# Diagnostic Drill-Downs

## Problem

Aggregate health numbers are useful, but DJs need to understand what is behind
each number before they can trust it. A count like "60 missing tracks" should be
clickable enough to answer: which tracks, which saved paths, and why did Serato
Doctor count them?

## Architecture

The health engine remains responsible for aggregate scoring. The web layer adds
a separate `details` payload beside the existing health report so the UI can show
examples without changing the core score model.

The drill-down payload is intentionally capped. Serato Doctor should explain the
finding quickly in the local browser, not dump an entire user library into the
page.

## Edge Cases

- Smart/dynamic crate references stay excluded from old-reference scoring.
- The same missing filename can appear more than once in Serato's database.
- Duplicate filename and cloud-conflict groups are informational only.
- Suggested matches remain read-only evidence and must never trigger repair.
- Empty drill-downs should feel reassuring, not broken.

## Testing

- Web analysis should include detail sections for old crate references,
  suggested matches, unused tracks, duplicates, cloud conflicts, broken
  symlinks, and missing Serato database tracks.
- Static assets should expose clickable diagnostic hooks.
- Browser behavior should be verified manually when the local browser policy
  allows access to the development server.