fix(bun): use PostgreSQL internal array type name for sqltypes array columns

bun's pgdialect overrides Field.Scan/Append with its own slice-only array
handling whenever the tag's type: value ends in "[]", clobbering the
sql.Scanner/driver.Valuer implemented on SqlXxxArray wrapper types and
causing "bun: Scan(unsupported sqltypes.SqlStringArray)" at query time.
Emit the underscore-prefixed internal type name (e.g. _text) instead,
which is DDL-valid but doesn't end in "[]" so bun leaves our scanner alone.

pkg/writers/bun/type_mapper.go

@@ -186,6 +186,40 @@ func (tm *TypeMapper) bunGoType(sqlType string) string {
 	return tm.sqlTypesAlias + ".SqlString"
 }
 
+// pgArrayInternalTypeName returns PostgreSQL's internal array type name
+// (e.g. "_text" for text[]) for the given canonical base element type.
+//
+// This is used instead of the "text[]" spelling in the sqltypes-style bun
+// tag: bun's pgdialect unconditionally overrides Field.Scan/Append with its
+// own array handling whenever the tag's "type:" value ends in "[]" (see
+// pgdialect.Dialect.onField), which clobbers the sql.Scanner/driver.Valuer
+// implemented on the SqlXxxArray wrapper types and causes
+// "bun: Scan(unsupported sqltypes.SqlXxxArray)" errors at query time. The
+// underscore-prefixed internal name is a real, DDL-valid PostgreSQL type
+// name that doesn't end in "[]", so it sidesteps the override.
+func (tm *TypeMapper) pgArrayInternalTypeName(baseElemType string) string {
+	typeMap := map[string]string{
+		"text": "_text", "varchar": "_varchar",
+		"char": "_bpchar", "character": "_bpchar", "bpchar": "_bpchar",
+		"citext": "_citext",
+		"inet":   "_inet", "cidr": "_cidr", "macaddr": "_macaddr",
+		"json": "_json", "jsonb": "_jsonb",
+		"integer": "_int4", "int": "_int4", "int4": "_int4", "serial": "_int4",
+		"smallint": "_int2", "int2": "_int2", "smallserial": "_int2",
+		"bigint": "_int8", "int8": "_int8", "bigserial": "_int8",
+		"real": "_float4", "float4": "_float4",
+		"double precision": "_float8", "float8": "_float8",
+		"numeric": "_numeric", "decimal": "_numeric",
+		"money":   "_money",
+		"boolean": "_bool", "bool": "_bool",
+		"uuid": "_uuid",
+	}
+	if pgType, ok := typeMap[baseElemType]; ok {
+		return pgType
+	}
+	return "_text"
+}
+
 // arrayGoType returns the Go type for a PostgreSQL array column.
 // The baseElemType is the canonical base type (e.g. "text", "integer").
 func (tm *TypeMapper) arrayGoType(baseElemType string) string {
@@ -360,6 +394,9 @@ func (tm *TypeMapper) BuildBunTag(column *models.Column, table *models.Table) st
 				typeStr = fmt.Sprintf("%s(%d)", typeStr, column.Precision)
 			}
 		}
+		if isArray && tm.typeStyle == writers.NullableTypeSqlTypes {
+			typeStr = tm.pgArrayInternalTypeName(tm.extractBaseType(typeStr))
+		}
 		parts = append(parts, fmt.Sprintf("type:%s", typeStr))
 		if isArray && tm.typeStyle == writers.NullableTypeStdlib {
 			parts = append(parts, "array")

pkg/writers/bun/writer_test.go

@@ -827,9 +827,45 @@ func TestTypeMapper_BuildBunTag(t *testing.T) {
 					t.Errorf("BuildBunTag() = %q, missing %q", result, part)
 				}
 			}
-			// sqltypes mode must NOT add "array" — SqlXxxArray uses sql.Scanner
+			// baselib mode must NOT add "array" — the Go type is already a
+			// real slice ([]string, []int32, ...), which bun's pgdialect
+			// scans natively without the explicit "array" tag option.
 			if strings.Contains(result, ",array,") || strings.HasSuffix(result, ",array,") {
-				t.Errorf("BuildBunTag() = %q, must not contain 'array' in sqltypes mode", result)
+				t.Errorf("BuildBunTag() = %q, must not contain 'array' in baselib mode", result)
+			}
+		})
+	}
+}
+
+// TestTypeMapper_BuildBunTag_SqlTypesArrayUsesInternalTypeName verifies that
+// array columns in sqltypes mode never produce a "[]"-suffixed "type:" tag.
+// bun's pgdialect unconditionally overrides Field.Scan/Append with its own
+// (slice-only) array handling whenever the tag's "type:" value ends in "[]",
+// which clobbers the sql.Scanner/driver.Valuer implemented on the
+// SqlXxxArray wrapper types and produces
+// "bun: Scan(unsupported sqltypes.SqlXxxArray)" at query time.
+func TestTypeMapper_BuildBunTag_SqlTypesArrayUsesInternalTypeName(t *testing.T) {
+	mapper := NewTypeMapper(writers.NullableTypeSqlTypes)
+
+	cases := []struct {
+		name       string
+		column     *models.Column
+		wantSubstr string
+	}{
+		{name: "text array", column: &models.Column{Name: "tags", Type: "text[]"}, wantSubstr: "type:_text,"},
+		{name: "varchar array", column: &models.Column{Name: "labels", Type: "varchar[]"}, wantSubstr: "type:_varchar,"},
+		{name: "integer array", column: &models.Column{Name: "scores", Type: "integer[]", NotNull: true}, wantSubstr: "type:_int4,"},
+		{name: "boolean array", column: &models.Column{Name: "flags", Type: "boolean[]"}, wantSubstr: "type:_bool,"},
+		{name: "uuid array", column: &models.Column{Name: "ids", Type: "uuid[]"}, wantSubstr: "type:_uuid,"},
+	}
+	for _, tt := range cases {
+		t.Run(tt.name, func(t *testing.T) {
+			result := mapper.BuildBunTag(tt.column, nil)
+			if !strings.Contains(result, tt.wantSubstr) {
+				t.Errorf("BuildBunTag() = %q, missing %q", result, tt.wantSubstr)
+			}
+			if strings.Contains(result, "[]") {
+				t.Errorf("BuildBunTag() = %q, must not use a \"[]\"-suffixed type in sqltypes mode", result)
 			}
 		})
 	}