Prompt-only inference
prediction = —
weight before = —
weight after = —
optimizer invoked = false
PARAMETER STATEUNCHANGED
Hold inference fixed, then run one real gradient step. See exactly why changing a target can reverse the parameter update while the forward prediction stays identical.
The forward prediction does not know the target. The labeled loss does. TensorFlow.js carries that target-relative error backward, and gradient descent moves the parameter in the resulting direction.