feat(env): Phase 71-73 - SSA fix + Stage-3 ENV consolidation

## Phase 71-SSA: StageBDriverBox birth warning 解消
- Fixed false-positive dev verify warning for static boxes
- StageBDriverBox is a static box, so it doesn't follow NewBox→birth pattern
- Modified lifecycle.rs to skip StageBDriverBox from birth() requirement

## Phase 73-A: Stage-3 legacy ENV 統一化
- Consolidated NYASH_PARSER_STAGE3 and HAKO_PARSER_STAGE3 → NYASH_FEATURES=stage3
- Updated 20 test files (46 direct replacements)
- Special handling for parser_stage3.rs compat layer and mir_static_main_args_loop.rs
- All test files now use unified NYASH_FEATURES=stage3

## Phase 72-73: ENV inventory documented
- Created phase72-73-env-inventory.md with complete usage analysis
- Identified 113 direct ENV reads requiring SSOT consolidation
- Prioritized Phase 72 (JoinIR EXPERIMENT SSOT) and Phase 73 (Stage-3 cleanup)

## Phase 74-SSA: Minimal reproduction for static box delegation
- Created parser_box_minimal.hako and ssa_static_delegation_min.hako
- Investigated spawn failure in selfhost compiler (arguments too long)
- Root cause: NYASH_NY_COMPILER_EMIT_ONLY=1 defaults to emit-only mode

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

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

src/mir/builder/lifecycle.rs

@@ -387,8 +387,9 @@ impl super::MirBuilder {
                         args,
                     } = &insns[idx]
                     {
-                        // Stage‑B dev verify OFF のときは StageBDriverBox の birth 警告のみスキップ
-                        if !stageb_dev_verify_on && box_type == "StageBDriverBox" {
+                        // Phase 71-SSA 71-11.2: StageBDriverBox is a static box → skip birth warning unconditionally
+                        // Static boxes don't follow NewBox→birth pattern by design
+                        if box_type == "StageBDriverBox" {
                             idx += 1;
                             continue;
                         }

src/tests/json_lint_stringutils_min_vm.rs

@@ -25,8 +25,8 @@ use crate::mir::MirCompiler;
 use crate::parser::NyashParser;
 
 fn ensure_stage3_env() {
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
-    std::env::set_var("HAKO_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
     std::env::set_var("NYASH_DISABLE_PLUGINS", "1");
     std::env::set_var("HAKO_MIR_BUILDER_METHODIZE", "0");
@@ -100,8 +100,8 @@ static box Main {
     }
 
     // cleanup
-    std::env::remove_var("NYASH_PARSER_STAGE3");
-    std::env::remove_var("HAKO_PARSER_STAGE3");
+    std::env::remove_var("NYASH_FEATURES");
+    std::env::remove_var("NYASH_FEATURES");
     std::env::remove_var("NYASH_PARSER_ALLOW_SEMICOLON");
     std::env::remove_var("NYASH_DISABLE_PLUGINS");
     std::env::remove_var("HAKO_MIR_BUILDER_METHODIZE");

src/tests/mir_breakfinder_ssa.rs

@@ -18,7 +18,7 @@ use crate::mir::{MirCompiler, MirPrinter, MirVerifier};
 use crate::parser::NyashParser;
 
 fn ensure_stage3_env() {
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
 }
 

src/tests/mir_ctrlflow_break_continue.rs

@@ -22,8 +22,8 @@ mod tests {
     #[test]
     fn vm_exec_continue_skips_body() {
         // Phase 59b: Stage-3 parser required for local variable declarations
-        std::env::set_var("NYASH_PARSER_STAGE3", "1");
-        std::env::set_var("HAKO_PARSER_STAGE3", "1");
+        std::env::set_var("NYASH_FEATURES", "stage3");
+        std::env::set_var("NYASH_FEATURES", "stage3");
 
         let code = r#"
         local i = 0
@@ -46,8 +46,8 @@ mod tests {
     #[test]
     fn vm_exec_break_inside_if() {
         // Phase 59b: Stage-3 parser required for local variable declarations
-        std::env::set_var("NYASH_PARSER_STAGE3", "1");
-        std::env::set_var("HAKO_PARSER_STAGE3", "1");
+        std::env::set_var("NYASH_FEATURES", "stage3");
+        std::env::set_var("NYASH_FEATURES", "stage3");
 
         let code = r#"
         local i = 0

src/tests/mir_funcscanner_parse_params_trim_min.rs

@@ -17,8 +17,8 @@ fn mir_funcscanner_parse_params_trim_min_verify_and_vm() {
     let test_file = "lang/src/compiler/tests/funcscanner_parse_params_trim_min.hako";
 
     // Align parser env to Stage‑3 + using 経路（既存の skip_ws 系と揃えておく）。
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
-    std::env::set_var("HAKO_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_ENABLE_USING", "1");
     std::env::set_var("HAKO_ENABLE_USING", "1");
     std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
@@ -92,8 +92,8 @@ fn mir_funcscanner_parse_params_trim_min_verify_and_vm() {
     );
 
     // Cleanup env vars
-    std::env::remove_var("NYASH_PARSER_STAGE3");
-    std::env::remove_var("HAKO_PARSER_STAGE3");
+    std::env::remove_var("NYASH_FEATURES");
+    std::env::remove_var("NYASH_FEATURES");
     std::env::remove_var("NYASH_ENABLE_USING");
     std::env::remove_var("HAKO_ENABLE_USING");
     std::env::remove_var("NYASH_PARSER_ALLOW_SEMICOLON");

src/tests/mir_funcscanner_skip_ws.rs

@@ -16,8 +16,8 @@ fn mir_funcscanner_skip_ws_direct_vm() {
     let test_file = "lang/src/compiler/tests/funcscanner_skip_ws_min.hako";
 
     // Enable required env vars for Stage-3 + using
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
-    std::env::set_var("HAKO_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_ENABLE_USING", "1");
     std::env::set_var("HAKO_ENABLE_USING", "1");
     std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
@@ -118,8 +118,8 @@ fn mir_funcscanner_skip_ws_direct_vm() {
     }
 
     // Cleanup env vars
-    std::env::remove_var("NYASH_PARSER_STAGE3");
-    std::env::remove_var("HAKO_PARSER_STAGE3");
+    std::env::remove_var("NYASH_FEATURES");
+    std::env::remove_var("NYASH_FEATURES");
     std::env::remove_var("NYASH_ENABLE_USING");
     std::env::remove_var("HAKO_ENABLE_USING");
     std::env::remove_var("NYASH_PARSER_ALLOW_SEMICOLON");

src/tests/mir_funcscanner_skip_ws_min.rs

@@ -11,8 +11,8 @@ fn mir_funcscanner_skip_ws_min_verify_and_vm() {
     let test_file = "lang/src/compiler/tests/funcscanner_skip_ws_min.hako";
 
     // Stage-3 + using
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
-    std::env::set_var("HAKO_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_ENABLE_USING", "1");
     std::env::set_var("HAKO_ENABLE_USING", "1");
     std::env::set_var("NYASH_DISABLE_PLUGINS", "1");
@@ -32,8 +32,8 @@ fn mir_funcscanner_skip_ws_min_verify_and_vm() {
     let mut vm = VM::new();
     vm.execute_module(&compiled.module).expect("VM exec failed");
 
-    std::env::remove_var("NYASH_PARSER_STAGE3");
-    std::env::remove_var("HAKO_PARSER_STAGE3");
+    std::env::remove_var("NYASH_FEATURES");
+    std::env::remove_var("NYASH_FEATURES");
     std::env::remove_var("NYASH_ENABLE_USING");
     std::env::remove_var("HAKO_ENABLE_USING");
     std::env::remove_var("NYASH_DISABLE_PLUGINS");

src/tests/mir_funcscanner_ssa.rs

@@ -19,7 +19,7 @@ use crate::mir::{MirCompiler, MirPrinter, MirVerifier};
 use crate::parser::NyashParser;
 
 fn ensure_stage3_env() {
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
     std::env::set_var("NYASH_ENABLE_USING", "1");
 }

src/tests/mir_funcscanner_trim_min.rs

@@ -16,8 +16,8 @@ fn mir_funcscanner_trim_min_verify_and_vm() {
     let test_file = "lang/src/compiler/tests/funcscanner_trim_min.hako";
 
     // Stage‑3 + using 系のパーサ設定を揃える（他の FuncScanner 系テストと同じ）。
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
-    std::env::set_var("HAKO_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_ENABLE_USING", "1");
     std::env::set_var("HAKO_ENABLE_USING", "1");
     std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
@@ -87,8 +87,8 @@ fn mir_funcscanner_trim_min_verify_and_vm() {
     }
 
     // Cleanup env vars
-    std::env::remove_var("NYASH_PARSER_STAGE3");
-    std::env::remove_var("HAKO_PARSER_STAGE3");
+    std::env::remove_var("NYASH_FEATURES");
+    std::env::remove_var("NYASH_FEATURES");
     std::env::remove_var("NYASH_ENABLE_USING");
     std::env::remove_var("HAKO_ENABLE_USING");
     std::env::remove_var("NYASH_PARSER_ALLOW_SEMICOLON");

src/tests/mir_locals_ssa.rs

@@ -12,7 +12,7 @@ use crate::parser::NyashParser;
 
 #[test]
 fn mir_locals_copy_instructions_emitted() {
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
 
     let src = r#"
@@ -102,7 +102,7 @@ static box TestLocals {
 
 #[test]
 fn mir_locals_uninitialized() {
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
 
     let src = r#"

src/tests/mir_pure_e2e_vm.rs

@@ -31,7 +31,7 @@ return (new StringBox("Hello")).length()
     /// Minimal smoke for MirInstruction::DebugLog
     #[test]
     fn mir_debuglog_minimal_printer_and_verifier() {
-        std::env::set_var("NYASH_PARSER_STAGE3", "1");
+        std::env::set_var("NYASH_FEATURES", "stage3");
         std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
         std::env::set_var("NYASH_MIR_DEBUG_LOG", "1");
 

src/tests/mir_stageb_like_args_length.rs

@@ -2,7 +2,7 @@ use crate::mir::MirPrinter;
 use crate::parser::NyashParser;
 
 fn ensure_stage3_env() {
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
 }
 use crate::ast::ASTNode;

src/tests/mir_stageb_loop_break_continue.rs

@@ -3,7 +3,7 @@ use crate::mir::{MirCompiler, MirPrinter, MirVerifier};
 use crate::parser::NyashParser;
 
 fn ensure_stage3_env() {
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
 }
 

src/tests/mir_stageb_string_utils_skip_ws.rs

@@ -47,8 +47,8 @@ static box Main {
     #[test]
     fn mir_stageb_string_utils_skip_ws_compile() {
         // Enable Stage-3 parser for 'local' keyword
-        std::env::set_var("NYASH_PARSER_STAGE3", "1");
-        std::env::set_var("HAKO_PARSER_STAGE3", "1");
+        std::env::set_var("NYASH_FEATURES", "stage3");
+        std::env::set_var("NYASH_FEATURES", "stage3");
 
         let src = make_minimal_src();
         let ast: ASTNode = NyashParser::parse_from_string(&src).expect("parse should succeed");
@@ -75,8 +75,8 @@ static box Main {
     #[ignore] // 修正前用テスト（commit b00cc8d5 で再現）
     fn mir_stageb_string_utils_skip_ws_exec_reproduce_void_lt_zero() {
         // Enable Stage-3 parser
-        std::env::set_var("NYASH_PARSER_STAGE3", "1");
-        std::env::set_var("HAKO_PARSER_STAGE3", "1");
+        std::env::set_var("NYASH_FEATURES", "stage3");
+        std::env::set_var("NYASH_FEATURES", "stage3");
 
         let src = make_minimal_src();
         let ast: ASTNode = NyashParser::parse_from_string(&src).expect("parse ok");
@@ -113,8 +113,8 @@ static box Main {
     #[test]
     fn mir_stageb_string_utils_skip_ws_exec_success() {
         // Enable Stage-3 parser
-        std::env::set_var("NYASH_PARSER_STAGE3", "1");
-        std::env::set_var("HAKO_PARSER_STAGE3", "1");
+        std::env::set_var("NYASH_FEATURES", "stage3");
+        std::env::set_var("NYASH_FEATURES", "stage3");
 
         let src = make_minimal_src();
         let ast: ASTNode = NyashParser::parse_from_string(&src).expect("parse ok");

src/tests/mir_static_box_naming.rs

@@ -28,8 +28,8 @@ fn load_fixture_with_string_helpers() -> String {
 #[test]
 fn mir_static_main_box_emits_canonical_static_methods() {
     // Enable Stage‑3 + using for the fixture.
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
-    std::env::set_var("HAKO_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
     std::env::set_var("NYASH_ENABLE_USING", "1");
     std::env::set_var("HAKO_ENABLE_USING", "1");
@@ -59,8 +59,8 @@ fn mir_static_main_box_emits_canonical_static_methods() {
 /// Execute the minimal fixture with Void-returning _nop() and confirm it lowers without SSA/arity drift.
 #[test]
 fn mir_static_main_box_executes_void_path_with_guard() {
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
-    std::env::set_var("HAKO_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_PARSER_ALLOW_SEMICOLON", "1");
     std::env::set_var("NYASH_ENABLE_USING", "1");
     std::env::set_var("HAKO_ENABLE_USING", "1");

src/tests/parser_block_postfix_catch.rs

@@ -1,7 +1,7 @@
 use crate::parser::NyashParser;
 
 fn enable_stage3() {
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     // Accept block‑postfix under Stage‑3 gate
     std::env::set_var("NYASH_BLOCK_CATCH", "1");
 }

src/tests/parser_block_postfix_errors.rs

@@ -1,7 +1,7 @@
 use crate::parser::NyashParser;
 
 fn enable_stage3() {
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_BLOCK_CATCH", "1");
 }
 

src/tests/parser_expr_postfix_catch.rs

@@ -1,7 +1,7 @@
 use crate::parser::NyashParser;
 
 fn enable_stage3() {
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
 }
 
 #[test]

src/tests/parser_method_postfix.rs

@@ -1,7 +1,7 @@
 use crate::parser::NyashParser;
 
 fn enable_stage3() {
-    std::env::set_var("NYASH_PARSER_STAGE3", "1");
+    std::env::set_var("NYASH_FEATURES", "stage3");
     std::env::set_var("NYASH_METHOD_CATCH", "1");
 }