How we bridged the gap between a VS Code extension, a Next.js frontend, and a Rust Axum backend — and the bizarre bugs we fought along the way. TL;DR: Integrating three stacks (Rust backend, Node.js/Electron extension, Next.js dashboard) is where the real bugs hide — not in your logic, but at the seams between ecosystems. This post covers 4 production-grade bugs: a silent fetch body corruption, a literal Rust compiler crash , a UI state machine that silently erased user work, and a secure OAuth token relay across three services. The Rust backend was bulletproof. The Next.js dashboard was polished. The VS Code extension felt completely native. We were on the home stretch. Then came the final 10%. If you've shipped anything real, you already know what this means. Not because the work is hard in the traditional sense — but because you've crossed out of any single ecosystem's comfort zone. You're no longer debugging your code. You're debugging the spaces between Rust, Node.js, and Next.js.…