Don't expect this will get to 20+ pages like tubular repair but it deserves a topic.
This spring I've been using Ultremo ZX tubeless in the time trials I've been doing. Last evening on particularly grotty and wet roads on the Bucklebury circuit I flatted and sealant didn't save me, the tyre went right down and I DNF'd and had to be rescued. I repaired the tyre this evening.
Here's the cut on the deflated tyre. It's a sidewall slash, the kind of damage that has been terminal on countless tyres.
The bead was a bit reluctant to come over the rim but not too bad. Here's what that cut looks like from the inside, too big for Stan's sealant to fill. You can see the muckiness of the existing sealant.
I repaired the cut with a conventional puncture patch. Adherence to the inside of the tyre was good and no need to dust the repair with chalk.
Then replenished the dose of sealant, remounted and re-inflated the tyre with a track pump. This is the repair with the tyre at 100psi. It's bulging slightly but not too bad. I've had clincher tyres with this sort of repair and they were stable until I chucked them out for being worn. However it would be desirable to use a repair patch with a bit of mechanical strength. I notice you can get tubeless-specific patches, I might get some of those.
This repair was easy with home facilities. It would be do-able at the roadside, I think, possibly with the help of a CO2 canister for re-inflation.