📚 Phase 12.5 最適化戦略 & Phase 15 セルフホスティング計画

Phase 12.5: MIR15最適化戦略 - コンパイラ丸投げ作戦
- optimization-strategy.txt: 詳細戦略（MIR側は軽量、コンパイラに丸投げ）
- implementation-examples.md: 具体的な実装例
- debug-safety-comparison.md: 現在のDebugBox vs ChatGPT5提案の比較分析

Phase 15: Nyashセルフホスティング - 究極の目標
- self-hosting-plan.txt: 内蔵Craneliftによる実現計画
- technical-details.md: CompilerBox設計とブートストラップ手順
- README.md: セルフホスティングのビジョン

重要な知見：
- LLVM統合完了済み（Phase 11）だが依存が重すぎる
- Craneliftが現実的な選択肢（3-5MB vs LLVM 50-100MB）
- 「コンパイラもBox、すべてがBox」の夢へ

MASTERロードマップ更新済み

src/runtime/global_hooks.rs

@@ -105,6 +105,8 @@ pub fn push_task_scope() {
     if let Ok(mut st) = group_stack_cell().write() {
         st.push(std::sync::Arc::new(crate::boxes::task_group_box::TaskGroupInner { strong: std::sync::Mutex::new(Vec::new()) }));
     }
+    // Set a fresh cancellation token for this scope (best-effort)
+    set_current_group_token(CancellationToken::new());
 }
 
 /// Pop a task scope. When depth reaches 0, join outstanding futures.
@@ -137,6 +139,8 @@ pub fn pop_task_scope() {
             join_all_registered_futures(ms);
         }
     }
+    // Reset token (best-effort)
+    set_current_group_token(CancellationToken::new());
 }
 
 /// Perform a runtime safepoint and poll the scheduler if available.
@@ -174,3 +178,19 @@ pub fn spawn_task_with_token(name: &str, token: crate::runtime::scheduler::Cance
     f();
     false
 }
+
+/// Spawn a delayed task via scheduler if available; returns true if scheduled.
+pub fn spawn_task_after(delay_ms: u64, name: &str, f: Box<dyn FnOnce() + Send + 'static>) -> bool {
+    if let Ok(s) = sched_cell().read() {
+        if let Some(sched) = s.as_ref() {
+            sched.spawn_after(delay_ms, name, f);
+            return true;
+        }
+    }
+    // Fallback: run inline after blocking sleep
+    std::thread::spawn(move || {
+        std::thread::sleep(std::time::Duration::from_millis(delay_ms));
+        f();
+    });
+    false
+}

src/runtime/plugin_loader_v2.rs

@@ -468,6 +468,17 @@ impl PluginLoaderV2 {
                 }
                 Ok(None)
             }
+            ("env.task", "cancelCurrent") => {
+                let tok = crate::runtime::global_hooks::current_group_token();
+                tok.cancel();
+                Ok(None)
+            }
+            ("env.task", "currentToken") => {
+                // Return a TokenBox representing current task group's cancellation token
+                let tok = crate::runtime::global_hooks::current_group_token();
+                let tb = crate::boxes::token_box::TokenBox::from_token(tok);
+                Ok(Some(Box::new(tb)))
+            }
             ("env.debug", "trace") => {
                 // Minimal debug trace; prints to stderr when enabled
                 if std::env::var("NYASH_DEBUG_TRACE").ok().as_deref() == Some("1") {
@@ -530,6 +541,21 @@ impl PluginLoaderV2 {
                 }
                 Ok(Some(Box::new(crate::boxes::result::NyashResultBox::new_err(Box::new(crate::box_trait::StringBox::new("InvalidArgs"))))))
             }
+            ("env.future", "delay") => {
+                // delay(ms) -> FutureBox resolved to void after ms
+                use crate::box_trait::NyashBox as _;
+                let fut = crate::boxes::future::FutureBox::new();
+                let ms = if let Some(arg0) = args.get(0) {
+                    if let Some(i) = arg0.as_any().downcast_ref::<crate::box_trait::IntegerBox>() { i.value.max(0) as u64 }
+                    else { arg0.to_string_box().value.trim().parse::<i64>().unwrap_or(0).max(0) as u64 }
+                } else { 0 };
+                let fut_setter = fut.clone();
+                let _scheduled = crate::runtime::global_hooks::spawn_task_after(ms, "env.future.delay", Box::new(move || {
+                    fut_setter.set_result(Box::new(crate::box_trait::VoidBox::new()));
+                }));
+                crate::runtime::global_hooks::register_future_to_current_group(&fut);
+                Ok(Some(Box::new(fut)))
+            }
             ("env.future", "spawn_instance") => {
                 // spawn_instance(recv, method_name, args...) -> FutureBox
                 // If a scheduler is available, schedule the call; else invoke synchronously.