Browsers as AI agent sandboxes + leadership transparency wins

Today's insights span from technical innovations in AI agent containment to management practices that treat engineers as adults, not children to be managed.

Browser sandboxing for AI agents: Paul Kinlan's Co-do demo proves browsers can safely run coding agents using File System Access API, CSP headers with iframe sandboxing, and WebAssembly in Web Workers—without multi-GB local containers. The <input type="file" webkitdirectory> tag works across all major browsers for directory access.

Unified exception testing in pytest: Instead of separate test methods for success/failure cases, use nullcontext as produces and pytest.raises in a single parameterized test—cleaner and more maintainable than the traditional approach.

Engineers in leadership meetings transforms decision-making: Will Larson reports 6 years of success having senior engineers report directly to him and join all leadership discussions. Key benefit: prevents managers from "managing stuff around reality" instead of reality itself, plus creates dual information propagation paths.

Curiosity before problem-solving reduces cost of being wrong: When someone misses expectations, asking "what happened?" before applying accountability damages fewer relationships and often reveals missing context that changes your response entirely.

Lighthouse hiring multiplies recruiting effectiveness: Hiring one well-connected person (like Julia Evans at Stripe) improves both quality and velocity of subsequent hires through network effects, though it requires careful navigation of power dynamics.

#browser-sandboxing#ai-agents#pytest-testing#engineering-leadership#hiring-strategy

8 articles published

Articles

Ned Batchelder

Testing: exceptions and caches

Two testing-related things I found recently. Unified exception testing Kacper Borucki blogged about parameterizing exception testing, and linked to pytest docs and a StackOverflow answer with similar

Will Larson

Writing Visualizations with Remotion

Remotion is having a bit of a moment at the moment, and I decided to play around with the Claude Code integration. Here are a couple videos I was able to make in <10 minutes summarizring data on my bl

Will Larson

Stripe's Lighthouse Hiring pattern.

I did a lot of hiring at Uber, some days I would be doing back-to-back 30 minute phone screens for several hours in a row. That said, while Uber taught me how to hire at scale, it was Stripe that taug

Will Larson

Pressure Without a Plan.

When we launched Digg v4, the old site turned off, but the new site didn’t turn on. There was a lot of pressure to get things working, but no one knew what to do about it. It took almost a month to ge