The proxy pattern here is clever - essentially treating the LLM context window as an untrusted execution environment and doing credential injection at a layer it can't touch.

One thing I've noticed building with Claude Code is that it's pretty aggressive about reading .env files and config when it has access. The proxy approach sidesteps that entirely since there's nothing sensitive to find in the first place.

Wonder if the Anthropic team has considered building something like this into the sandbox itself - a secrets store that the model can "use" but never "read".