Principal Engineer · 16+ years
Helping senior engineers think and design like architects.
I write about system design, mentor engineers moving toward staff and principal, and teach what I've learned the hard way.
Or go deeper: the live cohort ↗
Context Engineering: Budget the Window Like Memory
Context is an allocated resource with an eviction policy you did not choose. Do the arithmetic on yours.
Tue, 18 Aug · 6:30pm London · 30 minutes · Zoom
What engineers say
29+ engineers and colleagues, sharing what changed after we worked together.
“It has been a pleasure working with Ehsan. He is a dedicated, self-motivated and knowledgeable software engineer. He always embraces new challenges at work. He has a positive attitude and desire to produce quality work that serves him well. He would be a valuable team member of any software team.”
“Ehsan consistently delivers the best in company projects on time and to high standards. I have always admired his ability to stay calm and perform under pressure. He is a great asset to the team both on a professional and personal level. I would not hesitate to recommend Ehsan.”
“The session was amazing and so informative covering a lot of topics like reviewing linked profile, CV and GitHub profile. Thank you so much for your time, Gaz.”
More ways to learn
- Self-paced coursesClean Code Mastery free; System Design Mastery and Node.js & TypeScript interview prep premium.Browse courses →
- 1:1 mentorshipCareer, system-design judgment, and the path from senior to staff and principal.See programs →
- Writing & podcastHundreds of deep-dives on architecture, plus the Breakpoint podcast.Read the latest →
Latest writing
Containers vs Cloudflare Computer: There Is Not Enough Compute for One Box Per Agent
Nearly every agent framework decided that one agent means one container. Cloudflare says there are not enough computers on earth for that to work, and has flipped it around: the agent lives in a tiny sandbox with a filesystem that stays behind, and a container is only borrowed when Linux is truly needed. Here is the argument in plain words, why Cloudflare made it, and where I would use it.
Graph Engineering: Every Edge You Draw Takes a Decision Away From the Model
Agent graphs are state machines with a new name on them. The engineering question is not what a node is, it is which routing decisions you take away from the model and which you leave to it. The rule I apply: only draw edges for decisions you can make better in advance than the model can at runtime.
When Your Data Is Really a Graph: Write the Recursive Query First
Some questions cannot be answered by adding one more join, because the number of joins depends on the data rather than on the query. That is the moment your data has become a graph. Here is how to tell, what a graph actually buys you, and the two costs nobody mentions until you are already paying them.
Semantic Caching for AI Requests, Explained Simply
Your users ask the same question in different words, and you pay for every one. A semantic cache answers from meaning instead of exact text. Here is how it works, in plain language, with a working version you can build in an afternoon.
The Algorithms Worth Knowing in Code Review: Cutting Big O Without Being Clever
The small set of algorithm changes that actually come up in code review, each one shown as before and after, with the Big O it removes.
TypeScript Anti-Patterns That Cost You Twice: Build Time, Runtime, and the Interview
The TypeScript patterns I keep deleting in code review, what to write instead, where the cost lands, and the interview question each one turns into.
Popular this week
What other engineers have been reading in the last seven days.
oxlint vs ESLint: 12s to Under 1s, and What You Lose
I replaced ESLint with oxlint in a React TypeScript project and lint time went from 12 seconds to under one. The speed, the rules that do not exist yet, and when to switch.
Lefthook vs Husky: Why I Switched and Never Looked Back
Lefthook replaces Husky and lint-staged with a single Go binary, parallel hook execution, and built-in file filtering. Here is why I switched and kept going.
SQLZoo SELECT from WORLD: Solutions and Explanations
Worked solutions to every SQLZoo SELECT from WORLD exercise, from basic filtering to population and GDP-per-capita queries, each explained step by step.
Naming Conventions in TypeScript: Best Practices for Classes, Functions, Types, Interfaces, Variables and Parameters
I've reviewed code where a variable named data was used 14 times in one file. Each one meant something different. The person who wrote it understood it pe...
Situational Awareness: The Decade Ahead to AGI by Leopold Aschenbrenner
A short, simple review of Leopold Aschenbrenner essay. He says AI will reach human-level smarts around 2027. Here is what he gets right, what he gets wrong, and what it means for you.
CloudEvents: The Standard Your Event-Driven System Needs
Once a system has more than two or three services publishing events, the same problem shows up every time. One service uses event_type, another uses event...
Where to start
The deep dives I'd point a senior engineer at first, grouped by topic.
SQL, from SELECT to subqueries
Worked SQLZoo solutions, joins, aggregates, GROUP BY vs HAVING, and subqueries — the queries interviewers actually ask.
9 deep dives · Start reading →
Database performance & scaling
Indexes, query optimisation, sharding, replication and normalization — how to make a database fast and keep it fast.
8 deep dives · Start reading →Modern TypeScript tooling
Why oxlint replaced ESLint, pnpm vs npm, Lefthook vs Husky, and the Rust/Go shift in the frontend toolchain.
6 deep dives · Start reading →
Data structures in TypeScript
Arrays, linked lists, stacks, queues, trees, tries, graphs, heaps and hash tables — implemented and explained in TypeScript.
12 deep dives · Start reading →
Sorting & searching algorithms
Insertion, selection, merge and quick sort, plus binary and substring search — the classic algorithms, step by step.
6 deep dives · Start reading →
Design systems in practice
What a design system really is (per Atlassian), how Dropbox and Netflix build theirs, and how to roll out an internal UI component library.
6 deep dives · Start reading →
Scaling & system architecture
Horizontal vs vertical scaling, capacity estimation, resilience patterns and the architecture principles behind systems that grow.
6 deep dives · Start reading →
X vs Y: engineering trade-offs
Head-to-head breakdowns — oxlint vs ESLint, REST vs GraphQL, SQL vs NoSQL, Svelte/Preact vs React — with the trade-offs that decide it.
12 deep dives · Start reading →