diff --git a/cmake/fuzzing_build.cmake b/cmake/fuzzing_build.cmake
index 43f367001..7c7cb0f2c 100644
--- a/cmake/fuzzing_build.cmake
+++ b/cmake/fuzzing_build.cmake
@@ -106,7 +106,7 @@ endfunction()
 
 # Function to add fuzzing targets - compatible with both local and OSS-Fuzz builds
 function(add_fuzzing_targets)
-  set(FUZZERS bt_fuzzer script_fuzzer bb_fuzzer)
+  set(FUZZERS bt_fuzzer script_fuzzer bb_fuzzer bt_convert_fuzzer)
 
   foreach(fuzzer ${FUZZERS})
     add_executable(${fuzzer} fuzzing/${fuzzer}.cpp)
diff --git a/fuzzing/bt_convert_fuzzer.cpp b/fuzzing/bt_convert_fuzzer.cpp
new file mode 100644
index 000000000..e5dfea93d
--- /dev/null
+++ b/fuzzing/bt_convert_fuzzer.cpp
@@ -0,0 +1,379 @@
+// Fuzz target: bt_convert_fuzzer
+//
+// Threat model: every XML attribute, script literal and blackboard value that
+// enters a BehaviorTree.CPP application passes through BT::convertFromString<T>
+// (port parsing), SafeAny/Any type-erased casts, or typed blackboard access.
+// These string->type and type->type conversions are the numeric- and
+// string-parsing funnel for untrusted data (attacker-supplied XML documents,
+// Groot files, scripting expressions). polymorphic_cast_registry powers
+// shared_ptr port compatibility (Issue #943) and is dark in production
+// coverage (220 lines, 0.9%).
+//
+// Strategy (component-API harness, typed inputs):
+//   1. convertFromString<T> over the full builtin type matrix with a fuzzed
+//      string (numerics incl. int8..64/uint8..64/float/double overflow and
+//      underflow, bool, enums NodeStatus/NodeType/PortDirection, split
+//      containers vector<T>, SharedQueue<T>),
+//   2. Any value storage + tryCast/cast cross-type matrix,
+//   3. PolymorphicCastRegistry upcasts/downcasts/transitive chains over a
+//      harness-defined class hierarchy (Animal/Cat/Dog/Sphynx), including via
+//      a blackboard with the registry attached,
+//   4. blackboard typed set/get mismatch matrix.
+//
+// All thrown BT exceptions (RuntimeError/LogicError on invalid input) are
+// expected and caught; the point is exercising the conversion code paths, not
+// crashing on them.
+//
+// Expected bug classes: integer/float overflow and truncation handling,
+// out-of-bounds reads in split-string parsing, enum parsing mismatches,
+// type-confusion in Any casts, registry lookup errors on shared_ptr ports.
+
+#include "behaviortree_cpp/basic_types.h"
+#include "behaviortree_cpp/blackboard.h"
+#include "behaviortree_cpp/decorators/loop_node.h"
+#include "behaviortree_cpp/utils/polymorphic_cast_registry.hpp"
+#include "behaviortree_cpp/utils/safe_any.hpp"
+
+#include <cstdint>
+#include <memory>
+#include <string>
+
+#include <fuzzer/FuzzedDataProvider.h>
+
+namespace
+{
+
+// Harness-defined hierarchy for the polymorphic cast registry. No upstream
+// product code is involved: the registry API is public and standalone.
+struct Animal
+{
+  virtual ~Animal() = default;
+  virtual const char* species() const
+  {
+    return "Animal";
+  }
+};
+struct Cat : Animal
+{
+  const char* species() const override
+  {
+    return "Cat";
+  }
+};
+struct Dog : Animal
+{
+  const char* species() const override
+  {
+    return "Dog";
+  }
+};
+struct Sphynx : Cat
+{
+  const char* species() const override
+  {
+    return "Sphynx";
+  }
+};
+
+using AnimalPtr = std::shared_ptr<Animal>;
+using CatPtr = std::shared_ptr<Cat>;
+using DogPtr = std::shared_ptr<Dog>;
+using SphynxPtr = std::shared_ptr<Sphynx>;
+
+}  // namespace
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
+{
+  if(size < 8)
+  {
+    return 0;
+  }
+  FuzzedDataProvider fdp(data, size);
+
+  const std::string text = fdp.ConsumeRandomLengthString();
+  const BT::StringView sv(text);
+
+  // ---- Stage 1: convertFromString<T> over the builtin type matrix
+  try
+  {
+    switch(fdp.ConsumeIntegralInRange<uint8_t>(0, 19))
+    {
+      case 0:
+        (void)BT::convertFromString<std::string>(sv);
+        break;
+      case 1:
+        (void)BT::convertFromString<int8_t>(sv);
+        break;
+      case 2:
+        (void)BT::convertFromString<int16_t>(sv);
+        break;
+      case 3:
+        (void)BT::convertFromString<int32_t>(sv);
+        break;
+      case 4:
+        (void)BT::convertFromString<int64_t>(sv);
+        break;
+      case 5:
+        (void)BT::convertFromString<uint8_t>(sv);
+        break;
+      case 6:
+        (void)BT::convertFromString<uint16_t>(sv);
+        break;
+      case 7:
+        (void)BT::convertFromString<uint32_t>(sv);
+        break;
+      case 8:
+        (void)BT::convertFromString<uint64_t>(sv);
+        break;
+      case 9:
+        (void)BT::convertFromString<float>(sv);
+        break;
+      case 10:
+        (void)BT::convertFromString<double>(sv);
+        break;
+      case 11:
+        (void)BT::convertFromString<bool>(sv);
+        break;
+      case 12:
+        (void)BT::convertFromString<BT::NodeStatus>(sv);
+        break;
+      case 13:
+        (void)BT::convertFromString<BT::NodeType>(sv);
+        break;
+      case 14:
+        (void)BT::convertFromString<BT::PortDirection>(sv);
+        break;
+      case 15:
+        (void)BT::convertFromString<std::vector<int>>(sv);
+        break;
+      case 16:
+        (void)BT::convertFromString<std::vector<double>>(sv);
+        break;
+      case 17:
+        (void)BT::convertFromString<std::vector<bool>>(sv);
+        break;
+      case 18:
+        (void)BT::convertFromString<std::vector<std::string>>(sv);
+        break;
+      default:
+        (void)BT::convertFromString<BT::SharedQueue<int>>(sv);
+        break;
+    }
+  }
+  catch(const std::exception&)
+  {
+    // invalid numeric/enum input raises RuntimeError: expected
+  }
+
+  // Stages 2-4 are wrapped so that BT exceptions raised by the conversion
+  // APIs are contained per-iteration and never escape LLVMFuzzerTestOneInput.
+  try
+  {
+    // ---- Stage 2: Any storage + cross-type cast matrix
+    {
+      BT::Any any;
+      switch(fdp.ConsumeIntegralInRange<uint8_t>(0, 2))
+      {
+        case 0:
+          any = BT::Any(text);
+          break;
+        case 1:
+          any = BT::Any(static_cast<int64_t>(text.size()) * 1000000);
+          break;
+        default:
+          any = BT::Any(static_cast<double>(text.size()) * 1.5);
+          break;
+      }
+
+      (void)any.isNumber();
+      (void)any.isIntegral();
+      (void)any.isString();
+
+      switch(fdp.ConsumeIntegralInRange<uint8_t>(0, 5))
+      {
+        case 0: {
+          auto res = any.tryCast<int64_t>();
+          (void)res.has_value();
+          break;
+        }
+        case 1: {
+          auto res = any.tryCast<uint64_t>();
+          (void)res.has_value();
+          break;
+        }
+        case 2: {
+          auto res = any.tryCast<double>();
+          (void)res.has_value();
+          break;
+        }
+        case 3: {
+          auto res = any.tryCast<std::string>();
+          (void)res.has_value();
+          break;
+        }
+        case 4: {
+          auto res = any.tryCast<int>();
+          (void)res.has_value();
+          break;
+        }
+        default: {
+          // cast<T>() throws RuntimeError on a lossy/invalid cast
+          try
+          {
+            (void)any.cast<uint64_t>();
+          }
+          catch(const std::exception&)
+          {
+            // expected on invalid casts
+          }
+          break;
+        }
+      }
+    }
+
+    // ---- Stage 3: polymorphic cast registry
+    {
+      BT::PolymorphicCastRegistry registry;
+      registry.registerCast<Cat, Animal>();
+      registry.registerCast<Dog, Animal>();
+      registry.registerCast<Sphynx, Cat>();
+
+      BT::Any animal_any;
+      switch(fdp.ConsumeIntegralInRange<uint8_t>(0, 3))
+      {
+        case 0:
+          animal_any = BT::Any(AnimalPtr(std::make_shared<Animal>()));
+          break;
+        case 1:
+          animal_any = BT::Any(CatPtr(std::make_shared<Cat>()));
+          break;
+        case 2:
+          animal_any = BT::Any(DogPtr(std::make_shared<Dog>()));
+          break;
+        default:
+          animal_any = BT::Any(SphynxPtr(std::make_shared<Sphynx>()));
+          break;
+      }
+
+      switch(fdp.ConsumeIntegralInRange<uint8_t>(0, 4))
+      {
+        case 0: {
+          auto res = animal_any.tryCastWithRegistry<AnimalPtr>(registry);
+          (void)res.has_value();
+          break;
+        }
+        case 1: {
+          auto res = animal_any.tryCastWithRegistry<CatPtr>(registry);
+          (void)res.has_value();
+          break;
+        }
+        case 2: {
+          auto res = animal_any.tryCastWithRegistry<DogPtr>(registry);
+          (void)res.has_value();
+          break;
+        }
+        case 3: {
+          auto res = animal_any.tryCastWithRegistry<SphynxPtr>(registry);
+          (void)res.has_value();
+          break;
+        }
+        default: {
+          try
+          {
+            auto p = animal_any.cast<CatPtr>();
+            (void)p;
+          }
+          catch(const std::exception&)
+          {
+            // expected when the stored type is not Cat-compatible
+          }
+          break;
+        }
+      }
+
+      // Blackboard with an attached registry: typed set/get through the
+      // polymorphic path (Issue #943 usage pattern).
+      auto reg2 = std::make_shared<BT::PolymorphicCastRegistry>();
+      reg2->registerCast<Cat, Animal>();
+      reg2->registerCast<Sphynx, Cat>();
+      auto bb_poly = BT::Blackboard::create();
+      bb_poly->setPolymorphicCastRegistry(reg2);
+      bb_poly->set("obj", CatPtr(std::make_shared<Sphynx>()));
+      try
+      {
+        auto up = bb_poly->get<AnimalPtr>("obj");
+        (void)up;
+      }
+      catch(const std::exception&)
+      {
+        // expected when the registry cannot satisfy the cast
+      }
+      try
+      {
+        auto down = bb_poly->get<SphynxPtr>("obj");
+        (void)down;
+      }
+      catch(const std::exception&)
+      {
+        // expected on unsupported downcasts
+      }
+    }
+
+    // ---- Stage 4: blackboard typed set/get mismatch matrix
+    {
+      auto bb = BT::Blackboard::create();
+      switch(fdp.ConsumeIntegralInRange<uint8_t>(0, 3))
+      {
+        case 0:
+          bb->set("k", static_cast<int64_t>(text.size()));
+          break;
+        case 1:
+          bb->set("k", static_cast<double>(text.size()));
+          break;
+        case 2:
+          bb->set("k", text);
+          break;
+        default:
+          bb->set("k", !text.empty());
+          break;
+      }
+      const auto fetch = [&bb](auto type_tag) {
+        using T = decltype(type_tag);
+        try
+        {
+          // typed get: mismatched entry type raises RuntimeError (expected)
+          (void)bb->get<T>("k");
+        }
+        catch(const std::exception&)
+        {
+          // expected: type mismatch or missing key
+        }
+      };
+      switch(fdp.ConsumeIntegralInRange<uint8_t>(0, 4))
+      {
+        case 0:
+          fetch(int64_t{});
+          break;
+        case 1:
+          fetch(double{});
+          break;
+        case 2:
+          fetch(std::string{});
+          break;
+        case 3:
+          fetch(bool{});
+          break;
+        default:
+          fetch(int64_t{});  // on a missing key: RuntimeError path
+          break;
+      }
+    }
+  }
+  catch(const std::exception&)
+  {
+    // expected: Any/registry/blackboard APIs raise RuntimeError on
+    // lossy or mismatched conversions
+  }
+
+  return 0;
+}
diff --git a/fuzzing/corpus/bt_convert_fuzzer/bool-yes b/fuzzing/corpus/bt_convert_fuzzer/bool-yes
new file mode 100644
index 000000000..e433dab88
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/bool-yes differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/double-nan b/fuzzing/corpus/bt_convert_fuzzer/double-nan
new file mode 100644
index 000000000..7c4a54e40
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/double-nan differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/enum-nodetype b/fuzzing/corpus/bt_convert_fuzzer/enum-nodetype
new file mode 100644
index 000000000..e2a72a170
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/enum-nodetype differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/enum-status b/fuzzing/corpus/bt_convert_fuzzer/enum-status
new file mode 100644
index 000000000..8da63d33c
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/enum-status differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/float-overflow b/fuzzing/corpus/bt_convert_fuzzer/float-overflow
new file mode 100644
index 000000000..cd90582b2
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/float-overflow differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/int-max b/fuzzing/corpus/bt_convert_fuzzer/int-max
new file mode 100644
index 000000000..21e6b0689
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/int-max differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/int-underflow b/fuzzing/corpus/bt_convert_fuzzer/int-underflow
new file mode 100644
index 000000000..461be1bad
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/int-underflow differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/junk-mixed b/fuzzing/corpus/bt_convert_fuzzer/junk-mixed
new file mode 100644
index 000000000..f01c25001
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/junk-mixed differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/queue-int b/fuzzing/corpus/bt_convert_fuzzer/queue-int
new file mode 100644
index 000000000..9c0cbaac6
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/queue-int differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/uint-max b/fuzzing/corpus/bt_convert_fuzzer/uint-max
new file mode 100644
index 000000000..cf8762053
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/uint-max differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/vec-bool b/fuzzing/corpus/bt_convert_fuzzer/vec-bool
new file mode 100644
index 000000000..31d85e669
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/vec-bool differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/vec-double b/fuzzing/corpus/bt_convert_fuzzer/vec-double
new file mode 100644
index 000000000..8a228aab9
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/vec-double differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/vec-int b/fuzzing/corpus/bt_convert_fuzzer/vec-int
new file mode 100644
index 000000000..81af62b80
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/vec-int differ
diff --git a/fuzzing/corpus/bt_convert_fuzzer/vec-str b/fuzzing/corpus/bt_convert_fuzzer/vec-str
new file mode 100644
index 000000000..ce9ab17fb
Binary files /dev/null and b/fuzzing/corpus/bt_convert_fuzzer/vec-str differ
diff --git a/fuzzing/dictionaries/bt_convert_fuzzer.dict b/fuzzing/dictionaries/bt_convert_fuzzer.dict
new file mode 100644
index 000000000..4abcc6d60
--- /dev/null
+++ b/fuzzing/dictionaries/bt_convert_fuzzer.dict
@@ -0,0 +1,50 @@
+# Dictionary for bt_convert_fuzzer: numeric forms, enum names, separators.
+"9223372036854775807"
+"-9223372036854775808"
+"18446744073709551615"
+"0"
+"-1"
+"+1"
+"007"
+"0x1F"
+"0b101"
+"1e10"
+"1E-10"
+"1e999"
+"-1e999"
+"nan"
+"inf"
+"-inf"
+"3.14159"
+".5"
+"5."
+"1.0e-400"
+"true"
+"false"
+"TRUE"
+"False"
+"1;2;3"
+"-4;5;6"
+"1.5;2.5"
+"a;b;c"
+"true;false"
+"SUCCESS"
+"FAILURE"
+"RUNNING"
+"SKIPPED"
+"IDLE"
+"Action"
+"Condition"
+"Control"
+"Decorator"
+"SubTree"
+"UNDEFINED"
+"INPUT"
+"OUTPUT"
+"BIDIRECTIONAL"
+" "
+"  42  "
+";;"
+"--7"
+"12abc"
+"1;2;3;"