fix(recovery): cut ArgsSummary on a rune boundary

internal/runtime/recovery/args_summary_test.go

@@ -0,0 +1,29 @@
+package recovery
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+	"unicode/utf8"
+)
+
+func TestArgsSummaryCutsOnRuneBoundary(t *testing.T) {
+	// 20 bytes into this command falls inside a three-byte character.
+	cmd := "echo 'a" + strings.Repeat("测试", 10) + "'"
+	args, _ := json.Marshal(map[string]string{"command": cmd})
+	got := ArgsSummary(args, 20)
+	if !utf8.ValidString(got) {
+		t.Fatalf("ArgsSummary split a character: %q", got)
+	}
+	kept := strings.TrimSuffix(got, "…")
+	if kept == got || !strings.HasPrefix(cmd, kept) || len(kept) > 20 || len(kept) < 18 {
+		t.Fatalf("ArgsSummary = %q, want a prefix of the command just under 20 bytes ending in …", got)
+	}
+}
+
+func TestArgsSummaryKeepsShortCommand(t *testing.T) {
+	args, _ := json.Marshal(map[string]string{"command": "  go   test ./...  "})
+	if got := ArgsSummary(args, 20); got != "go test ./..." {
+		t.Fatalf("ArgsSummary = %q", got)
+	}
+}

internal/runtime/recovery/fingerprint.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"strings"
+	"unicode/utf8"
 )
 
 // CallFingerprint builds a one-shot authorization fingerprint from the
@@ -60,7 +61,11 @@ func ArgsSummary(args json.RawMessage, max int) string {
 	}
 	s = strings.Join(strings.Fields(s), " ")
 	if len(s) > max {
-		return s[:max] + "…"
+		cut := max
+		for cut > 0 && !utf8.RuneStart(s[cut]) {
+			cut--
+		}
+		return s[:cut] + "…"
 	}
 	return s
 }