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VM Simulation Materials

This page documents material handlers, distributed simulation, and post-run analysis. It also records current limits and test coverage.

Material Handlers

Simulator material handlers implement EffectHandler::step state updates with fixed-point conversions. Each handler has deterministic update rules under fixed seed and scheduling.

  • IsingHandler advances a two-species mean-field state with Euler integration.
  • HamiltonianHandler tracks peer position and force state and applies leapfrog integration.
  • ContinuumFieldHandler tracks peer field values and applies a two-phase diffusion update.

These handlers are constructed directly or through handler_from_material.

Distributed Simulation

DistributedSimBuilder constructs an outer VM plus per-site inner VMs through NestedVMHandler. Each site owns a local set of CodeImage protocols and one effect handler.

Build fails when site names do not match outer protocol roles. The builder also supports outer_concurrency(...) and inner_rounds_per_step(...). DistributedSimulation::run(max_rounds) advances outer and inner runtimes with the configured coupling.

Post-run Analysis

The analysis module provides deterministic trace checks that do not mutate VM state. Checks return structured pass and failure outputs.

Available checks include check_conservation, check_simplex, check_convergence, and check_energy_conservation. validate runs the standard analysis bundle for conservation, simplex, and per-role convergence.

Coverage and Conformance

Simulator tests include end_to_end.rs, regression.rs, distributed.rs, and material_handler_parity.rs. These tests cover projection integration, trace comparison, nested runtime behavior, and material parity fixtures.

material_handler_parity.rs is aligned with Lean mirror simulator tests. This keeps material-step semantics synchronized across Lean and Rust lanes.

Current Limits

run_with_scenario returns in-memory artifacts and stats. It does not write arbitrary scenario output files by itself.

active_per_role uses the maximum active-depth branch when estimating active node count. Trigger::AfterStep is evaluated against logical step count in the fault injector.