Seed
90-Day Goal Planner
A paper planning system: one achievement goal and one secondary goal per 90 days, a few habit goals, a weekly Big 3, a daily MIP / secondary / additional list on an hourly timeline, and a short weekly scan.
Learning systems
$ whoami
Matthew Castrillon-Madrigal
Software Engineer · platform engineering × AI-native architecture · real-time UIs · calisthenics as the lens
This is a knowledge garden, not a blog. Notes start as seeds 🌱, grow 🌿 and, with enough tending, become evergreen 🌳 — all linked, the way I actually think.
- notes
- 179
- topics
- 11
- links
- 910
- skills unlocked
- 131
- last tended
Recently tended
all notes →- Seed
Agentic System Design Checklist
Before drawing boxes, pin down the decision boundary, actions, tools, guardrails and memory; then design the architecture and plan for latency, hallucination, scale and integration.
AI, machine learning - Seed
Architecture Fitness Functions
Automated checks that fail the build when the architecture drifts, like a service importing a database driver directly. Cheap feedback that keeps a codebase on the shape it was designed for.
Platform engineering - Seed
Browser Fundamentals for Front-end Engineers
Where data can live in the browser, the order async work runs in (microtasks before macrotasks), CDNs, XSS, the n+1 request problem, and why file uploads should be multipart.
Frontend craft - Seedcase study
Building and Levelling Up a UI Team
Case study — as UI Lead on a low-code network automation platform, hiring and onboarding a UI team, then raising its standards with consistent UI, structured pull requests, regular syncs and one-to-one mentoring.
Career - Growing
Calisthenics Programming: Skill vs Hypertrophy Phases
Once the beginner routine stops working, alternate blocks that build capacity with blocks that turn it into skill, with a deload between. You can't push both at once.
Calisthenics Lab
Topics
all topics →Platform engineering × AI-native architecture
Golden paths, internal developer platforms, delivery metrics, and what changes when AI agents become users of the platform too.
49 notes🌿 25🌱 24
AI, machine learning & research
Machine learning fundamentals, AI agents, and the research I did at university: topic modelling, social network analysis and online communities.
26 notes🌿 12🌱 14
Backend & APIs
API design, services and data, messaging and migrations, Node.js and the JVM: the server side of the systems I build, and where I'm growing next.
23 notes🌳 3🌿 12🌱 8
Real-time UIs
Interfaces that stay smooth under a firehose. Streaming transports, 60fps rendering, state that doesn't thrash, and connections that heal themselves.
19 notes🌳 2🌿 15🌱 2
Frontend craft
Component architecture, React patterns, state, performance and the build tooling that keeps a front end fast and easy to change.
37 notes🌳 4🌿 26🌱 7
Testing, quality & security
Testing strategies teams actually adopt, mocking at the network, end-to-end confidence, shifting left, and the security habits that belong in the same pipeline.
19 notes🌳 4🌿 9🌱 6
Distributed systems
Failure, consistency, consensus and delivery guarantees. The fundamentals underneath every platform and real-time system, written down so I actually understand them.
31 notes🌳 4🌿 19🌱 8
Developer tooling & workflow
The environment I build to work fast: dotfiles, provisioning with Ansible, git worktrees, a keyboard-first setup, and tools that let me ramp up anywhere.
18 notes🌳 1🌿 11🌱 6
Learning systems
Second brains, spaced repetition and the daily loop that turns scattered notes into knowledge I can actually use. This site is its visible end.
16 notes🌳 2🌿 10🌱 4
Career & leadership
Leading UI teams, running communities of practice, communicating with stakeholders, and the habits that make a team better at its craft over time.
39 notes🌳 2🌿 25🌱 12
Calisthenics Lab
A calisthenics skills library, training principles, and the engineering lessons hiding inside them.
31 notes🌿 20🌱 11
Case studies
all work →- Seedcase study
Building and Levelling Up a UI Team
Case study — as UI Lead on a low-code network automation platform, hiring and onboarding a UI team, then raising its standards with consistent UI, structured pull requests, regular syncs and one-to-one mentoring.
Career - Seedcase study
Cutting CI Feedback Time with Checkpoint Restarts
Case study — pipelines that took over ten minutes, and restarted from scratch whenever a long job failed, were slowing delivery. Restructuring the pipeline and making long jobs resumable cut feedback time by roughly 5×.
Developer tooling - Growingcase study
Building a Graph Component Library
Case study — designing and shipping a React network-graph library for several teams, and why rendering tech, API shape and Storybook mattered most.
Frontend craft
$ nowOct 2026
Life. I became a dad this year, and it has changed how I spend my time. With an office five days a week, close to two hours' commute each way and longer hours, time comes in smaller blocks. So I get up early, keep the priority goals few and get things done effectively. I still train six days a week, and weekends are for my family.
Work. Owning front-end development as a software engineer at a fintech building real-time crypto trading interfaces. Most of my thinking goes into keeping fast-moving UIs smooth and predictable: decoupling rendering from the data feed, holding 60fps under a firehose of updates, and making click-to-trade flows feel instant without cutting corners on quality.
Thinking about. Platform engineering for an AI-native world. What a golden path looks like when coding agents walk it alongside people; how evals, tracing and sandboxes become platform capabilities rather than afterthoughts; and how to design platforms that both people and agents can trust.
$ radar
24 items · 11 adopt · 3 trial · 7 assess · 3 hold
My tech radar →$ ./lab --train
Calisthenics Lab
A library of 42 calisthenics skill families: 131 progressions unlocked, 18 current goals — and the engineering lessons hiding in progressive overload, deloads and balance.
Open the skills library →