Mike Hall

Principal Software Engineer

Strategic System Cartography & Technical Leadership

Principal Systems Cartographer & Platform Architect who discovers, maps, and modernizes critical software assets. Helps leadership make confident decisions about aging, undocumented architectures by constructing end-to-end dependency models—from browser and AI-agent interaction surfaces down through lateral state couplings, backend microservices, network access boundaries, and supply-chain risks. Works across Ruby on Rails, PostgreSQL, distributed services, and cloud infrastructure, combining technical cartography with OpenTelemetry observability, zero-downtime safety boundaries, and privacy-conscious AI-augmented investigation.

Areas of focus

  • Technical Leadership & Cartography
  • Legacy Systems & Modernization
  • Delivery & Observability
  • AI-Augmented Engineering

Experience

Development Manager

EMR-Bear, a MedSuite company | Remote | -

Engaged to conduct rapid system discovery and operational risk assessment for a multi-tenant healthcare SaaS platform serving 130+ clinics following a founder transition.

  • Architectural & Risk Cartography: Built a rapid 90-day system inventory and risk model spanning application codepaths, infrastructure dependencies, access boundaries, and operational risks.
  • Production & Compliance Governance: Protected production safety across 130+ clinical environments by establishing explicit release verification gates for 36+ pending platform updates, ensuring unvalidated changes were blocked prior to business sign-off and HIPAA compliance review.
  • Engineering Continuity: Created transparent component ownership, visible operational priorities, and collaborative decision rhythms for a distributed U.S.-Mexico engineering team.

Associate Director, Staff Engineer

OneMain Financial | Remote | -

Served as Senior Technical IC and Software Architecture Lead for the Acquisition lane of a regulated financial enterprise, combining hands-on system cartography with production stability, modernization, observability, and cross-team technical direction.

  • Full-Stack Dependency Cartography: Reconstructed end-to-end customer journeys spanning browser interaction surfaces, API gateways, application middleware, and legacy database layers, establishing a unified operational risk model for incident response and change governance.
  • Incident Response & Technical Escalation: Served as final escalation point for high-severity outages, translating live root-cause investigations into stronger telemetry, explicit component ownership, and reusable system knowledge.
  • Lateral State Coupling De-risking: Refactored fragile multi-step Rails workflow state machines, eliminating hidden lateral state mutations across asynchronous boundaries and resolving persistent data integrity failures in core acquisition flows.
  • Platform Enablement & Responsibility Realignment: Realigned Acquisition engineering around explicit business boundaries, then founded and technically led ACQ Enablement to protect platform reliability, remediation, and modernization work from feature pressure.
  • Observability & Boundary Instrumentation: Founded and led an enterprise OpenTelemetry initiative, instrumenting legacy microservices and third-party API supply-chain boundaries to convert dark system behavior into quantifiable telemetry and reduced MTTD.
  • AI-Augmented Systems Investigation: Introduced privacy-conscious local AI workflows for legacy code analysis and engineering support, expanding investigative capacity while keeping human review, security constraints, and source evidence explicit.

Senior Backend Developer

SK Holdings, Inc. | Chicago, IL | -

Led backend stability, performance, and modernization for high-traffic Rails products, improving full-text search, campaign delivery pipelines, and data layer reliability while systems remained under production load.

  • Replaced complex, outdated external search dependencies (Sphinx) with native MySQL full-text search and optimized relational queries, simplifying deployment and reducing platform infrastructure footprint.
  • Built and validated high-volume asynchronous messaging pipelines (SendGrid async batching) and managed IP warmup protocols for large-scale marketing campaign operations.
  • Authored complex analytical SQL queries powering data-driven infographics and international media coverage for high-volume content catalogs.
  • Led hands-on Ruby and Rails upgrades across multiple applications, sequencing legacy remediation to maintain service continuity through high-risk platform transitions.

Selected Current Work

AI-Augmented Systems Engineer (Phalanx Duel)

Independent | Remote | -

Designing and building a real-time tactical game platform as a current hands-on laboratory for deterministic systems, product architecture, and controlled AI-assisted engineering.

  • Designed a deterministic engine with replayable action logs and server-authoritative state transitions, making complex outcomes reproducible and independently verifiable.
  • Built replay validation, adversarial coverage, and CI verification gates so state transitions can be checked across the complete lifecycle.
  • Uses controlled agent workflows with bounded tasks, acceptance criteria, automated checks, and human-reviewed outputs rather than treating model output as authority.

Core Capabilities & Technologies

Technical Leadership & Cartography

  • System Cartography & Knowledge Recovery
  • Cross-Team Architecture & Technical Direction
  • Lateral State & Supply Chain Dependency Mapping
  • Evidence-Backed Technical Decision-Making

Legacy Systems & Modernization

  • Strangler-Fig Decoupling & API Contracts
  • Zero-Downtime Data Migration & Integrity
  • Incident Response & Root Cause Analysis
  • Distributed Systems & Asynchronous Processing

Delivery & Observability

  • OpenTelemetry & Observability Architecture
  • Network Boundary & Access Control Auditing
  • Platform Enablement & Developer Velocity
  • Database Performance & SQL Analysis

AI-Augmented Engineering

  • AI Agent & Automation Interaction Mapping
  • Codebase Discovery & Domain Rule Extraction
  • LLM Orchestration & Deterministic Evaluation
  • Bounded, Human-Reviewed Agent Workflows

Technologies

  • Ruby on Rails
  • PostgreSQL (including pgvector)
  • Sidekiq & Redis
  • AWS & Cloud Infrastructure
  • Kubernetes, Docker & Linux

Selected Earlier Experience

  • Senior Software Developer, BenchPrep | March 2017 - February 2018 | Chicago, IL : Owned enterprise assessment workflows, leading correctness and platform security in a high-concurrency environment.
  • Senior Software Developer, ReachLocal | March 2015 - November 2016 | Remote : Owned API design and modernization strategy, leading incremental legacy migration for a high-volume digital marketing platform.
  • Core Team Lead, Coderwall | January 2014 - December 2014 | Remote : Owned platform modernization and open-source transition, leading infrastructure cost reduction in a community-driven ecosystem.
  • Engineering Learning & Development Business Partner, Groupon | July 2011 - May 2013 | Chicago, IL : Owned core backend systems for fraud and taxonomy, leading global engineering enablement during hyper-growth.

Career Foundations

Built and operated enterprise integrations, transactional systems, and early web products across consulting and product organizations, establishing the production discipline and community-centered craftsmanship that still shape my leadership.

  • Revenue-critical commerce: Designed real-time inventory, locking, and fulfillment services for a high-volume ticket marketplace later acquired by a major industry operator.
  • Consulting and software craftsmanship: Delivered systems across client environments while mentoring engineers, adopting Ruby and Rails, and helping build Chicago's craftsmanship community.
  • Enterprise and operational systems: Built integration and operational software across large organizations, grounded in .NET, SQL, messaging, production support, and direct user needs.