diff --git a/src/main.cpp b/src/main.cpp
index 60facfa..79f9518 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1349,6 +1349,7 @@ async function poll(){
     document.getElementById('connDot').style.background='#f28a86';
     document.getElementById('bt').textContent='OFFLINE';
   }
+  setTimeout(poll, 1000);
 }
 
 document.getElementById('jp').addEventListener('input',e=>document.getElementById('pv').textContent=PT[+e.target.value]);
@@ -1358,7 +1359,7 @@ document.getElementById('aamp').addEventListener('click',async()=>{try{await fet
 document.getElementById('asw').addEventListener('click',async()=>{try{await fetch('/api/sweep',{method:'POST',headers:{'Content-Type':'application/json'},body:JSON.stringify({dwell_ms:+document.getElementById('sd').value,steps1:+document.getElementById('ss1').value,steps2:+document.getElementById('ss2').value,span1_mhz:+document.getElementById('sp1').value,span2_mhz:+document.getElementById('sp2').value})});}catch(e){}});
 document.getElementById('dl').addEventListener('click',()=>{const a=document.createElement('a');a.href='/api/log';a.download='jammer-log.txt';a.click();});
 
-poll();setInterval(poll,1000);
+poll();
 
 // ── Capture / Replay ─────────────────────────────────────────────────────────
 let capPolling=false;
@@ -1453,48 +1454,76 @@ static void handleTelemetry() {
   int8_t effDbm = jamPower + ampGainDb;
   float effWatts = powf(10.0f, effDbm / 10.0f) / 1000.0f; // dBm -> watts
 
-  String json = "{";
-  json += "\"uptime_ms\":"    + String(millis() - uptimeStart) + ",";
-  json += "\"free_heap\":"    + String(ESP.getFreeHeap()) + ",";
-  json += "\"temp_c\":"       + String(tempC, 1) + ",";
-  json += "\"jamming_enabled\":" + String(jammingEnabled ? "true" : "false") + ",";
-  json += "\"jam_power\":"    + String(jamPower) + ",";
-  json += "\"jam_power_idx\":" + String(jamPowerIdx) + ",";
-  json += "\"amp_gain_db\":"  + String(ampGainDb) + ",";
-  json += "\"eff_power_dbm\":" + String(effDbm) + ",";
-  json += "\"eff_power_w\":"  + String(effWatts, 3) + ",";
+  String err1 = jsonEscape(radio1Error);
+  String err2 = jsonEscape(radio2Error);
 
-  // Sweep state
-  json += "\"sweep_freq1\":"     + String(sweepFreq1, 4) + ",";
-  json += "\"sweep_center1\":"   + String(SWEEP_1_CENTER_MHZ, 2) + ",";
-  json += "\"sweep_span1\":"     + String(sweep1SpanMhz, 2) + ",";
-  json += "\"sweep_steps1\":"    + String(sweep1Steps) + ",";
-  json += "\"sweep_freq2\":"     + String(sweepFreq2, 4) + ",";
-  json += "\"sweep_center2\":"   + String(SWEEP_2_CENTER_MHZ, 2) + ",";
-  json += "\"sweep_span2\":"     + String(sweep2SpanMhz, 2) + ",";
-  json += "\"sweep_steps2\":"    + String(sweep2Steps) + ",";
-  json += "\"sweep_dwell_ms\":"  + String(sweepDwellMs) + ",";
+  static char jsonBuf[1024]; // Generously sized to avoid fragmentation
+  snprintf(jsonBuf, sizeof(jsonBuf),
+    "{"
+    "\"uptime_ms\":%lu,"
+    "\"free_heap\":%lu,"
+    "\"temp_c\":%.1f,"
+    "\"jamming_enabled\":%s,"
+    "\"jam_power\":%d,"
+    "\"jam_power_idx\":%d,"
+    "\"amp_gain_db\":%d,"
+    "\"eff_power_dbm\":%d,"
+    "\"eff_power_w\":%.3f,"
+    "\"sweep_freq1\":%.4f,"
+    "\"sweep_center1\":%.2f,"
+    "\"sweep_span1\":%.2f,"
+    "\"sweep_steps1\":%u,"
+    "\"sweep_freq2\":%.4f,"
+    "\"sweep_center2\":%.2f,"
+    "\"sweep_span2\":%.2f,"
+    "\"sweep_steps2\":%u,"
+    "\"sweep_dwell_ms\":%lu,"
+    "\"radio1_status\":%d,"
+    "\"radio1_error\":\"%s\","
+    "\"radio1_freq\":%.4f,"
+    "\"radio1_active\":%s,"
+    "\"radio2_status\":%d,"
+    "\"radio2_error\":\"%s\","
+    "\"radio2_freq\":%.4f,"
+    "\"radio2_active\":%s,"
+    "\"hop_count1\":%lu,"
+    "\"hop_count2\":%lu,"
+    "\"min_heap\":%lu,"
+    "\"ap_clients\":%d"
+    "}",
+    (unsigned long)(millis() - uptimeStart),
+    (unsigned long)ESP.getFreeHeap(),
+    (double)tempC,
+    jammingEnabled ? "true" : "false",
+    (int)jamPower,
+    (int)jamPowerIdx,
+    (int)ampGainDb,
+    (int)effDbm,
+    (double)effWatts,
+    (double)sweepFreq1,
+    (double)SWEEP_1_CENTER_MHZ,
+    (double)sweep1SpanMhz,
+    (unsigned)sweep1Steps,
+    (double)sweepFreq2,
+    (double)SWEEP_2_CENTER_MHZ,
+    (double)sweep2SpanMhz,
+    (unsigned)sweep2Steps,
+    (unsigned long)sweepDwellMs,
+    (int)radio1Status,
+    err1.c_str(),
+    (double)sweepFreq1,
+    radio1Status == 2 ? "true" : "false",
+    (int)radio2Status,
+    err2.c_str(),
+    (double)sweepFreq2,
+    radio2Status == 2 ? "true" : "false",
+    (unsigned long)hopCount1,
+    (unsigned long)hopCount2,
+    (unsigned long)(minFreeHeap == 0xFFFFFFFF ? ESP.getFreeHeap() : minFreeHeap),
+    (int)WiFi.softAPgetStationNum()
+  );
 
-  // Radio 1
-  json += "\"radio1_status\":"   + String(radio1Status) + ",";
-  json += "\"radio1_error\":\""  + jsonEscape(radio1Error) + "\",";
-  json += "\"radio1_freq\":"     + String(sweepFreq1, 4) + ",";
-  json += "\"radio1_active\":"   + String(radio1Status == 2 ? "true" : "false") + ",";
-
-  // Radio 2
-  json += "\"radio2_status\":"   + String(radio2Status) + ",";
-  json += "\"radio2_error\":\""  + jsonEscape(radio2Error) + "\",";
-  json += "\"radio2_freq\":"     + String(sweepFreq2, 4) + ",";
-  json += "\"radio2_active\":"   + String(radio2Status == 2 ? "true" : "false") + ",";
-
-  // 24-hour health metrics
-  json += "\"hop_count1\":"      + String(hopCount1) + ",";
-  json += "\"hop_count2\":"      + String(hopCount2) + ",";
-  json += "\"min_heap\":"        + String(minFreeHeap == 0xFFFFFFFF ? ESP.getFreeHeap() : minFreeHeap) + ",";
-  json += "\"ap_clients\":"      + String(WiFi.softAPgetStationNum());
-
-  json += "}";
-  server.send(200, "application/json; charset=utf-8", json);
+  server.send(200, "application/json; charset=utf-8", jsonBuf);
 }
 
 static void handleToggle() {