step,rule,n_before,n_after,n_removed,rationale
1,line must split into exactly 5 CSV fields,1200,1164,36,"corrupted export lines (random characters, wrong field count); cannot be read, not reconstructed"
2,"all fields parse: sale_id S+5 digits, known municipality, ISO date, integer price (plain or comma-thousands), positive numeric area",1164,1164,0,fields not unambiguously readable
3,sale_id unique,1164,1164,0,duplicated ids would be ambiguous