Prove

Can I show nobody changed the record?

Every decision is signed and chained to the last. Anyone can check one decision, offline, without trusting us.

xevrion / prove / logSearchExample data

Decision log

Last hourResult: anySearch actions

Time	Agent	Action	Amount	Answered by	Wait	Result
14:09:41	refund-agent	refund.issue	£540.00	PS	6m 12s	Approved
14:08:12	support-agent	email.send	–	M	1m 04s	Approved
14:06:55	billing-agent	db.update	–	Rule	12 ms	Passed
14:05:30	payout-agent	payout.create	£12,000.00	Rule	9 ms	Refused
14:03:02	support-agent	ticket.close	–	Rule	7 ms	Passed
14:01:17	refund-agent	refund.issue	£310.00	P	2m 41s	Approved
13:58:44	refund-agent	refund.issue	£880.00	PS	9m 30s	Approved
13:55:09	sales-agent	discount.apply	15%	M	4m 18s	Approved
13:52:31	billing-agent	invoice.void	£1,240.00	P	waiting	Waiting

Decisions per hour

Answered by peopleLet through by rule

Chain

Intact

#4819a41f…09d213:41
#4820c7e0…51ab13:52
#482109bd…e3f714:01
#48225be2…7c4414:09

Each record holds the fingerprint of the one before it.

Check it yourself

Offline

$ xevrion verify rec_4822 --key public.pem
✓ signature matches key 7f2c
✓ record is in the log (position 4,822)
✓ 4,821 links before it add up
verified in 38 ms, no network used

Signing keys

Public

7f2cActive since 1 AugSigning
3a91Retired 31 JulVerify only

Old records stay checkable after a key changes.

This hour

117decisions49by people0unsigned

Prove

Public proof

Share a link that lets anyone check a single decision against our published keys, offline.

Nothing else revealedThe check covers one decision. The rest of your log stays private.
Offline checkIn a browser, or with a few lines of code. No call to us needed.
Revocable linksSwitch a share link off whenever you like.

How Public proof works →

xevrion.co.uk / proof / d_7f3a91Example data

Shared decision

No sign-in needed

Action: refund.issue · £540
Decision: Approved by 2 of 2
Decided: 26 Oct 2026, 10:44 UTC
Policy: refunds v12
Hidden: Customer name, order contents

Checked in your browser

Offline

Receipt signature matchesed25519
Included in the logleaf 48,211
Checkpoint signed#9,402
Link not revoked

Prove

Append-only proof

Hold an old signed checkpoint. Later, get a proof that nothing was removed or rewritten since.

Consistency proofA short proof ties an old checkpoint to the new one.
Forks are caughtTwo signed roots for the same size are detected and flagged.
Checked offlineVerify on your own machine against published keys.

How Append-only proof works →

app.xevrion.co.uk / proof / logExample data

Signed checkpoints

Every hour

#9,40248,211 decisionsLatest
#9,40148,198 decisionsSaved
#9,37847,731 decisionsSaved by you
#9,10044,010 decisionsSaved by auditor

Consistency check

#9,378 → #9,402

Old checkpoint is a prefix
480 new decisions only added
No fork between two readers
Nothing removed or rewritten

Check it yourself

$ xevrion verify log \    --from 9378 --to 9402consistent: trueadded: 480, removed: 0

Prove

Signed receipts

Each decision comes with a signed receipt and an evidence pack: who, what, when, and why.

SignedA receipt cannot be changed without breaking its signature.
Evidence pack per requestThe data, the rule, the reviewer and the result in one bundle.
Hashes over the plain textHashes are taken over readable data, so proofs still verify when stored data is encrypted.

How Signed receipts works →

app.xevrion.co.uk / decided / r_01HX9Example data

Signed receipt

Refund £540

Who: Priya N., Sam O.
What: refund.issue · order 88231
When: 10:43 and 10:44 UTC
Why: Over £500, two reviewers
Signature: Valid

Evidence pack

Receiptreceipt.json2 KB
Policy at the timerefunds v121 KB
Reviewer answers2 signed3 KB
Log inclusion proofleaf 48,2111 KB

Hashes over plain text

action_hash  9c1e…a402policy_hash  41bd…77e0receipt_hash e3f8…10cd

Prove

Proof-carrying tokens

After a yes, a short-lived signed token binds the approval to the exact action. Change anything and it fails.

Bound to the actionThe token covers that payload only. A changed amount or target is refused.
Expires fastA short window, so an old approval cannot be replayed later.
Single useOnce spent, it is spent. A second try is refused.

How Proof-carrying tokens works →

docs.xevrion.co.uk / action-tokensExample data

Your agent presents the token

POST /payments/refundx-xevrion-token: xt_4c9…{ order: 88231, amount: 540 }// Change the amount to 541:→ rejected: action does not match

What the token locks

Action: refund.issue
Amount: £540
Expires: In 5 min
Uses: 1 of 1

Life of a token

Person approves
Token issued, 5 min
Used once by your agent
Second use refused

Know what your agents did.

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Signed, chained decisions
Checked offline, without us

Proof · decision #4822Example data

Signed decision

Decision: Approved, 2 of 2
Action: refund.issue, £540
Rule: Two reviewers must agree
Sealed: 14:09, key 7f2c
Hash: 5be2…7c44

Checked on your own machine

Signature matches the public key
Decision is in the log
Every link before it adds up