The same stable Neo-Hookean XPBD kernels as the 2026-09-19 build. The switch changes only how the jelly reaches the screen: kept in place on the GPU, or read back every step like the old build.
. In resident mode nothing else leaves the GPU.
Readback mode repeats the old path on purpose: 11 submits, onSubmittedWorkDone and 3 mapAsync per step, the CPU check over every tet, CPU skinning and normals, and a re-upload. It halts nothing, so both modes run the same steps.
A slap is a 35 mm sphere that enters along the view ray and leaves within 40 ms. The GPU finds where the ray meets the jelly as it is now (sagged, bulging or still wobbling), in the same submit, so nothing is read back to aim it. The sphere is swept between substeps, so even a 10 m/s slap cannot tunnel through the jelly or throw it back toward the hand.
If the GPU is reset (a backgrounded phone tab, memory pressure, a driver reset), the page says so and restarts on a new device.
Timings on a software adapter (SwiftShader) are not representative of a real GPU.