Nacho · building with Claude

1.5 years vibe coding, no code typed by hand. Claude Code built my app RITMUP: guided treadmill classes for iPhone + Apple Watch 🏃 Not affiliated w/ Anthropic

[Nacho · building with Claude @Nachoo0p]

A week ago I showed you the first version of my treadmill app, built by Claude Code.

Shipping it was the hard part. 7 days later: new name (RITMUP), native iPhone + Apple Watch app, 39 web releases, 14 builds. Since last night it's in App Review.

What broke ↓

[Nacho · building with Claude @Nachoo0p]

00:30, me to Claude Code about my treadmill app: “I'M GOING TO SLEEP��� AT 8AM I WANT IT FINISHED…”

1:59 AM, me: “THE 3D TUNNEL IS A BIT CHEAP.”
34 s later it stopped that workflow.
5 min later: 3 agents, 3 new 3D worlds, a jury of agents.

07:05: done.

Opus 5.5 · ultracode 🧵

[Nacho · building with Claude @Nachoo0p]

Spanish UI for now. The web version already works: https://t.co/d8GVhaXdkl

iPhone + Watch app: soon on the App Store. Reply 🏃 and I'll send you the link on launch day.

I don't code. Built with Claude Code (Opus 5.5) by @claudeai. Not affiliated with Anthropic.

[Nacho · building with Claude @Nachoo0p]

A week ago I showed you the first version of my treadmill app, built by Claude Code.

Shipping it was the hard part. 7 days later: new name (RITMUP), native iPhone + Apple Watch app, 39 web releases, 14 builds. Since last night it's in App Review.

What broke ↓

[Nacho · building with Claude @Nachoo0p]

00:30, me to Claude Code about my treadmill app: “I'M GOING TO SLEEP��� AT 8AM I WANT IT FINISHED…”

1:59 AM, me: “THE 3D TUNNEL IS A BIT CHEAP.”
34 s later it stopped that workflow.
5 min later: 3 agents, 3 new 3D worlds, a jury of agents.

07:05: done.

Opus 5.5 · ultracode 🧵

[Nacho · building with Claude @Nachoo0p]

What it is: guided classes for any treadmill, gym or home.

The coach calls every change 10 s ahead with a 3-2-1. You set the speed. DJ music that switches on the bar, 3D worlds at your belt speed, live HR from the Watch, on-device Apple Intelligence.

No accounts, no ads.

[Nacho · building with Claude @Nachoo0p]

The long version, hour by hour (54 s 🎥): the all-caps request, a 600-line spec, 6 builder agents, the DJ and the voice, “a bit cheap” at 01:59, the jury of agents, done at 07:05.

Then the iPhone bug the next morning, and the fix (tested offline on a Mac).

[Nacho · building with Claude @Nachoo0p]

00:30, me to Claude Code about my treadmill app: “I'M GOING TO SLEEP… AT 8AM I WANT IT FINISHED…”

1:59 AM, me: “THE 3D TUNNEL IS A BIT CHEAP.”
34 s later it stopped that workflow.
5 min later: 3 agents, 3 new 3D worlds, a jury of agents.

07:05: done.

Opus 5.5 · ultracode 🧵

[Nacho · building with Claude @Nachoo0p]

I asked Claude Code for a treadmill app at 22:05. Done by 07:05.

At 01:59 I called the 3D “a bit cheap”. 34 s later Claude pulled the plug. 3 agents built 3 new worlds; a jury of agents chose.

Today I ran 45 min with it at the gym. No music cuts 💪

Opus 5.5 · ultracode

[Nacho · building with Claude @Nachoo0p]

@dkolosovs Ha, it was a fair review 😅 Claude stopped that workflow 34 s later, put 3 agents on 3 new worlds in parallel and had a jury of agents pick one. Aurora won. Best feedback loop I've had.

[Nacho · building with Claude @Nachoo0p]

Credits. Music (Pixabay): NverAvetyanMusic, The_Mountain, ARPMedia, Tunetank, PaulYudin, arnaud136, deep_house_music, CONATHOR, tAUREON, 14584889, Eliveta, MC_QUATTRO, klavo85, BUZZPSY, Watermello, catch22music, DELOSound, Rizzlas
Voice: Eva Dorado · ElevenLabs
3D: three.js (MIT)

[Nacho · building with Claude @Nachoo0p]

Receipts: 100% Opus 5.5 · 44 agents (up to 6 at once) · 21.9 agent-hours · 56,867 lines · ~5M checks, 0 failures (mostly generated sweeps)

Try it (Spanish UI): https://t.co/d8GVhaXdkl

Clips: real app, demo session. Credits ↓
Not affiliated with Anthropic or Bestcycling.

[Nacho · building with Claude @Nachoo0p]

@thsottiaux I’ve used Codex since launch. I’m now building things I wouldn’t have considered realistic for one person: 600-page catalog drafts generated from real data in seconds, 3D tools connected to Unreal Engine, ERP pipelines, production automation and internal AI agents with real logic