smokes: add JSON nested/invalid cases; force VM backend; temp nyash.toml with json_native package for resolution

src/runner/modes/common_util/resolve/seam.rs

@@ -32,53 +32,5 @@ pub fn log_prelude_body_seam(prelude_clean: &str, body: &str, seam_dbg: bool) {
     eprintln!("[using][seam] body_head   =<<<{}>>>", head.replace('\n', "\\n"));
 }
 
-/// Apply optional seam safety: append missing '}' for unmatched '{' in prelude
-/// When `trace` is true, emits a short note with delta count.
-pub fn fix_prelude_braces_if_enabled(prelude_clean: &str, combined: &mut String, trace: bool) {
-    if !crate::config::env::resolve_fix_braces() {
-        return;
-    }
-    // compute { } delta ignoring strings and comments
-    let mut delta: i32 = 0;
-    let mut it = prelude_clean.chars().peekable();
-    let mut in_str = false;
-    let mut in_sl = false;
-    let mut in_ml = false;
-    while let Some(c) = it.next() {
-        if in_sl {
-            if c == '\n' { in_sl = false; }
-            continue;
-        }
-        if in_ml {
-            if c == '*' {
-                if let Some('/') = it.peek().copied() {
-                    it.next();
-                    in_ml = false;
-                }
-            }
-            continue;
-        }
-        if in_str {
-            if c == '\\' { it.next(); continue; }
-            if c == '"' { in_str = false; }
-            continue;
-        }
-        if c == '"' { in_str = true; continue; }
-        if c == '/' {
-            match it.peek().copied() {
-                Some('/') => { in_sl = true; it.next(); continue; }
-                Some('*') => { in_ml = true; it.next(); continue; }
-                _ => {}
-            }
-        }
-        if c == '{' { delta += 1; }
-        if c == '}' { delta -= 1; }
-    }
-    if delta > 0 {
-        if trace { eprintln!("[using][seam] fix: appending {} '}}' before body", delta); }
-        for _ in 0..delta {
-            combined.push('}');
-            combined.push('\n');
-        }
-    }
-}
+// Legacy brace fix function removed (Phase 15 cleanup)
+// AST-based integration handles syntax errors properly without text-level hacks

src/runner/modes/vm_fallback.rs

@@ -12,7 +12,7 @@ impl NyashRunner {
             Ok(s) => s,
             Err(e) => { eprintln!("❌ Error reading file {}: {}", filename, e); process::exit(1); }
         };
-        // Using preprocessing (legacy inline or AST-prelude merge when NYASH_USING_AST=1)
+        // Using preprocessing with AST-prelude merge (when NYASH_USING_AST=1)
         let mut code2 = code;
         let use_ast_prelude = crate::config::env::enable_using()
             && crate::config::env::using_ast_enabled();