diff --git a/gateway/scripts/xmpp_bot.py b/gateway/scripts/xmpp_bot.py
index 132df95..d23e5b2 100644
--- a/gateway/scripts/xmpp_bot.py
+++ b/gateway/scripts/xmpp_bot.py
@@ -97,37 +97,54 @@ def _is_mam_recovery() -> bool:
         return _MAM_RECOVERY
 
 # ── Silence cooldown: when user says shut up, actually shut up ──
-_SILENCE_UNTIL: float = 0.0
-_SILENCE_LOCK = threading.Lock()
-_SHUTUP_PATTERNS = [
-    "闭嘴", "住口",
-    "shut up", "shutup",
-]
+# ── Coordinator protocol (aligned with mohe/zhiwei/xiaoguo) ──
+# All in-band XMPP signaling, no DB dependency.
+_COORDINATOR: str = "mohe"          # which agent moderates
+_GRANTED: str | None = None         # agent granted one-time speak permission
+_REVOKED_UNTIL: float = 0.0         # timestamp until revoked agent can speak again
+_SHUTUP_PATTERNS = ["闭嘴", "别说话", "安静", "shut", "stfu", "别说了", "停"]
 
 
-def _is_silenced() -> bool:
-    """Check if bot is in silence mode.
-    If so, the caller should NOT process or respond to any message.
-    """
-    with _SILENCE_LOCK:
-        if time.time() < _SILENCE_UNTIL:
-            return True
-        return False
+def _process_coordinator_signals(nickname: str, body: str) -> bool:
+    """Parse coordinator/GRANT/REVOKE signals from group messages.
+    Returns True if the message was consumed as a control signal (no further processing)."""
+    global _COORDINATOR, _GRANTED, _REVOKED_UNTIL
+
+    # 1. hmo switches coordinator
+    if nickname == 'hmo' and 'coordinator=' in body.lower():
+        for name in ('mohe', 'zhiwei', 'xxm'):
+            if f'coordinator={name}' in body.lower():
+                _COORDINATOR = name
+                _GRANTED = None
+                log(f"Coordinator switched to {name} by hmo")
+                return True
+
+    # 2. GRANT signal (overrides REVOKE, one-time use)
+    gm = re.search(r'\[GRANT:(\w+)\]', body)
+    if gm:
+        _GRANTED = gm.group(1)
+        _REVOKED_UNTIL = 0  # lift revocation when granted
+        log(f"GRANT: {_GRANTED}")
+        return True  # signal consumed, don't need to process further
+
+    # 3. REVOKE signal (5min auto-restore)
+    rm = re.search(r'\[REVOKE:(\w+)\]', body)
+    if rm and rm.group(1) == 'xxm':
+        _REVOKED_UNTIL = time.time() + 300
+        log(f"REVOKEd: xxm silenced for 5min")
+        return True
+
+    # Not a control signal
+    return False
 
 
 def _check_shutup(body: str) -> bool:
-    """Check if the user is telling the bot to shut up.
-    Returns True and sets silence cooldown if so.
-    """
+    """Check if hmo is telling the bot to shut up. 5-min silence (matching coordinator pattern)."""
     lower = body.lower().strip()
-    # Require minimum match: at least one shut-up keyword appears
-    # and the message is primarily about silencing (not a longer discussion)
     for pat in _SHUTUP_PATTERNS:
         if pat.lower() in lower:
-            # Set 30s silence - long enough to break the loop
-            with _SILENCE_LOCK:
-                _SILENCE_UNTIL = time.time() + 30
-            log(f"(shutup detected: '{pat}' → 30s silence)")
+            _REVOKED_UNTIL = time.time() + 300
+            log(f"(shutup: '{pat}' → 5min silence)")
             return True
     return False
 
@@ -157,7 +174,7 @@ def on_message(msg):
         return
 
     # Shut-up check — hard silence before any processing
-    if _is_silenced():
+    if time.time() < _REVOKED_UNTIL:
         log(f"(silenced) <{sender}> {body[:60]}... dropped")
         return
     if _check_shutup(body):
@@ -552,14 +569,26 @@ def on_group_message(msg):
     # Record to message buffer for HTTP bridge monitoring
     _record_group_msg(nickname, body)
 
-    # Shut-up check — applies to group messages from others
-    if _is_silenced():
-        log(f"(group silenced) {body[:60]}... dropped")
+    # ── Coordinator signals (GRANT/REVOKE/coordinator switch) ──
+    if _process_coordinator_signals(nickname, body):
         return
+
+    # ── Revoke check: read-only mode (see but don't reply) ──
+    is_revoked = time.time() < _REVOKED_UNTIL
+    # GRANT overrides REVOKE
+    if is_revoked and _GRANTED == 'xxm':
+        _GRANTED = None
+        is_revoked = False
+        log("GRANTed: xxm can speak despite REVOKE")
+
+    # ── Shut-up check ──
     if _check_shutup(body):
-        log(f"(group shutup detected)")
         return
 
+    # ── Read-only mode for revoked agents ──
+    if is_revoked:
+        body = f"【只读消息】你目前被收回发言权。只需了解内容。输出 __SILENT__。\n\n[核心群 {room}] {nickname} 说: {body}"
+
     # Batch nearby messages (unless @mention → process immediately)
     if _batch_group_message(room, nickname, body):
         log(f"[Group][{room}] {nickname}: {body[:80]} (batched)")