id: DATA-DB-002
title: Backtest Settings Model
status: backlog
priority: high
dependencies:
  - DATA-DB-001
estimated_effort: 1 day
created: 2026-03-28
updated: 2026-03-28

description: |
  Create BacktestSettings model that captures user-configurable backtest parameters
  independent of portfolio settings. This allows running scenarios with custom start
  prices and position sizes without modifying the main portfolio.

acceptance_criteria:
  - BacktestSettings dataclass defined with all necessary fields
  - start_price can be 0 (auto-derive) or explicit value
  - underlying_units independent of portfolio.gold_ounces
  - loan_amount and margin_call_ltv for LTV analysis
  - data_source field supports "databento" and "yfinance"
  - Repository persists settings per workspace
  - Default settings created for new workspaces

implementation_notes: |
  Key fields:
  - settings_id: UUID for tracking
  - data_source: "databento" | "yfinance" | "synthetic"
  - dataset: "XNAS.BASIC" | "GLBX.MDP3"
  - underlying_symbol: "GLD" | "GC" | "XAU"
  - start_date, end_date: date range
  - start_price: 0 for auto-derive, or explicit
  - underlying_units: position size for scenario
  - loan_amount: debt level for LTV analysis
  
  Settings are stored in .workspaces/{workspace_id}/backtest_settings.json

dependencies_detail:
  - DATA-DB-001: Need data source configuration fields