Led end-to-end modernization of three critical services from .NET 4.8/EC2 to containerized .NET 9 on IKS AIR; reverse-engineered and rebuilt a lost-source Delphi DLL from scratch, achieving 87.6% cloud cost reduction and eliminating a major single point of failure with zero downtime during peak tax season. Directed migration of EasyAcct data layer from proprietary Btrieve ($1M/year licensing cost) to SQLite; led team of 6-8 engineers, ensured zero data loss, and eliminated the dependency — returning 16% of total EasyAcct revenue to the business. Resolved critical production instability in a high-scale system processing 400K+ work orders daily by diagnosing multiple root causes and implementing 13 coordinated Cassandra optimizations (including two-phase queries, sub-bucketing, atomic batch writes, and semaphore-controlled parallelism), eliminating all 504 gateway timeouts and NoNodeAvailableExceptions while delivering 10x faster response times. Designed AI-powered e-file error handling solution addressing 30.6% YoY increase in TY24 schema rejections (157,436 returns affected); built new endpoint with LL M-generated plain-English explanations and remediation guidance, plus AI-assisted routing to Live Expert, transforming silent failures into actionable insights across multiple products. Proposed and validated AI-powered personalized client letter generation for automated post-e-filing delivery, eliminating manual client copy distribution — a major seasonal productivity and staffing pain point for large professional tax firms; designed as a reusable platform capability across products (presented at GED Fall FY25). Architected K1 Delivery Automation platform from scratch, automating secure delivery of ~6 million K1 forms annually across multiple products using React 18 AppFabric widget and IDX integration. Developed Calendar Integration Framework (CIF) single-handedly for reliable one-way syncing of single and recurring events from Tax Product to Google Calendar, O utlook, and other calendars. Designed Practice Management (IPM) for bidirectional syncing between Tax Product and Karbon, delivering 84% performance improvement on FirstSync with 3-way conflict management. Built Billing Service end-to-end, a high-throughput service handling ~900 requests/second for license validation and REP transaction processing.…Led end-to-end modernization of three critical services from .NET 4.8/EC2 to containerized .NET 9 on IKS AIR; reverse-engineered and rebuilt a lost-source Delphi DLL from scratch, achieving 87.6% cloud cost reduction and eliminating a major single point of failure with zero downtime during peak tax season. Directed migration of EasyAcct data layer from proprietary Btrieve ($1M/year licensing cost) to SQLite; led team of 6-8 engineers, ensured zero data loss, and eliminated the dependency — returning 16% of total EasyAcct revenue to the business. Resolved critical production instability in a high-scale system processing 400K+ work orders daily by diagnosing multiple root causes and implementing 13 coordinated Cassandra optimizations (including two-phase queries, sub-bucketing, atomic batch writes, and semaphore-controlled parallelism), eliminating all 504 gateway timeouts and NoNodeAvailableExceptions while delivering 10x faster response times. Designed AI-powered e-file error handling solution addressing 30.6% YoY increase in TY24 schema rejections (157,436 returns affected); built new endpoint with LL M-generated plain-English explanations and remediation guidance, plus AI-assisted routing to Live Expert, transforming silent failures into actionable insights across multiple products. Proposed and validated AI-powered personalized client letter generation for automated post-e-filing delivery, eliminating manual client copy distribution — a major seasonal productivity and staffing pain point for large professional tax firms; designed as a reusable platform capability across products (presented at GED Fall FY25). Architected K1 Delivery Automation platform from scratch, automating secure delivery of ~6 million K1 forms annually across multiple products using React 18 AppFabric widget and IDX integration. Developed Calendar Integration Framework (CIF) single-handedly for reliable one-way syncing of single and recurring events from Tax Product to Google Calendar, O utlook, and other calendars. Designed Practice Management (IPM) for bidirectional syncing between Tax Product and Karbon, delivering 84% performance improvement on FirstSync with 3-way conflict management. Built Billing Service end-to-end, a high-throughput service handling ~900 requests/second for license validation and REP transaction processing.WWWW…