Every Step Counts: Step-Level Credit Assignment for Tool-Integrated Text-to-SQL

Yaxun Dai, Baolin Sun, Junying Wang, Pengfei Wang, Yingqi Gao, Xuemei Dong, Mengdie Chu, Xiang Qi, Pingfu Chao


Abstract
Tool-integrated reasoning has emerged as a promising paradigm for Text-to-SQL, framing SQL generation as sequential decision-making interleaved with tool execution. However, existing reinforcement learning approaches rely on coarse-grained outcome supervision, creating a credit assignment problem: models receive identical rewards regardless of whether intermediate steps are redundant or erroneous. We observe that tool-integrated reasoning offers a unique opportunity: each tool invocation produces structured, verifiable outputs that can serve as training-free step-level signals, eliminating the need for expensive reward model training. Building on this insight, we propose FineStep, a step-level credit assignment framework that leverages training-free process rewards derived from tool execution feedback. FineStep constructs a dual-channel value estimate for each step, combining backward-propagated outcome value with forward-smoothed process value, and synthesizes them via group-based normalization into a unified step-level advantage for policy optimization. Experiments on Text-to-SQL benchmarks show that FineStep achieves SOTA performance with a 3.25% EX gain over GRPO at the 4B scale, while results on AIME24 demonstrate transferability beyond SQL.
Anthology ID:
2026.findings-emnlp.1128
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
23876–23894
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1128/
DOI:
Bibkey:
Cite (ACL):
Yaxun Dai, Baolin Sun, Junying Wang, Pengfei Wang, Yingqi Gao, Xuemei Dong, Mengdie Chu, Xiang Qi, and Pingfu Chao. 2026. Every Step Counts: Step-Level Credit Assignment for Tool-Integrated Text-to-SQL. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 23876–23894, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Every Step Counts: Step-Level Credit Assignment for Tool-Integrated Text-to-SQL (Dai et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1128.pdf