Fix macOS multi-file copy to clipboard (#234)

[happyTonakai]

Summary

• Fix inability to copy multiple files to clipboard on macOS by reading back from NSPasteboard after writing (Cannot copy multiple files to clipboard 0 on macOS #234)
• Fix cb paste outputting text instead of files when external apps overwrite the system clipboard between copy and paste

Problem 1: Multiple files not preserved on macOS

macOS has a bug where NSPasteboard.writeObjects: only retains the last item when writing multiple file URLs. This caused cb copy file1 file2 file3 to only preserve one file on the system clipboard.

Fix: Read back from the pasteboard immediately after writing with readObjectsForClasses:, which forces macOS to internalize all written items.

The fix is based on a workaround shared by timhansinger in #234, who encountered the same macOS pasteboard bug in their own tool pbcp and solved it with the same read-back approach (implemented in Swift). The technique translates directly to our Objective-C++ code since both use the same NSPasteboard API.

Problem 2: cb paste outputs text instead of files

While testing Problem 1 over SSH, we discovered that cb paste would output shell command text (from the terminal's OSC 52 response) instead of the copied files. The root cause: syncWithExternalClipboards() was called at the start of every cb invocation, including paste/show. It would read whatever was on the system clipboard (which other apps like the terminal may have overwritten) and write it as a new clipboard entry via convertFromGUIClipboard(), effectively replacing the file entry with a text entry.

Fix: Skip calling convertFromGUIClipboard() for non-write actions (paste, show, etc.) since these operations should only read from internal storage, not ingest whatever is currently on the system clipboard.

[mohammadazeemwani]

I did build it from source and still only one file is getting copied to my system clipboard.

• can you assist my why Ctrl+y is not working for me on mac ?
  Here is my keymap.toml:

[[manager.prepend_keymap]]
on  = [ "<C-y>" ]
run = [ "plugin system-clipboard" ]
desc = "Copy selected files to system clipboard"

^^ this is the only thing in my keymap.toml
Edit, I got the keymap working

[happyTonakai]

@mohammadazeemwani hi, this did work for me on both of my two macbooks:

are you sure that which cb shows the binary which is just you built? or you can run path/to/cb copy

[mohammadazeemwani]

@happyTonakai

I built from source using your fork..

OS: macOS Tahoe 26.3.1 arm64
Host: MacBook Air (M2, 2022)
Kernel: Darwin 25.3.0

[happyTonakai]

I haven’t tested on macOS 26 and don't have a device for it, so this is probably an OS compatibility issue. Maybe some behavior is not the same on macOS 26.

[happyTonakai]

@mohammadazeemwani I think I found the cause.

The previous fix used readObjectsForClasses right after writing to force the system to persist multiple files — but macOS 26's new pasteboard privacy protections likely block this.

I've replaced it with NSPasteboardItem, which explicitly sets NSPasteboardTypeFileURL for each file. No more read-back hack needed.

Could you pull the latest and test again?

[mohammadazeemwani]

I build the project again after pulling latest changes and results still the same:

I am on this commit: 3a0ecd1

[mohammadazeemwani]

My bad man I guess I am on wrong branch.

It works now

Kudos to you.

But for some strange reasons, it only pastes both using cb paste,
If for example, I go in finder and use ⌘ + v it only pastes the top one in the cb show list