Fix keep-mutants flag and preserve header comments in mutants

bin/typefuzz

@@ -109,7 +109,6 @@ def main():
                 signal.signal(signal.SIGINT, stats_control_c)
             else:
                 signal.signal(signal.SIGINT, silent_control_c)
-                exit(OK_NOBUGS)
 
             fuzzer.run()
         except Exception as e:

yinyang/src/core/Fuzzer.py

@@ -87,16 +87,38 @@ def __init__(self, args, strategy):
         self.first_status_bar_printed = False
         self.name = random_string()
         self.timeout_of_current_seed = 0
+        self.header_comments = ""  # Store header comments to preserve in mutants
 
         init_logging(strategy, self.args.quiet, self.name, args)
 
+    def extract_header_comments(self, seed_file):
+        """
+        Extract header comments (lines starting with ;) that appear before
+        the first SMT-LIB command. These typically include EXPECT, COMMAND-LINE, etc.
+        """
+        header = []
+        try:
+            with open(seed_file, 'r') as f:
+                for line in f:
+                    stripped = line.strip()
+                    if stripped.startswith(';'):
+                        header.append(line.rstrip('\n'))
+                    elif stripped and not stripped.startswith(';'):
+                        # First non-comment, non-empty line - stop collecting headers
+                        break
+        except Exception:
+            pass
+        return '\n'.join(header) + ('\n' if header else '')
+
     def process_seed(self, seed):
         if not admissible_seed_size(seed, self.args):
             self.statistic.invalid_seeds += 1
             logging.debug("Skip invalid seed: exceeds max file size")
             return None, None
 
         self.currentseeds.append(pathlib.Path(seed).stem)
+        # Extract header comments before parsing
+        self.header_comments = self.extract_header_comments(seed)
         script, glob = parse_file(seed, silent=True)
 
         if not script:
@@ -220,6 +242,9 @@ def create_testbook(self, script):
             random_string(),
         )
         with open(testcase, "w") as testcase_writer:
+            # Prepend header comments if they exist
+            if self.header_comments:
+                testcase_writer.write(self.header_comments)
             testcase_writer.write(script.__str__())
 
         for cli in self.args.SOLVER_CLIS:
@@ -477,6 +502,7 @@ def terminate(self):
         exit(OK_BUGS)
 
     def __del__(self):
-        for fn in os.listdir(self.args.scratchfolder):
-            if self.name in fn:
-                os.remove(os.path.join(self.args.scratchfolder, fn))
+        if not self.args.keep_mutants:
+            for fn in os.listdir(self.args.scratchfolder):
+                if self.name in fn:
+                    os.remove(os.path.join(self.args.scratchfolder, fn))