SECTOR PAPER XVII — A Multi‑Probe Confrontation of ΛCDM and the Unified Information Substrate Late‑Time Growth, Early‑Time Collapse, Parity‑Odd Geometry, Real-Time Lensing Arcs, and ξ‑Field Cosmology

Sector XVII presents a multi‑probe confrontation between ΛCDM and the Unified Information Substrate, demonstrating that late‑time growth, early‑time collapse, parity‑odd geometry, and real‑time lensing arcs cannot be simultaneously reproduced within ΛCDM without introducing additional parameters. The δI‑substrate, by contrast, generates all four behaviours from a single correlation‑geometry mechanism with no free parameters. This sector shows that the substrate’s collapse‑regime dynamics naturally produce enhanced late‑time structure growth, suppressed early‑time expansion, parity‑odd cosmological signatures, and horizon‑proximal lensing arcs. Sector XVII establishes the first cosmological‑scale divergence between ΛCDM and δI‑substrate physics and forms the second component of the horizon‑collapse chain.