FidelityLimits

What the layer refuses to compute, and how loudly it says so

4/4 passed in 0ms

Test	What it does	Result
test_mixed_refused	A mixed two-mode pair raises NotImplementedError naming keep().	✅ pass
test_mode_mismatch	A one-mode against a two-mode state is a ValueError naming both counts.	✅ pass
test_not_a_state	A non-State argument is a TypeError, not a deep attribute error.	✅ pass
test_results_finite	Every quantity stays finite for a hot, strongly squeezed, far-displaced pair, where the rationalised prefactor is what prevents the cancellation.	✅ pass