Description

This issue is filed upstream based on OpenCode issue #18088:
anomalyco/opencode#18088

When a popup/overlay is opened on top of existing content, previously rendered CJK text becomes hidden. Since the issue appears during overlay rendering and affects underlying CJK text, it seems more likely to belong to OpenTUI’s rendering/compositing layer than to application-specific logic.

Notes

This may be related to overlay blending / wide-character grapheme handling in the buffer renderer.

I’m opening this issue first because I’d like to work on a PR.