The 3GPP V2X resource allocation framework defines two entity classes --- the base station and the vehicle UE --- and four modes across LTE and NR generations. We demonstrate that this binary taxonomy is structurally incomplete. Base station-led scheduling saturates at high-density traffic nodes, producing latency-tail failures even as mean delivery ratios approach the service-class target. UE autonomy cannot provide pre-emergence warning for occluded traffic participants and is insufficient for large-scope cascading environmental hazards. We propose Mode 0, a new 3GPP V2X category whose defining entity is the Roadside Computing Unit (RCU) --- an infrastructure ensemble integrating elevated sensing (Seeing), sidelink communication (Speaking), and local computational evaluation (Thinking), owned by traffic management authorities. Mode 0 defines a subfamily spectrum: Mode 0a (all-passive UEs, the guaranteed minimum) through Mode 0c (all-active UEs, the optimal target). Convergent deployment evidence from Chinese national standards, China Unicom's operator infrastructure, and European and US C-V2X programs confirms that both institutional sides are independently converging on the roadside traffic node without a coordination standard. A fifteen-run MAPPO simulation validates the architecture: Mode 0a in the shared-pool baseline sits at the symmetric-Nash coordination floor, unbreakable by shared-actor architecture; Mode 0c with demand separation achieves strict Pareto improvement for both traffic classes (M0 PDR 0.999, M1 PDR 0.998), and in the pigeonhole-impossible regime lifts the worst-TTI M0 delivery ratio from 0.113 under Mode 0a to 0.601 --- the only configuration to satisfy the 95th-percentile latency safety requirement structurally rather than on average. We call for a 3GPP study item on Mode 0 within the NR-V2X sidelink enhancement programme.

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