id: BT-004
title: Backtest Visualization Chart
status: backlog
priority: P1
effort: M
depends_on:
  - BT-001
tags: [backtesting, visualization, charts]
summary: Add interactive candlestick chart showing price OHLC with portfolio value line overlay.
acceptance_criteria:
  - Candlestick chart displays OHLC data (open, high, low, close) for each day.
  - Portfolio value (underlying + option) shown as line on secondary Y-axis.
  - Chart updates when backtest results change.
  - Chart is responsive and readable on mobile/tablet viewports.
  - Chart library matches existing app styling (dark mode support).
notes: |
  Consider using a lightweight charting library that integrates well with NiceGUI.
  Portfolio value line should be clearly distinguishable from candlesticks.
  May want to add toggle for showing/hiding different series.