ABAI at COLIEE 2026 Task 1: Multi-Stage Retrieval with GraphRAG-Enhanced Meta-Learning, and a Post-Hoc Study of the Cross-Validation-to-Test Gap
The ABAI submission to COLIEE 2026 Task 1, case law retrieval is presented, together with a controlled study of why it underperformed, and four evaluation artifacts are document, each of which reversed a result once the protocol was corrected.