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

src/parser/mod.rs

@@ -159,10 +159,10 @@ impl NyashParser {
     }
 
     /// 文字列からパース (トークナイズ + パース)
-    /// Note: Reads environment variables (NYASH_PARSER_STAGE3, etc.) for using-chain parsing
+    /// Note: Reads parser_stage3_enabled() (NYASH_FEATURES=stage3 or legacy env) for using-chain parsing
     pub fn parse_from_string(input: impl Into<String>) -> Result<ASTNode, ParseError> {
         // Ensure Stage-3 features are enabled when parsing using-chain files
-        // if the parent process has NYASH_PARSER_STAGE3=1 set
+        // when parent requested Stage-3 parsing via NYASH_FEATURES/legacy env
         Self::parse_from_string_with_fuel(input, Some(100_000))
     }