# example Obstruction Artifact H: OG1 Periodic Tight Core from Real Fibonacci Host Data (Strict 2-Cycle)

## Overview

RU is a certificate engine for universality and obstructions in constrained nonnegative propagation. Host structures supply finite inputs. Outputs are audited certificates or finite obstruction witnesses.

## What is shipped

| Artifact | Role | Path |
|---|---|---|
| Real host fusion data | Fusion rules + N_tau matrix | `sources/host_data/fibonacci_fusion_data.json` |
| Host model + period witness | Strict 2-cycle forces period 2 | `sources/ru_bridge/fibonacci_realhost_og1_period2_model.json` |
| RU robust certificate (obstruction) | Records periods=[2] and aperiodic_scc_count=0 | `sources/ru/robust_certificate_fibonacci_realhost_og1_period2.json` |
| Bridge wrapper | Reduction record + OG1 classification | `sources/ru_bridge/bridge_certificate_fibonacci_realhost_og1_period2.json` |

## OG1 witness (finite)

- Tight SCC periods = [2] and aperiodic_scc_count = 0.
- Therefore the strongest aperiodic universality claim is obstructed for this host constraint system.

This shows the engine’s periodic-core boundary using real host fusion data.
