Maglev Cycle 10: Dynamic Physics and Causal Ordering
The Context
With replication and banking proven in Cycle 9, Cycle 10 releases the cores to roll and runs the full mission. Causal ordering (VClock.le gating on core-slot events) is verified in the same run since mission events are its natural trigger.
Cycle 2 (observability) must be live before this cycle runs — a desync or ordering failure here without traces is undiagnosable.
The Problem Statement
This codebase must validate rolling physics under a dynamic normal force combined with cross-zone causal ordering of core-slot events. The cores change trajectory continuously as the train banks; any tick-rate mismatch between the zone server and either client can diverge positions.
Design
Confirm VictoriaTraces receives spans from the zone server before the 3-minute run begins. Core-slot events and their VClock timestamps appear in the trace output.
Load the Maglev train scene. The train banks on a fixed schedule. Quantum Data-Cores roll across the floor under authoritative physics. The zone server sends datagram state each tick; all clients display the result. Players fight drones and slot cores into the mainframe terminal over 3 minutes.
The PCVR client sees the car as a waist-height diorama; the Steam Deck client sees the same instance as an isometric action-RPG.
Pass criteria:
The Cyberprep environment with MToon shaders tuned for both targets is the first art cost in the cycle sequence and cannot begin until Cycle 8 is stable.
Estimate
10 days (2026-06-16 → 2026-06-30). VClock and DisjointRanges are formally verified in multiplayer-fabric-predictive-bvh; the work is wiring them to live core-slot events and confirming no out-of-order acceptance over a 3-minute run. Rolling physics under a banking normal force has no prior baseline; estimating equal to Cycle 9.
CRIS Score
| Factor | Score | Evidence |
|---|---|---|
| Complexity | 6 | Rolling physics under a dynamic normal force, combined with cross-zone causal ordering of core-slot events, is untested in this codebase. |
| Reach | 10 | All gameplay built on this stack requires authoritative physics replication under dynamic load. |
| Impediment | 9 | Physics desync here blocks game design; fixing it likely requires changes to the replication layer, not just parameters. |
| Stakeholder | 10 | Required for the full Maglev mission scenario. |
| Total | 8.25 | Build after Cycles 9 and 2 pass. |
The Downsides
A physics or ordering failure here could be replication, tick rate, dynamic normal force, or VClock gating; Cycles 1–9 narrow but do not eliminate that ambiguity.
The Road Not Taken
Separating causal ordering into its own cycle was rejected — mission events are the natural trigger for core-slot QueueOps, so the two are co-occurring and cheaper to verify together.
Status
Status: Draft
Decision Makers
- Lead Architect / Fabric Maintainer
- Game Director
Further Reading
@misc{v_sekai_2026,
title = {V-Sekai},
year = {2026},
url = {https://v-sekai.org/}
}