unicode/utf8 (Go 1.23.1): 14/14 tests validated against `go test -json`
through the Phase-4 -tests pipeline — converted external dot-import test
package, hand-owned go.testing host, differential oracle, digest-gated
manifests. 37 benchmark/example declarations disclosed-excluded.
Five defects root-caused en route, including golib []byte(s) string-backing
sharing and range-over-string byte-index semantics.
Behaviorally similar — now proven by Go's own tests.