Merge the ecosystem defect ids into the study (#233)

The four live divergences in the vendored Hexis client are now V-587, V-588,
V-590 and V-591, and the plan doc points at them.

(V-585)

docs/plans/20-two-artifacts-and-neither-is-spring.md

@@ -282,7 +282,10 @@ typed `ecosystemError`, and the same correlation key. Hexis is a separate client
 repository, vendored at `vendor/github.com/kami/hexis/pkg/client`, and it agrees on some of
 that and not the rest.
 
-Eleven divergences. Four of them are defects rather than style.
+Eleven divergences. Four of them are defects rather than style, and each is filed on its own:
+V-587 the 401, V-588 the unnamed Praxis service, V-590 the uncorrelated discovery hop, V-591
+the unsent causation id. They are ranked in that order, worst first, and none of them waits on
+this proposal. V-587 is the only one that makes the owner check the wrong thing.
 
 **A Hexis 401 is spoken as an outage.** Nexus and Praxis return `*ecosystemError` with
 `Unauthorized()`, `ContractMismatch()` and `Unreachable()` classifiers