# Katelyn Lesse

Markdown copy of https://realalpha.app/builders/katelyn-lesse/ on Real Alpha, the best minutes from long interviews with the people building AI. Cite and link the page, not this copy.

Real Alpha has cut 5 moments of Katelyn Lesse (Head of Platform Engineering, Anthropic) talking, from an interview on Latent Space published Oct 27, 2026.

- Role: Head of Platform Engineering, Anthropic
- About: Leads engineering for Claude’s APIs, developer tooling, and product infrastructure.
- Company: [Anthropic](https://realalpha.app/companies/#anthropic)
- On X: https://x.com/katelyn_lesse

## What Katelyn Lesse said

- [Claude helped cut Messages API CPU use by up to 50%](https://realalpha.app/s/claude-helped-cut-messages-api-cpu-use-by-up-to-50/)
  Latent Space · Oct 27, 2026 · 3 min
  > “we literally built, like, an entire fork of the entire API in Rust, and then started running shadow traffic through it” — Katelyn Lesse · [57:26](https://realalpha.app/v/MRQTlwcW-aQ/?t=3446)
- [Separating the agent from its sandbox limits security risks](https://realalpha.app/s/separating-the-agent-from-its-sandbox-limits-security-risks/)
  Latent Space · Oct 27, 2026 · 5 min
  > “the agent is never, like, in the same place where the credentials are, right?” — Katelyn Lesse · [1:05:59](https://realalpha.app/v/MRQTlwcW-aQ/?t=3959)
- [Anthropic makes reasoning harder to distill without breaking API use](https://realalpha.app/s/anthropic-makes-reasoning-harder-to-distill-without-breaking/)
  Latent Space · Oct 27, 2026 · 3 min
  > “we always have this really, really hard trade-off that we have to make between user experience” — Katelyn Lesse · [10:18](https://realalpha.app/v/MRQTlwcW-aQ/?t=618)
- [Model launches now include policy and authorization work](https://realalpha.app/s/model-launches-now-include-policy-and-authorization-work/)
  Latent Space · Oct 27, 2026 · 3 min
  > “Opus 5.5 that launched yesterday, for example, does not have those data retention requirements that Fable has” — Katelyn Lesse · [20:37](https://realalpha.app/v/MRQTlwcW-aQ/?t=1237)
- [Early-access model testing depends on customers with robust evals](https://realalpha.app/s/early-access-model-testing-depends-on-customers-with-robust/)
  Latent Space · Oct 27, 2026 · 4 min
  > “the only customers really that are part of our early access programs are customers that have really robust evals.” — Katelyn Lesse · [32:22](https://realalpha.app/v/MRQTlwcW-aQ/?t=1942)

## The episode

- [How Anthropic ships the #1 LLM in the World — with Katelyn Lesse and Angela Jiang](https://realalpha.app/v/MRQTlwcW-aQ/) · Latent Space · Oct 27, 2026