mesh-cli: give a terminal line the standard input mesh-cli carried, refuse it to any other, keep it nowhere

A secret given at the controller's terminal through mesh-cli (secret accept … --from -) never reached the
line: every line ran with no standard input. A line that runs as the terminal now reads what mesh-cli
carried (at most 64 KiB); an ordinary call carrying any is refused and nothing runs; the calls record keeps
only that some was given, the journal and the answer nothing of it.

internal/link/meshcli_test.go

@@ -30,6 +30,10 @@ func TestTheMeshCLIRequestAndAnswerKeepTheirFieldNames(t *testing.T) {
 	if got := keysIn(t, body); got != "cut exit refused stderr stdout terminal why" {
 		t.Fatalf("the answer's fields are %q", got)
 	}
+	body, _ = json.Marshal(CLIAsked{Line: []string{"secret"}, Account: "a", UID: 1, Stdin: []byte("x")})
+	if got := keysIn(t, body); got != "account line stdin uid" {
+		t.Fatalf("a request with standard input has the fields %q", got)
+	}
 	body, _ = json.Marshal(CLIAsked{Follow: "call-1", Account: "a", UID: 1})
 	if got := keysIn(t, body); got != "account follow uid" {
 		t.Fatalf("a follow's fields are %q", got)
@@ -267,3 +271,26 @@ func TestTheWithholdingTestsHoldSomething(t *testing.T) {
 		t.Fatalf("a record carrying the answer is not found carrying it: %s", body)
 	}
 }
+
+// novox/hq ADR 0259 §10: mesh-cli's standard input — a secret given at the terminal — is never in the calls record,
+// in any form, whichever way the request reaches it.
+func TestAMeshCLIRecordNeverKeepsItsStandardInput(t *testing.T) {
+	secret := "123456789:AAEhBOweik6ad9r_QxGivenAtTheTerminal"
+	raw, _ := json.Marshal(CLIAsked{Line: []string{"secret", "accept", "anchor", "telegram", "telegram-token", "--from", "-"},
+		Account: "operator", UID: 1000, Stdin: []byte(secret)})
+	for name, got := range map[string]json.RawMessage{"as answerCLI records it": kept(cliRecorded(raw)),
+		"as the record alone would keep it": kept(raw)} {
+		if carries(got, secret) || strings.Contains(string(got), base64.StdEncoding.EncodeToString([]byte(secret))[:20]) {
+			t.Fatalf("%s, the record keeps %s", name, got)
+		}
+		if !strings.Contains(string(got), "secret") || !strings.Contains(string(got), "given, not kept") &&
+			!strings.Contains(string(got), "stdin-given") {
+			t.Fatalf("%s, the record does not say a line was asked with standard input: %s", name, got)
+		}
+	}
+	// The record still reads as the request, so the asker can follow its call.
+	var asked CLIAsked
+	if err := json.Unmarshal(kept(cliRecorded(raw)), &asked); err != nil || asked.Account != "operator" || len(asked.Stdin) > 0 {
+		t.Fatalf("the recorded request reads as %+v (%v)", asked, err)
+	}
+}