The Orphan Stream breaks joint halo fits: halo shapes tuned to Sagittarius or GD-1 mispredict its curvature and kinematics, and fits to Orphan break the others (Belokurov 2007; Lux 2012; Koposov 2019). The Galactic potential is one thing, yet the model must reshape it stream by stream.
The model's potential is dominated by a triaxial, clumpy particle halo whose shape, orientation, and substructure are free functions to be fit. With enough freedom every stream can be matched alone; the failure is joint, because the fitted halos disagree with each other, and a potential that depends on the probe is the signature of a wrong parameterization.
SCT replaces the free-function halo with a nearly parameter-free potential: the Milky Way's gravity is its baryons coherently amplified, Φ_eff(r) = -G × A(r) × M_baryonic(<r)/r, with the amplification profile rising from near unity in the inner disk to the fixed point A* = 5.970 at the virial radius (P50, P52), the structure already confirmed by the rotation-curve transition at 3 disk scale lengths and the Keplerian decline beyond the disk edge. There is no triaxiality dial and no substructure population to tune, so the registered expectation is exactly what ΛCDM cannot deliver: every stream, Orphan included, must be fit by the same smooth potential, with residual discrepancies tracing visible perturbers like the LMC rather than invisible reshaping.
The stream-plane geometry rides on M3: the Orphan progenitor was a fragment of the same debris field as the other halo structures, its orbital plane inheriting the shared deposited J (P31, P32), which is why its pole sits near the satellite-plane architecture rather than randomly. The registered program is explicit in Paper 13, From Chaos to Coherent Gravity: stream geometry reproduced by A(r) × M_baryonic with no NFW halo parameter fit at all, with the Sagittarius wrap-spacing test (recid 138) as the sharpest member. The Orphan Stream, as the stream that most embarrasses tuned halos, is the natural second target.
Keystone economy: P52 fixes the potential, P31 sets the plane. A probe-independent potential is not an achievement to engineer; it is what honesty about the mass looks like.
The registered kill: if the Orphan Stream's track and kinematics cannot be reproduced by the A(r) × M_baryonic potential plus cataloged visible perturbers, requiring a genuinely triaxial or clumpy invisible component at high significance, the coherent-mesh potential fails its sharpest test. Symmetrically, LSST's expanded stream ensemble fitting consistently to one tuned NFW configuration across all streams would remove the joint-fit failure that motivates the SCT reading.