If your agent keeps a log, who besides you ever checks it?
Most AI agents record what they did. The catch is that the agent usually gets to write the record.
Arcaeon gives you a record you can check.
Every entry is chained to the one before it. Change a line, delete one, or swap two, and verification finds the break.
Put Arcaeon between your agent and its tools and it keeps its own copy of the calls. Then compare the two records. If they disagree, you'll know.
pip install arcaeonFree. MIT licensed. No account required to verify.
Let's break one.
Sixty seconds, two log lines, and one small act of vandalism. These are the real commands and the real output.
$ arcaeon log agent.jsonl '{"tool": "search", "query": "weather"}'
dfc75325fc36cda277a6a8f72d371fb9
$ arcaeon log agent.jsonl '{"tool": "send_email", "to": "ops"}'
ab6e673387bb0dedca6ca577c45e144f
$ arcaeon verify agent.jsonl
{
"verdict": "VERIFIED",
"ok": true,
"rows": 2,
...
}log prints the new line's chain value. Yours will differ.VERIFIED Two lines, chain intact.
Now change one word of history: weather becomes sunshine.
$ python -c "import pathlib; p = pathlib.Path('agent.jsonl'); p.write_text(p.read_text().replace('weather', 'sunshine'))"
$ arcaeon verify agent.jsonl
{
"verdict": "BROKEN",
"ok": false,
...
"first_break": "line 1: chain mismatch",
...
}BROKEN first_break: line 1: chain mismatch
One word changed. One line called out. Nobody had to take anybody's word for it.
The agent doesn't get to quietly edit history. What that run did not catch: someone cutting the last lines off the end. That's the witness's job, below.
What Arcaeon does
Record
Give your agent a log it can't quietly rewrite.
Observe
Sit between your agent and its MCP tools and keep a second record of every call.
Reconcile
Put the two records side by side and find where they stopped agreeing.
Check
Read an MCP server's source for the usual trouble, like unsafe exec or secrets in code, before you plug it in. None of it runs.
Witness
Hand the log's latest state to a witness the writer doesn't control, so a log cut short stops matching.
Deal
Give a buyer's agent and a seller one shared record of what they actually agreed to.
A log nobody else can check is just a story with better formatting.
Arcaeon lets someone else verify the record without your account, your key, or your permission. Your AI can write the log. It doesn't get to be the only copy.
The proof is yours. The checking is theirs.
One important catch
Arcaeon shows that every row of the record still hashes to the next, and, with a pin, that the rows up to the pinned head have not changed since the pin.
It does not prove the record was true.
An agent can faithfully record a lie, and Arcaeon will faithfully keep it. A chain on its own also can't see lines cut off the end; the witness catches that, but only as of the last time it was shown the log.
That's a different problem. We'd rather solve the first one properly than pretend we've solved the second.
The full list of what it does not prove →Built by someone who has spent twenty years where the record gets pulled.
On a 911 floor, "that's what I remember" is not an audit trail. There is a record, and someone else pulls it.
AI agents are starting to do consequential things. They should have one too.
Why Arcaeon →Pick a door
For your AI
One install on Windows, Mac or Linux. Or nothing to install at all.
Then one line tells your AI app where Arcaeon is, for example arcaeon connect claude-desktop. It prints what it would add and writes nothing.
For you
Stamp a file, verify a receipt, reconcile two records.
No terminal skill needed. The first five minutes guide and a dashboard that runs on your own computer (arcaeon open) come in the next release.
For a dispute
ComingA guided page from what happened to a verdict on the two records.
In the next release it ends in an evidence pack: the records, the check, and what the pack does not show, in one file someone else can verify.
Prepare