Supersede 'broker is part of the strategy'. A strategy outputs a time-ordered table of position events (event_ts, action[buy/sell/close], position_id, instrument_id, volume; open time = opening event's event_ts, so no open_ts; unsigned volume, direction in action). Brokers become downstream swappable plugins: a deterministic frictionless sim-optimal broker yields synthetic pip-equity for neutral comparison/optimization; realistic broker plugins add currency friction/constraints for viability/deploy. Stays within C7 (scalar columns). Updates CLAUDE.md invariant 7, the walking-skeleton line, provenance, and the day-in-the-life doc.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Brummel
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