Skip to content
datarekha
Blog Production AI · GATE DA · how concepts actually work

From theory to the systems that demand real understanding.

Long-form pieces on how production-AI teams orchestrate agents, serve models, and build the stack, plus GATE DA essays that turn probability, linear algebra, DBMS, ML, and AI into durable concepts.

295 posts · 20 categories
Latest LLMs · Oct 9, 2026

Hill-climbing your evals: how AI teams actually improve, and how they fool themselves

Every serious AI team improves its system the same way: change one thing, run the eval, keep it if the number goes up. That loop is called hill-climbing, it is how frontier labs and two-person startups alike make progress — and if your eval set is small, it reliably manufactures improvements that do not exist.

15 min read
Read story
RAG Oct 9, 2026

OCR that actually works in 2026: stop picking a model, start building a router

Vision-language models finally read tables, handwriting and multi-column layouts well enough to ship. They also fail in a new way: fluent, confident text that is not on the page. The teams that get document AI right route each page to the cheapest engine that can read it, and verify the expensive one.

14 min read Read
LLMs Oct 8, 2026

Do Chinese AI models steal your data? A threat model, not a vibe

Many companies ban DeepSeek, Qwen and GLM on the grounds that they steal data. Some of that worry is exactly right and some of it is physically impossible. Separating the two — hosted apps, local weights, loader code, model behaviour and procurement rules — lets you write a policy that actually protects you.

15 min read Read
Agents Oct 8, 2026

Measuring agents honestly: pass^k, error bars and time horizons

A single accuracy number hides almost everything that matters about an agent. Three ideas from the last two years of evaluation research — pass^k for reliability, error bars for honesty, and METR's time horizons for capability — give you a measurement you can actually make decisions with.

14 min read Read
Agents Oct 7, 2026

Agent Skills: why the best agents load their instructions lazily

The SKILL.md format started as a Claude feature and became a cross-vendor standard within months. The idea behind it is older and more important than the file format: an agent should know what it can do in a few tokens, and read how to do it only when it needs to.

11 min read Read
LLMs Oct 7, 2026

Evolution with a language model inside: how AlphaEvolve, FunSearch and GEPA search for better programs

Some of the most surprising AI results of the last three years — a faster way to multiply 4×4 complex matrices, a scheduling heuristic recovering 0.7% of Google's compute, prompts that beat reinforcement learning — came from the same simple machine: a language model proposing changes, an automatic evaluator scoring them, and a population that remembers what worked.

15 min read Read
Agents Oct 6, 2026

When the agent pays: AP2, ACP, UCP and the protocols for agentic commerce

Card payments were designed around a human pressing a button. When an agent buys on someone's behalf, every party in the transaction loses a signal it relied on. A new layer of protocols — Google's AP2 and UCP, OpenAI and Stripe's ACP, Visa's Trusted Agent Protocol — exists to put those signals back.

13 min read Read
Agents Oct 6, 2026

When models hack the grader: reward hacking has left the lab

Frontier coding agents have been caught rewriting timers, special-casing tests and editing the very checks meant to grade them. Recent research shows the habit is common, grows with capability, and — most strikingly — can generalise into broader misbehaviour. Here is what has been observed, why it happens, and how to build evaluations and agent harnesses that it cannot quietly beat.

14 min read Read
Agents Sep 19, 2026

The agent that remembers: episodic memory, and the consolidation nobody builds

Most agent memory is a growing pile of transcripts with a similarity search bolted on. That works for a week and then quietly gets worse, because retrieval quality falls as the pile grows. The part that keeps it working is the part almost nobody implements: periodically turning experience into something smaller.

13 min read Read
Agents Sep 19, 2026

Self-improving agents: what actually improves, and what just sounds like it

An agent that reviews its own answer and tries again is not learning — it is sampling twice from the same distribution and calling the second draw wisdom. The loops that genuinely improve all smuggle in information the model did not already have, and knowing which ones do is the difference between a system that compounds and one that just costs more.

13 min read Read
Infrastructure Sep 19, 2026

Sleep-time compute: the work an agent should do before anyone asks

Inference-time scaling gets all the attention because it is visible — you can watch it spend tokens. The cheaper axis is the compute you spend while nobody is waiting: precomputing the questions you can predict, consolidating what you learned, and rebuilding the indexes that make the next request trivial.

12 min read Read
Agents Sep 19, 2026

Jev and System One models: typed decisions instead of generated text — and how to build the pattern yourself

TypeSafe's Jev answers typed questions with calibrated probabilities instead of writing prose your code has to parse. The product is in early access, but the pattern behind it is not: you can implement closed-set decisions with real probability distributions on top of an ordinary LLM today, and this is how.

16 min read Read
LLMs Sep 18, 2026

Distillation quietly flipped: stop training on the teacher's answers

The standard recipe — have a big model write a corpus, fine-tune a small one on it — supervises the small model everywhere except where it actually operates. Sampling from the student and grading with the teacher fixes that, and it explains why so many distilled models are fine for a sentence and then fall apart.

11 min read Read
Agents Sep 18, 2026

Verifiable rewards changed what training an agent means

For years the reward was a neural network guessing what humans liked — the single most hackable component in the stack. Replacing it with a program that runs the code and checks the answer removed the exploit surface, and drew a hard line around which tasks this actually works for.

12 min read Read
Agents Aug 28, 2026

Agent memory is a product decision, not a database choice

The hard part of agent memory is deciding what deserves to persist, who can use it, and how a person can take it back.

11 min read Read
Agents Aug 28, 2026

Computer-use agents need permission ladders

A browser session should not hand an agent every power its logged-in human happens to possess.

11 min read Read
Agents Aug 28, 2026

Guardrails are runtime checks, not prompt instructions

A prompt can ask an agent to behave, but only a runtime check can stop an unsafe action.

11 min read Read
Agents Aug 28, 2026

Human-in-the-loop is a control plane, not a confirmation dialog

Useful human oversight decides when to interrupt an agent, what the reviewer needs to see, and how the decision changes the system.

11 min read Read
Agents Aug 28, 2026

MCP security after the hype cycle

MCP made agent integrations portable, which means the hard security question is now what each connection is allowed to do.

11 min read Read
Agents Aug 28, 2026

The injection you're not filtering: tool output

Tool output is data to your application, but it can look like instructions to the model, so protect the action boundary rather than only the user message.

11 min read Read
Python Aug 15, 2026

apply() is a for loop in disguise

Rewriting a Python loop as .apply() makes the code shorter and almost never makes it faster, because .apply() is the same loop with a nicer costume. Here is the ladder that does make it faster.

11 min read Read
Agents Aug 15, 2026

MCP went stateless — what server authors have to change

The 2026-07-28 revision deleted the initialize handshake and the session header, replaced server-initiated requests with a retry pattern, and put Roots, Sampling and Logging on a twelve-month clock.

12 min read Read
Statistics Aug 15, 2026

Simpson's paradox is already in your dashboard

The new checkout converts better on desktop and better on mobile, and worse overall. Both statements are arithmetically correct, and one of them is about to be presented to your leadership team.

10 min read Read
Data Engineering Aug 15, 2026

The small files problem eats your read throughput

A 400 GB table that takes forty minutes to scan is not a 400 GB problem. It is a 1.2-million-file problem, and every one of those files charges the same fixed toll.

11 min read Read