September 2025 (scroll-tech/ceno) monthly summary focused on reliability, correctness, and maintainability improvements in cryptographic and memory-related components of the ZKVM workflow. The work stabilizes test behavior, eliminates sources of transcript variability, and strengthens memory allocation guarantees, delivering clear business value and technical quality.

Month: 2025-08. This month delivered significant performance, reliability, and scalability improvements for scroll-tech/ceno's ZKVM stack. Key features delivered include core ZKVM circuit and memory performance optimizations: static selector witness generation for GKR-IOP, optimized witness inference, limb-based memory representation, limb-based mulh circuit, improved less-than and range checks, enhanced shift logic, and Keccak precompile limb handling (9 commits: 842d35e04df216aaea3fb0bc2b62386b609e27e4; d0b28b9f0de3fe3e094482bdff0feda483a6dec4; 0a960a4937fa7ee403ef972fcf95f2d9b881b130; a951275e2e01dc28348b4529c2fd30c06ca0047a; 4b4de4f670ec966b6d51f938bacde4a314471983; 0c89843fff4e657ebee6b6196a50d8d823e82caf; dc5a22ad0f541e49a2a9643c2e3ef047267d50c9; bad8dcace3a078c9f39bfb8411faec3e775c25ed; 815afe40077510537d64c31ce3a91696f0eef9a2).

July 2025 highlights for scroll-tech/ceno: Delivered a modular prover backend capable of supporting separate CPU and GPU implementations, enabling hardware-accelerated proofs and improved latency. Implemented cross-crate utilities and shared primitives (zkvm and gkr_iop) to streamline development and reduce duplication. Integrated the Keccak precompile into the end-to-end flow with memory read/write in the precompile circuit, and introduced a new ComposedConstrainSystem wrapper for the Keccak flow, defining Keccak as a first-class ecall-opcode and enabling cross-crate lookup table sharing. These changes enhance performance, flexibility, and maintainability, unlocking faster proof generation and broader hardware options.

June 2025 highlights for scroll-tech/ceno focused on refactoring the core constraint machinery to improve maintainability, reusability, and future-proofing. Delivered a generalized GKR sumcheck layer and pre-compilation alignment, with backend expressions cached inside the constraint system. This reduces future refactoring risk, simplifies the main sumcheck’s read/write lookup expression, and removes the post-evaluate() call without sacrificing performance.

May 2025: scroll-tech/ceno delivered a series of architectural and performance upgrades that strengthen reliability, developer experience, and end-user performance. Key initiatives include centralizing MLE expression handling in the multilinear_extensions crate, enabling reuse and consistency across the codebase; pre-allocating witness vectors with parallel allocation to reduce runtime overhead; integrating jemalloc as an optional global allocator to boost performance; adding 64-bit cycle counts in ZKVM to align with newer toolchains; and introducing a no-syscall Keccak implementation with host-side support to improve portability and testing. Additional tooling improvements (Cargo debug mode and enhanced IO visibility on failure) and protocol-level optimizations further contributed to stability and efficiency. These changes position Ceno for higher throughput, better scalability, and faster iteration in development and CI pipelines.

April 2025 performance and reliability sprint for scroll-tech/ceno. Delivered major MPCS performance improvements, enhanced runtime instrumentation, and stabilized CI/build pipelines, alongside a critical verifier padding fix and toolchain upgrade. The month reinforced end-to-end throughput, observability, and development reliability, with a modernization of the Rust toolchain to enable optimizations and reformats.

March 2025 highlights for scroll-tech/ceno: Delivered substantial Prover/Verifier core refactor and sumcheck enhancements, introduced detailed ZKVM proof size statistics with per-circuit attribution, fixed end-to-end proof validity through a halt-detection bug fix, and expanded public I/O support with end-to-end testing improvements. Also centralized dependencies via a new p3 crate and aligned CI/build workflows for easier maintenance and scalability.

February 2025 performance summary focused on delivering robust end-to-end ZK workflows, improving caching reliability, and refining data structures for 2-adic generators. The work across two repositories demonstrates value through both feature advancement and stability improvements.

January 2025 (2025-01) – Scroll Tech/ceno: Codebase modernization and refactor to remove v2 suffix and unify prover/virtual polynomial logic. This work reduces technical debt, standardizes interfaces, and prepares the codebase for future enhancements. No major defects fixed this month; focus was on architectural cleanup and maintainability, with one committed change that encapsulates the refactor.

December 2024 monthly summary for scroll-tech/ceno: Focused on delivering measurable performance tooling improvements and cleaner logs to enable faster debugging and reproducible benchmarks. Key features delivered, major bugs fixed, and the broader business impact are summarized below.

November 2024 performance summary for scroll-tech/ceno: Delivered significant platform enhancements and a critical bug fix with measurable impact on reliability and resource efficiency. Key deliveries include a unified SRA opcode with refined shift operation flow, and a streamlined thread management model using max_usable_threads. Also resolved a minimal-table sumcheck edge case, extending verifier correctness and test coverage. Emphasis on maintainability, documentation, and robust testing to support future scalability.

Month 2024-10 — Delivered modular circuit architecture with end-to-end public I/O and prover/verifier protocol for the scroll-tech/ceno repository. Implemented modular circuits for non-volatile and volatile tables, refactored memory management by separating program data into a dedicated circuit and keeping memory volatile, and added a prover/verifier protocol for evaluating public I/O and handling table address arguments. Change is tracked via commit 6541209c02e62566bc0b805bf6ff97ce3d0c656c (#457).