diff --git a/src/cli/banner.ts b/src/cli/banner.ts
index 670a1cddc..05541f1b5 100644
--- a/src/cli/banner.ts
+++ b/src/cli/banner.ts
@@ -10,6 +10,20 @@ type BannerOptions = TaglineOptions & {
 
 let bannerEmitted = false;
 
+const graphemeSegmenter =
+  typeof Intl !== "undefined" && "Segmenter" in Intl
+    ? new Intl.Segmenter(undefined, { granularity: "grapheme" })
+    : null;
+
+function splitGraphemes(value: string): string[] {
+  if (!graphemeSegmenter) return Array.from(value);
+  try {
+    return Array.from(graphemeSegmenter.segment(value), (seg) => seg.segment);
+  } catch {
+    return Array.from(value);
+  }
+}
+
 const hasJsonFlag = (argv: string[]) =>
   argv.some((arg) => arg === "--json" || arg.startsWith("--json="));
 
@@ -62,7 +76,7 @@ export function formatCliBannerArt(options: BannerOptions = {}): string {
         theme.accent("🦞")
       );
     }
-    return [...line].map(colorChar).join("");
+    return splitGraphemes(line).map(colorChar).join("");
   });
 
   return colored.join("\n");
diff --git a/src/cli/gateway-cli.ts b/src/cli/gateway-cli.ts
index ed853cb08..c040b8feb 100644
--- a/src/cli/gateway-cli.ts
+++ b/src/cli/gateway-cli.ts
@@ -98,7 +98,15 @@ type GatewayDiscoverOpts = {
 
 function parseDiscoverTimeoutMs(raw: unknown, fallbackMs: number): number {
   if (raw === undefined || raw === null) return fallbackMs;
-  const value = typeof raw === "string" ? raw.trim() : String(raw);
+  const value =
+    typeof raw === "string"
+      ? raw.trim()
+      : typeof raw === "number" || typeof raw === "bigint"
+        ? String(raw)
+        : null;
+  if (value === null) {
+    throw new Error("invalid --timeout");
+  }
   if (!value) return fallbackMs;
   const parsed = Number.parseInt(value, 10);
   if (!Number.isFinite(parsed) || parsed <= 0) {