diff --git a/src/core_ffi/CMakeLists.txt b/src/core_ffi/CMakeLists.txt
index 9c112b4..dd88c5d 100644
--- a/src/core_ffi/CMakeLists.txt
+++ b/src/core_ffi/CMakeLists.txt
@@ -17,8 +17,10 @@ endif()
 if (KLSK_RUST_FFI)
     # just for IDE highlight
     add_library(klotski_rust
-        rust_ffi/src/demo.cc
-        rust_ffi/target/cxxbridge/klotski/src/common_code.rs.cc
+        rust_ffi/adapter/common_code.cc
+        rust_ffi/target/cxxbridge/rust_ffi/src/common_code.rs.cc
     )
-    target_include_directories(klotski_rust PRIVATE rust_ffi/target/cxxbridge)
+    target_include_directories(klotski_rust PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
+    target_include_directories(klotski_rust PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/rust_ffi/target/cxxbridge)
+    target_link_libraries(klotski_rust PRIVATE klotski_core)
 endif()
diff --git a/src/core_ffi/rust_ffi/adapter/common_code.cc b/src/core_ffi/rust_ffi/adapter/common_code.cc
new file mode 100644
index 0000000..553c352
--- /dev/null
+++ b/src/core_ffi/rust_ffi/adapter/common_code.cc
@@ -0,0 +1,15 @@
+#include "rust_ffi/include/common_code.h"
+
+#include <common_code/common_code.h>
+
+using klotski::ffi::RsCommonCode;
+
+rust::String RsCommonCode::to_string() const noexcept {
+    return codec::CommonCode::unsafe_create(code).to_string();
+}
+
+// TODO: it seems that cxx.rs not support `std::optional`
+RsCommonCode klotski::ffi::from_string(rust::Str s) {
+    std::string_view sv {s.data(), s.length()};
+    return {codec::CommonCode::from_string(sv)->unwrap()}; // TODO: value check
+}
diff --git a/src/core_ffi/rust_ffi/build.rs b/src/core_ffi/rust_ffi/build.rs
index 80737d0..384a3f9 100644
--- a/src/core_ffi/rust_ffi/build.rs
+++ b/src/core_ffi/rust_ffi/build.rs
@@ -1,8 +1,33 @@
+use cxx_build::CFG;
+
+// NOTE: add `CC=clang-20 CXX=clang++-20 CXXFLAGS="-stdlib=libc++"` for cargo command
+//       we should keep cxx crate using clang for `cxx.cc`
+
+// NOTE: also, `RUSTFLAGS="-C linker=clang-20"` should be add to cargo env for using lld
+
 fn main() {
+    CFG.include_prefix = "rust_ffi";
+
+    // std::env::set_var("CC", "clang-20");
+    // std::env::set_var("CXX", "clang++-20");
+
     cxx_build::bridge("src/common_code.rs")
-        .file("src/demo.cc")
+        .file("adapter/common_code.cc")
+        .flag("-std=c++23")
+        .flag("-fno-rtti")
+        .flag("-fno-exceptions")
+        // .flag("-stdlib=libc++")
+        .include("../../core")
+        // .cpp_set_stdlib("c++")
+        // .cpp_link_stdlib("c++")
         .compile("klotski");
 
-    println!("cargo:rerun-if-changed=src/demo.cc");
+    println!("cargo:rustc-link-search=native=../../../cmake-build-release/src/core");
+    println!("cargo:rustc-link-lib=static=klotski_core");
+
+    println!("cargo:rustc-link-arg=-fuse-ld=lld-20");
+    println!("cargo:rustc-link-arg=-stdlib=libc++");
+
+    println!("cargo:rerun-if-changed=adapter/common_code.cc");
     println!("cargo:rerun-if-changed=src/common_code.rs");
 }
diff --git a/src/core_ffi/rust_ffi/include/common_code.h b/src/core_ffi/rust_ffi/include/common_code.h
new file mode 100644
index 0000000..c40e175
--- /dev/null
+++ b/src/core_ffi/rust_ffi/include/common_code.h
@@ -0,0 +1,9 @@
+#pragma once
+
+#include "rust_ffi/src/common_code.rs.h"
+
+namespace klotski::ffi {
+
+RsCommonCode from_string(rust::Str s);
+
+} // namespace klotski::ffi
diff --git a/src/core_ffi/rust_ffi/src/common_code.rs b/src/core_ffi/rust_ffi/src/common_code.rs
index f3fd878..b454f35 100644
--- a/src/core_ffi/rust_ffi/src/common_code.rs
+++ b/src/core_ffi/rust_ffi/src/common_code.rs
@@ -1,18 +1,37 @@
-#[cxx::bridge]
-pub mod ffi {
+#[cxx::bridge(namespace = "klotski::ffi")]
+mod ffi {
     #[derive(Debug)]
-    pub struct CommonCode {
+    struct RsCommonCode {
         code: u64
     }
 
-    extern "Rust" {}
-
     unsafe extern "C++" {
-        include!("klotski/src/klotski.h");
+        include!("rust_ffi/include/common_code.h");
+
+        fn to_string(self: &RsCommonCode) -> String;
+
+        fn from_string(s: &str) -> RsCommonCode;
+    }
+}
+
+pub use ffi::RsCommonCode as CommonCode;
 
-        // fn unwrap(self: &CommonCode) -> u64;
+impl CommonCode {
+    pub fn unsafe_create(code: u64) -> CommonCode {
+        CommonCode { code }
+    }
+
+    pub fn unwrap(self: &CommonCode) -> u64 {
+        self.code
+    }
+
+    pub fn from_string(s: &str) -> CommonCode {
+        ffi::from_string(s)
+    }
+}
 
-        // fn from_string(s: &str) -> CommonCode;
-        fn from_string() -> CommonCode;
+impl PartialEq for CommonCode {
+    fn eq(&self, other: &Self) -> bool {
+        self.code == other.code
     }
 }
diff --git a/src/core_ffi/rust_ffi/src/demo.cc b/src/core_ffi/rust_ffi/src/demo.cc
deleted file mode 100644
index 860aa39..0000000
--- a/src/core_ffi/rust_ffi/src/demo.cc
+++ /dev/null
@@ -1,8 +0,0 @@
-#include "klotski/src/klotski.h"
-#include "klotski/src/common_code.rs.h"
-
-#include <iostream>
-
-CommonCode from_string() {
-    return CommonCode {};
-}
diff --git a/src/core_ffi/rust_ffi/src/klotski.h b/src/core_ffi/rust_ffi/src/klotski.h
deleted file mode 100644
index 15d701d..0000000
--- a/src/core_ffi/rust_ffi/src/klotski.h
+++ /dev/null
@@ -1,5 +0,0 @@
-#pragma once
-
-#include "klotski/src/common_code.rs.h"
-
-CommonCode from_string();
diff --git a/src/core_ffi/rust_ffi/src/main.rs b/src/core_ffi/rust_ffi/src/main.rs
index 9e82f72..8222a48 100644
--- a/src/core_ffi/rust_ffi/src/main.rs
+++ b/src/core_ffi/rust_ffi/src/main.rs
@@ -1,12 +1,11 @@
 mod common_code;
 
-use common_code::ffi::CommonCode;
+use common_code::CommonCode;
 
 fn main() {
-    // let code = CommonCode { code: 123 };
-    // let val = code.unwrap();
-    // println!("val = {}", val);
+    let code = CommonCode::from_string("1A9BF0C");
+    println!("code: {:?}", code.unwrap());
+    println!("str: {}", code.to_string());
 
-    let code = common_code::ffi::from_string();
-    println!("code = {:?}", code);
+    println!("{}", code == CommonCode::unsafe_create(0x1A9BF0C00));
 }