id: CORE-002C
title: Historical Workspace Collateral to GLD Share Conversion Alignment
status: done
priority: P1
effort: M
depends_on:
  - CORE-002A
  - CORE-001C
tags:
  - core
  - units
  - backtesting
  - event-comparison
summary: Historical workspace defaults now convert persisted collateral weight into GLD share units through instrument metadata instead of dividing raw USD notional by historical entry spot.
completed_notes:
  - Added `asset_quantity_from_workspace_config(...)` in `app/domain/backtesting_math.py`.
  - Backtests and event comparison workspace defaults now seed GLD historical units from stored collateral weight via the instrument metadata seam.
  - Added regressions for workspace-seeded historical defaults and route-level browser checks.
  - Follow-up UX hardening now explains undercollateralized historical starts with user-facing validation instead of raw internal model errors.