diff --git a/client/scripts/sandbox/greybox_world.gd b/client/scripts/sandbox/greybox_world.gd
index 5ca4a7bc6..caf8a6784 100644
--- a/client/scripts/sandbox/greybox_world.gd
+++ b/client/scripts/sandbox/greybox_world.gd
@@ -155,6 +155,10 @@ var _free_slots: Array = [[], []]
 var _state_colors: Array[Color] = []
 var _last_tick: int = -1
 var _capacity_warned := false
+## Bottom-wall scan depth (tiles) along each camera-far direction — covers the
+## Gauntlet's 2-thick walls plus door trim.
+const BOTTOM_SCAN_DEPTH := 3
+
 ## Cutaway mode: 0 = sightline corridor, 1 = bottom walls low, 2 = both.
 var cutaway_mode: int = 0
 ## Camera-far sim-neighbor deltas for the bottom-wall rule (see
@@ -284,10 +288,13 @@ func _paint_new(key: Vector3i) -> void:
 	_slots[key] = Vector2i(kind, slot)
 	if kind == Store.Kind.WALL:
 		_refresh_bottom_flag(key)
-	else:
-		# A newly-learned floor can promote camera-ward walls to bottom walls.
-		for d in _behind_dirs:
-			_refresh_bottom_flag(key - d)
+	# Any newly-learned tile can promote camera-ward walls up the scan chain:
+	# a floor is the promotion itself; a wall can EXTEND a chain that previously
+	# stopped at unknown (Gauntlet walls are 2 tiles thick — the outer row sees
+	# floor only THROUGH the inner row).
+	for d in _behind_dirs:
+		for step in range(1, BOTTOM_SCAN_DEPTH + 1):
+			_refresh_bottom_flag(key - d * step)
 
 
 ## Cutaway mode (design amendment, live session 2026-07-06): 0 = sightline
@@ -322,6 +329,11 @@ func _compute_behind_dirs() -> void:
 		# hides lies OPPOSITE that face -> behind_dir = -d for camera-ward d.
 		if world_dir.z > 0.01:
 			_behind_dirs.append(-d)
+	# Corner pillars: at a wall-run junction the interior floor sits DIAGONALLY
+	# behind (neither straight scan line reaches it) — include the combined
+	# diagonal in the scan set.
+	if _behind_dirs.size() == 2:
+		_behind_dirs.append(_behind_dirs[0] + _behind_dirs[1])
 	# Repaint flags for walls painted before the deferred computation ran.
 	for key: Vector3i in _slots:
 		if (_slots[key] as Vector2i).x == Store.Kind.WALL:
@@ -332,11 +344,20 @@ func _refresh_bottom_flag(key: Vector3i) -> void:
 	var slot: Vector2i = _slots.get(key, Vector2i(-1, -1))
 	if slot.y < 0 or slot.x != Store.Kind.WALL:
 		return
+	# Scan up to BOTTOM_SCAN_DEPTH tiles along each camera-far direction,
+	# walking THROUGH consecutive known walls (Gauntlet walls are 2 thick):
+	# a known non-wall tile behind the wall run marks the whole run "bottom".
+	# Unknown tiles stop the scan — no assumptions past the info boundary.
 	var flag := 0.0
 	for d in _behind_dirs:
-		var n: Vector3i = key + d
-		if store.has_tile(n) and store.kind_of(n) != Store.Kind.WALL:
-			flag = 1.0
+		for step in range(1, BOTTOM_SCAN_DEPTH + 1):
+			var n: Vector3i = key + d * step
+			if not store.has_tile(n):
+				break
+			if store.kind_of(n) != Store.Kind.WALL:
+				flag = 1.0
+				break
+		if flag > 0.0:
 			break
 	_wall_mm.multimesh.set_instance_custom_data(slot.y, Color(flag, 0.0, 0.0, 0.0))
 
diff --git a/client/shaders/sandbox/greybox_wall_cutaway.gdshader b/client/shaders/sandbox/greybox_wall_cutaway.gdshader
index 882dc98b5..73f6f994d 100644
--- a/client/shaders/sandbox/greybox_wall_cutaway.gdshader
+++ b/client/shaders/sandbox/greybox_wall_cutaway.gdshader
@@ -38,19 +38,17 @@ uniform int u_cutaway_mode = 0;
 uniform vec3 u_base_albedo : source_color = vec3(0.66, 0.64, 0.60);
 
 varying vec3 v_world_pos;
-// Bottom-wall flag (INSTANCE_CUSTOM.r, set by GreyboxWorld): 1.0 when a KNOWN
-// non-wall tile sits on this wall's camera-far side — the wall would occlude
-// interior the player should see, X2-style.
-varying flat float v_bottom;
+// Whole-box cut decision, computed per-INSTANCE in vertex() from the box's tile
+// center — every wall box is either full height or the stub, no per-fragment
+// falloff curves carving organic notches (the "sphere" read). X2-crisp tile
+// cuts; the smoothstep bands only shape where the 0.5 threshold falls.
+varying flat float v_cut;
 
 void vertex() {
-    // MODEL_MATRIX folds in the per-instance MultiMesh transform.
-    v_world_pos = (MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz;
-    v_bottom = INSTANCE_CUSTOM.r;
-}
-
-void fragment() {
-    vec2 to_wall = v_world_pos.xz - u_char_pos_xz;
+    // MODEL_MATRIX folds in the per-instance MultiMesh transform; its origin
+    // is the box center — .xz is the wall tile's center in world space.
+    vec2 inst_xz = (MODEL_MATRIX * vec4(0.0, 0.0, 0.0, 1.0)).xz;
+    vec2 to_wall = inst_xz - u_char_pos_xz;
     // Lateral gate: full cut inside (half_w - band), fading to none at half_w.
     float lateral = 1.0 - smoothstep(u_corridor_half_w - u_cut_band, u_corridor_half_w, abs(to_wall.x));
     // Near gate: soft start just behind the character (no hard seam at their feet).
@@ -58,13 +56,20 @@ void fragment() {
     // Far gate: corridor ends where a WALL_H wall can no longer occlude.
     float far_f = 1.0 - smoothstep(u_cut_reach, u_cut_reach + u_cut_band, to_wall.y);
     float corridor_f = lateral * near_f * far_f;
+    // Bottom-wall flag (INSTANCE_CUSTOM.r, GreyboxWorld): KNOWN non-wall tile
+    // behind this wall run — it would occlude interior the player should see.
     float cut_f = corridor_f;
     if (u_cutaway_mode == 1) {
-        cut_f = v_bottom;
+        cut_f = INSTANCE_CUSTOM.r;
     } else if (u_cutaway_mode == 2) {
-        cut_f = max(corridor_f, v_bottom);
+        cut_f = max(corridor_f, INSTANCE_CUSTOM.r);
     }
-    float allowed = mix(u_wall_h, u_cut_height, cut_f);
+    v_cut = cut_f > 0.5 ? 1.0 : 0.0;
+    v_world_pos = (MODEL_MATRIX * vec4(VERTEX, 1.0)).xyz;
+}
+
+void fragment() {
+    float allowed = mix(u_wall_h, u_cut_height, v_cut);
     if (v_world_pos.y > allowed) {
         discard;
     }