Opus 5.5: Fable 5.1 level, 30% faster and 40% cheaper than Opus 5

By Javi and Rafa · Café con Codely

Anthropic releases Opus 5.5 this week. Anthropic says that it performs at a level similar to Fable 5.1. It is also 30% faster and 40% cheaper than Opus 5. Claude Code increases the 5-hour window limit by 20% and resets the limits so that you can try the model.

The benchmarks show that Opus 5.5 at medium effort is better than Fable 5.1 at high effort. Rafa's opinion is more careful: Opus 5.5 at medium is equal to Fable 5.1 at low. But it is two times faster and it uses fewer tokens for the same task. Like Fable 5.1, Opus 5.5 lets you change the effort in the middle of a task and keep the cache.

Addy Osmani publishes a guide on the official Claude blog. The main advice: define clearly what a finished task is. For example, the code runs in production, all the tests pass, or the design matches the Figma file. With this, you do not need /goal or prompts like "think harder". Rafa runs 3-hour sessions and uses less than half of his 5-hour window.

Rafa was moving away from Claude Code because Opus 5 gave very verbose output. With Opus 5.5, he uses Claude Code all the time again. Javi adds data from Has Been Released: the price per token is lower than Opus 5, but the price per task is higher. The OpenAI conference is next week, so the competition continues. Watch in the video.

The senior engineer death spiral: fewer megaprojects, more quick wins

Sunil Pai publishes "the senior engineer death spiral", a short post that goes viral. A friend starts a very senior job and asks how to work 60 to 80 hours per week to get a promotion. The pattern is common: the engineer takes a megaproject to show that they are senior. Then they work alone, give vague updates in the daily, burn out and leave the company.

Sunil Pai's advice is to drop a level: help the team with small tasks and share your work. Javi connects this with impostor syndrome, which also affects senior engineers after a job change. For him, the solution is to set clear expectations with the company. He also asks companies to stop requiring very large projects for a promotion. Watch in the video.

Jev in Postgres: natural language search without indexes or embeddings

System One models like Jev do not generate text: they select from a closed set of options and give a probability. This week, new use cases appear: a copy-paste that puts the correct data in each form field, and a real-time emoji search. Chris Tate from Vercel uses json-render with Jev to select design system components in milliseconds. Marco Porracin categorizes 35,000 products in 4 minutes, while an LLM needs hours.

The pg-jev extension adds a jev() function to PostgreSQL WHERE clauses. First, it applies the deterministic filters. Then it sends the rows to the Jev API in batches of 20, with concurrency and a cache. Javi suggests that you use Jev to build the deterministic filters and make the data set smaller. GitHub Next publishes localjev, a Jev-compatible API that runs small models locally. Watch in the video.

The utility of the week

PR Stats

An open source TUI by Dominic Elm with fewer than 100 stars. It shows the distribution of review times for your PRs, with the 50th and the 90th percentile. It also shows the PRs that wait for your review, a heatmap of your reviews and the trend of the average review time. You install it with npx.

https://github.com/d3lm/pr-stats

The chat weighs in

alexcaceres1486: We ran a benchmark with one of our use cases and the classification results are amazing: much better quality (based on evals), much faster and much cheaper

mcruffian: On the other hand, they push that need on you. In some companies, the trial period is like a beauty contest mixed with a hackathon that never ends

Agenda

Paralelo 37 in Jaén · 2026-09-26
Software Crafters Barcelona 2026 · 2026-10-16
Codely live stream from Software Crafters Barcelona · 2026-10-17

The song of the week

Rafa: «Do I Wanna Know?» — Arctic Monkeys (The classic song from the change of Arctic Monkeys to a more relaxed indie sound, with a riff that stays in your head all day.) Watch in the video.

Javi: «Venas con humo y palabras» — Marea (A great song from 2002, for its lyrics and for the energy of its live versions.) Watch in the video.

The café's music playlist: cdly.to/playlist

The saying of the week

«Tanto tienes, tanto vales (you are worth what you have)» Watch in the video.

More Codely

Event Bus en Kafka: diseño de infraestructura

Kafka 4 brings Kafka Queues and lets you use more than one consumer per partition. The course uses this feature to implement an event-driven architecture with dead letters, producers and consumer groups.

The joke of the week: Why is the God Object sad? Because it has too many responsibilities.

All the news we covered

#CaféConCodely · @CodelyTV · Previous cafés: cdly.to/cafe

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