BSS = 1 − (model_brier / baseline_brier). Positive = brain beats always-mean baseline. >0.10 = useful.
Brier = mean (predicted - actual)². Lower better.
Win rate = % of historical resolutions that went the brain's predicted direction.
Symbols with <10 resolutions don't have a skill score yet (statistical uncertainty too high).

The global Brier Skill Score says "is the brain learning?" overall. Per-symbol BSS says where it's learning. The brain may have +0.20 skill on SPY but -0.05 on TSLA — averaging hides this asymmetry.

How to use:

• Symbols with useful or strong skill: trade them confidently, full size.
• Symbols with fair skill: trade with reduced size and tighter risk.
• Symbols with weak / broken skill: skip them or run paper trades only — the brain hasn't figured these out.
• Symbols not yet on the board: still warming up; revisit after >10 resolutions.