fix(base): preserve attachment metadata on base uploads

shortcuts/base/base_dryrun_ops_test.go

@@ -137,6 +137,8 @@ func TestDryRunRecordOps(t *testing.T) {
 		"bitable_file",
 		"PATCH /open-apis/base/v3/bases/app_x/tables/tbl_1/records/rec_1",
 		"report-final.pdf",
+		`"mime_type":"\u003cdetected_mime_type\u003e"`,
+		`"size":"\u003cfile_size\u003e"`,
 		"deprecated_set_attachment",
 	)
 }

shortcuts/base/base_execute_test.go

@@ -1219,7 +1219,9 @@ func TestBaseRecordExecuteReadCreateDelete(t *testing.T) {
 			!strings.Contains(updateBody, `"image_height":480`) ||
 			!strings.Contains(updateBody, `"deprecated_set_attachment":true`) ||
 			!strings.Contains(updateBody, `"file_token":"file_tok_1"`) ||
-			!strings.Contains(updateBody, `"name":"report.txt"`) {
+			!strings.Contains(updateBody, `"name":"report.txt"`) ||
+			!strings.Contains(updateBody, `"size":16`) ||
+			!strings.Contains(updateBody, `"mime_type":"text/plain"`) {
 			t.Fatalf("update body=%s", updateBody)
 		}
 	})
@@ -1370,6 +1372,8 @@ func TestBaseRecordExecuteReadCreateDelete(t *testing.T) {
 		if !strings.Contains(updateBody, `"附件"`) ||
 			!strings.Contains(updateBody, `"file_token":"file_tok_big"`) ||
 			!strings.Contains(updateBody, `"name":"large-report.bin"`) ||
+			!strings.Contains(updateBody, `"size":20971521`) ||
+			!strings.Contains(updateBody, `"mime_type":"application/octet-stream"`) ||
 			!strings.Contains(updateBody, `"deprecated_set_attachment":true`) {
 			t.Fatalf("update body=%s", updateBody)
 		}

shortcuts/base/record_upload_attachment.go

@@ -4,11 +4,15 @@
 package base
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
+	"io"
+	"mime"
 	"path/filepath"
 	"strings"
+	"unicode/utf8"
 
 	"github.com/larksuite/cli/extension/fileio"
 	"github.com/larksuite/cli/internal/output"
@@ -105,6 +109,8 @@
 				map[string]interface{}{
 					"file_token":                "<uploaded_file_token>",
 					"name":                      fileName,
+					"mime_type":                 "<detected_mime_type>",
+					"size":                      "<file_size>",
 					"deprecated_set_attachment": true,
 				},
 			},
@@ -243,10 +249,14 @@
 }
 
 func uploadAttachmentToBase(runtime *common.RuntimeContext, filePath, fileName, baseToken string, fileSize int64) (map[string]interface{}, error) {
+	mimeType, err := detectAttachmentMIMEType(runtime.FileIO(), filePath, fileName)
+	if err != nil {
+		return nil, err
+	}
+
 	parentNode := baseToken
 	var (
 		fileToken string
-		err       error
 	)
 	if fileSize <= common.MaxDriveMediaUploadSinglePartSize {
 		fileToken, err = common.UploadDriveMediaAll(runtime, common.DriveMediaUploadAllConfig{
@@ -272,7 +282,78 @@
 	attachment := map[string]interface{}{
 		"file_token":                fileToken,
 		"name":                      fileName,
+		"mime_type":                 mimeType,
+		"size":                      fileSize,
 		"deprecated_set_attachment": true,
 	}
 	return attachment, nil
 }
+
+func detectAttachmentMIMEType(fio fileio.FileIO, filePath, fileName string) (string, error) {
+	if byExt := strings.TrimSpace(mime.TypeByExtension(strings.ToLower(filepath.Ext(fileName)))); byExt != "" {
+		return stripMIMEParams(byExt), nil
+	}
+	if byExt := strings.TrimSpace(mime.TypeByExtension(strings.ToLower(filepath.Ext(filePath)))); byExt != "" {
+		return stripMIMEParams(byExt), nil
+	}
+
+	f, err := fio.Open(filePath)
+	if err != nil {
+		return "", common.WrapInputStatError(err)
+	}
+	defer f.Close()
+
+	buf := make([]byte, 512)
+	n, readErr := f.Read(buf)
+	if readErr != nil && !errors.Is(readErr, io.EOF) {
+		return "", output.ErrValidation("cannot read file: %s", readErr)
+	}
+	return detectAttachmentMIMEFromContent(buf[:n]), nil
+}
+
+func stripMIMEParams(value string) string {
+	if i := strings.IndexByte(value, ';'); i != -1 {
+		value = value[:i]
+	}
+	return strings.TrimSpace(value)
+}
+
+func detectAttachmentMIMEFromContent(content []byte) string {
+	if len(content) == 0 {
+		return "application/octet-stream"
+	}
+	if bytes.HasPrefix(content, []byte{0x89, 'P', 'N', 'G', '\r', '\n', 0x1a, '\n'}) {
+		return "image/png"
+	}
+	if bytes.HasPrefix(content, []byte{0xff, 0xd8, 0xff}) {
+		return "image/jpeg"
+	}
+	if bytes.HasPrefix(content, []byte("GIF87a")) || bytes.HasPrefix(content, []byte("GIF89a")) {
+		return "image/gif"
+	}
+	if len(content) >= 12 && bytes.Equal(content[:4], []byte("RIFF")) && bytes.Equal(content[8:12], []byte("WEBP")) {
+		return "image/webp"
+	}
+	if bytes.HasPrefix(content, []byte("%PDF-")) {
+		return "application/pdf"
+	}
+	if looksLikeText(content) {
+		return "text/plain"
+	}
+	return "application/octet-stream"
+}
+
+func looksLikeText(content []byte) bool {
+	if !utf8.Valid(content) {
+		return false
+	}
+	for _, r := range string(content) {
+		if r == '\n' || r == '\r' || r == '\t' {
+			continue
+		}
+		if r < 0x20 || r == 0x7f {
+			return false
+		}
+	}
+	return true
+}

shortcuts/base/record_upload_attachment_test.go

@@ -0,0 +1,136 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package base
+
+import (
+	"bytes"
+	"io"
+	"io/fs"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/larksuite/cli/extension/fileio"
+)
+
+type attachmentTestFileIO struct {
+	openFile fileio.File
+	openErr  error
+}
+
+func (f attachmentTestFileIO) Open(string) (fileio.File, error) { return f.openFile, f.openErr }
+func (attachmentTestFileIO) Stat(string) (fileio.FileInfo, error) {
+	return attachmentTestFileInfo{}, nil
+}
+func (attachmentTestFileIO) ResolvePath(path string) (string, error) { return path, nil }
+func (attachmentTestFileIO) Save(string, fileio.SaveOptions, io.Reader) (fileio.SaveResult, error) {
+	return nil, nil
+}
+
+type attachmentTestFileInfo struct{}
+
+func (attachmentTestFileInfo) Size() int64       { return 0 }
+func (attachmentTestFileInfo) IsDir() bool       { return false }
+func (attachmentTestFileInfo) Mode() fs.FileMode { return 0 }
+
+type attachmentTestFile struct {
+	*bytes.Reader
+}
+
+func newAttachmentTestFile(content []byte) attachmentTestFile {
+	return attachmentTestFile{Reader: bytes.NewReader(content)}
+}
+
+func (attachmentTestFile) Close() error { return nil }
+
+type attachmentReadErrorFile struct{}
+
+func (attachmentReadErrorFile) Read([]byte) (int, error)          { return 0, os.ErrPermission }
+func (attachmentReadErrorFile) ReadAt([]byte, int64) (int, error) { return 0, io.EOF }
+func (attachmentReadErrorFile) Close() error                      { return nil }
+
+func TestDetectAttachmentMIMETypeUsesExtension(t *testing.T) {
+	got, err := detectAttachmentMIMEType(nil, "ignored", "note.TXT")
+	if err != nil {
+		t.Fatalf("detectAttachmentMIMEType() error = %v", err)
+	}
+	if got != "text/plain" {
+		t.Fatalf("detectAttachmentMIMEType() = %q, want %q", got, "text/plain")
+	}
+}
+
+func TestDetectAttachmentMIMETypeFallsBackToSourcePathExtension(t *testing.T) {
+	got, err := detectAttachmentMIMEType(nil, "report.docx", "report")
+	if err != nil {
+		t.Fatalf("detectAttachmentMIMEType() error = %v", err)
+	}
+	if got != "application/vnd.openxmlformats-officedocument.wordprocessingml.document" {
+		t.Fatalf("detectAttachmentMIMEType() = %q, want docx MIME type", got)
+	}
+}
+
+func TestDetectAttachmentMIMETypeFallsBackToContent(t *testing.T) {
+	fio := attachmentTestFileIO{openFile: newAttachmentTestFile([]byte("hello from base attachment"))}
+
+	got, err := detectAttachmentMIMEType(fio, "note", "note")
+	if err != nil {
+		t.Fatalf("detectAttachmentMIMEType() error = %v", err)
+	}
+	if got != "text/plain" {
+		t.Fatalf("detectAttachmentMIMEType() = %q, want %q", got, "text/plain")
+	}
+}
+
+func TestDetectAttachmentMIMETypeWrapsOpenError(t *testing.T) {
+	fio := attachmentTestFileIO{openErr: os.ErrNotExist}
+
+	_, err := detectAttachmentMIMEType(fio, "missing", "missing")
+	if err == nil {
+		t.Fatal("expected error for open failure")
+	}
+	if !strings.Contains(err.Error(), "cannot read file") {
+		t.Fatalf("error = %v, want wrapped read failure", err)
+	}
+}
+
+func TestDetectAttachmentMIMETypeReturnsReadError(t *testing.T) {
+	fio := attachmentTestFileIO{openFile: attachmentReadErrorFile{}}
+
+	_, err := detectAttachmentMIMEType(fio, "broken", "broken")
+	if err == nil {
+		t.Fatal("expected error for read failure")
+	}
+	if !strings.Contains(err.Error(), "cannot read file") {
+		t.Fatalf("error = %v, want read failure", err)
+	}
+}
+
+func TestDetectAttachmentMIMEFromContent(t *testing.T) {
+	tests := []struct {
+		name    string
+		content []byte
+		want    string
+	}{
+		{name: "empty", content: nil, want: "application/octet-stream"},
+		{name: "png", content: []byte{0x89, 'P', 'N', 'G', '\r', '\n', 0x1a, '\n'}, want: "image/png"},
+		{name: "jpeg", content: []byte{0xff, 0xd8, 0xff, 0xe0}, want: "image/jpeg"},
+		{name: "gif87a", content: []byte("GIF87a"), want: "image/gif"},
+		{name: "gif89a", content: []byte("GIF89a"), want: "image/gif"},
+		{name: "webp", content: []byte("RIFF1234WEBP"), want: "image/webp"},
+		{name: "pdf", content: []byte("%PDF-1.7"), want: "application/pdf"},
+		{name: "text", content: []byte("hello from base attachment"), want: "text/plain"},
+		{name: "text with newline", content: []byte("hello\nworld\tok"), want: "text/plain"},
+		{name: "control bytes", content: []byte{'h', 'i', 0x00}, want: "application/octet-stream"},
+		{name: "binary fallback", content: []byte{0x00, 0x01, 0x02, 0x03}, want: "application/octet-stream"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := detectAttachmentMIMEFromContent(tt.content)
+			if got != tt.want {
+				t.Fatalf("detectAttachmentMIMEFromContent() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}