  The current major challenge to reconstruct the chronology of the Milky Way
(MW) is the difficulty to derive precise stellar ages. CMD-fitting offers an
alternative to individual age determinations to derive the star formation
history (SFH). We present CMDft.Gaia and use it to analyse the CMD of the Gaia
Catalogue of Nearby Stars (GCNS), which contains a census of the stars within
100 pc of the Sun. The result is an unprecedented detailed view of the
evolution of the MW disk. The bulk of star formation started 11-10.5 Gyr ago at
[Fe/H]~solar and continued with a slightly decreasing metallicity trend until 6
Gyr ago. Between 6-4 Gyr ago, a break in the age-metallicity distribution is
observed, with 3 stellar populations with distinct metallicities (sub-solar,
solar, and super-solar), possibly indicating some dramatic event in the Galaxy.
Star formation resumed 4 Gyr ago with a bursty behaviour, metallicity near
solar and higher average SFR. The derived metallicity distribution closely
matches precise spectroscopic data, which also show stellar populations
deviating from solar metallicity. Interestingly, our results reveal the
presence of intermediate-age populations with both a metallicity typical of the
thick disk and supersolar metallicity. Our many tests indicate that, with high
precision Gaia photometric and distance data, CMDft.Gaia can achieve a
precision ~10% and an accuracy better than 6% in the dating of even old stellar
populations. The comparison with independent spectroscopic data shows that
metallicity distributions are determined with high precision, without imposing
a-priory metallicity information. This opens the door to obtaining detailed and
robust information on the evolution of the stellar populations of the MW over
cosmic time. As an example we provide an unprecedented detailed view of the age
and metallicity distributions of the stars within 100 pc of the Sun.
