A split, merge or rotate whose answer is 'Invalid or already spent k1.'
may be the refusal of a retried request that already LANDED - believing
it strands the fresh outputs server-side and desyncs the wallet (the
input is burned at the mint but still spendable locally, so every later
operation fails). All three flows now probe a would-be output when a
refusal carries fresh secrets: live outputs are adopted (or surfaced
unverified when the probe can't tell), a genuine refusal still fails.
protom