Jules,
in case it’ll save some other daft bugger a few minutes of head-scratching, the documentation for path:addArc and similar should make clear that the endRadians value accepts values beyond 2pi.
Because the documentation makes clear that the path is drawn in a clockwise manner, I was assuming that an arc 1.5 pi to 0.5 pi would draw from 9 o’clock to 3 o’clock via 12 o’clock rather than via 6. Once I realised that I need to use 1.5pi to 2.5pi, it made sense (though I’m a litttle perplexed by the clockwise reference as a result).
I’m sure someone somewhere will also be caught out by this though, so it might be worth throwing in a clarification.