Casey

I build all of the things

[Casey @Cmillstein1]

@mathewpregasen you absolutely COOKED with the ending and the music

[Mathew Pregasen @mathewpregasen]

Starting today, we are releasing a series of short videos depicting what you can do with Letterpress-1, spanning the agent, harness, and IDE. These were all filmed during our Utah sessions.

Today, I want to share how competitor tracking works in Letterpress-1.

[Casey @Cmillstein1]

@mathewpregasen @jareddavidson you’ll enjoy this

[Casey @Cmillstein1]

@mathewpregasen The world no longer runs on Dunkin’. It runs on ⌘+L

[Mathew Pregasen @mathewpregasen]

Introducing ⌘+L, the fastest way to dispatch Claude Code or Codex to edit your website.

[Mathew Pregasen @mathewpregasen]

Yesterday, our launch did pretty good. However, one thing we didn't capture was the ease of Letterpress-1.

Watch me issue a simple PR by just pressing ⌘+L.

[Casey @Cmillstein1]

The remix jerseys for @FlaPanthers are so sick

[Mathew Pregasen @mathewpregasen]

Today, the @lettercompany is releasing the beta of Letterpress-1, the world’s first coding agent, harness, and IDE purpose-built for growth engineering.

tl;dr: check out the 🧵 to see the product in action.

Growth is re-emerging as an engineering problem, but today’s coding tools weren’t designed for it. Your website isn’t isolated like your app: it reacts to the outside world (e.g. agent behavior, Google rankings, observed human interactions, and competitor activity).

Leading coding agents were built to scale complex codebases, not to autonomously build for outside signals. Letterpress-1 is.

Letterpress-1 is designed to tackle growth problems of every size. It’s also proactive: it suggests the nth next thing to build for growth. It'll issue pull requests for de-anonymization, experimental landing pages, warmed emails, blog automations, agent telemetry, etc.

The Letterpress IDE is also built into your site. Press ⌘+L, authenticate, and edit text directly on your website. Letterpress-1 automatically opens a pull request with the change.

Letterpress-1 ships with readily available infrastructure to stage futuristic growth strategies that win over agents. These include:

=> Proofs: autonomous evidence chains that verify customer success data for agent visitors

=> Simulations: staged mirror applications where agents can safely try solutions before buying

=> Benches: self-hosted, reproducible benchmarks with open-source, independent governance

=> Phantoms: autonomous websites to sandbox growth strategies

Build, automate, and refine your growth process with the Letterpress family of tools. We're proud to count some of the world's most forward-thinking startups as our customers.

Sign up today at https://t.co/2mk8pfqRsn.

I’ll share a few examples of Letterpress-1 in action in the thread below.

[Casey @Cmillstein1]

@betomoedano Sooo basically like what I built that’s already live? lol

[Casey @Cmillstein1]

@robiegomez Hey there! I actually have already launched this :) https://t.co/jZPH30h0jC you can check it out!

[Casey @Cmillstein1]

@bhardwajshash This is awesome dude!! Congrats! Any tips for someone like me? I built https://t.co/jZPH30h0jC and the mobile app. It’s incredible but I’m just struggling with the launch!

[Casey @Cmillstein1]

@moonpay It’ll never be me 🥲

[Fasil · AI, actually interesting @Fasil5255]

someone turned your iPhone into a second display for your Mac AND a control deck for your AI agents. Claude Code asks something, your phone lights up, one tap to approve. it is $9.99 once, no subscription. your phone just became your agent's supervisor.

[Casey @Cmillstein1]

I love hockey stats. @NHL be like “wow, that is the first time in HISTORY that @FlaPanthers scored at exactly 7:45pm on Friday, October 30th” 😂.

[Casey @Cmillstein1]

@_BlackjackTek_ I'm glad you asked :) https://t.co/Kfo7CBhd7F

[Casey @Cmillstein1]

5 coding agents running. One needs you. You're in the kitchen.

Sidekeys puts every Claude Code and Codex session on your iPhone. Tap Approve, keep going.

Plus one-tap keys for Xcode, Zoom and Final Cut, and a second screen.

TestFlight is open. Comment "Sidekeys" for the link.

[Casey @Cmillstein1]

5 coding agents running. One needs you. You're in the kitchen.

Sidekeys puts every Claude Code and Codex session on your iPhone. Tap Approve, keep going.

Plus one-tap keys for Xcode, Zoom and Final Cut, and a second screen.

TestFlight is open. Comment "Sidekeys" for the link.

[Casey @Cmillstein1]

@moonpay @IAmLydiabest Except me 😞

[Casey @Cmillstein1]

@JE4NVRG Hey Jean! Super glad you asked. I’m actually putting out a new TestFlight build in about ~2 hours that will cover edits, commands, big changes, and tests!

[Casey @Cmillstein1]

5 coding agents running. One needs you. You're in the kitchen.

Sidekeys puts every Claude Code and Codex session on your iPhone. Tap Approve, keep going.

Plus one-tap keys for Xcode, Zoom and Final Cut, and a second screen.

TestFlight is open. Comment "Sidekeys" for the link.

[Casey @Cmillstein1]

TestFlight: https://t.co/Bzob79b4sn

[Casey @Cmillstein1]

@moonpay Pls