id: DATA-004
title: Underlying Instrument Selector
status: backlog
priority: P2
size: L
depends_on:
  - PRICING-001
acceptance_criteria:
  - User can choose underlying instrument for options evaluation (GLD vs GC=F)
  - Settings page exposes underlying selector with brief descriptions
  - Workspace-scoped preference persisted
  - Overview and Hedge pages reflect chosen underlying for price display and options strategy
  - GC=F options data source placeholder exists (not yet wired to live data)
  - UI clearly indicates which underlying is active and whether data is live or placeholder
notes:
  - GLD is the MVP supported underlying with live data via yfinance
  - GC=F futures options will require a new data source (future roadmap item)
  - For now, GC=F selection can show "coming soon" or use estimated/stubbed pricing
  - Each underlying has different contract specs (100 shares vs futures contract multiplier)
implementation_hints:
  - Add underlying field to workspace/portfolio settings
  - Extend app/domain/instruments.py with GC=F metadata (futures contract specs)
  - Add underlying selector UI in settings
  - DataService routes quote/options requests based on selected underlying
  - For GC=F, stub with estimated pricing or clear "data source needed" state