// Normalize inline/display LaTeX delimiters \( \) \[ \] -> $$ for ai-generated content.
$map = ['\\(','\\)','\\[','\\]'];
$qChanged=[]; $qn=0;
DB::table('questions')->where('qa_status','ai_generated')->orderBy('id')
  ->chunkById(1000, function($rows) use (&$qChanged,&$qn,$map){
    foreach ($rows as $r) {
      $newQ = str_replace($map, '$$', (string)$r->question);
      $newE = str_replace($map, '$$', (string)$r->explanation);
      $upd=[];
      if ($newQ !== (string)$r->question) $upd['question']=$newQ;
      if ($newE !== (string)$r->explanation) $upd['explanation']=$newE;
      if ($upd) { $qChanged[]=['id'=>$r->id,'question'=>$r->question,'explanation'=>$r->explanation]; $upd['updated_at']=now(); DB::table('questions')->where('id',$r->id)->update($upd); $qn++; }
    }
  });
file_put_contents(storage_path('app/latexnorm_q_backup_'.date('Ymd_His').'.json'), json_encode($qChanged, JSON_UNESCAPED_UNICODE));

$sChanged=[]; $sn=0;
DB::table('solutions')->where('source','ai')->orderBy('id')
  ->chunkById(1000, function($rows) use (&$sChanged,&$sn,$map){
    foreach ($rows as $r) {
      $new = str_replace($map, '$$', (string)$r->solution);
      if ($new !== (string)$r->solution) { $sChanged[]=['id'=>$r->id,'solution'=>$r->solution]; DB::table('solutions')->where('id',$r->id)->update(['solution'=>$new,'updated_at'=>now()]); $sn++; }
    }
  });
file_put_contents(storage_path('app/latexnorm_s_backup_'.date('Ymd_His').'.json'), json_encode($sChanged, JSON_UNESCAPED_UNICODE));

echo "questions_updated=$qn solutions_updated=$sn\n";
$resQ = DB::table('questions')->where('qa_status','ai_generated')->where('question','like','%\\\\(%')->count();
$resS = DB::table('solutions')->where('source','ai')->where('solution','like','%\\\\(%')->count();
echo "residual_Q_with_backslash_paren=$resQ residual_SOL=$resS\n";