Fine-Tuning Qwen2-VL for Blockchain Graph Classification on AMD MI300X: What the Docs Don't Tell You

TL;DR: Graph renderings of blockchain transactions carry topology signals that serialize badly into token sequences. A hub node surrounded by 47 short-lived leaf wallets looks like a table of addresses and amounts in text form — recognizable only if you already know the pattern. 📖 Reading time: ~23 min What's in this article The Problem: Blockchain Forensics Needs Vision, Not Just Text Hardware and Environment Setup on MI300X Data Pipeline: Rendering Blockchain Graphs as Training Images Fine-Tuning Loop: LoRA on 7B vs Full-Parameter on 7B ROCm-Specific Failure Modes and How to Diagnose Them Inference Serving: vLLM on ROCm for Classification Throughput Verdict: When This Setup Makes Sense and When It Doesn't The Problem: Blockchain Forensics Needs Vision, Not Just Text Graph renderings of blockchain transactions carry topology signals that serialize badly into token sequences. A hub node surrounded by 47 short-lived leaf wallets looks like a table of addresses and amounts in text form — recognizable only if you already know the pattern. Rendered as an image, that star topology is immediately visible as a structural shape. The same applies to layering patterns in mixing operations, where funds move through sequential depth levels that form visually distinct bands, and to clustering signatures where tightly-coupled address groups show dense internal edges versus sparse external ones. A vision-language model can learn to classify on those shapes directly. A text-based LLM working from a transaction list has to reconstruct the topology from raw numbers, which is possible but brittle — edge count and clustering coefficient can be computed and injected as tokens, but that's you doing the feature engineering that the vision model can learn to do itself. The reason Qwen2-VL entered this experiment rather than a GNN is mostly practical. Graph neural networks are the academically correct tool for graph classification, but they require a fixed-schema graph dataset and a trainin