[codex] Fix Fern preview metadata upload

[lbliii]

Summary

• include hidden files when uploading the Fern preview artifact
• preserve the existing .preview-metadata/ producer/consumer contract

Root cause

actions/upload-artifact v4 excludes hidden files by default. The Fern preview build stores the pull request number, head ref, and changed-file list under .preview-metadata/, so the companion workflow_run downloaded the Fern sources without that metadata.

As a result, HEAD_REF and PR_NUMBER were empty: Fern published to the shared preview-default identifier and the PR-comment request failed with HTTP 404. This affected draft and ready-for-review pull requests alike.

Example failed publisher run: https://github.com/NVIDIA-NeMo/Curator/actions/runs/28404447988

Validation

• workflow YAML parses successfully
• git diff --check passes
• the pinned actions/upload-artifact@v4.6.2 step receives its supported include-hidden-files input

The PR's own Preview Fern Docs: Build and subsequent Preview Fern Docs: Comment runs provide the end-to-end validation.

[copy-pr-bot]

This pull request requires additional validation before any workflows can run on NVIDIA's runners.

Pull request vetters can view their responsibilities here.

Contributors can view more details about this message here.

[github-actions]

🌿 Preview your docs: https://nvidia-preview-codex-fix-fern-preview-metadata.docs.buildwithfern.com/nemo/curator

[greptile-apps]

Greptile Summary

This PR fixes a one-line bug in the Fern docs preview CI workflow where .preview-metadata/ was silently dropped during artifact upload because actions/upload-artifact v4 excludes hidden files (dot-prefixed paths) by default.

• Adds include-hidden-files: true to the Upload fern sources and metadata step so the .preview-metadata/ directory — containing pr_number, head_ref, and changed_mdx_files — is correctly bundled into the fern-preview artifact and available to the downstream workflow_run publisher job.

Confidence Score: 5/5

Safe to merge — the change is a single-line targeted fix that restores the intended artifact upload behavior.

The fix correctly addresses the root cause: actions/upload-artifact v4 silently omits dot-prefixed paths unless include-hidden-files: true is set, and .preview-metadata/ is exactly such a path. The action is pinned to a SHA, the retention-days is unchanged, and no secrets or permissions are touched. The companion workflow_run consumer gains the metadata it always expected.

No files require special attention.

Important Files Changed

Filename	Overview
.github/workflows/fern-docs-preview-build.yml	Adds include-hidden-files: true to upload-artifact step so .preview-metadata/ is included in the artifact; fix is correct and minimal.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant PR as Pull Request (PR branch)
    participant Build as Preview Fern Docs: Build (pull_request trigger)
    participant Artifact as actions/upload-artifact v4 (fern-preview)
    participant Comment as Preview Fern Docs: Comment (workflow_run trigger)

    PR->>Build: push / PR open/sync
    Build->>Build: Checkout PR branch
    Build->>Build: Save PR metadata to .preview-metadata/
    Note over Build: .preview-metadata/ is a hidden dot-prefixed directory
    Build->>Artifact: Upload fern/ + .preview-metadata/ with include-hidden-files: true
    Artifact-->>Comment: Download fern-preview artifact (metadata now present)
    Comment->>Comment: "Read PR_NUMBER & HEAD_REF from .preview-metadata/"
    Comment->>Comment: Build Fern preview with DOCS_FERN_TOKEN
    Comment->>PR: Post preview URL as PR comment

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sequenceDiagram
    participant PR as Pull Request (PR branch)
    participant Build as Preview Fern Docs: Build (pull_request trigger)
    participant Artifact as actions/upload-artifact v4 (fern-preview)
    participant Comment as Preview Fern Docs: Comment (workflow_run trigger)

    PR->>Build: push / PR open/sync
    Build->>Build: Checkout PR branch
    Build->>Build: Save PR metadata to .preview-metadata/
    Note over Build: .preview-metadata/ is a hidden dot-prefixed directory
    Build->>Artifact: Upload fern/ + .preview-metadata/ with include-hidden-files: true
    Artifact-->>Comment: Download fern-preview artifact (metadata now present)
    Comment->>Comment: "Read PR_NUMBER & HEAD_REF from .preview-metadata/"
    Comment->>Comment: Build Fern preview with DOCS_FERN_TOKEN
    Comment->>PR: Post preview URL as PR comment

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_{Reviews (2): Last reviewed commit: "Merge branch 'main' into codex/fix-fern-..." | Re-trigger Greptile}

[lbliii]

/ok to test 6906c88