Chord generation is an inherently constrained creative task that requires balancing stylistic diversity with music-theoretic feasibility. Existing approaches typically entangle candidate generation and constraint enforcement within a single model, making the diversity-feasibility trade-off difficult to control and interpret. In this work, we approach chord generation from a system-level perspective, introducing a Retrieval-Edit-Rerank (RER) framework that decomposes the task into three explicit stages: i) retrieval, which defines a stylistically plausible candidate space; ii) editing, which enforces music-theoretic feasibility through minimal modifications; and iii) reranking, which resolves soft preferences among feasible candidates. This separation provides a controllable pipeline, where each component addresses a distinct aspect of the generation process, thereby enhancing both the interpretability and adjustability of the output chords. Through objective metrics and subjective evaluation, our decomposed system outperforms all end-to-end chord generation baselines in balancing chord diversity and music-theoretic feasibility. Ablation studies further confirm the complementary roles of each stage in creative exploration and constraint satisfaction.

翻译：和弦生成本质上是一项受约束的创造性任务，需要在风格多样性与音乐理论可行性之间取得平衡。现有方法通常将候选生成与约束执行纠缠在单一模型中，使得多样性-可行性权衡难以控制和解释。本文从系统级视角出发，提出一种检索-编辑-重排序（RER）框架，将任务分解为三个明确的阶段：i）检索，定义风格上合理的候选空间；ii）编辑，通过最小修改强制执行音乐理论可行性；iii）重排序，在可行候选之间解析软偏好。这种分离提供了可控流水线，其中每个组件解决生成过程中的不同方面，从而增强输出和弦的可解释性与可调性。通过客观度量和主观评估，我们提出的分解系统在所有端到端和弦生成基线方法中，在平衡和弦多样性与音乐理论可行性方面表现更优。消融研究进一步证实了每个阶段在创造性探索与约束满足中的互补作用。