Graph nodes

A graph is a series chain of these, plus one aux bus. Each has its own page with the parameters and the arithmetic.

The fourteen

NODE	WHAT THE STAGE DOES	BUS	NONLINEAR
gain	Raises or lowers the level. The tone does not change	main	no
biquad	EQ and filters. Lifts, cuts or removes a band	main	no
dc_blocker	Removes the DC component	main	no
waveshaper	Saturation. Rounds the peaks and adds harmonics	main	yes
harmonic_shaper	Adds the 2nd to 5th harmonics in set proportions	main	yes
hysteresis	Magnetic saturation with memory	main	yes
envelope_follower	Measures the level and writes it to the aux bus	main to aux	no
one_pole_smoother	Smooths the control signal on the aux bus	aux only	no
signal_gain	Pulls the level down by the aux value (power sag)	aux to main	yes
elliptical_eq	Centres the low end, with a high shelf and width	main	no
allpass_decorrelator	Phase difference between channels, flat magnitude	main	no
crosstalk_canceller	Cancels what each speaker sends to the far ear	main	no
directional_eq	Height band and depth dip, on the side component	main	no
early_reflector	Early reflections from the side component	main	no

The chain is one line, upstream to downstream, plus one aux bus. Branching and merging cannot be expressed.
Order matters: a dc_blocker only removes what was created before it, and signal_gain only sees what an upstream envelope_follower wrote.
An empty list is a bypass.
One nonlinear node changes the whole chain: it is simulated before it can be heard, the output limiter is armed for the session, and it is soft started.
Every node is written in Hz and dB, so the same graph loads at both internal rates.

There is one aux bus, not one per node.
A second envelope_follower overwrites the first. If a side chain is not behaving, check whether something upstream is writing to the same bus.
Linear stages are combined for the A/B match.
gain, biquad and dc_blocker are combined from their coefficients. Nonlinear and spatial stages count as 0 dB, so their level changes are yours to compensate.