A tiny, dependency-free Rust binary that reads SO_PEERCRED off a unix socket and injects the
caller's UID/GID/PID into requests. The claude-box
launcher (launcherd) uses it to identify in-box callers by UID — so authority is anchored to who is
calling, not a forgeable token.
It is a launcherd helper, not a door (it holds no capability of its own). Linux-only
(SO_PEERCRED).
nix build .#peercred # via nix (what claude-box uses)
cargo build --release # or directlyclaude-box pins this repo as an input and builds the binary from a vendored mirror — the same
pinned-source pattern as guest-room / door-kit. There is no published artifact (the binary is
built from source by each consumer).
Extracted from claude-box peercred/ — decomposition epic prx-ii01, card 3.