If you deliver work to clients, you already know the weakest moment in the job.
It is not the work. It is the handoff.
Your AI ran for an hour. It sends you a summary: done, all steps complete, here is the result. You forward that to your client. And your client has exactly one option: believe it.
A screenshot can be cropped. A summary can be polished. A transcript can be edited after the fact, and the edited version reads exactly as clean as the original. Professionals feel this every week now, in invoices disputed, in deliverables questioned, in the quiet sentence no one wants to say out loud: "Can you show me it actually did that?"
Today Zambo shipped the answer to that sentence. It is called Handover. Then I spent the morning trying to break it like a client who trusts nothing.
What a handover is
When your AI works through Zambo, every step it runs leaves a verifiable receipt at the moment it happens: what ran, what came back, sealed with a hash.
Handover takes those receipts from a finished job and turns them into one link.
You say, in any AI: "Use zambo to hand this over to Acme."
Your client opens the link. No account. No install. They see every step of the job, which AI ran each part, and what was not checked. They press one button, Verify all, and their own browser re-checks every receipt on the page. Then they accept it, or flag it, in one tap. Their answer gets a receipt of its own.
It is proof of delivery for AI work.
The attack
I did a small job through Zambo: live prices, a safety scan, four steps in one session. I created the handover and opened it the way a skeptical client would.
First, Verify all. Ten checks ran in the browser: the root matches the summary receipt, every step copy verifies, the unchecked list and file list match the summary, every copy links back to the same summary. Ten out of ten passed, in under a second.
Then I tried to cheat.
The page has a box that invites you to break it: pick a step, change one character in its data, watch what happens. I changed one character at the end of step one.
The summary flipped instantly. "1 failed." The step read "Doesn't match the receipt," with the recomputed hash shown next to the real one. One character was enough. I reset it, and everything passed again.
I tried the cheap tricks too. A made-up handover link: 404. A fake client response: rejected with a plain error. Creating the same handover twice: the server hands back the same link instead of a duplicate.
Then I accepted the handover as the client. The acceptance itself became a receipt, pinned to the job's original root, sitting in the record for anyone to see.
The part I respect most
The second handover I made contains two steps that failed mid-job. Zambo did not hide them, tidy them, or drop them from the delivery.
They are listed, by name, in a section called "What was not checked."
That is the whole philosophy in one detail. A handover is not a highlight reel. It is the record, including the parts that did not run, labeled as not checked. And the page says plainly what it does not prove: it does not prove the work is correct or good. It does not prove who the producer is. It proves the record your client is looking at is the record the run actually produced, byte for byte, and that nobody has touched it since.
Try to break one yourself
I left a handover open for you:
https://zambo.dev/handover/bd7e5325-33fd-4c5e-b029-76b781fa2f51
Open it. Press Verify all. Change a character. Watch it fail. That will teach you more in thirty seconds than this article can in ten minutes.
When you are ready to send your own: add Zambo to your AI once (https://zambo.dev/mcp), do the work, and say "Use zambo to hand this over to" your client. Public handovers are free. Private links, your branding, and PDF and JSON export come with the Zambo Pass at $29/month, and a Day Pass ($0.99 for 24 hours) lifts free limits mid-job. Docs: https://zambo.dev/docs/handover
Handover is built on AER-1, the open format for AI execution receipts, published as an IETF Internet-Draft (draft-zambo-aer1-20): https://datatracker.ietf.org/doc/draft-zambo-aer1/20/
Every accepted handover builds your track record: a history of delivered, verified, accepted work that a new client can check before they ever meet you.
Your AI said "done." For $0.99, prove it: https://zambo.dev/day-pass/
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