Reading Open Interpreter rust-v0.0.42 Computer Use Internals — From the QA Skill to cua-driver CLI

I recently wrote a code-reading tour of Hermes Agent v2026.9.7 Computer Use. Open Interpreter's README also documents cua-driver usage, so I wanted to know how much of the agent-side implementation is actually shared and where it diverges. This article is that follow-up: a source-only tour pinned to Git tag rust-v0.0.42, tracing one QA request through the qa-testing skill, the cua-driver CLI, and the Cua daemon, then back to the model with the result and screenshot. Along the way it hits six design forks: a QA skill embedded in the binary, delegation to external CLIs instead of a bespoke tool schema, generic command execution and approval, the view_image bridge for images, the three-layer permission story, and the reproducibility gap because pinning the OI tag does not pin the Cua version.