add disclaimer

index.html

@@ -473,6 +473,9 @@ sequenceDiagram
           <div class="controls" style="margin-top: auto;">
             <button id="btnDecrypt" class="btn" disabled>🔓 Decrypt</button>
           </div>
+          <div class="disclaimer" style="margin-top: calc(var(--spacing-unit) * 3); font-size: 0.9rem; color: var(--black); opacity: 0.7; line-height: 1.5;">
+            <p><strong>Note about reliability:</strong> Watermark detection is most reliable with longer texts (100+ tokens). In this demo, we limit input to 16 tokens for performance, which may affect accuracy. Detection improves significantly with 10+ tokens but is less reliable with very short texts.</p>
+          </div>
         </div>
       </section>
     </div>

wasm-demo.js

@@ -193,8 +193,8 @@ $('tokenInput').addEventListener('input', () => {
             if (tokenCount > TOKEN_LIMIT) {
                 $('encStatus').textContent = `⚠️ ${tokenCount}/${TOKEN_LIMIT} tokens - text too long`;
                 $('encStatus').style.color = '#d32f2f';
-            } else if (tokenCount > TOKEN_LIMIT * 0.8) {
-                $('encStatus').textContent = `${tokenCount}/${TOKEN_LIMIT} tokens`;
+            } else if (tokenCount < 10) {
+                $('encStatus').textContent = `⚠️ ${tokenCount}/${TOKEN_LIMIT} tokens - low reliability`;
                 $('encStatus').style.color = '#f57c00';
             } else {
                 $('encStatus').textContent = `${tokenCount}/${TOKEN_LIMIT} tokens`;