TUI is overwritten by raw plugin or worker output

Description

Raw stdout/stderr writes from in-process plugins or the TUI server paint over opentui's alternate screen, making the session unreadable.

Plugins

WarpGrep/Morph

OpenCode version

1.18.4

Steps to reproduce

1. Run opencode --print-logs --log-level DEBUG.
2. Wait for worker or plugin output.
3. Raw log text overwrites the TUI frame.

The same result occurs when a plugin calls process.stderr.write(...) directly. console.error(...) is unaffected because opentui captures console.*.

Expected behavior

External writes must not paint over the active TUI frame.

Operating System

macOS 26.6.1

Terminal

iTerm2