feat(type_mapper): add support for serial types and auto-increment tags

pkg/writers/bun/type_mapper.go

@@ -62,6 +62,17 @@ func (tm *TypeMapper) isSimpleType(sqlType string) bool {
 	return simpleTypes[sqlType]
 }
 
+// isSerialType checks if a SQL type is a serial type (auto-incrementing)
+func (tm *TypeMapper) isSerialType(sqlType string) bool {
+	baseType := tm.extractBaseType(sqlType)
+	serialTypes := map[string]bool{
+		"serial":      true,
+		"bigserial":   true,
+		"smallserial": true,
+	}
+	return serialTypes[baseType]
+}
+
 // baseGoType returns the base Go type for a SQL type (not null, simple types only)
 func (tm *TypeMapper) baseGoType(sqlType string) string {
 	typeMap := map[string]string{
@@ -190,6 +201,11 @@ func (tm *TypeMapper) BuildBunTag(column *models.Column, table *models.Table) st
 		parts = append(parts, "pk")
 	}
 
+	// Auto increment (for serial types or explicit auto_increment)
+	if column.AutoIncrement || tm.isSerialType(column.Type) {
+		parts = append(parts, "autoincrement")
+	}
+
 	// Default value
 	if column.Default != nil {
 		// Sanitize default value to remove backticks

pkg/writers/bun/writer_test.go

@@ -90,8 +90,8 @@ func TestWriter_WriteTable(t *testing.T) {
 	}
 
 	// Verify Bun-specific elements
-	if !strings.Contains(generated, "bun:\"id,type:bigint,pk,") {
+	if !strings.Contains(generated, "bun:\"id,type:bigint,pk,autoincrement,") {
-		t.Errorf("Missing Bun-style primary key tag")
+		t.Errorf("Missing Bun-style primary key tag with autoincrement")
 	}
 }
 
@@ -624,6 +624,37 @@ func TestTypeMapper_BuildBunTag(t *testing.T) {
 			},
 			want: []string{"status,", "type:text,", "default:active,"},
 		},
+		{
+			name: "auto increment with AutoIncrement flag",
+			column: &models.Column{
+				Name:          "id",
+				Type:          "bigint",
+				NotNull:       true,
+				IsPrimaryKey:  true,
+				AutoIncrement: true,
+			},
+			want: []string{"id,", "type:bigint,", "pk,", "autoincrement,"},
+		},
+		{
+			name: "serial type (auto-increment)",
+			column: &models.Column{
+				Name:         "id",
+				Type:         "serial",
+				NotNull:      true,
+				IsPrimaryKey: true,
+			},
+			want: []string{"id,", "type:serial,", "pk,", "autoincrement,"},
+		},
+		{
+			name: "bigserial type (auto-increment)",
+			column: &models.Column{
+				Name:         "id",
+				Type:         "bigserial",
+				NotNull:      true,
+				IsPrimaryKey: true,
+			},
+			want: []string{"id,", "type:bigserial,", "pk,", "autoincrement,"},
+		},
 	}
 
 	for _, tt := range tests {