Glossary · Building the harness
Completion contract
A completion contract is an output schema treated as the definition of done — the run ends when a valid result is written — rather than as validation applied after the fact.
What we can add
Flipping when the schema is consulted is what makes it structural. Validation after the fact can only reject; a contract decides when work stops, which removes several unrelated failure modes at once — including the one where an agent ships whatever it happened to produce because nothing told it it was not finished.
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