Feature Implementation with Tests

Implement the following feature:

Feature: {{feature_description}}
Acceptance criteria:
{{acceptance_criteria}}

Technical context:
- Framework: {{framework}}
- Relevant existing files: {{relevant_files}}
- Similar existing feature to reference: {{reference_feature}}

Implementation plan:
1. List all files that need to be created or modified
2. Implement the feature following the patterns in {{reference_feature}}
3. Write tests for every acceptance criterion
4. Update any shared types/interfaces affected by the change
5. Add/update API routes if the feature requires backend changes

Rules:
- Follow existing project conventions exactly (check the reference feature)
- No new dependencies without explaining why existing ones can't work
- Every user-facing string should be in the existing i18n pattern (if one exists)
- Handle loading, error, and empty states for any new UI components

Deliver as a list of files with their complete contents, ordered by dependency (types first, then backend, then frontend).