id: DATA-DB-003
title: Databento Cache Management
status: backlog
priority: medium
dependencies:
  - DATA-DB-001
estimated_effort: 1 day
created: 2026-03-28
updated: 2026-03-28

description: |
  Implement cache lifecycle management for Databento data. Cache files should be
  invalidated after configurable age (default 30 days) and when request parameters
  change. Provide CLI tool for cache inspection and cleanup.

acceptance_criteria:
  - DatabentoCacheManager lists all cached entries
  - Entries invalidated after max_age_days
  - Parameters change detection triggers re-download
  - Cache size tracking available
  - CLI command to clear all cache
  - CLI command to show cache statistics

implementation_notes: |
  Cache files stored in .cache/databento/:
  - dbn_{hash}.parquet: Data file
  - dbn_{hash}_meta.json: Metadata (download_date, params, rows)
  
  Cache invalidation rules:
  1. Age > 30 days: re-download
  2. Parameters changed: re-download
  3. File corruption: re-download
  
  CLI commands:
  - vault-dash cache list
  - vault-dash cache clear
  - vault-dash cache stats

dependencies_detail:
  - DATA-DB-001: Needs DatabentoCacheKey structure