# ENV — `signoff-certificate-engine`

Measured 2026-09-17 on the machine that built this packet, under the estate proof environment
(`env -u LC_ALL PATH="/opt/homebrew/opt/python@3.11/libexec/bin:$HOME/.local/bin:$HOME/.elan/bin:$HOME/.cargo/bin:/opt/homebrew/bin:$PATH"`, stdin `/dev/null`),
in a tree holding exactly the committed HEAD (built by `repro/verify_packets.py`, never the lane's working tree).

| tool | version | probe |
|---|---|---|
| macOS | 26.6, arm64 | `sw_vers`, `uname -m` |
| python3 | 3.11.14 (`/opt/homebrew/opt/python@3.11/libexec/bin/python3`) | `python3 --version` |
| numpy / scipy | 2.2.6 / 1.17.1 | as above |
| git-lfs | 3.7.1 | 11 inputs in `INPUTS.sha256` are LFS objects (model files the certificate loads); a clone must have them smudged, or the witness cannot load them |

**Required tools, and the ENV branch.** `repro.sh` exits 69 with an `ENV:` line when `python3` cannot import
`scipy.stats` and numpy, because the witness would SKIP. Measured: with `PATH=/usr/bin:/bin` it printed `ENV: …` and
exited 69. An unsmudged LFS pointer is not an ENV branch: it makes the witness fail, and so the packet fails.

**Runtime and writes.** 4.4–5.1 s. It rewrites `benchmarks/certificate_v2/certificate_v2_gate_2026_07.json`, its own
output. It is clean in the lane's working tree, but run this packet in a clone anyway.

**Lean.** This witness runs no Lean. If a later packet needs it: the Lean 4 toolchain is `~/.elan/bin/lean` (4.34.0 here),
and `/opt/homebrew/bin/lean` is a different program (`lean 1.0.223`). Never trust whichever `lean` comes first on `PATH`.