Ewen Le Quéré

Building products end to end. Backend, AI, design, shipping. Moving everything off managed platforms onto my own server. Building in public, bugs included.

[Ewen Le Quéré @ewenlq]

Live at https://t.co/OydSfff4RG

One machine a week, built in public. Inspired by @uviii_03's Redis machine made with Anatomy.

[Ewen Le Quéré @ewenlq]

The usual fix, backoff with jitter, spreads the retries out. It doesn't cut them. Still 64.

What works: retry at one layer only, under 10% of requests (about 1.1× load instead of 64×), or a circuit breaker that fails fast.

Flip the switches: https://t.co/DvgGjG1HRu

[Ewen Le Quéré @ewenlq]

The slow query is gone. The database is fast again.

So why is the site still down?

[Ewen Le Quéré @ewenlq]

Then the report stops. The retries don't.

Every query times out, including orders that never needed a retry. Every timeout sends more retries.

The load now keeps the database down on its own. It has a name: a metastable failure. It outlives its cause.

[Ewen Le Quéré @ewenlq]

Next up is MCH-005, offline-first sync. Which concept should come after it?

[Ewen Le Quéré @ewenlq]

MCH-004: domain-driven design, as a machine you can run.

Order 42 has a 1,000 € limit. Its root checks every line: 950 € in, 1,050 € refused.

Flip one switch, add the line behind the root, and the same 1,050 € gets in. Nothing checks it.

https://t.co/cR5HvVO6wf

[Ewen Le Quéré @ewenlq]

Two more switches on the page:
· save without a version: two buyers, two checks that pass, one order over its limit
· call Shipping before the commit: Shipping is mid-deploy, Sales loses the order

Built on Evans's purchase order and Vernon's aggregate rules.

[Ewen Le Quéré @ewenlq]

The rule: the model doesn't get to invent arrows. Every arrow has to match a real import in the code, or the drawing goes back to the model.

Try it yourself: https://t.co/2sTrwqUmKG

[Ewen Le Quéré @ewenlq]

Tuesday: I drew my 3rd architecture machine by hand.
Wednesday: Nightprint read its own repo and drew itself.
Thursday: it draws yours.

Reply with a public JS/TS repo, I'll send back its machine.

[Ewen Le Quéré @ewenlq]

@itsluneri Very niceee !!

[Ewen Le Quéré @ewenlq]

@Justinaxu33 https://t.co/reo8zpCLhx

[Ewen Le Quéré @ewenlq]

Then flip a switch:
· chain microtasks forever → the page freezes: no task, no click, no frame runs again
· chain timeouts forever → each round is a new task, the page stays alive

https://t.co/49wcPjRcUn

Machine #2 of Nightprint, built in public.

[Ewen Le Quéré @ewenlq]

Quick quiz. What does this log?

console.log("A");
setTimeout(() => console.log("B"), 0);
Promise.resolve().then(() => console.log("C"));
console.log("D");

Reply before you watch. MCH-002 runs it through the browser's event loop, then freezes the page on purpose

[Ewen Le Quéré @ewenlq]

A, D, C, B.

The script is one task, so A and D run first. C is a microtask: it runs as soon as the stack is empty. B is a new task: the 0 ms timer queues it, and it waits until every microtask is done.

[Ewen Le Quéré @ewenlq]

@buildinpublic Live at https://t.co/OydSfff4RG

One machine a week, built in public.

Which concept should become MCH-003?
- Domain-driven design
- Offline-first sync
- CQRS + event sourcing
- Redis cache-aside

[Ewen Le Quéré @ewenlq]

@buildinpublic Architecture diagrams show you the boxes. Never why they're there.

So I'm building Nightprint: software architecture as 3D machines you can run. Send a request through, flip a "what if" switch, watch the pattern hold or break.

First one: hexagonal architecture

[Ewen Le Quéré @ewenlq]

@uviii_03 Which concept should become MCH-003?
- Domain-driven design
- Offline-first sync
- CQRS + event sourcing
- Redis cache-aside

[Ewen Le Quéré @ewenlq]

Architecture diagrams show you the boxes. Never why they're there.

So I'm building Nightprint: software architecture as 3D machines you can run. Send a request through, flip a "what if" switch, watch the pattern hold or break.

First one: hexagonal architecture

[Ewen Le Quéré @ewenlq]

Live at https://t.co/OydSfff4RG

One machine a week, built in public. Inspired by @uviii_03's Redis machine made with Anatomy.

[Ewen Le Quéré @ewenlq]

My app's architecture, as a tiny city.

Browser → Next.js on a VPS → Neon.
Share cards: my isometric engine → SVG → PNG with resvg.
GitHub repos become buildings.

Drawn by Sidetown's own engine, encoded in the browser.

Want one for your stack? Reply with it.