[2603.29088] WybeCoder: Verified Imperative Code Generation

Computer Science > Software Engineering arXiv:2603.29088 (cs) [Submitted on 31 Mar 2026] Title:WybeCoder: Verified Imperative Code Generation Authors:Fabian Gloeckle, Mantas Baksys, Darius Feher, Kunhao Zheng, Amaury Hayat, Sean B. Holden, Gabriel Synnaeve, Peter O'Hearn View a PDF of the paper titled WybeCoder: Verified Imperative Code Generation, by Fabian Gloeckle and 7 other authors View PDF Abstract:Recent progress in large language models (LLMs) has advanced automatic code generation and formal theorem proving, yet software verification has not seen the same improvement. To address this gap, we propose WybeCoder, an agentic code verification framework that enables prove-as-you-generate development where code, invariants, and proofs co-evolve. It builds on a recent framework that combines automatic verification condition generation and SMT solvers with interactive proofs in Lean. To enable systematic evaluation, we translate two benchmarks for functional verification in Lean, Verina and Clever, to equivalent imperative code specifications. On complex algorithms such as Heapsort, we observe consistent performance improvements by scaling our approach, synthesizing dozens of valid invariants and dispatching of dozens of subgoals, resulting in hundreds of lines of verified code, overcoming plateaus reported in previous works. Our best system solves 74% of Verina tasks and 62% of Clever tasks at moderate compute budgets, significantly surpassing previous evaluations and pa...