Angular momentum architecture and spin-axis inclination of β Pic b. Left: The orbital (﹩{{\boldsymbol{L}}}_{{\rm{o}}}﹩), disk (﹩{{\boldsymbol{L}}}_{{\rm{d}}}﹩), and stellar spin (﹩{{\boldsymbol{L}}}_{{\rm{s}}}﹩) angular momenta are mutually aligned to within a few degrees. This work constrains i_p and ﹩{{\boldsymbol{L}}}_{{\rm{p}}}﹩ relative to the line of sight. Middle: posterior distributions of the spin-axis inclination i_p of β Pic b derived from three independent ﹩v\sin i﹩ measurements. One calculation assumed a 10× inflated uncertainty in the period estimate. The dotted curve shows the random orientation prior (uniform in ﹩\cos {i}_{{\rm{p}}}﹩). All three posteriors peak at i_p = 90°, strongly favoring an equator-on viewing geometry. Right: line-of-sight obliquity ∣i_p − i_o∣ vs. semimajor axis for directly imaged companions with measured spin inclinations, color coded by companion-to-host mass ratios.