Thanks for the note re onContext() - I wasn’t aware of that, but makes sense given the current data it returns.
And whilst forcing a white background may make the text readable, I would be hesitant to call it a solution. If the viewer has chosen their Twitch background to be dark, then a bright white panel appearing in the middle of it all would look to them like an issue. From the perspective of my Extension’s design, any background color/text combination is fine, it just needs a way to know which to display. I know I could go for a neutral option somewhere in the middle, but that would really result in the panel looking “OK” in both views and “good” in neither.
Given that Twitch now has a native dark background I would really expect there to be a way for an Extension to know if this is selected.