Fix daily layer-package split jobs failing on first artifact

[michaelneale]

What this fixes

The daily automated layer-package split jobs (Queue Unsloth layer packages, cron 23 17 * * *) have been failing every day for ~10 days. Every run — across different models — died after ~2 minutes on the very first artifact:

Uploaded and removed shared/metadata.gguf (10944320 bytes)
gguf_init_from_file: failed to open GGUF file '.../shared/metadata.gguf' (No such file or directory)
Error: open package artifact .../shared/metadata.gguf
Caused by:
    ModelError: failed to open GGUF model metadata

After this change, split jobs run to completion again: no code or infra change is needed on the runner side, because each HF Job builds skippy-model-package from main at job start, so the next scheduled run picks up the fix automatically.

Root cause

write_package_artifact invoked the --after-artifact-command upload hook before reopening the artifact to record its tensor count, byte size, and sha256. The production upload hook in split-model-job.sh uploads each artifact and then unlinks it locally (by design, to stay under the HF Jobs ephemeral storage limit). So the reopen hit a file that had already been deleted, failing on the first artifact (shared/metadata.gguf).

The neighboring copy_projector_artifact already did this correctly — read metadata first, run the hook last. This change makes write_package_artifact use the same ordering.

Validation

Reproduced and verified with the real write-package binary against a real GGUF (unsloth/Qwen3.5-0.8B-GGUF:Q4_K_M), using a hook that mimics production (record upload, then rm -f the file):

	Before	After
Exit code	1 (exact production error)	0
Artifacts processed	dies on #1	all 27 (metadata + embeddings + output + 24 layers)
Manifest	never written	correct sha256 / bytes / tensor_count for every artifact, despite all files being deleted by the hook

Added a regression test (artifact_hook_tolerates_a_hook_that_deletes_the_uploaded_file) that runs a deleting hook and asserts success.

• cargo test -p skippy-model-package — 24 passed
• cargo test -p model-package — 9 passed
• cargo clippy -p skippy-model-package --all-targets -- -D warnings — clean
• cargo fmt --all --check — clean

Summary by CodeRabbit

• Bug Fixes

  • Packaging now completes successfully even if a post-processing hook moves or deletes the artifact file.
  • Artifact details are collected earlier, so packaging can still report the correct metadata after the file is no longer present.

• Tests

  • Added a regression test covering hooks that delete the uploaded artifact file while packaging still succeeds.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 8dc313d7-d685-4bfa-925f-828afb0d371a

📥 Commits

Reviewing files that changed from the base of the PR and between b4b33ef and 0bf3923.

📒 Files selected for processing (1)

• crates/skippy-model-package/src/main.rs

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📝 Walkthrough

Walkthrough

The change reorders write_package_artifact so artifact metadata (tensor list, sizes, sha256) is read before invoking ArtifactHook, preventing failures when a hook deletes or moves the artifact file. A regression test validates this behavior.

Changes

Artifact packaging hook fix

Layer / File(s)	Summary
Reorder metadata collection before hook invocation crates/skippy-model-package/src/main.rs	write_package_artifact reads tensor metadata, file size, and sha256 before calling run_artifact_hook, with a comment noting the hook may delete/move the file.
Regression test for hook deleting artifact crates/skippy-model-package/src/main.rs	Adds artifact_hook_tolerates_a_hook_that_deletes_the_uploaded_file test confirming success when the hook removes the artifact, and updates test imports.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main fix: daily layer-package split jobs failing on the first artifact.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/layer-package-split-artifact-hook-ordering

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