A Bounded Smart-Grid City as Unencumbered Encoder: Scale-Invariant Session Geometry, Landauer Halt, and Per-Observer Reconstruction on a Finite Urban Volume

This record extends the unencumbered room encoder to a bounded urban volume Ω_c whose topological boundary ∂Ω_c is a physical door. The encoder is the city itself: a genlocked optical field, a digital spine, and smart-grid actuators. The observer remains a session S ∈ {present, withdrawn}. Outward crossing of the door revokes coupling that required presence. Halt freezes the host interface and pays Landauer’s bound k_B T ln 2 per erased unknown control bit. The resident is not the halt object. Four planes (observer, encoder, lead, worker) support a one-way telemetry pipe and admit no shared write path. Per-observer reconstruction is a session parameter (Δt_i, L_i) on a single optical field. Conserved objects are discrete session identity, Landauer-accounted halt work, and Liu–Layland schedulability of the lead clock τ_L < τ_W. A laboratory protocol on one CAVE-class volume falsifies the scale-up before any urban footprint is claimed. This record does not report a constructed city or a measured urban EEG series. Cite with the unencumbered-VR, supervisory-isolation, and room-encoder parent records.