Andrew Schran developed core transaction processing, consensus, and security features for MystenLabs/sui, focusing on reliability, scalability, and maintainability. He engineered congestion control and execution time estimation systems in Rust, integrating protocol configuration and dynamic cost modeling to optimize throughput under load. His work included refactoring ownership models, implementing TLS-secured gRPC interfaces, and enhancing peer discovery for robust network operation. Andrew also delivered backward-compatible API and serialization upgrades, improved test automation, and authored technical documentation. By combining backend development, blockchain technology, and systems programming, he consistently delivered deeply integrated solutions that improved operational resilience and developer productivity across the codebase.
February 2026: Delivered key reliability, privacy, and compatibility improvements for MystenLabs/sui. The month focused on hardening consensus robustness, privacy-preserving node discovery, and forward-compatible serialization upgrades, with targeted tests and migrations support.
February 2026: Delivered key reliability, privacy, and compatibility improvements for MystenLabs/sui. The month focused on hardening consensus robustness, privacy-preserving node discovery, and forward-compatible serialization upgrades, with targeted tests and migrations support.
January 2026 – Monthly performance summary for MystenLabs/sui. Delivered major network and state-sync enhancements that strengthen security, reliability, and operator flexibility, while reducing log noise and improving cache correctness.
January 2026 – Monthly performance summary for MystenLabs/sui. Delivered major network and state-sync enhancements that strengthen security, reliability, and operator flexibility, while reducing log noise and improving cache correctness.
Monthly Summary for 2025-12 (MystenLabs/sui): The team delivered foundational feature work, reliability fixes, and network enhancements that improve business value, developer productivity, and operational visibility. Key value drivers include flexible signer policies via the Address Alias System, a streamlined transaction path through Congestion Control Simplification, and deeper workflow capability by exposing settlement effects to barrier transactions. Network reliability and onboarding were strengthened through Discovery Protocol and Peer Management enhancements, while test coverage and cost transparency were improved with GraphQL snapshot tests and Accumulator Storage Cost Accounting. Notable bug fixes addressed consensus validator transaction handling and clarified checkpoint signature ordering, alongside documentation cleanup to prevent confusion on mainnet transfers. Key deliverables: - Address Alias System: introduces address aliases with custom signer sets, alias state handling, and deferred transactions with aliases. Representative commits include 49d89a20e7bc940636be322b22a4f52264d44267 and related changes (#23790, #24636, #24637). - Congestion Control Simplification: remove all modes except ExecutionTimeEstimate to simplify and streamline transaction processing (commit 6fed5401b2c7b4d53513f64af9b410cf3fcc8763). - Settlement and Barrier Transaction Integration: expose effects of settlement transactions to barrier transactions and enable building/executing dependent barrier transactions (commits 3d69be10caf98849274a6ccae802b1d4bd273a1e, #24593). - Discovery Protocol and Peer Management Enhancements: refine trust separation and reconnect behavior with allowlisted vs seed peers, private peer filtering, and preconfigured peer tracking (commits 44276d2b0bc12ee0e82473b68bf10174f14df7e5, d346634879d2839c9132d509d68a9c94f694e380). - GraphQL Snapshot Testing Enhancements: update tests to validate schema changes against expected snapshots (commit 2ddfc6e7e3b95323f6514693d878fe51b9bbfcf1). - Accumulator Storage Cost Accounting: account for storage costs of accumulator objects at epoch end (commit d5aff4f9167014d02776387b0cc684c47762c890). - Checkpoint Signature Ordering Correctness: clarify and align required signer ordering for checkpoint contents (commit 4f0072ba4b42510fef00de0fd1a993d7fb6947c6). - Documentation Cleanup: remove misleading comments about unsupported party transfer functions on mainnet (commit 389055530db9ba61619bdde681a1afc3189f8a67). Major bugs fixed: - Consensus Validator Bug Fix: ensure transactions are properly processed and integrated (commit 5f4d4112481d28910f615dffeeda1e5c392281d0). - Checkpoint Signature Ordering: clarified ordering to ensure correctness of checkpoint contents (commit 4f0072ba4b42510fef00de0fd1a993d7fb6947c6). Overall impact and accomplishments: - Improved reliability, predictability, and throughput of transaction processing; reduced complexity in core paths; enhanced network reliability and protocol observability; and clearer cost accounting across epoch boundaries. These changes position the project for scalable growth and easier maintenance, while enabling advanced user workflows and governance scenarios. Technologies/skills demonstrated: - Rust systems programming, GraphQL testing, network protocol design and debugging, test automation, and performance-focused optimization. Business value delivered through clearer signer policies, streamlined processing, robust discovery, and transparent cost accounting.
Monthly Summary for 2025-12 (MystenLabs/sui): The team delivered foundational feature work, reliability fixes, and network enhancements that improve business value, developer productivity, and operational visibility. Key value drivers include flexible signer policies via the Address Alias System, a streamlined transaction path through Congestion Control Simplification, and deeper workflow capability by exposing settlement effects to barrier transactions. Network reliability and onboarding were strengthened through Discovery Protocol and Peer Management enhancements, while test coverage and cost transparency were improved with GraphQL snapshot tests and Accumulator Storage Cost Accounting. Notable bug fixes addressed consensus validator transaction handling and clarified checkpoint signature ordering, alongside documentation cleanup to prevent confusion on mainnet transfers. Key deliverables: - Address Alias System: introduces address aliases with custom signer sets, alias state handling, and deferred transactions with aliases. Representative commits include 49d89a20e7bc940636be322b22a4f52264d44267 and related changes (#23790, #24636, #24637). - Congestion Control Simplification: remove all modes except ExecutionTimeEstimate to simplify and streamline transaction processing (commit 6fed5401b2c7b4d53513f64af9b410cf3fcc8763). - Settlement and Barrier Transaction Integration: expose effects of settlement transactions to barrier transactions and enable building/executing dependent barrier transactions (commits 3d69be10caf98849274a6ccae802b1d4bd273a1e, #24593). - Discovery Protocol and Peer Management Enhancements: refine trust separation and reconnect behavior with allowlisted vs seed peers, private peer filtering, and preconfigured peer tracking (commits 44276d2b0bc12ee0e82473b68bf10174f14df7e5, d346634879d2839c9132d509d68a9c94f694e380). - GraphQL Snapshot Testing Enhancements: update tests to validate schema changes against expected snapshots (commit 2ddfc6e7e3b95323f6514693d878fe51b9bbfcf1). - Accumulator Storage Cost Accounting: account for storage costs of accumulator objects at epoch end (commit d5aff4f9167014d02776387b0cc684c47762c890). - Checkpoint Signature Ordering Correctness: clarify and align required signer ordering for checkpoint contents (commit 4f0072ba4b42510fef00de0fd1a993d7fb6947c6). - Documentation Cleanup: remove misleading comments about unsupported party transfer functions on mainnet (commit 389055530db9ba61619bdde681a1afc3189f8a67). Major bugs fixed: - Consensus Validator Bug Fix: ensure transactions are properly processed and integrated (commit 5f4d4112481d28910f615dffeeda1e5c392281d0). - Checkpoint Signature Ordering: clarified ordering to ensure correctness of checkpoint contents (commit 4f0072ba4b42510fef00de0fd1a993d7fb6947c6). Overall impact and accomplishments: - Improved reliability, predictability, and throughput of transaction processing; reduced complexity in core paths; enhanced network reliability and protocol observability; and clearer cost accounting across epoch boundaries. These changes position the project for scalable growth and easier maintenance, while enabling advanced user workflows and governance scenarios. Technologies/skills demonstrated: - Rust systems programming, GraphQL testing, network protocol design and debugging, test automation, and performance-focused optimization. Business value delivered through clearer signer policies, streamlined processing, robust discovery, and transparent cost accounting.
Concise September 2025 summary for MystenLabs/sui: delivered documentation updates clarifying pipelined transactions for party objects and simplified transaction processing by removing the address aliasing protocol configuration, with commits tied to both changes.
Concise September 2025 summary for MystenLabs/sui: delivered documentation updates clarifying pipelined transactions for party objects and simplified transaction processing by removing the address aliasing protocol configuration, with commits tied to both changes.
August 2025 monthly summary for MystenLabs/sui focusing on high-impact feature enablement, resilience tuning, and API terminology refactor. Key outcomes delivered a new Party Objects ownership model with end-to-end changes (tests, mainnet enablement, and documentation), paired with resilience and clarity improvements across the codebase. The work aligns with business goals of improving reliability, user trust, and maintainability while keeping backward-compatible RPC interfaces.
August 2025 monthly summary for MystenLabs/sui focusing on high-impact feature enablement, resilience tuning, and API terminology refactor. Key outcomes delivered a new Party Objects ownership model with end-to-end changes (tests, mainnet enablement, and documentation), paired with resilience and clarity improvements across the codebase. The work aligns with business goals of improving reliability, user trust, and maintainability while keeping backward-compatible RPC interfaces.
July 2025 monthly summary for MystenLabs/sui focusing on reliability, backward compatibility, and developer tooling. Delivered high-impact features across execution time estimation, simulation test robustness, and CLI/consensus tooling, with comprehensive documentation improvements. The work drives business value by increasing system reliability, reducing test flakiness, and improving visibility into consensus data for operators and developers.
July 2025 monthly summary for MystenLabs/sui focusing on reliability, backward compatibility, and developer tooling. Delivered high-impact features across execution time estimation, simulation test robustness, and CLI/consensus tooling, with comprehensive documentation improvements. The work drives business value by increasing system reliability, reducing test flakiness, and improving visibility into consensus data for operators and developers.
June 2025 monthly summary for MystenLabs/sui focused on security, observability, and performance, with a strong emphasis on testnet readiness and robust ownership handling. Delivered end-to-end features and benchmarking, improved diagnostic capabilities, and tightened security controls, all while clarifying ownership semantics and enhancing execution-time estimates to support reliable operation at scale.
June 2025 monthly summary for MystenLabs/sui focused on security, observability, and performance, with a strong emphasis on testnet readiness and robust ownership handling. Delivered end-to-end features and benchmarking, improved diagnostic capabilities, and tightened security controls, all while clarifying ownership semantics and enhancing execution-time estimates to support reliable operation at scale.
May 2025 monthly summary for MystenLabs/sui focusing on security hardening, performance improvements, and protocol refinements. Delivered security by default with TLS-enabled validator communications and sui-tool, while preserving network flexibility via --no-tls. Implemented ExecutionTimeEstimate congestion control on mainnet to boost transaction processing performance and stability, supported by protocol/config updates and observation limits. Refactored ConsensusV2 ownership semantics with a dedicated ConsensusAddressOwner variant and added related tests, enabling clearer ownership models and future authorization modes. Expanded devnet/testnet readiness with dynamic ConsensusV2 fields and party transfers, plus a transactional test suite and genesis/protocol updates. Maintained reliability with a rollback of an earlier TLS-default change to address regression while preserving secure-by-default options.
May 2025 monthly summary for MystenLabs/sui focusing on security hardening, performance improvements, and protocol refinements. Delivered security by default with TLS-enabled validator communications and sui-tool, while preserving network flexibility via --no-tls. Implemented ExecutionTimeEstimate congestion control on mainnet to boost transaction processing performance and stability, supported by protocol/config updates and observation limits. Refactored ConsensusV2 ownership semantics with a dedicated ConsensusAddressOwner variant and added related tests, enabling clearer ownership models and future authorization modes. Expanded devnet/testnet readiness with dynamic ConsensusV2 fields and party transfers, plus a transactional test suite and genesis/protocol updates. Maintained reliability with a rollback of an earlier TLS-default change to address regression while preserving secure-by-default options.
April 2025 contributions focused on strengthening consensus reliability, data availability, and network security within MystenLabs/sui. Delivered three major features with traceable commits, improved checkpoint resilience to enhance data availability, and hardened communications with TLS by default for validator gRPC clients. These efforts reduce risk, improve operational reliability, and demonstrate strong implementation of security and reliability best practices across the repo.
April 2025 contributions focused on strengthening consensus reliability, data availability, and network security within MystenLabs/sui. Delivered three major features with traceable commits, improved checkpoint resilience to enhance data availability, and hardened communications with TLS by default for validator gRPC clients. These efforts reduce risk, improve operational reliability, and demonstrate strong implementation of security and reliability best practices across the repo.
March 2025 monthly summary for MystenLabs/sui focusing on performance, reliability, and security improvements. Delivered core ExecutionTimeEstimator wiring with protocol/node config migration, enhanced observation sharing, and expanded metrics; enabled congestion-control mode on testnet to improve stability under high load. Added per-object utilization metrics and increased observer capacity to support realistic load testing and capacity planning. Strengthened ConsensusV2 with authentication checks, fixed same-owner transfer handling, and added start-version tracking for new streams. Completed maintenance and quality improvements including removal of unused crates, cleanup of epoch/flag handling, simplification of observer code, and added reachability assertions to improve stability and build times.
March 2025 monthly summary for MystenLabs/sui focusing on performance, reliability, and security improvements. Delivered core ExecutionTimeEstimator wiring with protocol/node config migration, enhanced observation sharing, and expanded metrics; enabled congestion-control mode on testnet to improve stability under high load. Added per-object utilization metrics and increased observer capacity to support realistic load testing and capacity planning. Strengthened ConsensusV2 with authentication checks, fixed same-owner transfer handling, and added start-version tracking for new streams. Completed maintenance and quality improvements including removal of unused crates, cleanup of epoch/flag handling, simplification of observer code, and added reachability assertions to improve stability and build times.
February 2025 highlights for MystenLabs/sui: Implemented execution time estimation system improvements with consensus integration, including refactoring SubmitToConsensus, new metrics and rate-limiting, updated default time estimates, dynamic ExecutionTimeEstimate mode, and improved mock consensus testing. Increased network throughput and efficiency via congestion control budgets for protocol v73+ and updated cost accounting and per-object overage allowances. Authored and published an advanced documentation guide on object-based local fee markets to help developers manage congestion, bid for priority, and optimize throughput. Stability improvements include adjusting MockConsensusClient to return errors on overflow rather than panicking to improve test resilience.
February 2025 highlights for MystenLabs/sui: Implemented execution time estimation system improvements with consensus integration, including refactoring SubmitToConsensus, new metrics and rate-limiting, updated default time estimates, dynamic ExecutionTimeEstimate mode, and improved mock consensus testing. Increased network throughput and efficiency via congestion control budgets for protocol v73+ and updated cost accounting and per-object overage allowances. Authored and published an advanced documentation guide on object-based local fee markets to help developers manage congestion, bid for priority, and optimize throughput. Stability improvements include adjusting MockConsensusClient to return errors on overflow rather than panicking to improve test resilience.
2025-01 monthly summary for MystenLabs/sui: Delivered three major capabilities to strengthen congestion control, dynamic cost estimation, and object version tracking, while stabilizing test suites for burst scenarios. Burst-mode congestion control was implemented with a new configuration parameter allowed_txn_cost_overage_burst_per_object_in_commit, updated protocol config, and unit tests, with test adjustments to validate burst behavior. ExecutionTimeEstimate congestion control mode was introduced to base cost estimates on local execution times and consensus-based projections. A migration to consensus marker tables for object version tracking, improved by protocol v2 support and FullObjectID/FullObjectKey usage, was completed along with object start version integration and version-table enhancements. These changes collectively improve throughput during traffic bursts, provide more accurate cost estimation, and enhance traceability of object versions across epochs.
2025-01 monthly summary for MystenLabs/sui: Delivered three major capabilities to strengthen congestion control, dynamic cost estimation, and object version tracking, while stabilizing test suites for burst scenarios. Burst-mode congestion control was implemented with a new configuration parameter allowed_txn_cost_overage_burst_per_object_in_commit, updated protocol config, and unit tests, with test adjustments to validate burst behavior. ExecutionTimeEstimate congestion control mode was introduced to base cost estimates on local execution times and consensus-based projections. A migration to consensus marker tables for object version tracking, improved by protocol v2 support and FullObjectID/FullObjectKey usage, was completed along with object start version integration and version-table enhancements. These changes collectively improve throughput during traffic bursts, provide more accurate cost estimation, and enhance traceability of object versions across epochs.
December 2024 monthly summary for MystenLabs/sui: Delivered end-to-end ConsensusV2 object support across execution and indexing, improved snapshot tooling reliability, and introduced congestion-control burst mode. These efforts strengthen data integrity, resilience to cost spikes, and overall system robustness, aligning with address-owned object semantics and inventory management.
December 2024 monthly summary for MystenLabs/sui: Delivered end-to-end ConsensusV2 object support across execution and indexing, improved snapshot tooling reliability, and introduced congestion-control burst mode. These efforts strengthen data integrity, resilience to cost spikes, and overall system robustness, aligning with address-owned object semantics and inventory management.
Month: 2024-11 — A focused set of security, performance, and readiness improvements across MystenLabs/sui and dwallet-labs/dwallet-network, delivering business value through safer communications, deterministic testing, and scalable congestion handling.
Month: 2024-11 — A focused set of security, performance, and readiness improvements across MystenLabs/sui and dwallet-labs/dwallet-network, delivering business value through safer communications, deterministic testing, and scalable congestion handling.
In 2024-10, three core features were delivered for MystenLabs/sui, delivering business value through cost predictability, resilience, and security. The work focused on gas-budget-based congestion control with an absolute cap, faster beacon readiness by reducing required random beacon shares, and securing validator interfaces with TLS for gRPC. No explicit bug fixes were recorded in the provided data; the month emphasized feature delivery and network hardening.
In 2024-10, three core features were delivered for MystenLabs/sui, delivering business value through cost predictability, resilience, and security. The work focused on gas-budget-based congestion control with an absolute cap, faster beacon readiness by reducing required random beacon shares, and securing validator interfaces with TLS for gRPC. No explicit bug fixes were recorded in the provided data; the month emphasized feature delivery and network hardening.
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