OpenAI slashes prices: Luna drops 80% and changes the rules of model selection

By Javi and Rafa · Café con Codely · Edition sponsored by Ucademy

OpenAI announced the price cut a few hours before the show: GPT-5.6 Luna now costs 80% less and Terra, 20% less. Sol gets a faster option through the API. The cut also applies to Codex and ChatGPT: Luna and Terra usage consumes less of your usage window, so you hit the limits later.

The announcement includes the classic cost-versus-intelligence chart, with obvious cherry picking but useful for context. Luna at max effort matches the intelligence of an Opus 5 at low. The difference is the price: around 0.06 dollars per task versus around 0.35.

The analyses came fast. According to a coding benchmark, picking Sol at medium is now absurd: Luna at max is better and three times cheaper. The same applies to Terra, even at extra high. The Artificial Analysis team confirms it: with its modest 20% cut, Terra stays behind Luna and Sol on the Pareto frontier.

Rafa added the nuance: the chart lacks the time dimension. Luna at max is slow, and an Opus 5 at low responds much faster. That variable matters for daily work. The show's conclusion: Luna gains a lot of relevance, and Terra stops making sense at several effort levels. Watch in the video.

Anthropic deletes 80% of the Claude Code system prompt and rewrites the rules of your AGENTS.md

Opus 5 shipped on July 24 and completes the Claude 5 family: Fable, Opus and Sonnet are now at level 5. The interesting part came with the post by Thariq, from the Claude Code team: the new rules of context engineering for this generation. Anthropic removed about 80% of the Claude Code system prompt with no loss of performance. The summary: remove from your CLAUDE.md everything the model can learn by reading the repo, and spend those tokens on the real gotchas.

The post turns several best practices into myths: give judgment instead of rules, design interfaces instead of stacking examples, use progressive disclosure instead of giving everything up front. The show's disagreement came with automemory: putting your team conventions there creates vendor lock-in, and it is not shared with the rest of the team. Better to keep them in agnostic files that work with any agent. OpenAI follows the same line, so your AGENTS.md can stay a single file. Watch in the video.

Kill the Cookie Banner: Brussels can retire the banners and Google pushes back

The European Union proposes in the Digital Omnibus a browser setting for cookies, like the language preference: you accept or reject once and every website must respect it. Goodbye banners. Google lobbies hard against it: most people accept cookies pushed by the design of the banners themselves, and that tracking would be lost. The killthecookiebanner.eu campaign gives you the contacts of your MEPs to defend the measure.

The same law brings fine print: the pseudonymous user ID would stop counting as personal data. A website that leaks that data would not have to report it. The campaign itself warns that it only supports the cookie part; the rest of the reforms cut rights. The show left the debate open: those IDs can be matched across leaks to identify you by patterns. Watch in the video.

The utility of the week

Codely's Agent Harness

Codely open sources its agent harness: the skills it uses daily, heavily iterated, plus a Claude Code plugin that speeds up TypeScript linting with TypeScript 7. The landing page builds the install command your way: global or per project, all the skills or only the ones you pick. As a gift, a free email course that starts next week: 5 days, one skill per day. And if you like it, star the repo on GitHub.

codely.com/agent-harness

The song of the week

Rafa: «ATWA» — System of a Down (The first song he learned to play on the guitar; Javi ruled it "a bit rough" for its excess of heaviness) Watch in the video.

Javi: «Autorretrato» — Extremoduro (It came up on shuffle and he confirmed it: one of his favorite Extremoduro tracks for the energy it transmits) Watch in the video.

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

The saying of the week

«Pocos y mal avenidos ("Few, and on bad terms")»

They are few, and on top of that they do not get along. The variant that won the show, for its extra fantasy: "One goes to the forest and the other goes for the firewood". Watch in the video.

More Codely

Spec-Driven Development con Research, Plan, Implement

The new course in the AI series: how Codely applies the Research-Plan-Implement flow, with the skills it uses daily. It is the recommended second step after Programación agéntica: fundamentos prácticos. The first video of the course is free on YouTube.

The joke of the week: What is the stacked PRs song? A PR on a PR, on a PR.

All the news we covered

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

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