fix: support pasting WeChat screenshots on macOS

internal/ui/model/clipboard.go

@@ -12,4 +12,5 @@ const (
 var (
 	errClipboardPlatformUnsupported = errors.New("clipboard operations are not supported on this platform")
 	errClipboardUnknownFormat       = errors.New("unknown clipboard format")
+	errClipboardImageUnavailable    = errors.New("clipboard does not contain a supported image format")
 )

internal/ui/model/clipboard_image_darwin.go

@@ -0,0 +1,112 @@
+//go:build darwin && !ios
+
+package model
+
+import (
+	"bytes"
+	"image/png"
+	"runtime"
+	"unsafe"
+
+	"github.com/ebitengine/purego"
+	"github.com/ebitengine/purego/objc"
+	"golang.org/x/image/tiff"
+)
+
+var (
+	nsPasteboardClass objc.Class
+	nsDataClass       objc.Class
+
+	selGeneralPasteboard objc.SEL
+	selDataForType       objc.SEL
+	selBytes             objc.SEL
+	selLength            objc.SEL
+
+	nsPasteboardTypeTIFF objc.ID
+
+	clipboardImageDarwinInitialized bool
+	clipboardImageDarwinInitError   error
+)
+
+func initClipboardImageDarwin() {
+	if clipboardImageDarwinInitialized {
+		return
+	}
+	clipboardImageDarwinInitialized = true
+
+	appkit, err := purego.Dlopen("/System/Library/Frameworks/AppKit.framework/AppKit", purego.RTLD_NOW|purego.RTLD_GLOBAL)
+	if err != nil {
+		clipboardImageDarwinInitError = err
+		return
+	}
+
+	nsPasteboardClass = objc.GetClass("NSPasteboard")
+	nsDataClass = objc.GetClass("NSData")
+
+	selGeneralPasteboard = objc.RegisterName("generalPasteboard")
+	selDataForType = objc.RegisterName("dataForType:")
+	selBytes = objc.RegisterName("bytes")
+	selLength = objc.RegisterName("length")
+
+	typeTIFFPtr, err := purego.Dlsym(appkit, "NSPasteboardTypeTIFF")
+	if err != nil {
+		clipboardImageDarwinInitError = err
+		return
+	}
+	nsPasteboardTypeTIFF = objc.ID(*(*uintptr)(unsafe.Pointer(typeTIFFPtr)))
+}
+
+// readClipboardImageFallback attempts to read image data from the macOS
+// clipboard in formats other than PNG (e.g., TIFF from WeChat screenshots).
+// It returns the image encoded as PNG.
+func readClipboardImageFallback() ([]byte, error) {
+	initClipboardImageDarwin()
+	if clipboardImageDarwinInitError != nil {
+		return nil, clipboardImageDarwinInitError
+	}
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	pasteboard := objc.ID(nsPasteboardClass).Send(selGeneralPasteboard)
+	if pasteboard == 0 {
+		return nil, errClipboardImageUnavailable
+	}
+
+	data := pasteboard.Send(selDataForType, nsPasteboardTypeTIFF)
+	if data == 0 {
+		return nil, errClipboardImageUnavailable
+	}
+
+	length := objc.Send[uint64](data, selLength)
+	if length == 0 {
+		return nil, errClipboardImageUnavailable
+	}
+
+	bytesPtr := data.Send(selBytes)
+	if bytesPtr == 0 {
+		return nil, errClipboardImageUnavailable
+	}
+
+	buf := make([]byte, length)
+	copyBytes(buf, uintptr(bytesPtr), int(length))
+
+	img, err := tiff.Decode(bytes.NewReader(buf))
+	if err != nil {
+		return nil, err
+	}
+
+	var out bytes.Buffer
+	if err := png.Encode(&out, img); err != nil {
+		return nil, err
+	}
+	return out.Bytes(), nil
+}
+
+// copyBytes copies n bytes from src to dst. It is defined locally to avoid
+// depending on the implementation details of go-nativeclipboard.
+func copyBytes(dst []byte, src uintptr, n int) {
+	for i := range n {
+		dst[i] = *(*byte)(unsafe.Pointer(src + uintptr(i)))
+	}
+}

internal/ui/model/clipboard_image_other.go

@@ -0,0 +1,10 @@
+//go:build !(darwin && !ios)
+
+package model
+
+// readClipboardImageFallback is a no-op on non-macOS platforms. The
+// go-nativeclipboard library already handles the common image formats on
+// Linux and Windows.
+func readClipboardImageFallback() ([]byte, error) {
+	return nil, errClipboardImageUnavailable
+}

internal/ui/model/ui.go

@@ -3730,6 +3730,12 @@ func (m *UI) handleFilePathPaste(path string) tea.Cmd {
 // interpreting clipboard text as a file path.
 func (m *UI) pasteImageFromClipboard() tea.Msg {
 	imageData, err := readClipboard(clipboardFormatImage)
+	if err != nil {
+		// The nativeclipboard library may not support every clipboard image
+		// format on all platforms (e.g., WeChat screenshots on macOS are
+		// copied as TIFF). Try a platform-specific fallback before giving up.
+		imageData, err = readClipboardImageFallback()
+	}
 	if int64(len(imageData)) > common.MaxAttachmentSize {
 		return util.InfoMsg{
 			Type: util.InfoTypeError,