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Jacar categories — explore the topics A rocket whose eyes follow your cursor.
Architecture

Agent-to-agent protocols: the next open layer

With MCP solving the agent-to-tool layer, a parallel problem surfaces: how do two agents from different vendors communicate with each other. Google's Agent2Agent protocol, donated to the Linux Foundation in June 2025, tries to fill that gap with an open standard.

Architecture

gVisor: sandboxing for multi-tenant containers

gVisor interpone un kernel en espacio de usuario entre el contenedor y el anfitrión. Después de años en producción en Google y adopción creciente en plataformas serverless, merece una lectura honesta sobre cuándo compensa frente a microVMs y runtimes clásicos.

Architecture

LLM caches: saving tokens without dropping quality

A caching proxy in front of a language model can cut the token bill significantly, but it introduces subtle risks if the design is not careful. Which cache types work in production, where the usual traps sit, and how to add them without degrading the experience.

Architecture

Inference routers: choosing a model based on the request

Un enrutador de inferencia decide qué modelo atiende cada petición en función de coste, latencia y complejidad. Bien diseñados reducen la factura de tokens sin que el usuario perciba degradación; mal diseñados introducen fallos sutiles difíciles de depurar.

Architecture

TigerBeetle: a database built for financial transactions

TigerBeetle is a distributed database written in Zig, specialized in one specific kind of workload: high-volume double-entry accounting with strong consistency guarantees. It does not aim to replace Postgres; it aims to be the right tool when the problem is counting financial transactions at millions per second without subtle failures.

Architecture

Platform engineering: consolidation after the boom

After three years of expansion and an overheated ecosystem around the term, platform engineering enters 2025 in a consolidation phase. The internal platforms that survive are the ones that understood their real function; those that mistook the label for the solution are dismantling their teams or cutting them drastically.

Architecture

Citus: scaling Postgres horizontally without leaving it

Tras la adquisición por Microsoft en 2019, Citus vivió un limbo comercial que terminó con Microsoft abriendo el código completo en 2022. Tres años después, la extensión de particionado para Postgres ha madurado y ofrece una ruta práctica para escalar sin abandonar el motor que ya conoces. Un repaso honesto.

Architecture

SQLite in production: patterns that have aged well

SQLite lleva años ganando terreno en servidores reales gracias a WAL, a proyectos como Litestream y libSQL, y a hardware con discos rápidos. Repaso los patrones que siguen funcionando después de varios años de uso, los que no, y por qué el tamaño medio de una aplicación web se come ya sin despeinarse.

Architecture

DuckDB in enterprise analytics: concrete cases

DuckDB has spent two or three years quietly working its way into data architectures. It is no longer just the embedded database for local analytics: in 2025 it keeps turning up in concrete enterprise cases where it replaces far pricier pieces. A tour of the real patterns.

Architecture

Agent OS: the concept shaping the new stack layer

The term Agent OS has spent a year gaining traction across research and product circles. It describes a layer that goes well beyond an agent library: request scheduling, context management, persistent memory, and isolation. A look at the real state of that concept.

User Experience

Accessibility overlays: the 2025 criticisms explained

Accessibility overlays were sold as a magic fix for WCAG and the European EAA directive in one step. In 2025 lawsuits against them have grown and disabled users are speaking out more critically than ever. A look at why they fail and what to do instead.

Architecture

Model Context Protocol in 2025: from announcement to ecosystem

Model Context Protocol turns ten months old since Anthropic's announcement, and it is no longer just a proposal: hundreds of servers, cross-vendor implementations and a public registry now back it. A look at what has worked, what is still weak, and why 2025 marks the shift from curiosity to basic infrastructure.

Software Development

Astro 5: when content and applications converge

Astro 5 has spent nine months in production and has settled into a place of its own in the JavaScript world. Its bet on typed content and friction-free mixed rendering puts it halfway between Next.js and the static-site generators. A time-tested assessment.

Architecture

YugabyteDB and CockroachDB: distributed databases in 2025

Distributed SQL databases have moved from promise to production reality. YugabyteDB and CockroachDB lead the segment from different angles. Choosing between them demands understanding what each design compromises and what horizontal scaling costs in practice.

Methodologies

User research in the age of generative AI

Los equipos de producto están tentados de sustituir entrevistas y tests reales por síntesis de IA. Dos años de experiencia ya permiten separar dónde la IA ayuda de verdad y dónde genera una falsa sensación de entender al usuario.

Architecture

Kubernetes 1.34: a summary for teams with little time

Kubernetes 1.34 ships with Dynamic Resource Allocation (DRA) graduating to stable, scheduler improvements, and CEL-based mutating admission policies that replace webhooks. A practical rundown of what is safe to upgrade now, what can wait, and what actually changes for teams running production clusters.

Architecture

Kafka without ZooKeeper: KRaft in production

Kafka 4.0 llegó en marzo con la promesa cumplida: el clúster se autoadministra sin ZooKeeper. Después de meses operando clústeres KRaft y de la migración obligada, qué cambia de verdad, dónde duelen las diferencias y qué hay que saber antes de migrar.

Software Development

Qwik in production: resumable and cheap on the client

Qwik has spent two years promising apps that start instantly because, instead of hydrating, they resume execution serialized on the server. With the 1.x series settled and real cases published, this guide checks whether resumability is worth the learning curve and which products benefit most from that client-side JavaScript saving.

Architecture

Delta Lake and Apache Iceberg: 2025 comparison

Open table formats over data lakes have moved from curiosity to backbone of many analytics architectures. Delta Lake 4.0 and Apache Iceberg 1.9 are the two with the most weight in 2025. We review where each one stands and which criteria make sense when choosing between them.

Architecture

containerd 2.0 in production: real migrations

Six months after containerd 2.0 reached general availability there is enough real-world mileage to judge the migration from the 1.x branch in production. We cover what changes in the config file, what breaks on Kubernetes and Docker Swarm, and when planning the jump actually pays off.

Architecture

Firecracker: microVMs for multi-tenant services

Firecracker is the Rust-based virtual machine monitor AWS uses in Lambda and Fargate: it boots microVMs in under 125 milliseconds with under 5 MB of overhead. Switching from containers pays off when a shared kernel does not give enough isolation, especially for untrusted LLM agent code, and versus gVisor it wins on I/O performance.

Software Development

Rust Edition 2024: what really changes day to day

Rust Edition 2024 became stable on February 20, 2025 alongside Rust 1.85. Seven weeks later, the changes that actually matter for daily work are three: more granular variable capture in closures and Return Position Impl Trait, an expanded prelude with Future and AsyncFn, and unsafe now mandatory in extern blocks.

Architecture

Applying graph RAG to a real product

Desde que Microsoft abrió GraphRAG, el patrón de usar grafos sobre tus propios datos ha pasado de experimento académico a técnica con aplicaciones prácticas. Reflexión sobre cuándo compensa, cómo se monta y qué errores se repiten.

Architecture

Coolify: a self-hosted Vercel on your own infrastructure

Coolify delivers a Vercel- or Heroku-like experience on your own servers: automatic HTTPS, managed databases, and branch previews without per-build or bandwidth fees. After several months using it on production VPS, here is where it shines, where it still has rough edges, and which teams will genuinely benefit from it.

Architecture

Microsoft’s GraphRAG in enterprise: patterns that work

GraphRAG has been in real enterprise use for over a year: during indexing, an LLM builds a knowledge graph that answers global questions about a corpus well, precisely where classic RAG fails because no single chunk holds the full answer. Here I compare indexing costs, the cases where it pays off, and the hybrid pattern that teams have settled on.

Software Development

Full-stack TypeScript in 2025: the good, the meh, the bad

Full-stack TypeScript with Next.js and tRPC removes type duplication between frontend and backend, but it is not a universal answer: Node still falls short on CPU-bound loads, testing remains fragmented, and large projects eventually split apart. It is the best fit for small-to-medium products with agile teams, not for sustained high-performance systems.

Software Development

WASI preview 3: threads and async in WebAssembly

WASI 0.3, also known as preview 3, was ratified on June 11, 2026, adding native asynchronous concurrency to the WebAssembly component model through streams, futures, and async functions. It fixes old fragmentation across languages and runtimes, enables real composition between Wasm services, and paves the way for cooperative threads planned in upcoming 0.3.x releases.

Architecture

Cloudflare Workers in 2025: from edge to enterprise

Cloudflare Workers turned eight in 2025 without slowing down: it now ships D1 for databases, R2 for egress-free storage, Durable Objects for distributed state, and Workers AI for running models without managing GPUs. It remains the fastest option for edge logic; for large in-memory processes or strict global consistency, other platforms fit better.

Architecture

How to install JuiceFS as a shared filesystem

JuiceFS is a distributed, POSIX-compliant file system that separates data, stored in an S3-compatible object store, from metadata, stored in a database such as PostgreSQL or Redis. This guide installs JuiceFS on a three-node Linux cluster to share files without relying on NFS.