  Insights from JWST observations suggest that AGN feedback evolved from a
short-lived, high redshift phase in which radiatively cooled turbulence and/or
momentum-conserving outflows stimulated vigorous early star formation
(``positive'' feedback), to late, energy-conserving outflows that depleted halo
gas reservoirs and quenched star formation. The transition between these two
regimes occurred at $z\sim 6$, independently of galaxy mass, for simple
assumptions about the outflows and star formation process. Observational
predictions provide circumstantial evidence for the prevalence of massive black
holes at the highest redshifts hitherto observed, and we discuss their origins.
