Scope and Limitations

The fit is deliberately constrained, and the constraints matter when reading a result:

G = 1 is an assumption unless channel sensitivity has been calibrated.
The fitted r(0) is the resolved time-zero anisotropy and may not equal the fundamental anisotropy.
A bound-hit result is reported as constrained or model-incompatible.
The rotational correlation time has not yet been validated against a known standard.

Not implemented: multiple lifetimes, multiple rotational components, per-pixel rotational fitting, calibrated confidence intervals.