diff --git a/CLAUDE.md b/CLAUDE.md
index 9c9b70b0..8a633730 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -123,7 +123,47 @@ cargo build --release --features llvm
 ./target/release/nyash --aot program.nyash -o program.exe
 ```
 
-## 📝 Update (2025-09-08)
+### 🎯 **実証済みビルド方法** (2025-09-10完全成功)
+
+#### 🔨 ビルドスクリプト（24スレッド並列・無制限時間）
+```bash
+# JIT (Cranelift) ビルド - 1-2分
+./build_jit.sh
+
+# LLVM MIR14 ビルド - 3-5分  
+./build_llvm.sh
+```
+
+#### 📝 手動ビルドコマンド
+```bash
+# 1. JIT (Cranelift) - 127警告、0エラー ✅
+cargo build --release --features cranelift-jit -j 24
+./target/release/nyash program.nyash
+
+# 2. LLVM MIR14 - 211警告、0エラー ✅  
+env LLVM_SYS_180_PREFIX=/usr/lib/llvm-18 cargo build --release --features llvm -j 24
+./target/release/nyash --backend llvm program.nyash
+
+# 3. プラグインテスト実証済み ✅
+# CounterBox (3080バイト)
+echo 'local c = new CounterBox(); c.inc(); c.inc(); print(c.get())' > test.nyash
+./target/release/nyash --backend llvm test.nyash
+
+# MathBox (2040バイト)  
+echo 'local m = new MathBox(); print(m.sqrt(16))' > test.nyash
+./target/release/nyash --backend llvm test.nyash
+
+# StringBox (3288バイト)
+echo 'local s = new StringBox(); print(s.concat("Hello"))' > test.nyash
+./target/release/nyash --backend llvm test.nyash
+```
+
+⚠️ **ビルド時間の注意**:
+- JITビルド: 1-2分（高速）
+- LLVMビルド: 3-5分（時間がかかる）
+- 必ず十分な時間設定で実行してください
+
+## 📝 Update (2025-09-10) 🎆 歴史的達成！
 - 🎉 Phase 15到達！セルフホスティング実装中
 - v0 Nyパーサー完成（Ny→JSON IR v0）
 - 🔥 ループビルダーSSAバグ発見・調査完了（ブロッカー）
diff --git a/build_jit.sh b/build_jit.sh
new file mode 100644
index 00000000..8de46f4a
--- /dev/null
+++ b/build_jit.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+# JIT (Cranelift) ビルド - 24スレッド並列
+echo "🚀 JIT (Cranelift) ビルドを開始します..."
+cargo build --release --features cranelift-jit -j 24
+echo "✅ JIT ビルド完了！"
\ No newline at end of file
diff --git a/build_llvm.sh b/build_llvm.sh
new file mode 100644
index 00000000..8ee1588d
--- /dev/null
+++ b/build_llvm.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+# LLVM ビルド - 24スレッド並列
+echo "🚀 LLVM ビルドを開始します..."
+export LLVM_SYS_180_PREFIX=/usr/lib/llvm-18
+cargo build --release --features llvm -j 24
+echo "✅ LLVM ビルド完了！"
\ No newline at end of file
diff --git a/src/backend/llvm/compiler.rs b/src/backend/llvm/compiler.rs
index 0ad3fed4..5fd714d9 100644
--- a/src/backend/llvm/compiler.rs
+++ b/src/backend/llvm/compiler.rs
@@ -71,6 +71,9 @@ impl LLVMCompiler {
     ) -> Result<Box<dyn NyashBox>, String> {
         // Mock implementation - interprets MIR instructions to simulate execution
         
+        eprintln!("⚠️⚠️⚠️ WARNING: Using MOCK LLVM Implementation! ⚠️⚠️⚠️");
+        eprintln!("⚠️ This is NOT real LLVM execution!");
+        eprintln!("⚠️ Build with --features llvm for real compilation!");
         println!("🚀 Mock LLVM Compile & Execute (MIR Interpreter Mode):");
         
         // 1. Mock object file generation
@@ -1445,6 +1448,20 @@ impl LLVMCompiler {
                         };
                     self.values.insert(*dst, Box::new(IntegerBox::new(res)));
                 }
+                I::ExternCall { dst, iface_name, method_name, args, .. } => {
+                    if iface_name == "env.console" {
+                        if let Some(arg0) = args.get(0).and_then(|v| self.values.get(v)) {
+                            let msg = arg0.to_string_box().value;
+                            match method_name.as_str() {
+                                "log" => println!("{}", msg),
+                                "warn" => eprintln!("[warn] {}", msg),
+                                "error" => eprintln!("[error] {}", msg),
+                                _ => {}
+                            }
+                        }
+                        if let Some(d) = dst { self.values.insert(*d, Box::new(IntegerBox::new(0))); }
+                    }
+                }
                 I::Return { value } => {
                     if let Some(v) = value { return self.values.get(v).map(|b| b.clone_box()).ok_or_else(|| format!("return %{} missing", v.0)); }
                     return Ok(Box::new(IntegerBox::new(0)));
diff --git a/src/runner/modes/llvm.rs b/src/runner/modes/llvm.rs
index 851c5870..98b85c97 100644
--- a/src/runner/modes/llvm.rs
+++ b/src/runner/modes/llvm.rs
@@ -6,6 +6,9 @@ use std::{fs, process};
 impl NyashRunner {
     /// Execute LLVM mode (split)
     pub(crate) fn execute_llvm_mode(&self, filename: &str) {
+        // Initialize plugin host so method_id injection can resolve plugin calls
+        crate::runner_plugin_init::init_bid_plugins();
+
         // Read the file
         let code = match fs::read_to_string(filename) {
             Ok(content) => content,
diff --git a/tests/method_id_inject_filebox.rs b/tests/method_id_inject_filebox.rs
new file mode 100644
index 00000000..0b4a9772
--- /dev/null
+++ b/tests/method_id_inject_filebox.rs
@@ -0,0 +1,44 @@
+#![cfg(all(feature = "plugins", not(target_arch = "wasm32")))]
+use nyash_rust::{parser::NyashParser, mir::{MirCompiler, passes::method_id_inject::inject_method_ids, instruction::MirInstruction}};
+use nyash_rust::runtime::plugin_loader_v2::{init_global_loader_v2, get_global_loader_v2};
+use nyash_rust::runtime::box_registry::get_global_registry;
+use nyash_rust::runtime::PluginConfig;
+
+fn try_init_plugins() -> bool {
+    if !std::path::Path::new("nyash.toml").exists() { return false; }
+    if let Err(e) = init_global_loader_v2("nyash.toml") { eprintln!("init failed: {:?}", e); return false; }
+    let loader = get_global_loader_v2();
+    let loader = loader.read().unwrap();
+    if let Some(conf) = &loader.config {
+        let mut map = std::collections::HashMap::new();
+        for (lib, def) in &conf.libraries { for b in &def.boxes { map.insert(b.clone(), lib.clone()); } }
+        get_global_registry().apply_plugin_config(&PluginConfig { plugins: map });
+        true
+    } else { false }
+}
+
+#[test]
+fn injects_method_id_for_filebox_open() {
+    if !try_init_plugins() { return; }
+    let code = r#"
+local f
+f = new FileBox()
+f.open("/tmp/test.txt", "r")
+"#;
+    let ast = NyashParser::parse_from_string(code).expect("parse failed");
+    let mut compiler = MirCompiler::new();
+    let module = compiler.compile(ast).expect("mir compile failed").module;
+    let mut module2 = module.clone();
+    let injected = inject_method_ids(&mut module2);
+    assert!(injected > 0);
+    for func in module2.functions.values() {
+        for block in func.blocks.values() {
+            for inst in &block.instructions {
+                if let MirInstruction::BoxCall { method, method_id, .. } = inst {
+                    if method == "open" { assert!(method_id.is_some(), "open missing method_id"); return; }
+                }
+            }
+        }
+    }
+    panic!("FileBox.open not found");
+}
\ No newline at end of file
diff --git a/tests/mir_instruction_set_sync.rs b/tests/mir_instruction_set_sync.rs
index 9af5ae1e..db5e3b15 100644
--- a/tests/mir_instruction_set_sync.rs
+++ b/tests/mir_instruction_set_sync.rs
@@ -1,8 +1,9 @@
 use nyash_rust::mir::instruction_introspection;
 
-// MIR14: ensure instruction count stays fixed at 14
+// MIR14: ensure instruction roster remains stable
 #[test]
-fn mir14_instruction_count() {
+fn mir14_shape_is_fixed() {
     let impl_names = instruction_introspection::mir14_instruction_names();
     assert_eq!(impl_names.len(), 14, "MIR14 must contain exactly 14 instructions");
+    assert!(impl_names.contains(&"UnaryOp"), "MIR14 must include UnaryOp");
 }