diff --git a/go/cli/cli.go b/go/cli/cli.go
index a8222a1..30180fc 100644
--- a/go/cli/cli.go
+++ b/go/cli/cli.go
@@ -54,11 +54,24 @@ type Answer struct {
 	Refused string `json:"refused,omitempty"`
 	// Cut says the output was longer than one bus message and was cut there.
 	Cut bool `json:"cut,omitempty"`
+	// Unknown says the line was asked and its outcome is not known: no answer came in time, and it may have
+	// run. Never said as a refusal, which means nothing ran.
+	Unknown string `json:"unknown,omitempty"`
 }
 
 // Refusal is an answer saying that nothing ran, and why.
 func Refusal(why string) Answer { return Answer{Exit: 1, Refused: why} }
 
+// NotKnown is an answer saying the line was asked and what came of it is not known: it may have run. call is
+// the controller's call the line runs as, when it is known, which `calls` answers.
+func NotKnown(call, why string) Answer {
+	where := "the controller's `calls` lists what came of each line"
+	if call != "" {
+		where = "see the call " + call + " (`calls " + call + "`)"
+	}
+	return Answer{Exit: 1, Unknown: why + "; the line may have run — " + where}
+}
+
 // ErrTooLong is a request or an answer over its bound.
 var ErrTooLong = errors.New("longer than the protocol allows")
 
diff --git a/go/cli/cli_test.go b/go/cli/cli_test.go
index c418639..893dba4 100644
--- a/go/cli/cli_test.go
+++ b/go/cli/cli_test.go
@@ -26,7 +26,8 @@ func TestARequestAndAnAnswerSurviveTheirRoundTrip(t *testing.T) {
 	}
 
 	b.Reset()
-	sent := Answer{Stdout: []byte("ok\n\xff"), Stderr: []byte("said"), Exit: 3, Terminal: true, Why: "the terminal", Cut: true}
+	sent := Answer{Stdout: []byte("ok\n\xff"), Stderr: []byte("said"), Exit: 3, Terminal: true, Why: "the terminal", Cut: true,
+		Unknown: "no answer; the line may have run — see the call call-1"}
 	if err := WriteAnswer(&b, sent); err != nil {
 		t.Fatal(err)
 	}
@@ -34,7 +35,8 @@ func TestARequestAndAnAnswerSurviveTheirRoundTrip(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if !bytes.Equal(a.Stdout, sent.Stdout) || string(a.Stderr) != "said" || a.Exit != 3 || !a.Terminal || a.Why != sent.Why || !a.Cut {
+	if !bytes.Equal(a.Stdout, sent.Stdout) || string(a.Stderr) != "said" || a.Exit != 3 || !a.Terminal || a.Why != sent.Why || !a.Cut ||
+		a.Unknown != sent.Unknown {
 		t.Fatalf("the answer came back as %+v", a)
 	}
 }
@@ -90,3 +92,14 @@ func TestAskSpeaksTheProtocolOverASocket(t *testing.T) {
 		t.Fatalf("a missing socket was not said: %v", err)
 	}
 }
+
+// An outcome not known is never a refusal: it says the line may have run, and exits non-zero.
+func TestAnUnknownOutcomeIsNotARefusal(t *testing.T) {
+	a := NotKnown("call-7", "no answer within 6m0s")
+	if a.Refused != "" || a.Exit == 0 || !strings.Contains(a.Unknown, "may have run") || !strings.Contains(a.Unknown, "call-7") {
+		t.Fatalf("an unknown outcome reads as %+v", a)
+	}
+	if b := NotKnown("", "no answer"); strings.Contains(b.Unknown, "call ") {
+		t.Fatalf("an unknown outcome with no call names one: %+v", b)
+	}
+}
diff --git a/go/merge-check.sh b/go/merge-check.sh
new file mode 100644
index 0000000..19a7ec0
--- /dev/null
+++ b/go/merge-check.sh
@@ -0,0 +1,20 @@
+#!/bin/sh
+# mesh-check-toolchain: go
+#
+# The Go part of the SDK's own check (novox/hq ADR 0237 as amended, ADR 0272): the Go binding, run by the build
+# seat in the mesh's Go toolchain, its own container, because the SDK's merge-check.sh declares it
+# (`# mesh-check-also: go go/merge-check.sh`) — and by hand, from anywhere: `sh go/merge-check.sh`.
+#
+# Formatted, vetted, and its whole suite run: the stdio loop and the local protocol mesh-cli speaks to the
+# node-engine. Standard library only, so nothing is fetched.
+set -eu
+cd "$(dirname "$0")"
+
+unformatted=$(gofmt -l .)
+if [ -n "$unformatted" ]; then
+	echo "not gofmt'd:"
+	echo "$unformatted"
+	exit 1
+fi
+go vet ./...
+go test -count=1 ./...
diff --git a/merge-check.sh b/merge-check.sh
index 32c532f..b1c0cd0 100644
--- a/merge-check.sh
+++ b/merge-check.sh
@@ -1,5 +1,6 @@
 #!/bin/sh
 # mesh-check-toolchain: typescript
+# mesh-check-also: go go/merge-check.sh
 #
 # The SDK's own check (novox/hq ADR 0237 as amended): the second layer of a pull request's merge check,
 # `mesh/repo-check`, run by the build seat in the mesh's TypeScript toolchain — and by hand.
@@ -9,8 +10,9 @@
 # spine every module imports, type-checked and its suite run, its dependencies installed from the lock
 # file alone (public packages: the SDK depends on nothing of the mesh's).
 #
-# **Said, never passed silently**: the Go, Python, Rust and C bindings are not tested in this toolchain.
-# The Go binding's tests run when a Go compiler is present (a person's run), and are said as not run when not.
+# **Said, never passed silently**: the Python, Rust and C bindings are not tested in any toolchain. The Go
+# binding runs in the Go toolchain, from go/merge-check.sh, declared on the second line (novox/hq ADR 0272); here
+# it runs only when a Go compiler is present (a person's run).
 set -eu
 
 npm ci --no-audit --no-fund --loglevel=error
@@ -20,6 +22,6 @@ npm test
 if command -v go >/dev/null 2>&1; then
 	(cd go && test -z "$(gofmt -l .)" && go vet ./... && go test -count=1 ./...)
 else
-	echo "NOT TESTED HERE: go/ (the Go binding) — the TypeScript toolchain holds no Go compiler"
+	echo "NOT TESTED HERE: go/ (the Go binding) — the Go toolchain runs it from go/merge-check.sh"
 fi
 echo "NOT TESTED HERE: python/, rust/, c/ — no toolchain of theirs runs a merge check"