fix: address audit execution failures and unsafe type conversions

pkg/writers/pgsql/migration_writer_test.go

@@ -136,7 +136,7 @@ func TestWriteMigration_AltersColumnTypeWhenActualTypeDiffers(t *testing.T) {
 	}
 }
 
-func TestWriteMigration_AltersColumnTypeFallsBackToRenameAndAddOnConversionFailure(t *testing.T) {
+func TestWriteMigration_AltersColumnTypePreservesConversionFailure(t *testing.T) {
 	current := models.InitDatabase("testdb")
 	currentSchema := models.InitSchema("public")
 	currentTable := models.InitTable("learnings", "public")
@@ -167,17 +167,13 @@ func TestWriteMigration_AltersColumnTypeFallsBackToRenameAndAddOnConversionFailu
 	}
 
 	output := buf.String()
-	if !strings.Contains(output, "EXCEPTION WHEN OTHERS THEN") {
-		t.Fatalf("expected migration to guard the type conversion with an exception handler, got:\n%s", output)
+	if !strings.Contains(output, "ALTER COLUMN details TYPE integer USING details::integer;") {
+		t.Fatalf("expected explicit type conversion, got:\n%s", output)
 	}
-	if !strings.Contains(output, "RENAME COLUMN details TO %I") {
-		t.Fatalf("expected migration to rename the old column (derived from the live type) on conversion failure, got:\n%s", output)
-	}
-	if !strings.Contains(output, "renamed_column := 'details_' || trim(both '_' from regexp_replace(lower(current_type)") {
-		t.Fatalf("expected migration to derive the renamed column name from the live type, got:\n%s", output)
-	}
-	if !strings.Contains(output, "ADD COLUMN details integer") {
-		t.Fatalf("expected migration to add a fresh column with the new type on conversion failure, got:\n%s", output)
+	for _, unsafe := range []string{"EXCEPTION WHEN OTHERS", "renamed_column", "RENAME COLUMN"} {
+		if strings.Contains(output, unsafe) {
+			t.Fatalf("type conversion must propagate errors without replacing the column (%s):\n%s", unsafe, output)
+		}
 	}
 }