# example Obstruction Artifact G: OG4 Avoidable Doeblin from Real Fibonacci Host Data (Idle Channel)

## 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 + OG4 witness | Idle loop produces avoidance cycle | `sources/ru_bridge/fibonacci_realhost_og4_idle_avoidable_model.json` |
| RU robust certificate (obstruction) | Records OG4 avoidance cycle | `sources/ru/robust_certificate_fibonacci_realhost_og4_idle_avoidable.json` |
| Bridge wrapper | Reduction record + OG4 classification | `sources/ru_bridge/bridge_certificate_fibonacci_realhost_og4_idle_avoidable.json` |

## OG4 witness (finite)

- Doeblin witness exists: (N_tau,N_tau) is strictly positive (via N_tau²).
- But the tight identity loop eI yields an infinite tight path eI,eI,eI, avoiding every Doeblin block that uses N_tau.

So forced universality is not certified. That is OG4 in real host form.
