Every experiment on this campaign, newest first, with headline numbers.

THE LIST IS AN OBJECT, NOT A BARE ARRAY: {"experiments": [...]}. A top-level array is a dead end — there is nowhere to hang a cursor, a total or a "some of these could not be read" note without breaking every caller on the day it is needed — and it is the shape the client already reads. tests/routes/test_experiments_wire_contract.py pins it.

last_readout is the most recent PERSISTED look, not a fresh measurement: computing one is a real pass over every enrolled contact's interactions, and doing it per experiment to render a list would make opening the list the most expensive thing in the product. Its p_better is a probability in 0..1, and each group's allocation is a proportion in 0..1.