Context graphs are essential for modern AI applications including question answering, pattern discovery, and data analysis. Building accurate context graphs from structured databases requires inferring join relationships between entities. Invalid joins introduce ambiguity and duplicate records, compromising graph quality. We present a scalable join inference approach combining statistical pruning with Large Language Model (LLM) reasoning. Unlike purely statistics-based methods, our hybrid approach mimics human semantic understanding while mitigating LLM hallucination through data-driven inference. We first identify primary key candidates and use LLMs for adjudication, then detect inclusion dependencies with the same two-stage process. This statistics-LLM combination scales to large schemas while maintaining accuracy and minimizing false positives. We further leverage the database query history to refine the join inferences over time as the query workloads evolve. Our evaluation on TPC-DS, TPC-H, BIRD-Dev, and production workloads demonstrates that the approach achieves high precision (78-100%) on well-structured schemas, while highlighting the inherent difficulty of join discovery in poorly normalized settings.