audit: isolate BCI role learner from environment map

1 files changed, 13 insertions, 6 deletions

diff --git a/sdil/bci.py b/sdil/bci.py
index 2978e5a..e20bbb6 100644
--- a/sdil/bci.py
+++ b/sdil/bci.py
@@ -165,18 +165,18 @@ class BCISDIL:
         directional_derivative = (loss_plus - loss_minus) / (2.0 * sigma)
         return -directional_derivative.unsqueeze(1) * perturbations
 
-    def causal_role_targets(self, soma, perturbations):
+    def causal_role_targets(self, cursor_plus, cursor_minus, perturbations):
         """Estimate each cell's signed causal effect on the BCI cursor.
 
         Unlike ``causal_targets``, this target contains no instantaneous error
         magnitude.  A scalar antithetic cursor difference is tagged by the
         locally available perturbation at each cell; its expectation is the
-        experimenter-unknown causal role vector.
+        experimenter-unknown causal role vector.  The learner receives the two
+        scalar cursor observations and cannot read the environment's role map.
         """
         sigma = self.cfg.perturb_sigma
-        plus = (soma + sigma * perturbations) @ self.role
-        minus = (soma - sigma * perturbations) @ self.role
-        directional_derivative = (plus - minus) / (2.0 * sigma)
+        directional_derivative = (
+            cursor_plus - cursor_minus) / (2.0 * sigma)
         return directional_derivative.unsqueeze(1) * perturbations
 
     def exact_causal_direction(self, soma, target):
@@ -255,8 +255,15 @@ class BCISDIL:
             causal_target = None
             if did_perturb:
                 if self.cfg.feedback == "performance_velocity":
+                    sigma = self.cfg.perturb_sigma
+                    # These two scalar values are environment observations.
+                    # ``causal_role_targets`` has no access to ``self.role``.
+                    cursor_plus = (
+                        base_soma + sigma * perturbations) @ self.role
+                    cursor_minus = (
+                        base_soma - sigma * perturbations) @ self.role
                     causal_target = self.causal_role_targets(
-                        base_soma, perturbations)
+                        cursor_plus, cursor_minus, perturbations)
                 else:
                     causal_target = self.causal_targets(
                         base_soma, self.cfg.target, perturbations)