Phase 30.1 & 73: Stage-3 features env and JoinIR flag cleanup

src/runner/child_env.rs

@@ -43,6 +43,12 @@ pub fn apply_core_wrapper_env(cmd: &mut std::process::Command) {
     // When selfhost builder uses `using` to load modules, the inline compiler
     // needs Stage-3 support for `local` keyword. Without this, we get:
     // "Undefined variable: local" in nested compilation.
+    // Preferred propagation: NYASH_FEATURES carries Stage-3 (legacy envs kept for compatibility)
+    if let Ok(val) = std::env::var("NYASH_FEATURES") {
+        cmd.env("NYASH_FEATURES", val);
+    } else if crate::config::env::parser_stage3_enabled() {
+        cmd.env("NYASH_FEATURES", "stage3");
+    }
     if let Ok(val) = std::env::var("NYASH_PARSER_STAGE3") {
         cmd.env("NYASH_PARSER_STAGE3", val);
     }

src/runner/modes/vm.rs

@@ -169,11 +169,8 @@ impl NyashRunner {
             }
         }
 
-        if trace
-            && (std::env::var("NYASH_PARSER_STAGE3").ok() == Some("1".into())
-                || std::env::var("HAKO_PARSER_STAGE3").ok() == Some("1".into()))
-        {
-            eprintln!("[vm] Stage-3: enabled (env) for {}", filename);
+        if trace && crate::config::env::parser_stage3_enabled() {
+            eprintln!("[vm] Stage-3: enabled (NYASH_FEATURES/legacy env) for {}", filename);
         }
 
         // Fail‑Fast (opt‑in): Hako 構文を Nyash VM 経路で実行しない
@@ -500,8 +497,10 @@ impl NyashRunner {
         }
 
         // Phase 33-10.0: If lowering ドライラン統合（箱化版）
-        // HAKO_JOINIR_IF_SELECT=1 で有効化、IfLoweringDryRunner を使用
-        if crate::config::env::joinir_if_select_enabled() {
+        // JoinIR dev + IfSelect 有効時に IfLoweringDryRunner を使用
+        if crate::config::env::joinir_dev_enabled()
+            && crate::config::env::joinir_if_select_enabled()
+        {
             let debug_level = crate::config::env::joinir_debug_level();
             let runner =
                 crate::mir::join_ir::lowering::if_dry_runner::IfLoweringDryRunner::new(debug_level);

src/runner/modes/vm_fallback.rs

@@ -86,11 +86,11 @@ impl NyashRunner {
             code2 = crate::runner::modes::common_util::hako::strip_local_decl(&code2);
         }
 
-        if trace
-            && (std::env::var("NYASH_PARSER_STAGE3").ok() == Some("1".into())
-                || std::env::var("HAKO_PARSER_STAGE3").ok() == Some("1".into()))
-        {
-            eprintln!("[vm-fallback] Stage-3: enabled (env) for {}", filename);
+        if trace && crate::config::env::parser_stage3_enabled() {
+            eprintln!(
+                "[vm-fallback] Stage-3: enabled (NYASH_FEATURES/legacy env) for {}",
+                filename
+            );
         }
 
         // Fail‑Fast (opt‑in): Hako 構文を Nyash VM 経路で実行しない

src/runner/stage1_bridge/env.rs

@@ -12,7 +12,7 @@ use std::process::Command;
 ///
 /// Sets defaults for:
 /// - Runtime behavior (NYASH_NYRT_SILENT_RESULT, NYASH_DISABLE_PLUGINS, etc.)
-/// - Parser toggles (NYASH_PARSER_STAGE3, NYASH_ENABLE_USING, etc.)
+/// - Parser toggles (NYASH_FEATURES=stage3, legacy NYASH_PARSER_STAGE3, NYASH_ENABLE_USING, etc.)
 /// - Stage-B configuration (HAKO_STAGEB_APPLY_USINGS, HAKO_STAGEB_MODULES_LIST, etc.)
 pub(super) fn configure_stage1_env(
     cmd: &mut Command,
@@ -87,17 +87,49 @@ pub(super) fn configure_stage1_env(
             if env::enable_using() { "1" } else { "0" },
         );
     }
-    if std::env::var("NYASH_PARSER_STAGE3").is_err() {
-        cmd.env(
-            "NYASH_PARSER_STAGE3",
-            if env::parser_stage3() { "1" } else { "0" },
-        );
+    // Stage-3 gate (default ON): prefer NYASH_FEATURES for propagation, but keep
+    // legacy envs if parent explicitly set them.
+    let stage3_enabled = env::parser_stage3_enabled();
+    let merge_feature = |current: &str, feature: &str| -> String {
+        let mut list: Vec<String> = current
+            .split(',')
+            .filter_map(|s| {
+                let trimmed = s.trim();
+                if trimmed.is_empty() {
+                    None
+                } else {
+                    Some(trimmed.to_string())
+                }
+            })
+            .collect();
+        let normalized_feature = feature.replace(['-', '_'], "");
+        let contains = list.iter().any(|f| {
+            let n = f.to_ascii_lowercase().replace(['-', '_'], "");
+            n == normalized_feature
+        });
+        if !contains {
+            list.push(feature.to_string());
+        }
+        list.join(",")
+    };
+    match std::env::var("NYASH_FEATURES") {
+        Ok(current) => {
+            if stage3_enabled {
+                cmd.env("NYASH_FEATURES", merge_feature(&current, "stage3"));
+            } else {
+                cmd.env("NYASH_FEATURES", current);
+            }
+        }
+        Err(_) if stage3_enabled => {
+            cmd.env("NYASH_FEATURES", "stage3");
+        }
+        Err(_) => {}
     }
-    if std::env::var("HAKO_PARSER_STAGE3").is_err() {
-        cmd.env(
-            "HAKO_PARSER_STAGE3",
-            if env::parser_stage3() { "1" } else { "0" },
-        );
+    if let Ok(val) = std::env::var("NYASH_PARSER_STAGE3") {
+        cmd.env("NYASH_PARSER_STAGE3", val);
+    }
+    if let Ok(val) = std::env::var("HAKO_PARSER_STAGE3") {
+        cmd.env("HAKO_PARSER_STAGE3", val);
     }
 
     // Modules list