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/pgsql/writer_test.go

@@ -426,11 +426,11 @@ func TestWriteAllConstraintTypes(t *testing.T) {
 
 	// Verify all constraint types are present
 	expectedConstraints := map[string]string{
-		"Primary Key":      "PRIMARY KEY",
-		"Unique":           "ADD CONSTRAINT uq_order_number UNIQUE (order_number)",
-		"Check (total)":    "ADD CONSTRAINT ck_total_positive CHECK (total > 0)",
-		"Check (status)":   "ADD CONSTRAINT ck_status_valid CHECK (status IN ('pending', 'completed', 'cancelled'))",
-		"Foreign Key":      "FOREIGN KEY",
+		"Primary Key":    "PRIMARY KEY",
+		"Unique":         "ADD CONSTRAINT uq_order_number UNIQUE (order_number)",
+		"Check (total)":  "ADD CONSTRAINT ck_total_positive CHECK (total > 0)",
+		"Check (status)": "ADD CONSTRAINT ck_status_valid CHECK (status IN ('pending', 'completed', 'cancelled'))",
+		"Foreign Key":    "FOREIGN KEY",
 	}
 
 	for name, expected := range expectedConstraints {
@@ -715,11 +715,11 @@ func TestColumnSizeSpecifiers(t *testing.T) {
 
 	// Verify valid patterns ARE present
 	validPatterns := []string{
-		"integer",     // without size
-		"bigint",      // without size
-		"smallint",    // without size
-		"varchar(100)", // text converted to varchar with length
-		"varchar(50)",  // varchar with length
+		"integer",       // without size
+		"bigint",        // without size
+		"smallint",      // without size
+		"varchar(100)",  // text converted to varchar with length
+		"varchar(50)",   // varchar with length
 		"decimal(19,4)", // decimal with precision and scale
 	}
 	for _, pattern := range validPatterns {
@@ -729,6 +729,56 @@ func TestColumnSizeSpecifiers(t *testing.T) {
 	}
 }
 
+func TestGenerateColumnDefinition_PreservesExplicitTypeModifiers(t *testing.T) {
+	writer := NewWriter(&writers.WriterOptions{})
+
+	cases := []struct {
+		name      string
+		colType   string
+		length    int
+		precision int
+		scale     int
+		wantType  string
+	}{
+		{
+			name:     "character varying already includes length",
+			colType:  "character varying(50)",
+			length:   50,
+			wantType: "character varying(50)",
+		},
+		{
+			name:      "numeric already includes precision",
+			colType:   "numeric(10,2)",
+			precision: 10,
+			scale:     2,
+			wantType:  "numeric(10,2)",
+		},
+		{
+			name:     "custom vector modifier preserved",
+			colType:  "vector(1536)",
+			wantType: "vector(1536)",
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			col := models.InitColumn("sample", "events", "public")
+			col.Type = tc.colType
+			col.Length = tc.length
+			col.Precision = tc.precision
+			col.Scale = tc.scale
+
+			def := writer.generateColumnDefinition(col)
+			if !strings.Contains(def, " "+tc.wantType+" ") && !strings.HasSuffix(def, " "+tc.wantType) {
+				t.Fatalf("generated definition %q does not contain expected type %q", def, tc.wantType)
+			}
+			if strings.Contains(def, ")(") {
+				t.Fatalf("generated definition %q appears to duplicate modifiers", def)
+			}
+		})
+	}
+}
+
 func TestGenerateAddColumnStatements(t *testing.T) {
 	// Create a test database with tables that have new columns
 	db := models.InitDatabase("testdb")