feat: Reorder highlight items on favorite action

[chethan2106]

Description

This PR implements stable favorite ordering behavior for highlight set items so that favorites maintain deterministic insertion order and ranking updates correctly when items are unfavorited.

Related Jira: ENT-10610

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Overview

This change updates highlight favorite toggling logic to enforce stable sort behavior for favorited items:

• Favoriting an item places it just below the current lowest-ranked favorite (or at rank 0 if no favorites exist).
• Unfavoriting an item compacts subsequent favorite sort orders so there are no gaps.
• Retrieval now consistently returns favorites first, ordered by favorite rank, then by creation order for non-favorites.

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Changes Made

• Updated favorite toggle behavior in highlights.py
• Added transactional and locking safeguards for concurrent favorite updates in highlights.py
• Improved highlighted content query ordering and prefetch efficiency in highlights.py
• Updated serializer ordering fallback to match new backend ordering in serializers.py
• Added/expanded tests for boolean handling and favorite reordering behavior in test_curation_views.py

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Implementation Details

Favorite Toggle Logic

File: highlights.py

• Validates request inputs up front:

  • Missing content_uuid
  • Missing favorite parameter (supports explicit boolean false)
  • Invalid UUID values

• Uses transaction.atomic with row-level locks via select_for_update for consistency.

On favorite = true:

• Finds current max sort_order
• Assigns next position (max + 1), or 0 if this is the first favorite

On favorite = false:

• Resets unfavorited item:

  • sort_order = 0
  • is_favorite = false

• Decrements sort_order for favorites ranked below the removed item

• Ensures stable behavior under concurrent requests

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Retrieval Ordering

Files:

• highlights.py

• serializers.py

• Added shared ordering tuple:

  1. Favorites first
  2. Then sort_order
  3. Then created

• Prefetches highlighted content using ordered queryset in the view layer

• Serializer:

  • Uses prefetched data when available
  • Applies same ordering when not prefetched

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Tests Added / Updated

File: test_curation_views.py

• Verifies favorite accepts boolean false
• Verifies favoriting multiple items assigns stable ascending sort_order
• Verifies API response returns favorites first in correct order
• Verifies unfavoriting compacts remaining favorite sort_order correctly

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Additional CI Stability Updates Included

• Date-robust test fixture updates in factories.py
• Matching test expectation updates in test_tasks.py
• Lint suppression cleanup and model/migration alignment in models.py

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Testing

All mandatory checks passed locally:

make test
make quality
make validate
python manage.py makemigrations --check --dry-run
make check_keywords

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Acceptance Criteria (ENT-10610)

• Upon favoriting a highlight item, it moves just below the current lowest-ranked favorite
• If no favorites exist, newly favorited item is placed at top favorite rank
• Upon unfavoriting, subsequent favorite sort orders are adjusted to remove gaps
• Favorite ordering is stable and consistently reflected in highlight set responses

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Merge Checklist

• No new requirements added
• No new API endpoint introduced
• No new data model introduced
• No new migration required
• Tests updated to cover favorite reorder behavior
• Mandatory validation and quality checks passing

Sample Response:
Sort Favourites.txt