[hub] Add download command to the CLI

[assafvayner]

Adds a download command group to the @huggingface/hub CLI, one subcommand per download library function.

Subcommands

command	library fn	destination
hfjs download file <repo> <path> [local-path]	downloadFile	arbitrary local path (default: basename in cwd), with a progress bar
hfjs download cache <repo> <path>	downloadFileToCacheDir	HF cache dir
hfjs download snapshot <repo>	snapshotDownload	HF cache dir (whole repo)

Common flags on all three: --repo-type {dataset|model|space}, --revision, --token, --quiet/-q. cache/snapshot also accept --cache-dir. Repo type can be given via flag or name prefix (datasets/...). Downloads use Xet (file passes xet: true explicitly; cache/snapshot inherit Xet-on by default).

download file on a missing file prints an error and exits non-zero without creating a file.

Implementation

• New streamBlobToFile util streams a lazy Blob to disk with a cumulative-progress callback, removing the partial file on error. It's extracted from the CLI so it's unit-testable (cli.ts runs on import).
• cli.ts gets the download command group, modeled on the existing branch/repo groups.
• README updated with examples.

Testing

• Unit tests for streamBlobToFile (exact bytes, cumulative progress, error cleanup).
• Manual end-to-end against public repos: file (default + explicit path, quiet), not-found → exit 1 with no file, cache, and snapshot.

---

Note

Low Risk
Additive CLI and docs only; reuses existing library download functions with local file writes guarded on missing files.

Overview
Adds a download command group to the @huggingface/hub CLI so users can pull Hub content from the terminal, mirroring existing upload flows.

download file fetches one file via downloadFile (with xet: true), streams it to a local path (default: basename in cwd) using new streamBlobToFile (progress callback, deletes partial files on failure), optional cli-progress bar, and exits non-zero without writing when the path is missing. download cache and download snapshot call downloadFileToCacheDir and snapshotDownload into the HF cache (optional --cache-dir).

All subcommands share --repo-type, --revision, --token, and --quiet, with help wired like branch. The hub README documents npx/hfjs download examples and help download.

^{Reviewed by Cursor Bugbot for commit f9e1d4b. Bugbot is set up for automated code reviews on this repo. Configure here.}

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[coyotte508]

This doesn't really belong to a utils function, only used in cli, behavior too specific (eg catch error & unlink file)

[coyotte508]

@moonbot what's the huggingface_hub's hf cli syntax?