Hi Johann, Just a quick clarification — the imsg library I'm referring to is the OpenBSD IPC library (imsg_init, imsg_compose, etc.), not the macOS iMessage CLI tool at github.com/openclaw/imsg. They share a name but are completely unrelated projects.
The OpenBSD imsg library provides structured message passing over Unix domain sockets, and is used by many OpenBSD daemons (OpenSMTPD, OpenBGPD, etc.). tmux bundles a compat copy of it in its source tree (compat/imsg.c, compat/imsg-buffer.c) so it can build on non-OpenBSD systems like Linux and macOS. This is not a Linux-vs-SUS issue. It's simply that tmux upgraded its bundled copy of this library between releases 3.5a and 3.6b, and the new version changed the wire format in a way that's incompatible with the old one. When an old server and new client try to communicate, the fd-passing mechanism breaks. Best, Liam > 2026年5月27日 16:59，Johann 'Myrkraverk' Oskarsson <[email protected]> 写道： > > Johann
