Anthropic just dropped Claude Opus 4.5 with an "effort" dial—finally, a model that lets you control your reasoning budget instead of the other way around! Meanwhile, someone's vibe-coded SaaS killed a team (the cautionary tale we all needed but hoped to avoid), and Elio Capella Sánchez migrated 6,000 React tests in one week using AI agents and ASTs—proof that AI actually shines when wrangling legacy code.
Also in this issue: Matt Perry ranks animation performance like a fighting game tier list (spoiler: width is F-tier), Josh Comeau makes CSS Subgrid finally click, and Lazar Nikolov shows how the Speculation Rules API can push e-commerce loads under 100ms. PostgreSQL 19 learns to aggregate first and join later, Matteo Collina squeezes 93% more performance out of Next.js on Kubernetes, and Burak Yigit Kaya teaches us to publish packages with valet keys for better supply chain security.
On the tools front: Rete.js brings visual programming to React, Vue, Angular, and Svelte; gitlogue turns your Git history into terminal cinema; Athas offers a lightweight Cursor alternative with vim mode and agentic AI; and SyncKit makes local-first apps simple with CRDTs and zero-config offline support.
Enjoy!
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Find the 13 highlighted links of weeklyfoo #113:
Migrating 6000 React tests using AI Agents and ASTs
by Elio Capella Sánchez
The internet is flooded with very impressive vibe-style coding demos, but in my day-to-day job at Filestage we rarely start codebases from scratch and we have to deal with hundreds of thousands of lines of code and their dependencies.
🚀 Read it!, tests, ai, migration
by Anthropic
Our newest model, Claude Opus 4.5, is available today.
📰 Good to know, anthropic, claude, ai
The Web Animation Performance Tier List
by Matt Perry
Animation performance is one of the topics I'm asked about the most.
📰 Good to know, animations, performance
Brand New Layouts with CSS Subgrid
by Josh W. Comeau
When CSS Grid layout was first released, it came with a big asterisk: only the grid’s direct children could participate in the layout.
📰 Good to know, css, grid
by Lazar Nikolov
Instant loads with Speculation Rules API
📰 Good to know, performance, web
A Vibe Coded SaaS Killed My Team
by cendyne.dev
I considered it a possibility.
📰 Good to know, ai, vibe-coding
Releasing Packages with a Valet Key
by Burak Yigit Kaya
npm, PyPI, and beyond
📰 Good to know, npm, security
Super fast aggregations in PostgreSQL 19
by Hans-Jürgen Schönig
PostgreSQL 18 has just been born and we are already talking about the blessings of PostgreSQL 19 and beyond? Well, yes, and there is a good reason for it.
📰 Good to know, postgres, performance
93% Faster Next.js in (your) Kubernetes
by Matteo Collina
Including the benchmarks!
📰 Good to know, kubernetes, nextjs
by retejs.org
JavaScript framework for visual programming
🧰 Tools, javascript
by Yuji Ueki
A cinematic Git commit replay tool for the terminal, turning your Git history into a living, animated story.
🧰 Tools, git, terminal, animation
by athas.dev
A lightweight code editor with vim mode, Git integration, and agentic AI editing.
🧰 Tools, editor
by Daniel Bitengo
A powerful, type-safe sync engine for building real-time collaborative applications. Local-first, CRDT-based, with zero-config offline support.
🧰 Tools, sync, local-first, crdt
Want to read more? Check out the full article here.
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