Spread is the one microstructure channel that survived the API audit - FX-available, and
genuinely historical in the tester ("During testing, the spread is not modeled but is taken
from historical data"), unlike swap (no history), signed tick flow (empty on FX) or depth
of market (absent on retail FX, never replayed).
test_spread.py measures four spread features against the triple-barrier label with the same
block-permutation null as test_volume.py. spr/atr - cost relative to the volatility a trade
must overcome - is the strongest reading anywhere in this project so far: significant on 5
of 8 instrument/geometry cells and 2-4x the magnitude of any volume feature.
Which immediately looked too good, because the label is computed WITH the spread charged
inside the barriers. A bar with high spread/ATR has its barriers shifted more adversely and
is mechanically likelier to resolve as a loss - so the feature would partly predict its own
cost model, which is not tradeable information.
Tested directly by relabelling at zero cost and re-measuring the identical feature:
EURUSD 2:3 +0.000655 -> +0.000485 (p 0.030 -> 0.066, loses significance)
EURUSD 1:2 +0.000626 -> +0.000399 (p 0.003 -> 0.017)
USDJPY 2:3 +0.000418 -> +0.000164 (never significant either way)
USDJPY 1:2 +0.000876 -> +0.000532 (p 0.003 -> 0.003)
XAUUSD 2:3 +0.000769 -> +0.000744 (p 0.027 -> 0.027)
XAUUSD 1:2 +0.000876 -> +0.000698 (p 0.003 -> 0.003)
So roughly 20-40% of it WAS the tautology, and the majority is not. What remains is a
volatility-regime reading: spread is near-fixed while ATR is not, so spr/atr is high
exactly when realised volatility is running below its own ATR estimate - which genuinely
predicts whether ATR-scaled barriers get reached at all.
Note what that does and does not buy. Like volume, spread is UNSIGNED: it informs Neutral
vs directional, never Buy vs Sell. It is the best-measured feature in this project and it
still cannot pick a side.
No EA changes in this commit - measurement only, and the MQL5 side already has an
uncompiled backlog.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
