Dad, husband👨👩👧👦, musician🎹🎺, and engineering leader @github ⌨️💻 from 🇵🇷. Opinions are my own.
Durham, NC
Joined September 2009
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José Arzuaga 🇵🇷 retweeted
PMs: your engineers live in GitHub.
What would it take for you to move in too? Better docs? Less issue wrangling? Something to exist pre-ticket? What would make it feel "native" for you, too?
Hooray 🎉 to my teams for all the work this year in moving us away for css-in-js and the great impact they had on making @github faster! ⚡️⚡️ Checkout the details in our latest blog post: github.blog/engineering/arch…
José Arzuaga 🇵🇷 retweeted
Release pages just got an upgrade 🚀
📋 New sidebar table of contents for easier navigation
📊 Download counts per asset now visible in the UI - no API needed
Check it out and let us know what you think
José Arzuaga 🇵🇷 retweeted
Now live 🎉
Repository admins can now restrict issue creation to collaborators only.
This is a highly requested follow-up to the pull request controls we shipped in February, and a big step toward giving maintainers more control to help reduce low-quality contributions.
José Arzuaga 🇵🇷 retweeted
We’ve been studying how team rituals change for AI-forward engineering teams across @Microsoft.
Jay Parikh's top rules for agentic AI: 1️⃣ Plans are the real work. 2️⃣ Code is disposable. Specs & context are the durable assets.
What rules are you seeing? 🚀
commandline.microsoft.com/ne…
José Arzuaga 🇵🇷 retweeted
Wanted to provide more clarity about this.
Yesterday, we had a regression in merge queue behavior where, in some cases, squash or rebase commits were generated from the wrong base state, making earlier changes appear reverted in branch history. 2,804 pull requests out of over 4M merged on April 23 (roughly 0.07%) were affected. We fixed the issue, we've contacted every impacted customer, and we're expanding our automated test coverage for merge queue operations. The team will be updating the status page with RCA details as well.
This GitHub incident is insane. Merge queue commits have been reverting previously merged commits at random.
This not only breaks the mental contract teams have with Git in general, but is subtle enough to be really hard to unravel after the fact.
githubstatus.com/incidents/z…
We added intent preloading to the Files Changed tab on pull requests. When you hover the tab, we start fetching data before you click.
The result? Page loads are 20-35% faster across the board. You'll feel it the next time you switch tabs on a PR. Enjoy! ✨
José Arzuaga 🇵🇷 retweeted
After overhauling the React architecture of GitHub's "Files changed" tab, we dropped Interaction to Next Paint (INP) from ~450ms to ~100ms.
📉 React components cut from 8 to 2 per line
🔑 O(1) data access with JS Maps
🪟 Window virtualization for giant PRs
Yesterday at the East Carolina University Trombone Festival. Great turnout and amazing master class and concert by Peter Steiner ❤️
José Arzuaga 🇵🇷 retweeted
Two of the top GitHub Actions community requests are now live
1. Timezone support in crons
schedule:
- cron '30 5 * * 1-5'
timezone: "America/New_York"
2. Use environments without auto-deployments
environment:
name: staging
deployment: false
José Arzuaga 🇵🇷 retweeted
We've introduced dockable panels to improve navigating changes in PRs
In the files changed view you can now dock
→ Comments
→ Merge status
→ Alerts
→ PR overview
Have you noticed things feel a bit faster? We improved repository navigation and cut render times by over 30% for the slowest loads, and you'll feel it everywhere: code, pull requests, and issues. All snappier. ✨
ALT Chart showing a downward trend in navigation render times on GitHub, with a steep drop in early March 2026.
José Arzuaga 🇵🇷 retweeted
Are we talking about Copilot CLI or some other Copilot?
Copilot CLI is pretty good, honestly, I'd say on par or better than the most coding agent harnesses. It's not trendy on X circles but they're shipping quick.
José Arzuaga 🇵🇷 retweeted
Why did it have access? If a junior engineer takes down prod, it's never the junior's fault. That's an access and SDLC issue
Claude Code wiped our production database with a Terraform command.
It took down the DataTalksClub course platform and 2.5 years of submissions: homework, projects, and leaderboards.
Automated snapshots were gone too.
In the newsletter, I wrote the full timeline + what I changed so this doesn't happen again.
If you use Terraform (or let agents touch infra), this is a good story for you to read.
alexeyondata.substack.com/p/…
ALT A console screen shows a critical warning about a destroyed database and missing backups, outlining deleted infrastructure components.
José Arzuaga 🇵🇷 retweeted
Many such cases and hoping for more...
If you're a builder like Evan and want to come and shape the future of GitHub, say hey in email or DM
José Arzuaga 🇵🇷 retweeted
Merge status in the PR header is beginning rollout, let us know what you think! Lots of improvements to the experience like this coming -- I'm excited!
José Arzuaga 🇵🇷 retweeted
🧑🍳 Fresh out of the oven! New markdown tables are available now on Copilot CLI. Make sure to update!
José Arzuaga 🇵🇷 retweeted
A little caching goes a long way at GitHub scale
Since the start of the year, code view page loads under 100ms are up around 10x and climbing
This is both a result of caching and a number of other frontend improvements that rolled out to 100% today
José Arzuaga 🇵🇷 retweeted
Since the start of Feb we’re seeing around 38% decrease in INP at P95 and 24% at P75
This is not from one single change but a number of smaller changes across perf initiatives that add up
We’re continuing to push every single day on making GitHub fast, particularly in code and PR views where there’s more coming over the next few weeks
