[bug] macOS terminal rendering can corrupt and ghost into chat until fullscreen toggle #3504

Describe the bug

Summary

On macOS, terminal rendering can become corrupted after normal pane switching or window state changes. I see garbled glyphs, stale terminal lines drawn in the wrong place, and sometimes background terminal content ghosting into the chat view.

This is not specific to one CLI. I reproduced it with Claude CLI, Codex CLI, OpenCode, and also inside Superset own conversation UI when a background terminal was running.

Actual behavior

• Text in terminal panes becomes unreadable with wrong glyph shapes.
• Sometimes parts of a hidden or background terminal are painted over the chat area.
• Toggling fullscreen fixes it right away, but the problem comes back later.
• The problem looks like a renderer or compositor issue, not a shell encoding issue.

Expected behavior

• Hidden or background terminal panes should never paint outside their own pane.
• Switching tabs, switching panes, or resizing the window should not corrupt terminal text.
• Fullscreen should not be needed as a recovery step.

Repro notes

Environment I checked locally:

• Superset.app 1.5.5
• Electron 40.8.5
• macOS
• xterm 6.1.0-beta.195
• @xterm/addon-webgl 0.20.0-beta.194
• @xterm/addon-ligatures 0.11.0-beta.195

What i usually do:

1. Open a workspace with one or more terminal panes.
2. Run a long lived CLI session like Claude CLI, Codex CLI, or OpenCode.
3. Switch between terminal and chat panes, or use the app in a non fullscreen window for a while.
4. At some point the terminal text becomes garbled, or a background terminal line is drawn over the chat view.
5. If i toggle fullscreen on and off, the rendering becomes normal again.

Related findings

• I could not find an open issue for this exact symptom.
• #1873 looks related because it also mentions terminal reattach problems and blank space after switching.
• xterm has an open issue here: xtermjs/xterm.js#3303 about WebGL and ligature rendering artifacts. One comment there says manual clearTextureAtlas() makes the issue go away.

I also checked the current source:

• apps/desktop/src/renderer/screens/main/components/WorkspaceView/ContentView/TabsContent/Terminal/helpers.ts always tries to load LigaturesAddon and then WebglAddon.
• apps/desktop/src/renderer/screens/main/components/WorkspaceView/ContentView/TabsContent/Terminal/v1-terminal-cache.ts reattaches the cached wrapper and calls xterm.refresh(...), but it does not clear or recreate the WebGL texture atlas on reattach or resize.
• apps/desktop/src/lib/electron-app/factories/app/setup.ts already has a macOS specific workaround with this comment: occluded window throttling can corrupt GPU compositor layers.

Proposed fix

I think this is likely in the overlap between Superset terminal lifecycle and xterm WebGL rendering on macOS.

Possible directions:

1. Clear the WebGL texture atlas on reattach and resize, then force refresh.
2. Recreate or dispose the WebGL addon when a cached terminal is detached and attached again.
3. Add a safe DOM renderer fallback or a setting to disable WebGL and maybe ligatures on macOS.

If useful, i can try a follow up patch after maintainers confirm which direction they want.