Copy/Paste broken in Copilot CLI when using SSH inside a tmux session on macOS/Linux → Windows Server 2025

[kzh125]

Describe the bug

After upgrading to Copilot CLI v1.0.45, copy/paste no longer works when accessing Copilot CLI on a remote Windows Server 2025 machine via SSH from inside a tmux session.

Affected version

v1.0.45

Steps to reproduce the behavior

Scenario	Copy/Paste
Open Copilot CLI directly on macOS/Linux	✅ Works
SSH into Windows Server, open Copilot CLI	✅ Works
Open tmux session → SSH into Windows Server → open Copilot CLI	❌ Broken

Other CLI tools (Codex CLI, Gemini CLI) handle copy/paste correctly in all three scenarios.

tmux Configuration

set -g prefix C-a
unbind C-b

bind C-a send-prefix
bind | split-window -h -c "#{pane_current_path}"
bind - split-window -v -c "#{pane_current_path}"
unbind '"'
unbind %

set -g mouse on
set -g history-limit 50000
set -g allow-passthrough on

set -g default-terminal "tmux-256color"
set -as terminal-features ",xterm*:RGB"

bind r source-file ~/.tmux.conf \; display "Reloaded!"

set -g @plugin 'tmux-plugins/tpm'
set -g @plugin 'tmux-plugins/tmux-sensible'

set -g @plugin 'egel/tmux-gruvbox'
set -g @tmux-gruvbox 'light'
set -g @tmux-gruvbox-statusbar-alpha 'true'

set -g @plugin 'tmux-plugins/tmux-resurrect'
set -g @plugin 'tmux-plugins/tmux-continuum'
set -g @continuum-restore 'on'
set -g @resurrect-capture-pane-contents 'on'

run '~/.tmux/plugins/tpm/tpm'

set -g status-right ''

Expected behavior

Copy/paste should work consistently regardless of whether the terminal is running inside a tmux session.

Additional context

The set -g allow-passthrough on option is already set in the tmux config, which is typically required for OSC52 clipboard passthrough. This suggests Copilot CLI may be using a different clipboard mechanism that does not survive the tmux → SSH chain.