The chain

Every action heso gates produces a receipt: a signed record of what your agent did. Those receipts are not loose files sitting in a folder. heso keeps them in order, and each receipt carries a short reference back to the one before it. That ordering is what we call the chain.

What the chain is

Think of receipts as a numbered list where each entry holds the fingerprint of the entry right before it. The first receipt in a session is the start. The next one names the first, the one after names the second, and so on.

receipt #1   (start)
receipt #2   prev -> #1
receipt #3   prev -> #2
receipt #4   prev -> #3

Because every receipt names its parent, the receipts form a single line you can walk from the first action to the last. There is no version of the history that skips a step.

Why it matters

The chain gives you two guarantees that loose files cannot:

• Nothing can be quietly changed. Each receipt is signed, and the next receipt points at it by fingerprint. Edit an old receipt and its fingerprint changes, so the receipt that came after no longer points at anything real. The break is visible.
• Nothing can be quietly dropped. Pull a receipt out of the middle and the one after it points back at a receipt that is no longer there. The gap shows.

So you can lay out everything your agent did, in order, and be confident the list is whole. Anyone can read it top to bottom and see that no entry was swapped out or removed.

Where the chain lives

Your SDK builds the chain as actions happen, and heso stores a small signed copy of each link in its cloud. heso keeps a stripped record, the fingerprints and the ordering, not your action bodies. That copy is what makes the chain checkable later by someone who was not there when the actions ran.

A chain on its own proves the receipts you hold are in order and unedited. To also prove that no receipt was hidden from you, that the list you got is the same list everyone else got, see Transparency.

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