diff --git a/gateway/platforms/signal.py b/gateway/platforms/signal.py
index 2ce072ae3..4bedf4b07 100644
--- a/gateway/platforms/signal.py
+++ b/gateway/platforms/signal.py
@@ -179,6 +179,11 @@ class SignalAdapter(BasePlatformAdapter):
         # Normalize account for self-message filtering
         self._account_normalized = self.account.strip()
 
+        # Track recently sent message timestamps to prevent echo-back loops
+        # in Note to Self / self-chat mode (mirrors WhatsApp recentlySentIds)
+        self._recent_sent_timestamps: set = set()
+        self._max_recent_timestamps = 50
+
         logger.info("Signal adapter initialized: url=%s account=%s groups=%s",
                      self.http_url, _redact_phone(self.account),
                      "enabled" if self.group_allow_from else "disabled")
@@ -353,10 +358,26 @@ class SignalAdapter(BasePlatformAdapter):
         # Unwrap nested envelope if present
         envelope_data = envelope.get("envelope", envelope)
 
-        # Filter syncMessage envelopes (sent transcripts, read receipts, etc.)
-        # signal-cli may set syncMessage to null vs omitting it, so check key existence
+        # Handle syncMessage: extract "Note to Self" messages (sent to own account)
+        # while still filtering other sync events (read receipts, typing, etc.)
+        is_note_to_self = False
         if "syncMessage" in envelope_data:
-            return
+            sync_msg = envelope_data.get("syncMessage")
+            if sync_msg and isinstance(sync_msg, dict):
+                sent_msg = sync_msg.get("sentMessage")
+                if sent_msg and isinstance(sent_msg, dict):
+                    dest = sent_msg.get("destinationNumber") or sent_msg.get("destination")
+                    sent_ts = sent_msg.get("timestamp")
+                    if dest == self._account_normalized:
+                        # Check if this is an echo of our own outbound reply
+                        if sent_ts and sent_ts in self._recent_sent_timestamps:
+                            self._recent_sent_timestamps.discard(sent_ts)
+                            return
+                        # Genuine user Note to Self — promote to dataMessage
+                        is_note_to_self = True
+                        envelope_data = {**envelope_data, "dataMessage": sent_msg}
+            if not is_note_to_self:
+                return
 
         # Extract sender info
         sender = (
@@ -371,8 +392,8 @@ class SignalAdapter(BasePlatformAdapter):
             logger.debug("Signal: ignoring envelope with no sender")
             return
 
-        # Self-message filtering — prevent reply loops
-        if self._account_normalized and sender == self._account_normalized:
+        # Self-message filtering — prevent reply loops (but allow Note to Self)
+        if self._account_normalized and sender == self._account_normalized and not is_note_to_self:
             return
 
         # Filter stories
@@ -577,9 +598,18 @@ class SignalAdapter(BasePlatformAdapter):
         result = await self._rpc("send", params)
 
         if result is not None:
+            self._track_sent_timestamp(result)
             return SendResult(success=True)
         return SendResult(success=False, error="RPC send failed")
 
+    def _track_sent_timestamp(self, rpc_result) -> None:
+        """Record outbound message timestamp for echo-back filtering."""
+        ts = rpc_result.get("timestamp") if isinstance(rpc_result, dict) else None
+        if ts:
+            self._recent_sent_timestamps.add(ts)
+            if len(self._recent_sent_timestamps) > self._max_recent_timestamps:
+                self._recent_sent_timestamps.pop()
+
     async def send_typing(self, chat_id: str, metadata=None) -> None:
         """Send a typing indicator."""
         params: Dict[str, Any] = {
@@ -635,6 +665,7 @@ class SignalAdapter(BasePlatformAdapter):
 
         result = await self._rpc("send", params)
         if result is not None:
+            self._track_sent_timestamp(result)
             return SendResult(success=True)
         return SendResult(success=False, error="RPC send with attachment failed")
 
@@ -665,6 +696,7 @@ class SignalAdapter(BasePlatformAdapter):
 
         result = await self._rpc("send", params)
         if result is not None:
+            self._track_sent_timestamp(result)
             return SendResult(success=True)
         return SendResult(success=False, error="RPC send document failed")
 
diff --git a/website/docs/user-guide/messaging/signal.md b/website/docs/user-guide/messaging/signal.md
index e1fd5463b..51d8f9629 100644
--- a/website/docs/user-guide/messaging/signal.md
+++ b/website/docs/user-guide/messaging/signal.md
@@ -177,6 +177,19 @@ All phone numbers are automatically redacted in logs:
 - `+15551234567` → `+155****4567`
 - This applies to both Hermes gateway logs and the global redaction system
 
+### Note to Self (Single-Number Setup)
+
+If you run signal-cli as a **linked secondary device** on your own phone number (rather than a separate bot number), you can interact with Hermes through Signal's "Note to Self" feature.
+
+Just send a message to yourself from your phone — signal-cli picks it up and Hermes responds in the same conversation.
+
+**How it works:**
+- "Note to Self" messages arrive as `syncMessage.sentMessage` envelopes
+- The adapter detects when these are addressed to the bot's own account and processes them as regular inbound messages
+- Echo-back protection (sent-timestamp tracking) prevents infinite loops — the bot's own replies are filtered out automatically
+
+**No extra configuration needed.** This works automatically as long as `SIGNAL_ACCOUNT` matches your phone number.
+
 ### Health Monitoring
 
 The adapter monitors the SSE connection and automatically reconnects if: