From ce843bc068331d4239ace6ae5f71b15dbe60cdd2 Mon Sep 17 00:00:00 2001
From: David Sobek <david.sobek@picknik.ai>
Date: Mon, 27 Apr 2026 14:39:56 -0600
Subject: [PATCH 1/2] Revert "Preserve numeric types for literal subtree port
 values"

This reverts commit d248867772523cfce322bc36e84578b42f5bebb6.
---
 src/xml_parsing.cpp     | 55 ++---------------------------------------
 tests/gtest_subtree.cpp | 38 ----------------------------
 2 files changed, 2 insertions(+), 91 deletions(-)

diff --git a/src/xml_parsing.cpp b/src/xml_parsing.cpp
index ba1bb9f26..a25a53a6f 100644
--- a/src/xml_parsing.cpp
+++ b/src/xml_parsing.cpp
@@ -12,12 +12,10 @@
 
 #include <algorithm>
 #include <cctype>
-#include <charconv>
 #include <cstdio>
 #include <cstring>
 #include <functional>
 #include <iostream>
-#include <limits>
 #include <list>
 #include <sstream>
 #include <string>
@@ -1008,59 +1006,10 @@ void BT::XMLParser::PImpl::recursivelyCreateSubtree(const std::string& tree_ID,
         }
         else
         {
-          // constant value: set it into the BB with appropriate type
+          // constant string: just set that constant value into the BB
           // IMPORTANT: this must not be autoremapped!!!
           new_bb->enableAutoRemapping(false);
-          const std::string str_value(port_value);
-
-          // Try to preserve numeric types so that Script expressions
-          // can perform arithmetic without type-mismatch errors.
-          // Use std::from_chars with strict full-string validation to avoid
-          // false positives on compound strings like "1;2;3" or "2.2;2.4".
-          bool stored = false;
-          if(!str_value.empty())
-          {
-            const char* begin = str_value.data();
-            const char* end = begin + str_value.size();
-            // Try integer first (no decimal point, no exponent notation).
-            // Use int when the value fits, to match the most common port
-            // declarations. Fall back to int64_t for larger values.
-            if(str_value.find('.') == std::string::npos &&
-               str_value.find('e') == std::string::npos &&
-               str_value.find('E') == std::string::npos)
-            {
-              int64_t int_val = 0;
-              auto [ptr, ec] = std::from_chars(begin, end, int_val);
-              if(ec == std::errc() && ptr == end)
-              {
-                if(int_val >= std::numeric_limits<int>::min() &&
-                   int_val <= std::numeric_limits<int>::max())
-                {
-                  new_bb->set(port_name, static_cast<int>(int_val));
-                }
-                else
-                {
-                  new_bb->set(port_name, int_val);
-                }
-                stored = true;
-              }
-            }
-            // Try double
-            if(!stored)
-            {
-              double dbl_val = 0;
-              auto [ptr, ec] = std::from_chars(begin, end, dbl_val);
-              if(ec == std::errc() && ptr == end)
-              {
-                new_bb->set(port_name, dbl_val);
-                stored = true;
-              }
-            }
-          }
-          if(!stored)
-          {
-            new_bb->set(port_name, str_value);
-          }
+          new_bb->set(port_name, static_cast<std::string>(port_value));
           new_bb->enableAutoRemapping(do_autoremap);
         }
       }
diff --git a/tests/gtest_subtree.cpp b/tests/gtest_subtree.cpp
index 8d15893ed..479b3ffc1 100644
--- a/tests/gtest_subtree.cpp
+++ b/tests/gtest_subtree.cpp
@@ -799,41 +799,3 @@ TEST(SubTree, SubtreeNameNotRegistered)
   ASSERT_ANY_THROW(auto tree = factory.createTreeFromText(xml_text));
   ASSERT_ANY_THROW(factory.registerBehaviorTreeFromText(xml_text));
 }
-
-// Regression test: literal numeric values passed to subtrees should preserve
-// their numeric type so that Script expressions can do arithmetic.
-TEST(SubTree, LiteralNumericPortsPreserveType)
-{
-  // clang-format off
-  static const char* xml_text = R"(
-<root BTCPP_format="4" main_tree_to_execute="MainTree">
-
-    <BehaviorTree ID="MainTree">
-        <Sequence>
-            <SubTree ID="DoMath" int_val="42" dbl_val="3.14" str_val="hello"
-                     remapped_val="{from_parent}" />
-        </Sequence>
-    </BehaviorTree>
-
-    <BehaviorTree ID="DoMath">
-        <Sequence>
-            <ScriptCondition code=" int_val + 1 == 43 " />
-            <ScriptCondition code=" dbl_val > 3.0 " />
-            <ScriptCondition code=" remapped_val + 1 == 101 " />
-        </Sequence>
-    </BehaviorTree>
-
-</root>
-)";
-  // clang-format on
-
-  BehaviorTreeFactory factory;
-
-  auto tree = factory.createTreeFromText(xml_text);
-
-  // Set the remapped parent value as an integer
-  tree.rootBlackboard()->set("from_parent", 100);
-
-  const auto status = tree.tickWhileRunning();
-  ASSERT_EQ(status, NodeStatus::SUCCESS);
-}

From 959730c4615df1e19b30a0adbbf16780a59f4ddd Mon Sep 17 00:00:00 2001
From: David Sobek <david.sobek@picknik.ai>
Date: Mon, 27 Apr 2026 16:47:48 -0600
Subject: [PATCH 2/2] Allow for strongly typed numbers to be added with
 non-strongly typed numbers

---
 .../behaviortree_cpp/scripting/operators.hpp  |  6 +-
 tests/gtest_subtree.cpp                       | 70 +++++++++++++++++++
 2 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/include/behaviortree_cpp/scripting/operators.hpp b/include/behaviortree_cpp/scripting/operators.hpp
index 4d41b6a88..5f121da20 100644
--- a/include/behaviortree_cpp/scripting/operators.hpp
+++ b/include/behaviortree_cpp/scripting/operators.hpp
@@ -213,7 +213,11 @@ struct ExprBinaryArithmetic : ExprBase
       throw RuntimeError(ErrorNotInit("right", opStr()));
     }
 
-    if(rhs_v.isNumber() && lhs_v.isNumber())
+    // If just one value is strongly typed as a number, and the other can be casted to one, do arithmetic. If both are not strongly typed, continue. In the case of `+`, non-strongly typed values will result in concatenation.
+    bool are_numbers = (rhs_v.isNumber() && lhs_v.isNumber()) ||
+                       ((rhs_v.tryCast<double>().has_value() && lhs_v.isNumber()) !=
+                        (rhs_v.isNumber() && lhs_v.tryCast<double>().has_value()));
+    if(are_numbers)
     {
       auto lv = lhs_v.cast<double>();
       auto rv = rhs_v.cast<double>();
diff --git a/tests/gtest_subtree.cpp b/tests/gtest_subtree.cpp
index 479b3ffc1..0bf48f8ae 100644
--- a/tests/gtest_subtree.cpp
+++ b/tests/gtest_subtree.cpp
@@ -332,6 +332,76 @@ TEST(SubTree, StringConversions_Issue530)
   tree.tickOnce();
 }
 
+// Regression test for https://github.com/PickNikRobotics/moveit_pro/issues/18587.
+TEST(SubTree, ScriptingTypingIssue)
+{
+  static const char* xml_text = R"(
+
+<root BTCPP_format="4" >
+    <BehaviorTree ID="MainTree">
+        <Sequence>
+            <SubTree ID="mySubtree" in_value="1.0" out_value="{y}" />
+        </Sequence>
+    </BehaviorTree>
+
+    <BehaviorTree ID="mySubtree">
+      <Script code = "out_value := in_value + 1" />
+    </BehaviorTree>
+  <TreeNodesModel>
+    <SubTree ID="mySubtree">
+      <input_port name="in_value" />
+      <output_port name="out_value" />
+    </SubTree>
+  </TreeNodesModel>
+</root> )";
+
+  BehaviorTreeFactory factory;
+  factory.registerBehaviorTreeFromText(xml_text);
+
+  auto blackboard = BT::Blackboard::create();
+  Tree tree = factory.createTree("MainTree", blackboard);
+
+  auto status = tree.tickWhileRunning();
+  ASSERT_EQ(status, NodeStatus::SUCCESS);
+
+  EXPECT_EQ(blackboard->get<int>("y"), 2);
+}
+
+// Test to make sure that the fix for the addressed bug above doesn't cause another regression: string concatenation with `+` should still work... for now.
+TEST(SubTree, ScriptingTypingIssue_StringConcatWorks)
+{
+  static const char* xml_text = R"(
+
+<root BTCPP_format="4" >
+    <BehaviorTree ID="MainTree">
+        <Sequence>
+            <SubTree ID="mySubtree" in_value="12" out_value="{y}" />
+        </Sequence>
+    </BehaviorTree>
+
+    <BehaviorTree ID="mySubtree">
+      <Script code = "out_value := in_value + '34'" />
+    </BehaviorTree>
+  <TreeNodesModel>
+    <SubTree ID="mySubtree">
+      <input_port name="in_value" />
+      <output_port name="out_value" />
+    </SubTree>
+  </TreeNodesModel>
+</root> )";
+
+  BehaviorTreeFactory factory;
+  factory.registerBehaviorTreeFromText(xml_text);
+
+  auto blackboard = BT::Blackboard::create();
+  Tree tree = factory.createTree("MainTree", blackboard);
+
+  auto status = tree.tickWhileRunning();
+  ASSERT_EQ(status, NodeStatus::SUCCESS);
+
+  EXPECT_EQ(blackboard->get<std::string>("y"), "1234");
+}
+
 class NaughtyNav2Node : public BT::SyncActionNode
 {
 public: