Doby Baxter

Python Engineer • Validation/ Reliability • PLC • QA / Security-Focused Tooling

Open Source • ESA Pyxel • Schema Validation • Deterministic Systems • CI/CD

✅ Improved configuration validation and error handling in ESA Pyxel, reducing invalid states in scientific workflows
✅ Built Pyxel Config Lab — a schema-driven YAML system enforcing structural correctness and preventing misconfiguration
✅ Focused on deterministic systems, actionable errors, and predictable behavior in developer tooling
✅ Merged contributor to GitLab core across backend systems, input validation, GraphQL access control, and developer tooling

Recognition

Small infrastructure improvements can have meaningful impact on system reliability and developer experience.

What I work on

< What I can do for your team />

I design and build tooling that improves system reliability, reduces invalid states, and makes complex workflows easier to understand and debug. My work focuses on validation, configuration safety, and clear, actionable error handling.

Developer tooling • Validation & configuration systems

Schema-driven architecture • Open source

Documentation • Usable, accessible interfaces

Outcome
Fewer errors • Clearer feedback • Better developer experience • Predictable systems

< Professional Profile />

⚧️ Pronouns: He/Him
Doby Baxter - Python engineer specializing in validation, system reliability, and developer tooling.

I build systems that prevent invalid states, improve error clarity, and make complex configurations easier to reason about. My focus is on creating predictable, maintainable tooling that supports both developer experience and system correctness.

Contributor to ESA Pyxel, improving validation, reliability, and developer experience within scientific simulation workflows.

I work in Git-based environments with an emphasis on maintainability, clear documentation, and systems that are easy to understand, debug, and hand off.

< Technical Competencies />
Programming	Python • TypeScript • JavaScript • Node.js • Bash
Data & Configuration	JSON • YAML • JSON Schema Design • AJV Validation • Schema-Driven Architecture
DevOps & Tooling	Git • GitLab • GitLab CI/CD • Docker • PyPI • CLI Tooling
Validation & Reliability	Configuration Validation • Schema Design • Deterministic Workflows • CI/CD Integration
Browser & Extension Dev	WebExtensions API • Firefox Add-ons • DOM Manipulation • MutationObserver • Tooltip Systems
Documentation & Communication	Technical Writing • Architecture Documentation • Open Source Collaboration • Async Remote Communication
PLC & Industrial Automation	PLC Programming · Ladder Logic (LD) · Motor Control Logic · Industrial Logic Design · OpenPLC · Autonomy Edge · PLC Simulation & Debugging
Robotics & Middleware	ROS 2 • RViz • Distributed systems • Real-time communication
Security & Systems Awareness	Input validation • Secure configuration practices • Network analysis (Wireshark, Nmap) • System inspection & debugging
Engineering Experience	ESA Pyxel – Scientific Simulation Framework (Python) Contributed to validation, simulation, and developer tooling within a scientific detector simulation framework, improving configuration safety, system robustness, and developer clarity. Validation Systems: Designed schema-aware validation using `typing.Annotated` to enforce constraints at the model level. Developer Tooling: Built Pyxel Config Lab to guide YAML configuration and reduce invalid states. Simulation & Core Features: Implemented photon flux modulation for time-dependent illumination modeling. System Robustness: Stabilized JSON schema generation against ordering and structural inconsistencies. Developer Experience: Improved error messaging for faster debugging and clearer feedback loops. Documentation: Clarified configuration semantics to reduce ambiguity in complex simulation setups. Forward-Looking Design: Explored `typing.Annotated`-driven metadata and MCP-based validation architecture. GitLab Ecosystem – Backend, Frontend & Reliability Improved reliability, validation, and usability across GitLab backend, frontend, and documentation through targeted contributions to core systems. Backend Reliability: Hardened JSON handling using `Gitlab::Json.safe_parse` to prevent unsafe parsing. Frontend & UX: Introduced input constraints to prevent invalid states and reduce user-facing errors. Access Control: Strengthened GraphQL filtering to enforce correct permission boundaries. Documentation: Clarified AST structure and API behavior to reduce ambiguity for developers. Infrastructure: Delivered Terraform Provider feature enabling Kroki (Mermaid) configuration via IaC.

< Full ESA Pyxel & Project Index />

< Professional Endorsement />
			"Doby has demonstrated strong technical skills, thoughtful
			system-level thinking, and a clear focus on usability and
			maintainability. He played a key role in developing innovative
			tooling driven by real user and community needs. He is proactive,
			reliable, and communicates clearly, particularly when working on
			complex or cross-cutting features."
		
			– Mission Payload Senior Software Engineer, European Space Agency
		

< Featured Projects />

Pyxel Config Lab

A schema-aware YAML configuration system for ESA Pyxel simulation modes, designed to reduce misconfiguration risk in scientific workflows. Implements guided configuration flows, integrated validation, and contextual error handling to enforce structural correctness and improve usability in complex detector simulation environments.

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ESA Pyxel Contributions

A structured contribution index documenting system-level improvements to a scientific detector simulation framework, including validation architecture, simulation models, and developer tooling. Highlights clarity-driven design, reduction of configuration ambiguity, and improvements to reliability and developer experience.

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Pyxel Assistive Reading Companion

A browser extension designed to enhance comprehension of scientific documentation through inline semantic augmentation. Introduces a layered concept system that detects domain-specific terminology and provides contextual explanations directly within the reading flow. Emphasizes cognitive accessibility, reduced context-switching, and a scalable architecture.

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Multi-Scale Earth Observation

A full-stack geospatial application integrating a FastAPI backend with the Copernicus Sentinel Hub API for real-time Sentinel-2 imagery, NDVI computation, and statistical aggregation. Orbital mechanics are computed via Skyfield (SGP4 propagation) to contextualize satellite passes. The frontend uses CesiumJS to render an interactive 3D globe with toggleable data overlays. Render hosting the API.

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PLC Programming & Industrial Automation

A growing portfolio of PLC programming projects focused on industrial automation, control systems, and machine logic design. Includes motor control systems, latching circuits, sensor-based automation, and troubleshooting workflows using Ladder Logic and PLC simulation. Focused on reliable system behavior, fault isolation, and practical industrial problem-solving where software meets hardware.

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Lumenoid-AI

An AI systems architecture framework exploring bounded, human-centered design. Focuses on deterministic workflows, structural safeguards, and transparent system behavior to preserve human agency and accountability in AI-assisted environments.

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GitLab Systems Contributions

A technical portfolio of contributions across backend, frontend, and documentation within the GitLab ecosystem. Focused on validation, data integrity, and preventing invalid system states through safer parsing, input constraints, and improved API clarity in large-scale production systems.

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SentinelPi — CLI Cyberlab

A Raspberry Pi Zero 2 W–based systems lab for network analysis, monitoring, and security experimentation within a constrained hardware environment. Designed for hands-on exploration of system behavior, service configuration, and command-line automation under real-world resource limitations.

▶ Visit Repo

< 🌐 Browse All Projects />

Flagship Infrastructure Project

< LLM Workflow Router />

A Python-based tool for managing structured LLM workflows with clear and predictable execution. Designed to help prevent errors and make complex workflows easier to understand and control.

Deterministic workflow execution

YAML-based workflow configuration

Workflow structure validation

Cycle detection and safe re-entry handling

CLI tools for analysis and logging

Usage Model
The repository is publicly available for inspection and non-commercial use.
Commercial or production deployment requires a license.

Commercial Licensing
Starting from £249 for single-project commercial usage.
Team and enterprise licensing available upon request.

What’s Included
• Commercial license grant
• Packaged Python wheel (.whl) distribution
• Usage and integration instructions

View Repository Request Commercial License

< How I think about building />

A few principles I try to keep in mind when working on tooling, configuration, and developer-facing systems.

Clarity over cleverness

Code and tooling should be easy to read and understand — for the next person, and for yourself six months later.

Catch problems early

Good configuration handling and clear error messages make it much easier to spot mistakes before they become bigger issues.

Predictable behavior

Tools that behave consistently are easier to trust, debug, and hand off to someone else.

Useful errors

When something goes wrong, the error should tell you what happened and ideally point you toward fixing it.

< My Soft Skills Journey />

A living constellation of personal growth – from empathy to confidence, advocacy to connection. Click or hover to expand the details for each milestone.

< Work With Me />

I'm open to collaborating on projects around developer tooling, configuration, open source contribution, and building things that are easier to work with. I try to keep scope realistic and communication straightforward.

💻 Direct Collaboration

If you have a project you'd like to work on together, feel free to reach out using the form below. It helps to have a rough idea of what you're building, what you need, and any relevant timelines.

Things I typically help with: • Developer tooling and workflow improvements
• Configuration handling and error messaging
• Open source contributions and code review
• Documentation and project structure

Responses are typically provided within 3–5 business days. Please include sufficient technical detail to allow initial evaluation. Submissions without clear scope may not receive a response.

☀️ Solar Journey (Playable Demo)

Explore the Solar System in a pixel-art spaceship made in PICO-8!

Tap or Click to Play Fullscreen

< A Note on Perseverance />

A small rover standing alone on a dusty landscape

I am disabled and neurodivergent, and my path through education and work has been shaped more by the absence of accommodation than by any lack of ability.
I dropped out of university because the environment was not built to support the way I learn, work, and recover. The same pattern followed into employment: burnout, health flare-ups, and inaccessible environments often made long-term stability difficult, even when the technical work itself was never the problem.
There was a period of nearly two years when severe burnout left me unable to work and, at times, unable to leave my room. That experience changed how I think about systems, sustainability, and what meaningful support actually looks like.
I have been rejected from many roles in IT, and one of the few opportunities I had ended when a lack of accommodation led to a health collapse. Those experiences did not reduce my capability, but instead made my priorities clearer.
They also made something else impossible to ignore: many parts of the industry are still built around narrow definitions of who is allowed to participate. Too often, talent is filtered through rigid expectations that quietly exclude disabled, neurodivergent, and nontraditional people - not because they lack ability, but because the system was never designed with them in mind.
That shaped how I think about technology itself. I care deeply about the human experience where it intersects with engineering. Good systems should not create more barriers - they should remove them. Technology should expand participation, not reduce it. It should create space for more people to contribute, think differently, and build meaningful things.
This is part of why I care so strongly about validation, maintainability, and developer experience. Clearer systems, better tooling, and predictable workflows are not just technical improvements - they are forms of accessibility. They reduce friction, prevent unnecessary failure, and make participation more possible.
I have always been capable. I have not always been allowed to participate.
The time outside traditional employment deepened my relationship with my skills, my values, and the kind of engineer I want to be. I continue to build because I believe better systems can create a more humane and inclusive future for everyone.
Like a rover on Mars, arrival does not automatically create belonging. For me, belonging comes through curiosity, imagination, and the creation of structures that help people move forward - together.

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