diff --git a/CLAUDE.md b/CLAUDE.md
index 08106f80..17807614 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -330,6 +330,28 @@ echo 'print("Hello Nyash!")' > local_tests/test_hello.nyash
 - プラグインのみのビルドは数秒で完了します
 - Phase 9.75fで動的ライブラリ分離により改善作業中
 
+### 🔧 **Rustビルドエラー対処法**
+**Rustのコンパイルエラーは詳細が見づらいため、以下のパターンで対処：**
+
+#### 1. エラーをファイルに出力
+```bash
+# エラーをファイルに保存して解析
+cargo build --lib -j32 2>&1 > build_errors.txt
+
+# 特定のエラーコードを検索
+grep -A10 "error\[E0308\]" build_errors.txt
+```
+
+#### 2. 32スレッドビルドの基本ルール
+- **時間制限なし**: `--timeout 300000` (5分)以上を設定
+- **エラー出力**: 必ずファイルに保存して解析
+- **並列度**: `-j32` で最大並列化
+
+#### 3. よくあるエラーパターン
+- `Box<dyn NyashBox>` vs `Arc<dyn NyashBox>`: `.into()` で変換
+- `unsafe` ブロックでの型推論: 明示的な型指定が必要
+- deprecatedワーニング: MIR命令の移行期間中は無視可
+
 ### 🐛 デバッグ
 
 #### パーサー無限ループ対策（NEW! 2025-08-09）
diff --git a/src/bid/error.rs b/src/bid/error.rs
new file mode 100644
index 00000000..f7bf9696
--- /dev/null
+++ b/src/bid/error.rs
@@ -0,0 +1,80 @@
+/// BID-1 Standard Error Codes
+#[repr(i32)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum BidError {
+    /// Operation successful
+    Success = 0,
+    
+    /// Buffer too small (need to call again with larger buffer)
+    ShortBuffer = -1,
+    
+    /// Invalid type ID
+    InvalidType = -2,
+    
+    /// Invalid method ID
+    InvalidMethod = -3,
+    
+    /// Invalid arguments
+    InvalidArgs = -4,
+    
+    /// Plugin internal error
+    PluginError = -5,
+    
+    /// Memory allocation failed
+    OutOfMemory = -6,
+    
+    /// UTF-8 encoding error
+    InvalidUtf8 = -7,
+    
+    /// Handle not found
+    InvalidHandle = -8,
+    
+    /// Version mismatch
+    VersionMismatch = -9,
+}
+
+impl BidError {
+    /// Convert from raw i32
+    pub fn from_raw(code: i32) -> Self {
+        match code {
+            0 => BidError::Success,
+            -1 => BidError::ShortBuffer,
+            -2 => BidError::InvalidType,
+            -3 => BidError::InvalidMethod,
+            -4 => BidError::InvalidArgs,
+            -5 => BidError::PluginError,
+            -6 => BidError::OutOfMemory,
+            -7 => BidError::InvalidUtf8,
+            -8 => BidError::InvalidHandle,
+            -9 => BidError::VersionMismatch,
+            _ => BidError::PluginError, // Unknown errors map to plugin error
+        }
+    }
+    
+    /// Get human-readable error message
+    pub fn message(&self) -> &'static str {
+        match self {
+            BidError::Success => "Operation successful",
+            BidError::ShortBuffer => "Buffer too small, call again with larger buffer",
+            BidError::InvalidType => "Invalid type ID",
+            BidError::InvalidMethod => "Invalid method ID",
+            BidError::InvalidArgs => "Invalid arguments",
+            BidError::PluginError => "Plugin internal error",
+            BidError::OutOfMemory => "Memory allocation failed",
+            BidError::InvalidUtf8 => "Invalid UTF-8 encoding",
+            BidError::InvalidHandle => "Handle not found",
+            BidError::VersionMismatch => "BID version mismatch",
+        }
+    }
+}
+
+impl std::fmt::Display for BidError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{} (code: {})", self.message(), *self as i32)
+    }
+}
+
+impl std::error::Error for BidError {}
+
+/// Result type for BID operations
+pub type BidResult<T> = Result<T, BidError>;
\ No newline at end of file
diff --git a/src/bid/mod.rs b/src/bid/mod.rs
new file mode 100644
index 00000000..96e1e40b
--- /dev/null
+++ b/src/bid/mod.rs
@@ -0,0 +1,23 @@
+// BID-FFI: Box Interface Definition with Foreign Function Interface
+// Everything is Box philosophy meets practical FFI/ABI design!
+
+pub mod types;
+pub mod tlv;
+pub mod error;
+
+pub use types::*;
+pub use tlv::*;
+pub use error::*;
+
+/// BID-1 version constant
+pub const BID_VERSION: u16 = 1;
+
+/// Platform-dependent pointer size
+#[cfg(target_pointer_width = "32")]
+pub type Usize = u32;
+
+#[cfg(target_pointer_width = "64")]
+pub type Usize = u64;
+
+/// Standard alignment requirement
+pub const BID_ALIGNMENT: usize = 8;
\ No newline at end of file
diff --git a/src/bid/tlv.rs b/src/bid/tlv.rs
new file mode 100644
index 00000000..9b5da2dd
--- /dev/null
+++ b/src/bid/tlv.rs
@@ -0,0 +1,324 @@
+use super::{BidError, BidResult, BidHandle, BidTag, BID_VERSION};
+use std::mem;
+
+/// BID-1 TLV Header
+#[repr(C)]
+#[derive(Debug, Clone, Copy)]
+pub struct BidTlvHeader {
+    pub version: u16,    // BID version (1)
+    pub argc: u16,       // Argument count
+}
+
+/// TLV Entry structure
+#[repr(C)]
+#[derive(Debug, Clone, Copy)]
+pub struct TlvEntry {
+    pub tag: u8,         // Type tag
+    pub reserved: u8,    // Reserved for future use (0)
+    pub size: u16,       // Payload size
+    // Payload follows immediately after
+}
+
+/// TLV encoder for BID-1 format
+pub struct TlvEncoder {
+    buffer: Vec<u8>,
+    entry_count: u16,
+}
+
+impl TlvEncoder {
+    /// Create a new TLV encoder
+    pub fn new() -> Self {
+        let mut encoder = Self {
+            buffer: Vec::with_capacity(256),
+            entry_count: 0,
+        };
+        
+        // Reserve space for header
+        encoder.buffer.extend_from_slice(&[0; mem::size_of::<BidTlvHeader>()]);
+        encoder
+    }
+    
+    /// Encode a boolean value
+    pub fn encode_bool(&mut self, value: bool) -> BidResult<()> {
+        self.encode_entry(BidTag::Bool, &[if value { 1 } else { 0 }])
+    }
+    
+    /// Encode a 32-bit integer
+    pub fn encode_i32(&mut self, value: i32) -> BidResult<()> {
+        self.encode_entry(BidTag::I32, &value.to_le_bytes())
+    }
+    
+    /// Encode a 64-bit integer
+    pub fn encode_i64(&mut self, value: i64) -> BidResult<()> {
+        self.encode_entry(BidTag::I64, &value.to_le_bytes())
+    }
+    
+    /// Encode a 32-bit float
+    pub fn encode_f32(&mut self, value: f32) -> BidResult<()> {
+        self.encode_entry(BidTag::F32, &value.to_le_bytes())
+    }
+    
+    /// Encode a 64-bit float
+    pub fn encode_f64(&mut self, value: f64) -> BidResult<()> {
+        self.encode_entry(BidTag::F64, &value.to_le_bytes())
+    }
+    
+    /// Encode a string
+    pub fn encode_string(&mut self, value: &str) -> BidResult<()> {
+        let bytes = value.as_bytes();
+        if bytes.len() > u16::MAX as usize {
+            return Err(BidError::InvalidArgs);
+        }
+        self.encode_entry(BidTag::String, bytes)
+    }
+    
+    /// Encode binary data
+    pub fn encode_bytes(&mut self, value: &[u8]) -> BidResult<()> {
+        if value.len() > u16::MAX as usize {
+            return Err(BidError::InvalidArgs);
+        }
+        self.encode_entry(BidTag::Bytes, value)
+    }
+    
+    /// Encode a handle
+    pub fn encode_handle(&mut self, handle: BidHandle) -> BidResult<()> {
+        self.encode_entry(BidTag::Handle, &handle.to_u64().to_le_bytes())
+    }
+    
+    /// Encode void (no payload)
+    pub fn encode_void(&mut self) -> BidResult<()> {
+        self.encode_entry(BidTag::Void, &[])
+    }
+    
+    /// Internal: encode a TLV entry
+    fn encode_entry(&mut self, tag: BidTag, payload: &[u8]) -> BidResult<()> {
+        let entry = TlvEntry {
+            tag: tag as u8,
+            reserved: 0,
+            size: payload.len() as u16,
+        };
+        
+        // Write entry header
+        self.buffer.push(entry.tag);
+        self.buffer.push(entry.reserved);
+        self.buffer.extend_from_slice(&entry.size.to_le_bytes());
+        
+        // Write payload
+        self.buffer.extend_from_slice(payload);
+        
+        self.entry_count += 1;
+        Ok(())
+    }
+    
+    /// Finalize the encoding and return the buffer
+    pub fn finish(mut self) -> Vec<u8> {
+        // Update header
+        let header = BidTlvHeader {
+            version: BID_VERSION,
+            argc: self.entry_count,
+        };
+        
+        // Write header at the beginning
+        self.buffer[0..2].copy_from_slice(&header.version.to_le_bytes());
+        self.buffer[2..4].copy_from_slice(&header.argc.to_le_bytes());
+        self.buffer
+    }
+}
+
+/// TLV decoder for BID-1 format
+pub struct TlvDecoder<'a> {
+    data: &'a [u8],
+    position: usize,
+    header: BidTlvHeader,
+}
+
+impl<'a> TlvDecoder<'a> {
+    /// Create a new TLV decoder
+    pub fn new(data: &'a [u8]) -> BidResult<Self> {
+        if data.len() < mem::size_of::<BidTlvHeader>() {
+            return Err(BidError::InvalidArgs);
+        }
+        
+        // Read header safely
+        let version = u16::from_le_bytes([data[0], data[1]]);
+        let argc = u16::from_le_bytes([data[2], data[3]]);
+        let header = BidTlvHeader { version, argc };
+        
+        if header.version != BID_VERSION {
+            return Err(BidError::VersionMismatch);
+        }
+        
+        Ok(Self {
+            data,
+            position: mem::size_of::<BidTlvHeader>(),
+            header,
+        })
+    }
+    
+    /// Get the argument count
+    pub fn arg_count(&self) -> u16 {
+        self.header.argc
+    }
+    
+    /// Decode the next entry
+    pub fn decode_next(&mut self) -> BidResult<Option<(BidTag, &'a [u8])>> {
+        if self.position >= self.data.len() {
+            return Ok(None);
+        }
+        
+        // Read entry header
+        if self.position + mem::size_of::<TlvEntry>() > self.data.len() {
+            return Err(BidError::InvalidArgs);
+        }
+        
+        // Read entry safely
+        let tag = self.data[self.position];
+        let reserved = self.data[self.position + 1];
+        let size = u16::from_le_bytes([
+            self.data[self.position + 2],
+            self.data[self.position + 3],
+        ]);
+        let entry = TlvEntry { tag, reserved, size };
+        self.position += mem::size_of::<TlvEntry>();
+        
+        // Read payload
+        let payload_end = self.position + entry.size as usize;
+        if payload_end > self.data.len() {
+            return Err(BidError::InvalidArgs);
+        }
+        
+        let payload = &self.data[self.position..payload_end];
+        self.position = payload_end;
+        
+        // Convert tag
+        let tag = match entry.tag {
+            1 => BidTag::Bool,
+            2 => BidTag::I32,
+            3 => BidTag::I64,
+            4 => BidTag::F32,
+            5 => BidTag::F64,
+            6 => BidTag::String,
+            7 => BidTag::Bytes,
+            8 => BidTag::Handle,
+            9 => BidTag::Void,
+            20 => BidTag::Result,
+            21 => BidTag::Option,
+            22 => BidTag::Array,
+            _ => return Err(BidError::InvalidType),
+        };
+        
+        Ok(Some((tag, payload)))
+    }
+    
+    /// Decode a boolean from payload
+    pub fn decode_bool(payload: &[u8]) -> BidResult<bool> {
+        if payload.len() != 1 {
+            return Err(BidError::InvalidArgs);
+        }
+        Ok(payload[0] != 0)
+    }
+    
+    /// Decode an i32 from payload
+    pub fn decode_i32(payload: &[u8]) -> BidResult<i32> {
+        if payload.len() != 4 {
+            return Err(BidError::InvalidArgs);
+        }
+        Ok(i32::from_le_bytes([payload[0], payload[1], payload[2], payload[3]]))
+    }
+    
+    /// Decode an i64 from payload
+    pub fn decode_i64(payload: &[u8]) -> BidResult<i64> {
+        if payload.len() != 8 {
+            return Err(BidError::InvalidArgs);
+        }
+        let mut bytes = [0u8; 8];
+        bytes.copy_from_slice(payload);
+        Ok(i64::from_le_bytes(bytes))
+    }
+    
+    /// Decode a handle from payload
+    pub fn decode_handle(payload: &[u8]) -> BidResult<BidHandle> {
+        if payload.len() != 8 {
+            return Err(BidError::InvalidArgs);
+        }
+        let mut bytes = [0u8; 8];
+        bytes.copy_from_slice(payload);
+        Ok(BidHandle::from_u64(u64::from_le_bytes(bytes)))
+    }
+    
+    /// Decode an f32 from payload
+    pub fn decode_f32(payload: &[u8]) -> BidResult<f32> {
+        if payload.len() != 4 {
+            return Err(BidError::InvalidArgs);
+        }
+        Ok(f32::from_le_bytes([payload[0], payload[1], payload[2], payload[3]]))
+    }
+    
+    /// Decode an f64 from payload
+    pub fn decode_f64(payload: &[u8]) -> BidResult<f64> {
+        if payload.len() != 8 {
+            return Err(BidError::InvalidArgs);
+        }
+        let mut bytes = [0u8; 8];
+        bytes.copy_from_slice(payload);
+        Ok(f64::from_le_bytes(bytes))
+    }
+    
+    /// Decode a string from payload
+    pub fn decode_string(payload: &[u8]) -> BidResult<&str> {
+        std::str::from_utf8(payload).map_err(|_| BidError::InvalidUtf8)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    
+    #[test]
+    fn test_encode_decode_primitives() {
+        let mut encoder = TlvEncoder::new();
+        encoder.encode_bool(true).unwrap();
+        encoder.encode_i32(42).unwrap();
+        encoder.encode_i64(9876543210).unwrap();
+        encoder.encode_string("Hello Nyash!").unwrap();
+        
+        let data = encoder.finish();
+        let mut decoder = TlvDecoder::new(&data).unwrap();
+        
+        assert_eq!(decoder.arg_count(), 4);
+        
+        // Decode bool
+        let (tag, payload) = decoder.decode_next().unwrap().unwrap();
+        assert_eq!(tag, BidTag::Bool);
+        assert_eq!(TlvDecoder::decode_bool(payload).unwrap(), true);
+        
+        // Decode i32
+        let (tag, payload) = decoder.decode_next().unwrap().unwrap();
+        assert_eq!(tag, BidTag::I32);
+        assert_eq!(TlvDecoder::decode_i32(payload).unwrap(), 42);
+        
+        // Decode i64
+        let (tag, payload) = decoder.decode_next().unwrap().unwrap();
+        assert_eq!(tag, BidTag::I64);
+        assert_eq!(TlvDecoder::decode_i64(payload).unwrap(), 9876543210);
+        
+        // Decode string
+        let (tag, payload) = decoder.decode_next().unwrap().unwrap();
+        assert_eq!(tag, BidTag::String);
+        assert_eq!(TlvDecoder::decode_string(payload).unwrap(), "Hello Nyash!");
+    }
+    
+    #[test]
+    fn test_encode_decode_handle() {
+        let mut encoder = TlvEncoder::new();
+        let handle = BidHandle::new(6, 12345);
+        encoder.encode_handle(handle).unwrap();
+        
+        let data = encoder.finish();
+        let mut decoder = TlvDecoder::new(&data).unwrap();
+        
+        let (tag, payload) = decoder.decode_next().unwrap().unwrap();
+        assert_eq!(tag, BidTag::Handle);
+        assert_eq!(TlvDecoder::decode_handle(payload).unwrap(), handle);
+    }
+}
\ No newline at end of file
diff --git a/src/bid/types.rs b/src/bid/types.rs
new file mode 100644
index 00000000..342d82e9
--- /dev/null
+++ b/src/bid/types.rs
@@ -0,0 +1,152 @@
+use super::Usize;
+
+/// BID-1 Type System (ChatGPT Enhanced Edition)
+#[derive(Clone, Debug, PartialEq)]
+pub enum BidType {
+    // === Primitives (pass by value across FFI) ===
+    Bool,       // i32 (0=false, 1=true)
+    I32,        // 32-bit signed integer
+    I64,        // 64-bit signed integer
+    F32,        // 32-bit floating point
+    F64,        // 64-bit floating point
+    
+    // === Composite types (pass as ptr+len) ===
+    String,     // UTF-8 string (ptr: usize, len: usize)
+    Bytes,      // Binary data (ptr: usize, len: usize)
+    
+    // === Handle design (ChatGPT recommendation) ===
+    Handle {
+        type_id: u32,       // Box type ID (1=StringBox, 6=FileBox, etc.)
+        instance_id: u32,   // Instance identifier
+    },
+    
+    // === Meta types ===
+    Void,       // No return value
+    
+    // === Phase 2 reserved (TLV tags reserved) ===
+    #[allow(dead_code)]
+    Option(Box<BidType>),         // TLV tag=21
+    #[allow(dead_code)]
+    Result(Box<BidType>, Box<BidType>), // TLV tag=20
+    #[allow(dead_code)]
+    Array(Box<BidType>),          // TLV tag=22
+}
+
+/// Handle representation for efficient Box references
+#[repr(C)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct BidHandle {
+    pub type_id: u32,
+    pub instance_id: u32,
+}
+
+impl BidHandle {
+    /// Create a new handle
+    pub fn new(type_id: u32, instance_id: u32) -> Self {
+        Self { type_id, instance_id }
+    }
+    
+    /// Pack into single u64 (type_id << 32 | instance_id)
+    pub fn to_u64(&self) -> u64 {
+        ((self.type_id as u64) << 32) | (self.instance_id as u64)
+    }
+    
+    /// Unpack from single u64
+    pub fn from_u64(packed: u64) -> Self {
+        Self {
+            type_id: (packed >> 32) as u32,
+            instance_id: (packed & 0xFFFFFFFF) as u32,
+        }
+    }
+}
+
+/// TLV (Type-Length-Value) tags for BID-1
+#[repr(u8)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum BidTag {
+    Bool = 1,    // payload: 1 byte (0/1)
+    I32 = 2,     // payload: 4 bytes (little-endian)
+    I64 = 3,     // payload: 8 bytes (little-endian)
+    F32 = 4,     // payload: 4 bytes (IEEE 754)
+    F64 = 5,     // payload: 8 bytes (IEEE 754)
+    String = 6,  // payload: UTF-8 bytes
+    Bytes = 7,   // payload: binary data
+    Handle = 8,  // payload: 8 bytes (type_id + instance_id)
+    Void = 9,    // payload: 0 bytes
+    
+    // Phase 2 reserved
+    Result = 20,
+    Option = 21,
+    Array = 22,
+}
+
+impl BidType {
+    /// Get the TLV tag for this type
+    pub fn tag(&self) -> BidTag {
+        match self {
+            BidType::Bool => BidTag::Bool,
+            BidType::I32 => BidTag::I32,
+            BidType::I64 => BidTag::I64,
+            BidType::F32 => BidTag::F32,
+            BidType::F64 => BidTag::F64,
+            BidType::String => BidTag::String,
+            BidType::Bytes => BidTag::Bytes,
+            BidType::Handle { .. } => BidTag::Handle,
+            BidType::Void => BidTag::Void,
+            _ => panic!("Phase 2 types not yet implemented"),
+        }
+    }
+    
+    /// Get the expected payload size (None for variable-length types)
+    pub fn payload_size(&self) -> Option<usize> {
+        match self {
+            BidType::Bool => Some(1),
+            BidType::I32 => Some(4),
+            BidType::I64 => Some(8),
+            BidType::F32 => Some(4),
+            BidType::F64 => Some(8),
+            BidType::Handle { .. } => Some(8),
+            BidType::Void => Some(0),
+            BidType::String | BidType::Bytes => None, // Variable length
+            _ => panic!("Phase 2 types not yet implemented"),
+        }
+    }
+}
+
+/// Box type IDs (matching existing Nyash boxes)
+#[repr(u32)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum BoxTypeId {
+    StringBox = 1,
+    IntegerBox = 2,
+    BoolBox = 3,
+    FloatBox = 4,
+    ArrayBox = 5,
+    FileBox = 6,      // Plugin example
+    FutureBox = 7,    // Existing async support
+    P2PBox = 8,       // Existing P2P support
+    // ... more box types
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    
+    #[test]
+    fn test_handle_packing() {
+        let handle = BidHandle::new(6, 12345);
+        let packed = handle.to_u64();
+        let unpacked = BidHandle::from_u64(packed);
+        
+        assert_eq!(handle, unpacked);
+        assert_eq!(unpacked.type_id, 6);
+        assert_eq!(unpacked.instance_id, 12345);
+    }
+    
+    #[test]
+    fn test_type_tags() {
+        assert_eq!(BidType::Bool.tag(), BidTag::Bool);
+        assert_eq!(BidType::String.tag(), BidTag::String);
+        assert_eq!(BidType::Handle { type_id: 6, instance_id: 0 }.tag(), BidTag::Handle);
+    }
+}
\ No newline at end of file
diff --git a/src/instance.rs b/src/instance.rs
index 6197dfc9..56aee71e 100644
--- a/src/instance.rs
+++ b/src/instance.rs
@@ -516,7 +516,7 @@ mod tests {
         
         // フィールドに値を設定
         let int_value = Box::new(IntegerBox::new(42)) as Box<dyn NyashBox>;
-        instance.set_field("value", int_value).unwrap();
+        instance.set_field("value", int_value.into()).unwrap();
         
         // フィールドの値を取得
         let retrieved = instance.get_field("value").unwrap();
diff --git a/src/lib.rs b/src/lib.rs
index 91610e1f..e217df4f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -29,6 +29,9 @@ pub mod box_arithmetic; // 🚀 Arithmetic operations moved from box_trait.rs
 // 🔥 NyashValue Revolutionary System (NEW!)
 pub mod value;
 
+// 🚀 BID-FFI: Box Interface Definition with FFI (NEW!)
+pub mod bid;
+
 // 🌐 P2P Communication Infrastructure (NEW!)
 pub mod messaging;
 pub mod transport;