A receipt for every decision.
What was decided, why, on which papers at which version, by whom and when. Each entry is hashed onto the one before it, so a change anywhere in the book shows. An auditor can open it, run it again, and get the same answer.
Harlow price £412.2m
- Change
- Basis 2026.1 → 2026.2
- Why
- Committee item: coverage 196% → 184%
- Papers
- Basis 2026.2 · v3, Scheme deed 2011 · v1
- By
- Aksel, 25 Oct 2026, 14:32
- Confirmed
- Touch ID on this Mac
How it keeps it there.
Seven things, each checked against the code. Two are macOS-only for now, and say so.
It runs on your servers
The engines run on servers you control, reached over SSH. Nothing is exposed beyond the access you already have, and we have no way in unless you invite us.
It works without the internet
Everything Henselian needs, including the assistant, is installed on your machines. It works on a network cut off from the internet.
Every decision has a receipt
A decision goes on a record that cannot be changed without it showing: the data, the assumptions, the steps and who approved it. An auditor can run it again and get the same answer.
A person confirms before the record
Approving a decision asks the person at the machine first, with Touch ID or the machine's password. Cancel, and nothing is recorded.
On macOS today.
Keys stay in the system's store
The keys that reach your engines and your trading venue live in the Keychain, never in a config file.
On macOS today.
Servers are checked before they are trusted
A server the app has never met shows its host key first, to be checked once with its administrator. A key that changes is refused, with no button to override it.
Updates are signed, and yours to time
The app verifies a new version against its signing key before installing it, and installs it when you choose. Past results stay exactly as they were.
What security teams ask first.
Do you ever see our data?
No. Henselian runs on your servers, so your data stays with you. We have no way in unless you invite us, and then only for the time and the task you agree to.
Can it run without internet access?
Yes. Everything it needs, including the assistant, is installed on your machines, and it works fully on a network cut off from the internet.
What happens when we update?
You decide when. The new version is checked against its signing key; your team installs it when it suits you, and past results and their receipts stay as they were.
How do auditors check a result?
They open the receipt: the data, the assumptions, the steps and who approved the result. They can run it again and get the same answer.