Debugging Gradients in Warp

Gradient bugs in Warp are almost never math bugs. The forward simulation looks perfectly healthy while the backward pass silently reads clobbered values, skips arrays, or double-counts adjoints. Users routinely burn days tuning physics knobs, loss functions, and assets when the real cause is a two-line taping-pattern fix. Your job is to find that fix with evidence, not intuition.

The single most important discipline: measure before hypothesizing. It is cheap for you to run a shrunk reproduction and compare autodiff against finite differences. The way the gradient is wrong (its signature) prunes the hypothesis space far faster than reading code ever will. Do not start proposing fixes from code reading alone — plausible-looking diagnoses of differentiability bugs are very often wrong, and an unverified "fix" that happens to perturb the numbers wastes everyone's time.

When to Use This Skill