Pseudophilautus sarasinorum — Muller’s Shrub Frog
The first two photos above are of the same frog, which was so striking in coloration that my guide Udaya Chanaka initially thought it was none of the known species of Pseudophilautus. The third photo is (obviously) of a different individual. Sri Lankan frog experts on iNaturalist eventually led me to P. sarasinorum as the ID for both of these frogs. Tell-tale marks apparently include the dark bar between the eyes, the dark W-shaped scapular mark, and the banding on the hind legs. I haven't found any other photos of this species as colorful as that first individual.