The leeward boat gybed and her main landed on mine — she hit me, so doesn't she pay?
No. Same tack and overlapped, Rule 11 makes the windward boat keep clear, and the definition of Keep Clear adds that when overlapped the right-of-way boat must be able to change course in both directions without immediately making contact. Bearing away into a gybe is a change of course — if she can't do it without hitting you, you weren't keeping clear. After the gybe she is on starboard and Rule 10 takes over. Rule 15 doesn't help you: she never acquired right of way, she always had it.
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<p><a href="https://sailing.kiwi.nz/v/ZqMhnYj12_E/">Source: Sailing Kiwi</a></p>