test(training): cover wall rebound geometry

Game/scripts/training_mode.gd

@@ -595,12 +595,26 @@ func _place_wall_state(rebound: bool) -> void:
 		randf_range(1.0, minf(FIELD_MAX_Y, 7.0)),
 		randf_range(-FIELD_HALF_Z, FIELD_HALF_Z)
 	)
-	var toward_field := Vector3(-side, randf_range(-0.15, 0.15), randf_range(-0.15, 0.15)).normalized()
-	var direction := -toward_field if rebound else toward_field
-	var velocity := direction * randf_range(WALL_PLAY_SPEED.x, WALL_PLAY_SPEED.y)
+	var velocity := wall_state_velocity(
+		rebound, side, randf_range(WALL_PLAY_SPEED.x, WALL_PLAY_SPEED.y),
+		randf_range(-0.15, 0.15), randf_range(-0.15, 0.15)
+	)
 	_place_body(ball, Transform3D(Basis.IDENTITY, ball_position), velocity, Vector3.ZERO)
 
 
+# Pure geometry seam for adversarial tests. `side` identifies the selected
+# wall (+1 or -1); a wall-play vector points into the field and a rebound
+# vector points into that wall. Normalize the perturbed normal before applying
+# speed so random tangential components cannot accidentally change the speed
+# distribution between the two state types.
+static func wall_state_velocity(rebound: bool, side: float, speed: float, vertical: float, lateral: float) -> Vector3:
+	if speed < 0.0:
+		return Vector3.ZERO
+	var wall_side := -1.0 if side < 0.0 else 1.0
+	var toward_field := Vector3(-wall_side, vertical, lateral).normalized()
+	return (-toward_field if rebound else toward_field) * speed
+
+
 # Air-intercept drill geometry. These six ranges are not free tuning knobs —
 # together they decide whether the drill is solvable at all, and the original
 # values made it arithmetically impossible (see the Round 9 note in

Game/tests/cases/test_teamplay_rewards.gd

@@ -1,4 +1,4 @@
-extends TestCase
+extends "res://tests/test_case.gd"
 
 const ShipAIControllerScript = preload("res://scripts/ship_ai_controller.gd")
 

Game/tests/cases/test_wall_play_states.gd

@@ -0,0 +1,21 @@
+extends "res://tests/test_case.gd"
+
+const TrainingModeScript = preload("res://scripts/training_mode.gd")
+
+func test_wall_play_points_into_the_field() -> void:
+	var velocity: Vector3 = TrainingModeScript.wall_state_velocity(false, 1.0, 8.0, 0.1, -0.2)
+	assert_true(velocity.x < 0.0, "positive-side wall play travels inward")
+	assert_almost_eq(velocity.length(), 8.0, 0.0001, "wall-play speed is preserved")
+
+func test_rebound_points_into_the_selected_wall() -> void:
+	var velocity: Vector3 = TrainingModeScript.wall_state_velocity(true, 1.0, 8.0, 0.1, -0.2)
+	assert_true(velocity.x > 0.0, "positive-side rebound travels toward the wall")
+	assert_almost_eq(velocity.length(), 8.0, 0.0001, "rebound speed is preserved")
+
+func test_opposite_walls_mirror_the_normal_component() -> void:
+	var positive: Vector3 = TrainingModeScript.wall_state_velocity(false, 1.0, 6.0, 0.0, 0.0)
+	var negative: Vector3 = TrainingModeScript.wall_state_velocity(false, -1.0, 6.0, 0.0, 0.0)
+	assert_eq(positive.x, -negative.x, "opposite wall starts mirror the x direction")
+
+func test_negative_speed_fails_closed() -> void:
+	assert_eq(TrainingModeScript.wall_state_velocity(false, 1.0, -1.0, 0.0, 0.0), Vector3.ZERO, "negative speed cannot create velocity")