Mouse selection does not copy on Windows clipboard-forwarding terminals

[hdosys]

Description

OpenCode disables copy-on-select by default on Windows. In an OSC 52-aware terminal host, mouse drag highlights text, but release never invokes OpenCode's existing clipboard writer. No OSC 52 is emitted and the native clipboard stays unchanged.

This is the remaining Windows case from #5046, which was closed for inactivity. It also blocks herdrdev/herdr#1183.

Plugins

None

OpenCode version

1.18.21

Steps to reproduce

1. Run OpenCode on Windows in Herdr with mouse support enabled.
2. Drag-select regular TUI text and release.
3. Observe that the selection remains and the Windows clipboard is unchanged.

Expected: copy-on-select uses the existing clipboard writer by default. Users who prefer manual Ctrl+C can still set OPENCODE_EXPERIMENTAL_DISABLE_COPY_ON_SELECT=true.

Screenshot and/or share link

N/A

Operating System

Windows 11

Terminal

Herdr 0.8.2