libra media

FastCDC LFS media chunking client (lore.md §6) — a feature-gated Libra extension (fastcdc, compiled only into builds with --features fastcdc; absent from the default binary). It content-defines chunks of a media file, builds a versioned manifest, stores chunks in a private local store, reassembles and verifies them, and negotiates a remote's chunked-LFS capability with a safe fallback to standard Git LFS.

media is a Libra-only extension (intentionally-different): Git has no media chunking concept. The Git object graph is never touched — a chunk is never a Git object ID, and chunks/manifests live in a private .libra/media/ store that is a sibling of objects/. The media_oid is always SHA-256 of the full file (independent of core.objectformat), byte-identical to a standard LFS pointer OID.

Subcommands

Subcommand	Description	Example
chunk <path> [--store]	FastCDC-chunk a file and emit its manifest; --store persists chunks + manifest to .libra/media.	libra media chunk big.psd --store
inspect <manifest>	Parse and validate a manifest JSON file.	libra media inspect .libra/media/manifests/<oid>.json
verify <path> | --media-oid <oid>	Reassemble from the local chunk store and verify the full media_oid (never publishes a corrupt file).	libra media verify big.psd
probe [--remote <name>]	Probe the remote's media capability endpoint and report the transfer decision (chunked vs standard-LFS fallback).	libra media probe --remote origin
--json	Structured JSON envelope on stdout (global flag).	libra --json media chunk big.psd

Safe fallback

media probe reports one of: chunked (fastcdc-v1) (a fully compatible Libra-aware media server), standard-lfs (fallback) with a reason (no capability endpoint, disabled by server, incompatible algorithm, disabled by repo policy, unknown higher version, or a server error after backoff), or blocked (the server keeps no standard fallback object AND no local complete object exists — a chunk-only upload is refused rather than silently produced). Against every reachable remote today — none of which run the (frozen) Libra media server — the decision is a standard Git LFS fallback.

Deferred

The Libra-aware media server (real cross-machine chunked upload/download, capability + chunk + manifest-finalize endpoints, the manifest lifecycle, GC/fsck/heal, and every anti-side-channel guarantee) is frozen in lore.md §6.5–6.8 and not part of this client v1. Chunk-only repo policy (dropping the standard LFS fallback object) and range-based hydration are also deferred.

Examples

libra media chunk big.psd                 # chunk a file; print the manifest summary
libra media chunk big.psd --store         # also persist chunks + manifest locally
libra media inspect .libra/media/manifests/<oid>.json
libra media verify big.psd                # reassemble from the store and verify media_oid
libra media probe --remote origin         # capability-probe; falls back to standard LFS
libra --json media chunk big.psd          # structured JSON output for agents