[labs/context] ContextRoot fails for consumers in nested shadowRoots

[sorvell]

Which package(s) are affected?

Context (@lit-labs/context)

Description

When a ContextRoot caches a context-request event, it stores the event.target. However, if the event is retargeted, this is not the element that fired the event and therefore needs the context to be fulfilled.

Likely instead, it should be caching the root target, or event.composedPath()[0].

Reproduction

https://lit.dev/playground/#gist=83c8ff4813b2edd082b29fb03557a82b

The bottom element's context value in the example above is not provided due to this issue.

Workaround

I have not found a workaround.

Is this a regression?

Yes. This used to work, but now it doesn't.

Affected versions

all

Browser/OS/Node environment

All