Staff Engineer @brexhq. I like to build cool shit and ride bikes 🏍️

Joined March 2016
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Pinned Tweet
What if the Silicon Valley HBO intro covered 2020–2026?
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Why haven’t we seen a new FIFA street game for new gen consoles? That would be SO sick, I remember being one of the most fun PS2 games
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Enjoying my slick @linear Diff hoodie in the great LA summer 🫪 thanks team, loved it!!
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which mic do you use for voice to speech in an office environment? Considering the DJI mini mic, any other options? Want something that doesn’t need earbuds
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Marcelo Prado retweeted
I've got an agent in a loop optimizing a renderer with the goal to minimize frame times (and tests to measure). It got times down from 88ms to 2ms and allocations down from ~150K to 500. Sounds good, right? Wrong. This is exactly why agent psychosis is a big fucking problem. As an experiment, I rewrote the Ghostty core render state in Go, with access to identically laid out data structures as Ghostty and the exact same validation tests. I made a purposely naive renderer (simple, correct, but slow). 88ms per frame with 150,000 allocations (horrendous, lol)! I then kickstarted a Ralph loop to bring the frame times down. I told it it can't modify input data structures or the public API or tests (they're correct), but it can do anything else it wants. It got to work. It has worked for about 4 hours. I've spent around $350 on this experiment so far. The results? 88ms => 1.5ms 150K allocs => ~500 allocs Incredible right? Nope. My hand-written renderer I ported has frame times (same benchmark) of ~20us (0.020ms) and 0 allocations in the update path. This is the problem with psychosis and lacking systems understanding. If you don't understand the system, you're going to accept that this is an incredible result. If you understand the system, you'll see better solutions immediately and can do roughly 75x better on throughput. The people who blindly trust agent output are in the former camp. They're sheeple, overdrinking from a fountain of mediocrity. Standard disclaimer: I use AI all the time. I like AI. The point I'm making is to not blindly accept results. Think. Analyze. Learn.
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Did codex 5.5 get any dumber to you over the last week or so? Yesterday the thing was on crack seriously
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This is legit funny. Human body is amazing
The Men’s 50m Backstroke crown goes to non-enhanced athlete Hunter Armstrong. Winning time: 24.21s Prize: $250,000
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anyone from @OpenAI 's Codex app team: can you please fix the flickering that happens on large displays? codex is unusable if i have it fully opened on a 32 inch
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never doing my expense management in the same way
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One of the cool emergent behaviors of our new agent is the fact we can customize its style to match exactly our preferences
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gdrive is in such a bad state right now. For instance, their sticky Gemini upsell is impossible to collapse/hide, wasting around 10-15% of my screen in a 13" inch laptop @Google plz fix this - @ammaar can you route internally?
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oh boy imagine trying to find a place in SF now that a whole block got 11M richer 😮
600 OpenAI employees sold an average of $11M each of equity in October Anecdotally it does feel like that’s when things started getting particularly nutty in the $5-10M segment of SF real estate
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100% agree here. Pure FE is dead - and I’m speaking from someone that has been a FE my whole career. Everyone is full stack now. You may have your expertise, but if you’re not contributing E2E in your company’s products, ngmi
If you're a frontend dev and you're not actively converting to a fullstack product engineer this graph is the last thing you see before that "difficult decision" email hits
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all I'll say is that I expected more from 5.5 Extra High...
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One of my top 3 MCPs: DeepWiki's MCP I use it all the time. Whenever I'm solving a tricky problem, I point Claude and Codex to 3-4 key OSS repos and explore how did they solve my problem. Incredibly powerful for iterating on architecture. Oh, and it's free!
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another day, another github incident... We had to halt PR merges with this one, super critical. Can't leave PR comments, but you can approve it. Recipe for disaster.
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super excited about this launch! Run openclaw other harnesses securely in your organizations
OpenClaw is the fastest-growing open source project, but there are no stories of running it safely in production at scale. As we started deploying agents internally at @brexHQ, we couldn’t stop thinking about this question. Agents work, but nobody wants to give them real credentials. Instead of waiting for a solution to emerge, we decided to try a novel approach: using LLMs to judge the network traffic of an AI agent. Today we’re announcing CrabTrap, an open-source proxy that intercepts every outbound request and blocks risky activity using LLMs, before it ever hits an external API. The results are promising; we believe it’s a meaningful step forward in the security of agent harnesses in production environments. Try it out today. (As a side note, it was really fun to work personally on a real systems problem again. And btw, if you want to work at a place where the CEO is building proxies at night, we’re hiring!)
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damn 5 years at brex... time really flies!
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Bambu printers are legit good but dude what a shit show their software stack is. They need to hire a great designer ASAP
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Brex is finally having its liquidity moment and guess what happens to the USD/BRL ration??? Timing is a bitch
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happy liquidity day to my colleagues ✨ super excited about next steps 🚀
Today @brexHQ is officially part of @CapitalOne ! When we started Brex, we always believed that how a company spends money defines what it becomes. Finance isn't back office, but the core of how every business decision gets made. With AI reshaping how companies run, there's never been a better time to rebuild business finance from the ground up. Brex now serves tens of thousands of businesses, from 1 in 3 startups in the US to the largest companies on the planet, including all major AI labs. But we're still less than 2% of the way to bringing intelligent finance to the majority of US businesses, and we couldn't think of a better partner than Capital One to close that gap. Together, we'll build something truly unique: an n-of-1 combination of a fintech and a bank, unmatched in technology, scale, distribution, and brand. This is a special day. The ceiling just got lifted. I'm so grateful to our team, customers, investors, and everyone who bet on us over the past 8 years. The opportunity ahead is bigger and more ambitious than we've ever dreamed. Onwards!
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