Emergency department discharge delays are a critical operational bottleneck shaped by diagnostic completion intervals, inpatient bed scarcity, consultant responsiveness, and patient acuity. Understanding these drivers in real time is essential for improving flow and reducing avoidable crowding. Current ED analytics often describe aggregate delays after they occur. Clinicians and operational managers therefore lack transparent patient-level tools that indicate which factor is most responsible for a specific delayed discharge episode. This article proposes an explainable gradient-boosting framework for identifying key contributors to delayed ED discharge. The framework focuses on diagnostic order completion times, bed availability, consultant response delays, and patient acuity scores. The proposed framework uses a gradient-boosted tree ensemble trained on historical ED visit data and paired with SHAP-based post-hoc explanations. It is designed conceptually for real-time use with live electronic health record, bed-board, order, and consultation data. Conceptually, the framework would generate both a delay-risk score and an interpretable decomposition of that risk. These explanations could support targeted actions such as expediting a pending diagnostic test, escalating bed-management review, or re-contacting a delayed consultant service. The framework would shift ED discharge management from reactive reporting toward proactive operational decision support. Explainability is positioned as the foundation for clinician trust, workflow alignment, and accountable deployment.