Phase 12.7完了 + ChatGPT5によるVMリファクタリング

## 📚 Phase 12.7 ドキュメント整理
- ChatGPT5作成のANCP Token仕様書v1を整備
- フォルダ構造を機能別に再編成:
  - ancp-specs/ : ANCP圧縮技法仕様
  - grammar-specs/ : 文法改革仕様
  - implementation/ : 実装計画
  - ai-feedback/ : AIアドバイザーフィードバック
- 各フォルダにREADME.md作成で導線改善

## 🔧 ChatGPT5によるVMリファクタリング
- vm_instructions.rs (1927行) をモジュール分割:
  - boxcall.rs : Box呼び出し処理
  - call.rs : 関数呼び出し処理
  - extern_call.rs : 外部関数処理
  - function_new.rs : FunctionBox生成
  - newbox.rs : Box生成処理
  - plugin_invoke.rs : プラグイン呼び出し
- VM実行をファイル分割で整理:
  - vm_state.rs : 状態管理
  - vm_exec.rs : 実行エンジン
  - vm_control_flow.rs : 制御フロー
  - vm_gc.rs : GC処理
- plugin_loader_v2もモジュール化

## ✨ 新機能実装
- FunctionBox呼び出しのVM/MIR統一進捗
- ラムダ式のFunctionBox変換テスト追加
- 関数値の直接呼び出し基盤整備

次ステップ: ANCPプロトタイプ実装開始（Week 1）

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/box_factory/builtin.rs

@@ -0,0 +1,74 @@
+/*!
+ * Builtin Box Factory
+ *
+ * Provides constructors for core builtin Box types so that the unified
+ * registry can create them without relying on plugins.
+ * Priority order in UnifiedBoxRegistry remains: builtin > user > plugin.
+ */
+
+use super::BoxFactory;
+use crate::box_trait::{NyashBox, StringBox, IntegerBox, BoolBox};
+use crate::interpreter::RuntimeError;
+
+/// Factory for builtin Box types
+pub struct BuiltinBoxFactory;
+
+impl BuiltinBoxFactory {
+    pub fn new() -> Self { Self }
+}
+
+impl BoxFactory for BuiltinBoxFactory {
+    fn create_box(
+        &self,
+        name: &str,
+        args: &[Box<dyn NyashBox>],
+    ) -> Result<Box<dyn NyashBox>, RuntimeError> {
+        match name {
+            // Primitive wrappers
+            "StringBox" => {
+                if let Some(arg0) = args.get(0) {
+                    if let Some(sb) = arg0.as_any().downcast_ref::<StringBox>() {
+                        return Ok(Box::new(StringBox::new(&sb.value)));
+                    }
+                }
+                Ok(Box::new(StringBox::new("")))
+            }
+            "IntegerBox" => {
+                if let Some(arg0) = args.get(0) {
+                    if let Some(ib) = arg0.as_any().downcast_ref::<IntegerBox>() {
+                        return Ok(Box::new(IntegerBox::new(ib.value)));
+                    }
+                }
+                Ok(Box::new(IntegerBox::new(0)))
+            }
+            "BoolBox" => {
+                if let Some(arg0) = args.get(0) {
+                    if let Some(bb) = arg0.as_any().downcast_ref::<BoolBox>() {
+                        return Ok(Box::new(BoolBox::new(bb.value)));
+                    }
+                }
+                Ok(Box::new(BoolBox::new(false)))
+            }
+
+            // Collections and common boxes
+            "ArrayBox" => Ok(Box::new(crate::boxes::array::ArrayBox::new())),
+            "MapBox" => Ok(Box::new(crate::boxes::map_box::MapBox::new())),
+            "ConsoleBox" => Ok(Box::new(crate::boxes::console_box::ConsoleBox::new())),
+            "NullBox" => Ok(Box::new(crate::boxes::null_box::NullBox::new())),
+
+            // Leave other types to other factories (user/plugin)
+            _ => Err(RuntimeError::InvalidOperation { message: format!("Unknown Box type: {}", name) }),
+        }
+    }
+
+    fn box_types(&self) -> Vec<&str> {
+        vec![
+            // Primitive wrappers
+            "StringBox", "IntegerBox", "BoolBox",
+            // Collections/common
+            "ArrayBox", "MapBox", "ConsoleBox", "NullBox",
+        ]
+    }
+
+    fn is_builtin_factory(&self) -> bool { true }
+}

src/box_factory/mod.rs

@@ -208,6 +208,7 @@ impl UnifiedBoxRegistry {
 /// Re-export submodules
 pub mod user_defined;
 pub mod plugin;
+pub mod builtin;
 
 #[cfg(test)]
 mod tests {