test(drawdb): add test for converting column types with modifiers

* Implement tests to ensure explicit type modifiers are preserved during conversion.
* Validate behavior for varchar, numeric, and custom vector types.

pkg/writers/bun/type_mapper.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 
 	"git.warky.dev/wdevs/relspecgo/pkg/models"
+	"git.warky.dev/wdevs/relspecgo/pkg/pgsql"
 	"git.warky.dev/wdevs/relspecgo/pkg/writers"
 )
 
@@ -39,14 +40,7 @@ func (tm *TypeMapper) SQLTypeToGoType(sqlType string, notNull bool) string {
 
 // extractBaseType extracts the base type from a SQL type string
 func (tm *TypeMapper) extractBaseType(sqlType string) string {
-	sqlType = strings.ToLower(strings.TrimSpace(sqlType))
-
-	// Remove everything after '('
-	if idx := strings.Index(sqlType, "("); idx > 0 {
-		sqlType = sqlType[:idx]
-	}
-
-	return sqlType
+	return pgsql.CanonicalizeBaseType(pgsql.ExtractBaseTypeLower(sqlType))
 }
 
 // isSimpleType checks if a type should use base Go type when NOT NULL
@@ -184,9 +178,10 @@ func (tm *TypeMapper) BuildBunTag(column *models.Column, table *models.Table) st
 	if column.Type != "" {
 		// Sanitize type to remove backticks
 		typeStr := writers.SanitizeStructTagValue(column.Type)
-		if column.Length > 0 {
+		hasExplicitTypeModifier := pgsql.HasExplicitTypeModifier(typeStr)
+		if !hasExplicitTypeModifier && column.Length > 0 {
 			typeStr = fmt.Sprintf("%s(%d)", typeStr, column.Length)
-		} else if column.Precision > 0 {
+		} else if !hasExplicitTypeModifier && column.Precision > 0 {
 			if column.Scale > 0 {
 				typeStr = fmt.Sprintf("%s(%d,%d)", typeStr, column.Precision, column.Scale)
 			} else {

pkg/writers/bun/writer_test.go

@@ -698,3 +698,23 @@ func TestTypeMapper_BuildBunTag(t *testing.T) {
 		})
 	}
 }
+
+func TestTypeMapper_BuildBunTag_PreservesExplicitTypeModifiers(t *testing.T) {
+	mapper := NewTypeMapper()
+
+	col := &models.Column{
+		Name:      "embedding",
+		Type:      "vector(1536)",
+		Length:    1536,
+		Precision: 0,
+		Scale:     0,
+	}
+
+	tag := mapper.BuildBunTag(col, nil)
+	if !strings.Contains(tag, "type:vector(1536),") {
+		t.Fatalf("expected explicit modifier to be preserved, got %q", tag)
+	}
+	if strings.Contains(tag, ")(") {
+		t.Fatalf("type modifier appears duplicated in %q", tag)
+	}
+}