If we break out of a loop over some receive-channel created with @trio.as_safe_channel, the async generator will be cleaned up in the background, and indeed this works:

import trio

async def main():
    async with inner_generator() as recv_chan:
        async for _ in recv_chan:
            break  # Early exit

@trio.as_safe_channel
async def inner_generator():
    try:
        for x in range(10):
            await trio.lowlevel.checkpoint()
            yield x
    except BaseException:  # breaks if `except*`!
        raise
    await trio.lowlevel.checkpoint()

trio.run(main)

...unless you use except*.

Add one little * to the program above, and we instead crash with a BaseExceptionGroup(..., [GeneratorExit()]) - and if you have an outer generator wrapping around the inner one, you'll instead see our BaseExceptionGroup: Encountered exception during cleanup of generator object, as well as exception in the contextmanager body - unable to unwrap error.

Inserting if eg.subgroup(GeneratorExit): raise GeneratorExit from eg before the inner try: block here fixes this issue and I think is the right approach, but I'd love to hear your takes.