8f46495426
A witness in a _test.go file fires on go test and go vet but NOT on go build alone — and a build-only step is exactly how the R-88 Part 2 near-miss would have shipped. Moved beside the type it pins, and added one for AgentVersionReporter. No defect found: quiesceBackend and *Client both satisfy their interfaces today. No version bump, no deploy — compile-time only.