parameter; the CLI lane resolves ${XDG_CACHE_HOME:-$HOME/.cache}/snapdir. Hashing is in-process via the Hasher abstraction (the shipped default is BLAKE3); we never shell out to b3sum. The sharded path layout is reused from crate::store (object_path/manifest_path); it is not reimplemented here.

Structs

CacheReport

Outcome of a whole-cache scan by verify_cache.

Enums

CacheError

Errors the cache integrity machinery can surface.

Functions

check_manifest_integrity

Like check_snapshot_integrity but for an already-loaded Manifest.

check_snapshot_integrity

Verifies a cached snapshot by its id — mirrors _snapdir_check_integrity.

flush_cache

Empties the local cache — mirrors snapdir flush-cache.

load_cached_manifest

Loads a cached manifest by snapshot id from cache_dir.

verify_cache

Verifies every object in the cache — mirrors snapdir verify-cache.