feat: add custom cover image support for datasets

[xuang7]

What changes were proposed in this PR?

This PR adds support for dataset owners to set a custom cover image from files within their dataset. This improves visual presentation and makes datasets easier to recognize on the hub/home page.

Changes:

• Database:

  • Added a cover_image column to the dataset table.
  • Stores cover image as {dvid}/{relative_path} format (e.g., v1/demo.png)

• Backend:

  • POST /api/dataset/{did}/update/cover – Set dataset cover image
    • Validates file type (.jpg, .jpeg, .png, .gif, .webp) and size (max 10 MB)
  • GET /api/dataset/{did}/cover – Get cover image with 307 redirect to presigned URL
    • Only accessible for public datasets

• Frontend:

  • Adds a “Set as Cover” button next to image files in the version file tree, button only visible for image file (.jpg, .jpeg, .png, .gif, .webp)
    
  • home page displays cover images on dataset cards with automatic fallback to default background

Public datasets display:

Before (default cover)	After (customized cover)

Any related issues, documentation, discussions?

Closes #4115

How was this PR tested?

Test cases include: path traversal rejection, absolute path rejection, invalid file type rejection, empty/null path rejection, unauthorized user rejection, private dataset access checks, and validateSafePath coverage.

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Claude for code review

[chenlica]

@aicam please review it first before @aglinxinyuan does it.

[aicam]

LGTM, left minor comments

[chenlica]

@xuang7 Please resolve those comments after they are taken care of.

[chenlica]

@aglinxinyuan Please review this PR.

[xuang7]

This PR is using a recently removed API (dataset/file). I’ll update the code soon.

[Copilot]

Pull request overview

This PR adds functionality for dataset owners to set custom cover images from files within their datasets, improving visual presentation on the hub/home page. However, there is a critical issue with the SQL migration file that must be addressed before merging.

• Added a cover_image column to the dataset table to store image paths in {dvid}/{relative_path} format
• Implemented a backend API endpoint (POST /api/dataset/{did}/update/cover) with file size validation (10 MB limit)
• Added UI controls in the file tree to set cover images for image files and display them on the hub/home page

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
sql/updates/17.sql	CRITICAL: Migration adds wrong column to wrong table (affiliation to user instead of cover_image to dataset)
sql/texera_ddl.sql	Adds cover_image column definition to dataset table schema
frontend/src/app/hub/component/browse-section/browse-section.component.ts	Implements cover image URL construction and fallback logic
frontend/src/app/hub/component/browse-section/browse-section.component.html	Updates template to use dynamic cover images with error handling
frontend/src/app/dashboard/type/dashboard-entry.ts	Adds coverImageUrl property to DashboardEntry type
frontend/src/app/dashboard/service/user/dataset/dataset.service.ts	Adds updateDatasetCoverImage service method with inconsistent API design
frontend/src/app/dashboard/component/user/user-dataset/user-dataset-explorer/user-dataset-version-filetree/user-dataset-version-filetree.component.ts	Adds image file detection and cover image setter functionality
frontend/src/app/dashboard/component/user/user-dataset/user-dataset-explorer/user-dataset-version-filetree/user-dataset-version-filetree.component.scss	Renames CSS class from delete-button to icon-button for reusability
frontend/src/app/dashboard/component/user/user-dataset/user-dataset-explorer/user-dataset-version-filetree/user-dataset-version-filetree.component.html	Adds "Set as Cover" button for image files in file tree
frontend/src/app/dashboard/component/user/user-dataset/user-dataset-explorer/user-dataset-version-creator/user-dataset-version-creator.component.ts	Initializes coverImage field to undefined in dataset creation
frontend/src/app/dashboard/component/user/user-dataset/user-dataset-explorer/dataset-detail.component.ts	Implements onSetCoverImage handler with error notification
frontend/src/app/dashboard/component/user/user-dataset/user-dataset-explorer/dataset-detail.component.html	Connects cover image event to handler
frontend/src/app/common/type/dataset.ts	Adds coverImage property to Dataset interface
file-service/src/main/scala/org/apache/texera/service/resource/DatasetResource.scala	Adds updateDatasetCoverImage endpoint with size validation but missing file type validation and tests

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[aglinxinyuan]

Please address the comments.

[chenlica]

@aicam Please take the lead to finish this PR.

[aicam]

Make sure to add test cases with corner cases

[aicam]

LGTM! just fix the comments and makes sure no logics are duplicate

[aicam]

I think one missing test is a correct test that should set cover and retrieve it

[xuang7]

I didn’t add “set cover successfully” tests because they would require a real file in storage. Would you like me to add test file setup? I could upload a minimal JPEG (a few hundred bytes) during the test setup to enable this kind of test.

[aicam]

Just create a JPEG image from empty byte array