# How do I pin a Hugging Face download to an exact commit so a generation pipeline reproduces, and why is a branch or tag name not enough?

- id: art_01M5P4CRMNSP3YPWYEXZ2HQ59Y
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T08, T09, T20 · tags: none
- updated: 2026-10-24T04:58:34.509Z
- url: https://veyrul.com/articles/art_01M5P4CRMNSP3YPWYEXZ2HQ59Y

Problem. A workflow that downloads 'main' gets different weights after the repo owner pushes. Conditions. Any hf_hub_download, snapshot_download or hf download call. Method. Pass revision= (or hf://ID@REVISION) as a branch, tag, refs/pr/N or a FULL 40-character commit hash; record the hash that snapshot_download returns in the snapshot path. Short 7-character hashes are not accepted. A commit is immutable, so its file list is cached forever and a repeat download of the same commit needs no per-file network call. Failure modes. A branch or tag ref is re-resolved on each online run and refs/<branch> in the cache moves to the new commit; a mutable PR ref may change. Limitations. Pinning fixes which bytes you request, not whether they are safe to load (see C3-B710). Version/date: huggingface_hub docs main branch fetched 2026-10-24 (stamp per bibliography); behaviour may differ in older releases.

Problem. A workflow that downloads 'main' gets different weights after the repo owner pushes. Conditions. Any hf_hub_download, snapshot_download or hf download call. Method. Pass revision= (or hf://ID@REVISION) as a branch, tag, refs/pr/N or a FULL 40-character commit hash; record the hash that snapshot_download returns in the snapshot path. Short 7-character hashes are not accepted. A commit is immutable, so its file list is cached forever and a repeat download of the same commit needs no per-file network call. Failure modes. A branch or tag ref is re-resolved on each online run and refs/<branch> in the cache moves to the new commit; a mutable PR ref may change. Limitations. Pinning fixes which bytes you request, not whether they are safe to load (see C3-B710). Version/date: huggingface_hub docs main branch fetched 2026-10-24 (stamp per bibliography); behaviour may differ in older releases.

Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources.

Limitations: Docs do not say whether a force-pushed or deleted commit stays fetchable; whether a pinned hash protects against repo deletion is untested here.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://huggingface.co/docs/huggingface_hub/main/en/guides/download.md",
      "note": "Download from a specific version; Download an entire repository; Refs; Trees; researcher reasoning"
    },
    {
      "url": "https://huggingface.co/docs/huggingface_hub/main/en/guides/manage-cache.md",
      "note": "Download from a specific version; Download an entire repository; Refs; Trees; researcher reasoning"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Problem. A workflow that downloads 'main' gets different weights after the repo owner pushes. Conditions. Any hf_hub_download, snapshot_download or hf download call. Method. Pass revision= (or hf://ID@REVISION) as a branch, tag, refs/pr/N or a FULL 40-character commit hash; record the hash that snapshot_download returns in the snapshot path. Short 7-character hashes are not accepted. A commit is immutable, so its file list is cached forever and a repeat download of the same commit needs no per-file network call. Failure modes. A branch or tag ref is re-resolved on each online run and refs/<branch> in the cache moves to the new commit; a mutable PR ref may change. Limitations. Pinning fixes which bytes you request, not whether they are safe to load (see C3-B710). Version/date: huggingface_hub docs main branch fetched 2026-10-24 (stamp per bibliography); behaviour may differ in older releases. · locator: Download from a specific version; Download an entire repository; Refs; Trees; researcher reasoning · source: https://huggingface.co/docs/huggingface_hub/main/en/guides/download.md

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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