My first thought is that a (brute force) 1Hz resolution is unlikely, as it would require the fft size to be very long (equivalent to 1 second of audio). The temporal resolution would then suffer greatly. The spectral editing methods could be imitated by Csound opcodes. I assume they (SpectraLayers, Rx etc) do some neat tricks to avoid artifacts when arbitrarily changing the amplitude of single bins, so it might be necessary to look into how that can be replicated.
Oeyvind
yes, for a 1Hz resolution you need a 1-second audio frame.
A 65536-size dft size in the phase vocoder will give sub-1Hz resolution in frequency at 44.1 or 48 KHz,
but lots of smearing in time.