  Some of the highest-transition-temperature superconductors across various
materials classes exhibit linear-in-temperature `strange metal' or `Planckian'
electrical resistivities in their normal state. It is thus believed by many
that this behavior holds the key to unlock the secrets of high-temperature
superconductivity. However, these materials typically display complex phase
diagrams governed by various competing energy scales, making an unambiguous
identification of the physics at play difficult. Here we use electrical
resistivity measurements into the micro-Kelvin regime to discover
superconductivity condensing out of an extreme strange metal state -- with
linear resistivity over 3.5 orders of magnitude in temperature. We propose that
the Cooper pairing is mediated by the modes associated with a recently
evidenced dynamical charge localization-delocalization transition, a mechanism
that may well be pertinent also in other strange metal superconductors.
