let any blueprint transfer configuration, not just single-building ones (if the orientation matches)

src/lib/sim/PlacementRules.cpp

@@ -144,24 +144,29 @@ BlueprintGhostResolved resolveBlueprintGhost(const FactoryState& state, const Ga
         findCoincidingSameTypeBuilding(state, config, type, anchor, rotation);
     if (coinciding.has_value())
     {
-        // A single configurable building hands its settings over, whatever way the target
-        // faces: a transfer never rotates anything, so the target's facing does not matter
-        // (REQ-UI-BLUEPRINT-TRANSFER). Tested before the overlap rule, which then governs
-        // only what this does not claim.
-        if (blueprintHoldsOneBuilding && isConfigurableBuildingType(type))
-        {
-            return BlueprintGhostResolved{BlueprintGhostAction::Transfer, coinciding->id};
-        }
+        const bool configurable = isConfigurableBuildingType(type);
 
-        // Otherwise the building the blueprint wants must already be there in full,
-        // facing the same way, because nothing here may re-orient it
-        // (REQ-UI-BLUEPRINT-OVERLAP). Tunnels are not excluded: nothing is rotated, so
-        // the reason for their REQ-BLD-ROTATE-IN-PLACE exception does not arise.
+        // The building the blueprint wants is already there, facing the same way. It
+        // takes the blueprint's settings if it has any to take (REQ-UI-BLUEPRINT-TRANSFER)
+        // and is otherwise left exactly as it is (REQ-UI-BLUEPRINT-OVERLAP). Tunnels are
+        // not excluded from the latter: nothing is rotated, so the reason for their
+        // REQ-BLD-ROTATE-IN-PLACE exception does not arise.
         if (coinciding->rotation == rotation)
         {
-            return BlueprintGhostResolved{BlueprintGhostAction::CompatibleOverlap,
+            return BlueprintGhostResolved{configurable
+                                              ? BlueprintGhostAction::Transfer
+                                              : BlueprintGhostAction::CompatibleOverlap,
                                           coinciding->id};
         }
+
+        // Facing the other way. Placement may not re-orient it, so this is invalid --
+        // except for the deliberate one-click gesture of a single-building blueprint,
+        // where a transfer rotates nothing anyway and the target's facing is beside the
+        // point (REQ-UI-BLUEPRINT-TRANSFER).
+        if (blueprintHoldsOneBuilding && configurable)
+        {
+            return BlueprintGhostResolved{BlueprintGhostAction::Transfer, coinciding->id};
+        }
         return BlueprintGhostResolved{BlueprintGhostAction::Invalid, std::nullopt};
     }