🎉 Phase 11.8/12.7: MIR Core-13 完全実装 + 糖衣構文ドキュメント更新

主要な変更:
- MIR Core-13命令セット確定（Load/Store削除の革命的設計）
  - Const, BinOp, Compare（値・計算）
  - Jump, Branch, Return, Phi（制御）
  - Call, BoxCall, ExternCall（呼び出し）
  - TypeOp, Safepoint, Barrier（メタ）
- Phase 12.7糖衣構文ドキュメント整理（超圧縮重視、可逆変換保証）
- MIRビルダーのモジュール分割完了
- vtableテストスイート拡充
- AI協調開発ツール追加（並列リファクタリング支援）

詳細:
- src/mir/instruction_introspection.rs: core13_instruction_names()追加
- MIRビルダー分割: decls.rs, exprs_*.rs, fields.rs
- plugin_loader_v2: errors.rs, host_bridge.rs分離
- 論文用データ: mir13-final.md作成

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

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

src/jit/lower/extern_thunks.rs

@@ -762,10 +762,6 @@ pub(super) extern "C" fn nyash_string_from_ptr(ptr: u64, len: u64) -> i64 {
 }
 
 // ===== FunctionBox call shims (by arity, up to 4) =====
-#[cfg(feature = "cranelift-jit")]
-fn vmvalue_from_jit_arg_i64(v: i64) -> crate::backend::vm::VMValue { super::vmvalue_from_jit_arg_i64(v) }
-#[cfg(feature = "cranelift-jit")]
-fn i64_from_vmvalue(v: crate::backend::vm::VMValue) -> i64 { super::i64_from_vmvalue(v) }
 
 #[cfg(feature = "cranelift-jit")]
 fn fn_call_impl(func_h: u64, args: &[i64]) -> i64 {

src/jit/policy/invoke.rs

@@ -1,8 +1,7 @@
 //! InvokePolicyPass (minimal scaffold)
-//! Centralizes decision for plugin/hostcall/any to keep lowerer slim.
-//! Current implementation covers a small subset (ArrayBox length/get/set/push,
-//! MapBox size/get/has/set) when NYASH_USE_PLUGIN_BUILTINS=1, falling back
-//! to existing hostcall symbols otherwise. Extend incrementally.
+//! Centralizes decision for plugin/hostcall to keep lowerer slim.
+//! HostCall優先（Core-13方針）。ENV `NYASH_USE_PLUGIN_BUILTINS=1` の場合のみ
+//! plugin_invoke を試し、解決できない場合はHostCallへフォールバックする。
 
 #[derive(Debug, Clone)]
 pub enum InvokeDecision {
@@ -17,15 +16,7 @@ fn use_plugin_builtins() -> bool {
 
 /// Decide invocation policy for a known Box method.
 pub fn decide_box_method(box_type: &str, method: &str, argc: usize, has_ret: bool) -> InvokeDecision {
-    // Prefer plugin path when enabled and method is resolvable
-    if use_plugin_builtins() {
-        if let Ok(ph) = crate::runtime::plugin_loader_unified::get_global_plugin_host().read() {
-            if let Ok(h) = ph.resolve_method(box_type, method) {
-                return InvokeDecision::PluginInvoke { type_id: h.type_id, method_id: h.method_id, box_type: h.box_type, method: method.to_string(), argc, has_ret };
-            }
-        }
-    }
-    // Minimal hostcall mapping for common collections/math symbols
+    // HostCall mapping for common collections/strings/instance ops
     let symbol = match (box_type, method) {
         ("ArrayBox", "length") | ("StringBox", "length") | ("StringBox", "len") => crate::jit::r#extern::collections::SYM_ANY_LEN_H,
         ("ArrayBox", "get") => crate::jit::r#extern::collections::SYM_ARRAY_GET_H,
@@ -39,9 +30,18 @@ pub fn decide_box_method(box_type: &str, method: &str, argc: usize, has_ret: boo
         ("StringBox","charCodeAt") => crate::jit::r#extern::collections::SYM_STRING_CHARCODE_AT_H,
         _ => "" // unknown
     };
-    if symbol.is_empty() {
+    // Prefer HostCall when available
+    if !symbol.is_empty() {
+        InvokeDecision::HostCall { symbol: symbol.to_string(), argc, has_ret, reason: "mapped_symbol" }
+    } else if use_plugin_builtins() {
+        // Try plugin_invoke as a secondary path when enabled
+        if let Ok(ph) = crate::runtime::plugin_loader_unified::get_global_plugin_host().read() {
+            if let Ok(h) = ph.resolve_method(box_type, method) {
+                return InvokeDecision::PluginInvoke { type_id: h.type_id, method_id: h.method_id, box_type: h.box_type, method: method.to_string(), argc, has_ret };
+            }
+        }
         InvokeDecision::Fallback { reason: "unknown_method" }
     } else {
-        InvokeDecision::HostCall { symbol: symbol.to_string(), argc, has_ret, reason: "mapped_symbol" }
+        InvokeDecision::Fallback { reason: "unknown_method" }
     }
 }