# echo-interface

The smallest honest reproduction of the `ArchitectureBlueprint.md` §33 worked
example, used as the conformance fixture.

Two revisions of one interface over the same backend data:

| Revision | Shape | Requests per completed task |
|---|---|---|
| **R-1** | `GET /v1/entries` only — consumers list everything and filter locally | ~3 |
| **R-2** | adds `GET /v1/entries/latest` — the concept consumers actually wanted | 1 |

R-1 is not a strawman. It is the interface a careful designer produces before
they have seen how it is used: a clean collection resource with no special
cases. The pressure it generates is the point — consumers repeatedly fetching
a collection to discard all but one item is the evidence that "latest" is a
first-class concept the contract failed to name.

The fixture has no external dependencies and runs in CI. It exists so the
revision–experiment–fitness loop is proven mechanically before a real workload
depends on it.