Risk MVP: emergency stop, forced exit, and final-auction flatten policy

[phenomenoner]

Why

Day-trading controls are a first-class product requirement, especially for latency-sensitive exits and short-side failure modes.

Scope

• define executable policy shape for:
  • emergency stop-loss (percent-based and/or ticks-from-limit variants)
  • intraday forced exit windows
  • final-auction flatten mode around the close
  • capital controls such as per-order and daily notional caps
• encode mode differences across replay-sim / live-sim / live
• document operator involvement for flatten and emergency procedures

Acceptance criteria

• policy can express the short-side upper-limit / cannot-cover risk clearly
• cards can declare exit timing while deck/global policy retains final authority
• a bounded final-auction flatten flow exists for Asia/Taipei close handling
• the design treats latency as a core requirement, not an afterthought