- Implemented across bootstrap.php, chat frontend, and dashboard:

Per-tier audio bitrate: Free 64, Plus 96, Pro 128 kbps.
Configurable text/voice reply threads and depth.
Registration/login-only honeypot and internal CAPTCHA.
Optional Google reCAPTCHA v2/v3 with server verification.
Archive/export support for replies and bitrate.
Dashboard controls for all settings.
Verified JavaScript, JSON, SQLite migrations, desktop/mobile UI, and 
browser console. Native PHP lint was unavailable because PHP is not 
installed.
Google implementation follows Siteverify and reCAPTCHA v3.

assets/css/cyberchat.css

@@ -283,7 +283,7 @@ input, button { font-family: inherit; }
 
 .cc-auth-panel {
   width: 100%;
-  max-width: 340px;
+  max-width: 380px;
   background: var(--bg1);
   border: 1px solid var(--bd);
   border-radius: var(--r2);
@@ -505,6 +505,50 @@ input, button { font-family: inherit; }
   opacity: 1;
 }
 
+.cc-captcha-trap {
+  position: absolute !important;
+  left: -10000px !important;
+  top: auto !important;
+  width: 1px !important;
+  height: 1px !important;
+  overflow: hidden !important;
+  opacity: 0 !important;
+  pointer-events: none !important;
+}
+
+.cc-captcha-block {
+  margin: 4px 0 13px;
+  padding: 10px;
+  border: 1px solid var(--bd);
+  background: var(--bg2);
+}
+
+.cc-captcha-row {
+  display: grid;
+  grid-template-columns: minmax(72px, auto) 1fr auto;
+  align-items: center;
+  gap: 7px;
+  color: var(--g);
+  font: 11px var(--mono);
+}
+
+.cc-captcha-row .cc-input {
+  min-width: 0;
+  padding: 6px 8px;
+}
+
+.cc-captcha-refresh {
+  height: 31px;
+  padding: 0 8px;
+  border: 1px solid var(--b);
+  background: transparent;
+  color: var(--b);
+  font: 8px var(--mono);
+}
+
+.cc-google-captcha { margin-top: 10px; min-height: 78px; }
+.cc-captcha-note { margin-top: 7px; color: var(--t1); font: 8px var(--mono); }
+
 /* ──────────────────────────────────────────────────────────────────────────
    CHAT SCREEN
    ────────────────────────────────────────────────────────────────────────── */
@@ -604,6 +648,8 @@ input, button { font-family: inherit; }
 }
 
 .cc-msg:hover { background: rgba(255,255,255,0.02); }
+.cc-msg-thread { padding-left: calc(12px + var(--cc-reply-indent, 0px)); }
+.cc-msg-focus { background: rgba(0,184,255,0.12); box-shadow: inset 2px 0 0 var(--b); }
 
 .cc-msg-time {
   font-size: 9px;
@@ -641,6 +687,37 @@ input, button { font-family: inherit; }
 
 .cc-msg-own .cc-msg-text { color: #ddeeff; }
 
+.cc-reply-ref {
+  display: flex;
+  max-width: min(100%, 470px);
+  margin: 0 0 3px;
+  padding: 3px 6px;
+  gap: 6px;
+  border: 0;
+  border-left: 2px solid var(--v);
+  background: rgba(191,95,255,0.07);
+  color: var(--t1);
+  font: 9px var(--mono);
+  text-align: left;
+}
+
+.cc-reply-ref b { color: var(--v); flex-shrink: 0; }
+.cc-reply-ref span { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+
+.cc-msg-reply {
+  align-self: center;
+  margin-left: 7px;
+  padding: 2px 5px;
+  border: 1px solid transparent;
+  background: transparent;
+  color: var(--t2);
+  font: 8px var(--mono);
+  opacity: 0;
+}
+
+.cc-msg:hover .cc-msg-reply,
+.cc-msg-reply:focus { opacity: 1; border-color: var(--bd); color: var(--b); }
+
 .cc-voice-message {
   display: inline-flex;
   align-items: center;
@@ -1040,6 +1117,28 @@ input, button { font-family: inherit; }
 .cc-voice-action.send { border-color: var(--g); color: var(--g); }
 .cc-voice-action:disabled { opacity: 0.35; cursor: not-allowed; }
 
+.cc-reply-context {
+  display: grid;
+  grid-template-columns: auto minmax(0, 1fr) auto;
+  gap: 8px;
+  align-items: center;
+  padding: 5px 10px;
+  border-top: 1px solid rgba(191,95,255,0.35);
+  background: rgba(191,95,255,0.07);
+  color: var(--t1);
+  font: 8px var(--mono);
+}
+
+.cc-reply-context[hidden] { display: none; }
+.cc-reply-context b { color: var(--v); }
+.cc-reply-context > span:nth-child(2) { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+.cc-reply-context button {
+  border: 1px solid var(--r);
+  background: transparent;
+  color: var(--r);
+  font: 8px var(--mono);
+}
+
 /* Compose bar */
 .cc-compose {
   display: flex;
@@ -1184,6 +1283,7 @@ html, body {
 .cc-archive-row { display: grid; grid-template-columns: 145px 55px 1fr; gap: 8px; align-items: center; padding: 8px 10px; border: 1px solid var(--bd); background: var(--bg1); font: 11px var(--mono); }
 .cc-archive-row time { color: var(--t1); font-size: 9px; }
 .cc-archive-row audio { display: none; }
+.cc-archive-reply { margin-bottom: 5px; padding-left: 6px; border-left: 2px solid var(--v); color: var(--t1); font-size: 9px; }
 .cc-type-tag { color: var(--o); font-size: 8px; text-transform: uppercase; }
 .cc-switch { display: flex; align-items: center; gap: 8px; margin-top: 14px; color: var(--t0); font: 10px var(--mono); }
 .cc-switch input { accent-color: var(--g); }
@@ -1203,4 +1303,10 @@ html, body {
   .cc-cyber-audio { min-width: 0; width: 100%; grid-template-columns: 26px 18px minmax(60px, 1fr) 64px 32px; }
   .cc-compact-select { max-width: 145px; }
   .cc-page { padding: 12px; }
+  .cc-msg-reply { opacity: 1; }
+}
+
+@media (max-width: 360px) {
+  .cc-google-captcha { width: 268px; overflow: hidden; }
+  .cc-google-captcha > div { transform: scale(.88); transform-origin: left top; }
 }