Deterministic pricing · measured 2026-08-16 · engine v0.2.1
Five different GPUs.
One identical hash.
LuxiBook priced the same 237-row option book on an H200, an H100, an A100, a 5090 and a 4090 - four NVIDIA architecture generations, CPU path and CUDA path, ten runs - and every run produced the hash below. Download the binary, price the book, and check that you get it too.
Do not take our word for it. Take four minutes.
The binary is public, the book is public, and the expected hash is printed above. If your machine disagrees with ours, you have found something we want to know about.
# 1. get the binary and the book $ curl -sLO .../downloads/luxibook/luxi-book-linux-x86_64 $ chmod +x luxi-book-linux-x86_64 # 2. price the book $ ./luxi-book-linux-x86_64 price --book stress_book_a.csv \ --out out.csv --receipt r.json engine_version 0.2.1 git_sha 02388f778d9017d251bb0fc905a82b89a2e94c9a output_hash 902667a1070b83bf...e9e196e2 book_total 488338590.9188194 receipt lxq2_TFhRAgCLCm2h... # 3. check it $ ./luxi-book-linux-x86_64 verify --receipt r.json [OK ] signature Ed25519, install b487b0ab3ec0008e [OK ] input hash matches stress_book_a.csv [OK ] output hash matches out.csv [OK ] canonical bits 66 f64 little-endian [OK ] mode cpu scalar deterministic exit 0 # 4. now try to break it: change one byte of out.csv $ ./luxi-book-linux-x86_64 verify --receipt r.json [FAIL] output hash does not match out.csv exit 1
What a receipt proves, and what it does not
A receipt is not a claim that the number is correct. It is a claim about provenance, and the exact wording matters.
Three layers, often confused
| SHA-256 | Content fingerprint of the input CSV and the output numbers. Answers "are these the exact same numbers?" |
| Ed25519 |
The seal, the lxq2_ token. Answers "which
install asserted them?"
|
| drand round | A public not-before time anchor. Answers "no earlier than when?" |
The honest limit
The public key travels inside the receipt. So a checker that reads the key out of the receipt it is checking proves only that the receipt is internally consistent, not that it came from us. Anyone with Python can mint one that passes that test.
Pinning is the defense. Pass --expect-pubkey with a
key you already trust from the published evidence, and it
becomes a real identity check. We publish five distinct install
keys precisely so you can.
Independently measured: less energy per position
TestFort QA Lab, July 23 2026. Qwen2-7B-Instruct packed prefill, batch 16, sequence length 128, one NVIDIA H100 80GB. Board joules per prefill position, lower is better. This is our inference work, not LuxiBook.
Who this is for
You have to prove a number to someone who does not trust you
Model validation and model risk teams, fund administrators and valuation agents, audit and expert-witness work. If your job includes reproducing what was computed last quarter and documenting that you did, a signed receipt is not a feature, it is your deliverable.
You buy watts
Capacity and platform teams measuring inference against a power envelope rather than a latency target. Start with the independently measured prefill numbers above, then bring your own workload and comparator.