Bytes: The masculine urge to multiplex everything

Today’s issue: Hacker News bingo, a heartwarming love story, and narrowly avoiding a second “Michael Jackson situation”.

Welcome to #534.

The Main Thing

The joy of watching your agents multiplex for the first time

The masculine urge to multiplex everything

I usually try and avoid the type of developers who talk about how much they love tmux, you know because of the neck beard and odor situations. But I got access to Rex public beta yesterday because I have special influencer access was one of the lucky 12,000 people who got access, and as a Ghostty enjoyer, I couldn’t say no.

So what is Rex?

Rex, much like tmux, is a multiplexer that comes with a client / server system and its own terminal app powered by libghostty. We all definitely know what a multiplexer is, but just so we’re on the same page, a multiplexer combines multiple data sources into a single channel, allowing a receiving system to read and process each stream through one shared connection. Rex currently connects all of your terminals via sessions, but in the future you’ll be able to connect all of your dev tools and even things like Slack or a browser.

In practice, this gives you a control center that lets tools and agents read output from one terminal and send input to another through a shared interface.

Here’s what Rex can do today:

• Programmable workspaces: Create, organize, and control named terminal sessions through commands and APIs, allowing scripts and AI agents to launch programs, read output, and send input to specific terminals. It also lets you do things like have codex send prompts to and approve commands in claude and vice versa.

• Session continuity: Keep sessions and programs running on their host independently of your connection, so you can disconnect and return to the same work from another device.

• Runtime observability: Inspect terminal output and program activity, including progress and blocked states reported by supported programs, to understand what’s happening and what needs attention.

Bottom line: Sexy Rexy is going to make multiplexing mainstream in 2027, you heard it here first 🫡.

Our Friends
(With Benefits)

Your database when it inserts a timestamp

Your database lies to you about time

Not really what you want from the thing that’s supposed to be THE source of truth in your application. But database timestamps can be misleading. How?

• Time can stand still: A transaction’s timestamp may stay fixed even as wall-clock time moves forward.

• Creation order isn’t commit order: A transaction that starts first can finish last, so a creation timestamp may not reflect commit order.

• Your worker can miss records: Advancing a cursor by creation time can skip writes that commit later.

Whether you’re using Convex or not, this whiteboard session will help you better understand what database timestamps actually mean—and how to keep your queues and workers from silently skipping records.

That said, once you use Convex, it’s hard to go back. Give it a try today.

Cool Bits

1. Will Binns-Smith wrote about how to use agents to reduce your Next.js bundle size. Glad Will kept the hyphen in his name because we did NOT need another Michael Jackson situation.

2. Felix Rieseberg wrote some advice for junior engineers. Basically “stay hungry stay foolish” but for the AI era. Good luck out there.

3. Node2Shell? Broccoli2Shell? Call it *2Shell. Attackers are already exploiting it while your coding agent is blissfully unaware and shipping code. Semgrep Guardian catches vulnerabilities and makes your agent fix them as it builds, so the bad stuff never makes it to a PR. Bytes readers can get an exclusive 60-day free trial here. [sponsored]

4. Google released Gemini Carbon their latest frontier model. Any bets on how many elements they get through before people start using their models?

5. Luke Edwards created an HTML parser that’s 3-6x faster than other JavaScript parsers complete with source offsets and CSS selectors.

6. Cartesia Research shared some of their learnings about how to scale hierarchical networks. TLDR h-nets use bytes instead of tokens, 10x less compute, and work for all kinds of data 🤯.

7. Jam’s new Mac app lets you record your screen and hand your agent the video, logs and transcript, all synced to the moment you’re talking about. It’s the most targeted context you can give an agent to fix a bug or redesign the UI. [sponsored]

8. Someone with way too much time (or tokens) documented a Romeo and Juliet style love story between two tech leads at competing AI labs.

9. Nolan Lawson did some research on what front end frameworks cost the most tokens to use. None of this will matter when we’re all using H-nets right?

10. Congrats, your AI agent writes code 10x faster. Now you just review it 10x slower – which is why teams at Dropbox, Wiz and ElevenLabs use Meticulous to verify every user flow and edge case. There’s no developer effort, so they can get back to actual engineering. [sponsored]

11. Alexandre Trotel whipped up an in-depth guide walking you through React’s internals.

12. Antonio Scandurra wrote about how he built fine grained version control for his agents using Rust, CRDTs and Durable Objects. Congrats Antonio I think you checked off every buzzword on my Hacker News bingo card.

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