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Why Tests Became the Product: A Conversation with Titus Winters

A conversation with Titus Winters · Notes From The Fleet series

Watch the full interview

I sat down with Titus Winters to talk about developer experience and infrastructure at scale. Titus co-wrote Software Engineering at Google; he is now a Senior Principal Scientist at Adobe. I expected a conversation about build systems. What I got was a line I've been thinking about ever since:

"The question is not what can you build with an incredibly fast, 80% accurate tool. It's what can't you build with an infinite army of incredibly fast, 80% accurate tools."

An infinite army of 80% accurate tools. That army doesn't have a code generation problem. It has a verification problem. Whether it helps you or buries you depends on the systems that check, integrate, and maintain everything it produces.

Titus Winters interview

Titus Winters on the shift from code generation to verification in the AI era

Four War Stories and a Demo: Seattle Build Meetup 2026

Waleed Khan from Stripe presents in Seattle at Uber’s offices

On July 28, 2026, Uber and EngFlow co-hosted a Build Meetup at Uber’s Seattle office. This wouldn’t have been possible without the help of Sergey Balabanov at Uber, who not only presented one of the talks, but also energetically arranged and helped support this event from the Uber side. Thanks again, Sergey!

And, even though nobody planned a theme for this particular meetup (our meetups are holistically focused on “Build, Scale, Investigate”), one showed up anyway. Code is getting cheaper to produce. Uber put it flatly: “AI is a problem, apparently.” Every talk examined some part of the machinery that turns abundant code into software you can trust. Let’s take a look!

Say hello to the new bazel.build website

Today, the new https://bazel.build/ website has finally launched. This is the first step in a larger evolution of Bazel's documentation story. Much of the content remains the same (the eagle-eyed among you may notice a few new pages), but this change marks a new era of Bazel documentation.

What motivated this change?

The Bazel site migration is more than just a fresh coat of paint. One of the underlying motivations for this change is to empower the Bazel community to make more changes to Bazel's documentation. Before the migration, Bazel's website was built on Google documentation infrastructure. While the capabilities of that infrastructure were largely sufficient for Bazel's needs up to now, the contribution experience was not.

Today's https://bazel.build/ is built on Mintlify. With this new platform, each incoming documentation pull request to Bazel is automatically greeted with a preview. For even faster iteration, you can build the site locally. These improvements eliminate guesswork, and better equip contributors to make changes to the Bazel docs with confidence.

Build Forensics: How we uncovered a Rust HTTP/2 bug

Last year, one of our customers began reporting that 5% of their jobs based on Meta's Buck2 build system were failing. Even though there was no simple way to reproduce the phenomenon, all signs pointed to network hangs when a Buck2 client made API calls to their EngFlow cluster. If a simple timeout was added, the request would quickly time out, potentially indicating the issue was a bug in our remote execution platform.

Because of the potential for it to expose a broader issue in our software, especially in terms of compatibility issues with Buck2, we elevated the urgency of this investigation. After examining a few thread dumps that revealed nothing conclusive, we eventually scheduled a call with the customer. After performing multiple tests, it became evident that our schedulers were simply idle. If it were truly a problem in our system, we were unable to find evidence.

Democratizing Build Scalability: Eugene Yokota on Bringing Bazel Features to sbt 2.0

In this interview, Eugene Yokota—a software build expert who spent years maintaining Scala's sbt tool at Lightbend before working with hyperscaled Bazel monorepos at Twitter and Netflix—details his multi-year project to build a Bazel-compatible remote caching system into the newly released sbt 2.0. He explores the mechanics and benefits of Bazel, such as its robust remote caching and test cycle speed, and highlights how these modern, scalable build tools can eliminate CI bottlenecks for growing teams while protecting toolchain security.

Munich Bazel Build Meetup 2026: Tackling Supply Chain Security and Monorepo Scalability

Following a phenomenal annual EngFlow company summit, the Bazel community gathered at the Salesforce offices in Munich for an evening dedicated to expanding the boundaries of build systems, developer tooling, and software supply chain integrity.

With a keynote analyzing the complexities of SLSA 3 and technical lightning talks spanning Bazel integrations, IDE optimization, and parallelization, the event showcased how top-tier teams are solving today's hardest platform engineering problems.

If you missed the live event, we’ve aggregated the core architectural takeaways in this post.

December 2025 Bazel Central Registry Outage

On December 26, 2025, Bazel users worldwide struggled with running their builds, as Bazel reported errors due to expired TLS certificates:

ERROR: Error computing the main repository mapping: Error accessing registry https://bcr.bazel.build/: Failed to fetch registry file https://bcr.bazel.build/modules/platforms/0.0.7/MODULE.bazel: PKIX path validation failed: java.security.cert.CertPathValidatorException: validity check failed

Build Meetup in London – Recap

In May, we co-hosted the London Build Meetup with Tweag by Modus Create and Jane Street. Build system insights, stories about first-hand build challenges, and great conversations packed the afternoon and evening. The lineup covered everything from large-scale migration battles to new research. If you missed it, here’s what you need to know.

Build Meetup in Munich – Recap

Another successful build meetup done! Our April meetup was co-hosted by JetBrains. The night was all about swapping stories, learning something new, and enjoying some good food and drinks. If you missed out, read the recap below and check out meetup.build for the next one!

Build Meetup April 2025