Marcos Hernanz

▲ Incoming Software Engineer Intern @vercel
Founder of (2k users)
Codeforces Expert (1800)
Building privacy-first ML systems
Rust, Wasm, Next.js

[Marcos Hernanz @MarcosHernanz]

WhatsApp search is broken, so I fixed it.

Introducing ChatVault 🔒

A local-first semantic search engine running 100% in the browser.

⚡️ Rust + Wasm for vector storage
🧠 Quantized BERT model (Candle) running locally
🚫 Zero data egress (Offline capable)

Open source & built with @nextjs 16.

Try it: https://t.co/fg9xVjk5Hv
Repo: https://t.co/6ZpZVN2cFj

[Gadi Borovich @GadiBorovich]

Puentes starts this Sunday.

We're flying 15 of the best young engineers from Latin America to SF.

They’re among the most talented in their countries, and they want to be here to compete with the best.

Our goal at @antigravitysf is to help them stay.

Meet the engineers 👇

[Marcos Hernanz @MarcosHernanz]

@rauchg @aisdk @lgrammel Can't believe the AI Gateway is ~2M weekly downloads behind.

I bet this is from people who don't know about it yet.

[Marcos Hernanz @MarcosHernanz]

@ChrisLaubAI The biggest problem is the knowledge cutoff

[Marcos Hernanz @MarcosHernanz]

@tomfgoodwin Because LLMs are also trained on books.

Em dashes are pretty common in books

[Marcos Hernanz @MarcosHernanz]

@nicdunz Infinite funding / consulting I guess. I've been extensively using it for the past 6 months to get all models for free

[Marcos Hernanz @MarcosHernanz]

@ZackKorman This is a good move they're doing

[Marcos Hernanz @MarcosHernanz]

@antigravity W

[Marcos Hernanz @MarcosHernanz]

@jack @blocks Engineers are not getting replaced by AI.

Bad engineers are getting replaced by 100x engineers.

[Marcos Hernanz @MarcosHernanz]

Why don't we have a `.agentignore`?

[Marcos Hernanz @MarcosHernanz]

@rauchg For learning, focus is still king

[Marcos Hernanz @MarcosHernanz]

@theo GPT-5.3

[Marcos Hernanz @MarcosHernanz]

@rauchg Natural language is the final form of communication

[Marcos Hernanz @MarcosHernanz]

AGI is not even close.

People forget the 'G' stands for General.

No AI today is actually general.

Go play a full game of chess against Claude Opus (or any SOTA model) without plugins. Watch it hallucinate an illegal move by turn 15.

We have a long way to go.

[Marcos Hernanz @MarcosHernanz]

AI killed the manual.

Users are pasting errors into LLMs, not reading your docs.

If your DevTool relies on users reading instructions to avoid breaking things, you’ve already lost.

The new definition of DX: Making it technically impossible to do the wrong thing.

[Marcos Hernanz @MarcosHernanz]

GPT-5.2 > GPT-5.2-Codex

"We need a specialized model for our coding agent."

The specialized model: Loses to the base model by 6 points.

Maybe the alignment tax is real. Just give me the raw compute.

[Marcos Hernanz @MarcosHernanz]

The LLM wars are saturating. The next frontier is Embodied AI (robots).

But you can’t iterate hardware at the speed of software, unless you simulate it.

The most valuable skill in 2027 won’t be prompt engineering, it will be building physically accurate 3D sandboxes.

If you want to be irreplaceable stop building wrappers and start building worlds.

[Marcos Hernanz @MarcosHernanz]

@jamwt @convex Out of the box auth (or enabling it with 1 command)

The only place where supabase/firebase are ahead is auth.

[Marcos Hernanz @MarcosHernanz]

@Figure_robot Houses are already full of robots (dishwasher, washing machine, microwave...).

The only piece missing is a robot to orchestrate them.

[Marcos Hernanz @MarcosHernanz]

@bayeslord Opus 4.5 is better for fast iteration
GPT 5.2 (xhigh) is better for good iteration

[Marcos Hernanz @MarcosHernanz]

We are entering the Agentic Era.

Your human-facing UI is just a fallback. Your machine-facing API is the product.

Optimize for inference, not clicks.

UI is dead. TI is king. 👑