fix output read: scan for NUL terminator instead of using rc as length

index.html

@@ -75,8 +75,11 @@ async function run() {
     const qP = enc(q);
     const cap = 1 << 20, outP = mod._malloc(cap);
     const rc = mod._needle_complete(qP, 512, outP, cap);
-    const bytes = mod.HEAPU8.subarray(outP, outP + Math.min(rc, cap));
-    let end = bytes.indexOf(0); if (end < 0) end = bytes.length;
+    if (rc < 0) throw new Error("needle_complete returned " + rc);
+    // rc is NOT the output length: the engine writes a NUL-terminated string,
+    // so scan the whole buffer for the first NUL terminator.
+    const bytes = mod.HEAPU8.subarray(outP, outP + cap);
+    let end = bytes.indexOf(0); if (end < 0) end = cap;
     const response = new TextDecoder().decode(bytes.subarray(0, end));
 
     out.textContent = response;