The Standard Siren Error Budget Recomputed Term by Term

This paper asks a single question and computes its answer. What are the individual contributions — detector noise, weak lensing, peculiar velocities, and calibration — to a siren distance error as a function of redshift, and which term dominates in each redshift decade? Working in a flat LambdaCDM background and carrying the bounce-frame density ceiling explicitly — the Aldred Limit, rho_A = rho_Pl (m/m_Pl)^2/(8 pi C), with the neutron branch at 9.72e+54 g per cubic centimetre — the calculation gives the headline values tot005 = 3.6, tot05 = 5.0, tot2 = 14.9, rhoA = 9.72e+54. Peculiar velocities dominate the nearest bin, the instrumental term dominates through the middle redshifts, and lensing takes over at high redshift. Calibration never dominates but sets a floor that no amount of additional events in a single bin can cross by averaging, because it is common to all of them. Every number reported here comes from the deposited computation script, which states its assumptions in full. This study is simulated and computed from stated assumptions and published catalogue values; it is not a measurement.