Lead Software Engineer in Swindon

Become a part of our caring community and help us put health first. We are seeking a seasoned Lead Software Engineer to architect and deliver the foundational services that enable real-time recommendations to become dependable, auditable, and scalable outcomes. In this position, you will own the design and implementation of the State Machine (managing authoritative state and legal transitions) and Transactional Outbox (ensuring exactly-once intent emission for downstream consumers). Your solutions must be robust, traceable, and maintain high performance under significant concurrency and latency demands. This role is hands-on, combining technical leadership with active engineering: you will architect systems, set technical standards, mentor peers, and collaborate closely across platform, data, and product teams.

Key Responsibilities

• State Machine Architecture
  • Define execution lifecycles and business states, implementing strict legal transition guards.
  • Ensure deterministic, auditable, and testable state transitions, eliminating hidden state in code.
  • Enforce idempotency; design composite idempotency keys to prevent duplicate actions or invalid transitions.
  • Support late events and backfills; maintain append-only history and current-state projections for efficient retrieval.
  • Provide clear APIs for state snapshots, transitions, and feedback events.
• Transactional Outbox Implementation
  • Apply the Transactional Outbox pattern, encompassing atomic persist-and-publish, idempotency keys, retry/backoff logic, and dead-letter queue management.
  • Establish robust contracts for downstream executors and manage ingestion of delivery receipts.
  • Guarantee exactly-once effects through idempotent consumers and deduplication strategies.
• Data Modeling, ORM, and Storage Leadership
  • Design relational schemas for transition logs, current-state projections, and outbox records, focusing on correctness and scalability.
  • Implement composite constraints, foreign keys, upserts, and optimized indexing/partitioning for high-throughput scenarios.
  • Define transaction boundaries and isolation levels to prevent data anomalies.
  • Lead zero-downtime migrations using Liquibase or Flyway, utilizing forward/backward-compatible rollout strategies.
  • Employ TypeORM or JPA/Hibernate/jOOQ pragmatically, and optimize query performance as needed.
  • Build resilient projections and caches; leverage CDC tools (e.g., Debezium) for safe reprocessing.
• Distributed Systems and Concurrency
  • Architect systems for correctness amid concurrent updates, partitions, and partial failures.
  • Apply advanced knowledge of event ordering, idempotency, retries, and backpressure management.
  • Balance consistency and reliability with performance objectives.
• Observability, Audit, and Operations
  • Instrument systems for tracing, metrics, and structured logs; develop dashboards monitoring key system indicators.
  • Build replay tools and maintain immutable audit trails for compliance and incident response.
  • Own runbooks and operational practices for issue resolution and system health.
• Collaboration and Technical Mentorship
  • Partner with decision-service owners, ensuring statelessness and side-effect-free integration.
  • Collaborate with channel teams on event schema, delivery receipt, and failure semantics.
  • Lead design reviews and establish standards for contract-first development, migrations, and idempotent patterns.
  • Mentor engineers on data modeling, concurrency, ORM/JPA best practices, and observability; foster a culture of rigorous testing and code review.
• Responsible AI-Assisted Engineering
  • Utilize AI tools to expedite scaffolding, testing, migration, and documentation.
  • Ensure that core business logic and correctness remain human-authored and subject to thorough review.
• Working Principles
  • Maintain strict separation of concerns between decision services and state management components.
  • Enforce idempotency across all code and schema layers.
  • Achieve exactly-once intent through robust transport and consumer logic.
  • Guarantee traceable audit and replay capabilities.
  • Adhere to privacy and compliance standards, including consent management, secure logging, encryption, and role-based access.

Use your skills to make an impact.

Required Qualifications

• Minimum of 8 years in backend/platform service development; at least 3 years in a senior or lead role overseeing mission-critical systems.
• Advanced proficiency in Python and/or Java/Kotlin.
• Direct experience with Transactional Outbox patterns, idempotent consumers, and exactly-once delivery mechanisms.
• Strong expertise in relational modeling (Postgres/MySQL), query optimization, and partitioning.
• Skilled in TypeORM and/or JPA/Hibernate/jOOQ (Java/Kotlin); experienced in zero-downtime migrations.
• Deep understanding of transactions, isolation levels, locking, and backpressure in high-throughput environments.
• Experience developing contract-first APIs (OpenAPI), managing schema versioning, and ensuring backward compatibility.

Preferred Qualifications

• Experience with stateful pipelines for notifications, fulfillment, or workflow engines.
• Familiarity with CDC (e.g., Debezium), CQRS, event sourcing, outbox-poller architectures.
• Operated in regulated or mission-critical domains (healthcare, finance, telco).
• Experience with OpenTelemetry, SRE practices (error budgets/SLOs), and on-call operations.