diff --git a/src/components/spatial/DeviceCard.tsx b/src/components/spatial/DeviceCard.tsx
index 87b78df..32a7a1d 100644
--- a/src/components/spatial/DeviceCard.tsx
+++ b/src/components/spatial/DeviceCard.tsx
@@ -1,6 +1,7 @@
 "use client";
 
 import { useMemo } from "react";
+import { sanitize, validateLabel } from "@/utils/sanitize";
 
 interface DeviceCardProps {
   label: string;
@@ -9,20 +10,6 @@ interface DeviceCardProps {
   metrics?: Record<string, string | number>;
 }
 
-function sanitize(input: string): string {
-  return input
-    .replace(/[<>]/g, "")
-    .replace(/javascript:/gi, "")
-    .replace(/on\w+=/gi, "")
-    .trim();
-}
-
-function validateLabel(raw: string): string {
-  const cleaned = sanitize(raw);
-  if (cleaned.length > 64) return cleaned.slice(0, 64);
-  return cleaned;
-}
-
 export function DeviceCard({ label, location, status, metrics }: DeviceCardProps) {
   const safeLabel = useMemo(() => validateLabel(label), [label]);
   const safeLocation = useMemo(() => sanitize(location), [location]);
@@ -53,7 +40,7 @@ export function DeviceCard({ label, location, status, metrics }: DeviceCardProps
           {Object.entries(metrics).map(([key, value]) => (
             <div key={key} className="flex justify-between">
               <span className="text-muted-foreground">{sanitize(key)}</span>
-              <span className="font-mono tabular-nums">{String(value)}</span>
+              <span className="font-mono tabular-nums">{sanitize(String(value))}</span>
             </div>
           ))}
         </div>
diff --git a/src/utils/sanitize.ts b/src/utils/sanitize.ts
new file mode 100644
index 0000000..c68bace
--- /dev/null
+++ b/src/utils/sanitize.ts
@@ -0,0 +1,12 @@
+export function sanitize(input: string): string {
+  return input
+    .replace(/[<>]/g, "")
+    .replace(/javascript:/gi, "")
+    .replace(/on\w+=/gi, "")
+    .trim();
+}
+
+export function validateLabel(raw: string): string {
+  const cleaned = sanitize(raw);
+  return cleaned.length > 64 ? cleaned.slice(0, 64) : cleaned;
+}
diff --git a/tests/unit/sanitize.test.ts b/tests/unit/sanitize.test.ts
new file mode 100644
index 0000000..82d6702
--- /dev/null
+++ b/tests/unit/sanitize.test.ts
@@ -0,0 +1,66 @@
+import { describe, it, expect } from "vitest";
+import { sanitize, validateLabel } from "@/utils/sanitize";
+
+describe("sanitize()", () => {
+  it("strips < and > characters", () => {
+    expect(sanitize("<script>alert(1)</script>")).toBe("scriptalert(1)/script");
+  });
+
+  it("removes javascript: URI scheme (case-insensitive)", () => {
+    expect(sanitize("javascript:alert(1)")).toBe("alert(1)");
+    expect(sanitize("JAVASCRIPT:alert(1)")).toBe("alert(1)");
+    expect(sanitize("JavaScript:void(0)")).toBe("void(0)");
+  });
+
+  it("strips onerror= and other on* event handlers", () => {
+    expect(sanitize("img src=x onerror=alert(1)")).toBe("img src=x alert(1)");
+    expect(sanitize("onclick=doSomething()")).toBe("doSomething()");
+    expect(sanitize("onmouseover=steal()")).toBe("steal()");
+  });
+
+  it("leaves safe strings unchanged", () => {
+    expect(sanitize("Sensor A")).toBe("Sensor A");
+    expect(sanitize("Floor 3 - Room 12")).toBe("Floor 3 - Room 12");
+    expect(sanitize("  trim me  ")).toBe("trim me");
+  });
+
+  it("handles empty string", () => {
+    expect(sanitize("")).toBe("");
+  });
+
+  it("handles combined payloads", () => {
+    const payload = '<img src=x onerror=alert(1) />';
+    const result = sanitize(payload);
+    expect(result).not.toContain("<");
+    expect(result).not.toContain(">");
+    expect(result).not.toContain("onerror=");
+  });
+
+  it("removes javascript: even when embedded in larger string", () => {
+    const payload = "click here: javascript:void(0)";
+    expect(sanitize(payload)).not.toContain("javascript:");
+  });
+});
+
+describe("validateLabel()", () => {
+  it("truncates to 64 characters", () => {
+    const long = "a".repeat(100);
+    expect(validateLabel(long).length).toBe(64);
+  });
+
+  it("leaves short labels unchanged", () => {
+    expect(validateLabel("My Device")).toBe("My Device");
+  });
+
+  it("sanitizes before truncating", () => {
+    const payload = "<script>" + "x".repeat(100);
+    const result = validateLabel(payload);
+    expect(result).not.toContain("<");
+    expect(result).not.toContain(">");
+    expect(result.length).toBeLessThanOrEqual(64);
+  });
+
+  it("returns empty string for pure XSS label", () => {
+    expect(validateLabel("<><><>")).toBe("");
+  });
+});