diff --git a/cmd/ingestor/coverage_boost_test.go b/cmd/ingestor/coverage_boost_test.go
index fa7315c0..9b093cff 100644
--- a/cmd/ingestor/coverage_boost_test.go
+++ b/cmd/ingestor/coverage_boost_test.go
@@ -203,21 +203,13 @@ func TestHandleMessageChannelMessage(t *testing.T) {
 		t.Errorf("direction=%v, want rx", direction)
 	}
 
-	// Should create sender node
+	// Sender node should NOT be created (see issue #665: synthetic "sender-" keys
+	// are unreachable from the claiming/health flow)
 	if err := store.db.QueryRow("SELECT COUNT(*) FROM nodes").Scan(&count); err != nil {
 		t.Fatal(err)
 	}
-	if count != 1 {
-		t.Errorf("nodes count=%d, want 1 (sender node)", count)
-	}
-
-	// Verify sender node name
-	var nodeName string
-	if err := store.db.QueryRow("SELECT name FROM nodes LIMIT 1").Scan(&nodeName); err != nil {
-		t.Fatal(err)
-	}
-	if nodeName != "Alice" {
-		t.Errorf("node name=%s, want Alice", nodeName)
+	if count != 0 {
+		t.Errorf("nodes count=%d, want 0 (no phantom sender node)", count)
 	}
 }
 
diff --git a/cmd/ingestor/main.go b/cmd/ingestor/main.go
index 0beb3ec2..4de850fc 100644
--- a/cmd/ingestor/main.go
+++ b/cmd/ingestor/main.go
@@ -446,13 +446,11 @@ func handleMessage(store *Store, tag string, source MQTTSource, m mqtt.Message,
 			log.Printf("MQTT [%s] channel insert error: %v", tag, err)
 		}
 
-		// Upsert sender as a companion node
-		if sender != "" {
-			senderKey := "sender-" + strings.ToLower(sender)
-			if err := store.UpsertNode(senderKey, sender, "companion", nil, nil, now); err != nil {
-				log.Printf("MQTT [%s] sender node upsert error: %v", tag, err)
-			}
-		}
+		// Note: we intentionally do NOT create a node entry for channel message senders.
+		// Channel messages don't carry the sender's real pubkey, so any entry we create
+		// would use a synthetic key ("sender-<name>") that doesn't match the real pubkey
+		// used for claiming/health lookups. The node will get a proper entry when it
+		// sends an advert. See issue #665.
 
 		log.Printf("MQTT [%s] channel message: ch%s from %s", tag, channelIdx, firstNonEmpty(sender, "unknown"))
 		return
diff --git a/cmd/server/routes_test.go b/cmd/server/routes_test.go
index d18c4d7e..da9724dd 100644
--- a/cmd/server/routes_test.go
+++ b/cmd/server/routes_test.go
@@ -774,6 +774,67 @@ func TestNodeHealthNotFound(t *testing.T) {
 	}
 }
 
+// TestNodeHealthPartialFromPackets verifies that a node with packets in the
+// in-memory store but no DB entry returns a partial 200 response instead of 404.
+// This is the fix for issue #665 (companion nodes without adverts).
+func TestNodeHealthPartialFromPackets(t *testing.T) {
+	srv, router := setupTestServer(t)
+
+	// Inject a packet into byNode for a pubkey that doesn't exist in the nodes table
+	ghostPubkey := "ghost_companion_no_advert"
+	now := time.Now().UTC().Format(time.RFC3339)
+	snr := 5.0
+	srv.store.mu.Lock()
+	if srv.store.byNode == nil {
+		srv.store.byNode = make(map[string][]*StoreTx)
+	}
+	if srv.store.nodeHashes == nil {
+		srv.store.nodeHashes = make(map[string]map[string]bool)
+	}
+	srv.store.byNode[ghostPubkey] = []*StoreTx{
+		{Hash: "abc123", FirstSeen: now, SNR: &snr, ObservationCount: 1},
+	}
+	srv.store.nodeHashes[ghostPubkey] = map[string]bool{"abc123": true}
+	srv.store.mu.Unlock()
+
+	req := httptest.NewRequest("GET", "/api/nodes/"+ghostPubkey+"/health", nil)
+	w := httptest.NewRecorder()
+	router.ServeHTTP(w, req)
+
+	if w.Code != 200 {
+		t.Fatalf("expected 200 for ghost companion, got %d (body: %s)", w.Code, w.Body.String())
+	}
+
+	var body map[string]interface{}
+	if err := json.Unmarshal(w.Body.Bytes(), &body); err != nil {
+		t.Fatalf("json unmarshal: %v", err)
+	}
+
+	// Should have a synthetic node stub
+	node, ok := body["node"].(map[string]interface{})
+	if !ok || node == nil {
+		t.Fatal("expected node in response")
+	}
+	if node["role"] != "unknown" {
+		t.Errorf("expected role=unknown, got %v", node["role"])
+	}
+	if node["public_key"] != ghostPubkey {
+		t.Errorf("expected public_key=%s, got %v", ghostPubkey, node["public_key"])
+	}
+
+	// Should have stats from the packet
+	stats, ok := body["stats"].(map[string]interface{})
+	if !ok || stats == nil {
+		t.Fatal("expected stats in response")
+	}
+	if stats["totalPackets"] != 1.0 { // JSON numbers are float64
+		t.Errorf("expected totalPackets=1, got %v", stats["totalPackets"])
+	}
+	if stats["lastHeard"] == nil {
+		t.Error("expected lastHeard to be set")
+	}
+}
+
 func TestBulkHealthEndpoint(t *testing.T) {
 	_, router := setupTestServer(t)
 	req := httptest.NewRequest("GET", "/api/nodes/bulk-health?limit=10", nil)
diff --git a/cmd/server/store.go b/cmd/server/store.go
index 973625b3..5896dd85 100644
--- a/cmd/server/store.go
+++ b/cmd/server/store.go
@@ -5629,9 +5629,25 @@ func (s *PacketStore) GetBulkHealth(limit int, region string) []map[string]inter
 func (s *PacketStore) GetNodeHealth(pubkey string) (map[string]interface{}, error) {
 	// Fetch node info from DB (fast single-row lookup)
 	node, err := s.db.GetNodeByPubkey(pubkey)
-	if err != nil || node == nil {
+	if err != nil {
 		return nil, err
 	}
+	// If the node isn't in the DB (e.g. companion that never advertised),
+	// check if we have any packet data for it. If so, build a partial response.
+	if node == nil {
+		s.mu.RLock()
+		hasPackets := len(s.byNode[pubkey]) > 0
+		s.mu.RUnlock()
+		if !hasPackets {
+			return nil, nil
+		}
+		// Build a synthetic node stub so the rest of the function works
+		node = map[string]interface{}{
+			"public_key": pubkey,
+			"name":       "Unknown",
+			"role":       "unknown",
+		}
+	}
 
 	s.mu.RLock()
 	defer s.mu.RUnlock()
diff --git a/public/home.js b/public/home.js
index 4b1018e6..69ff2ffd 100644
--- a/public/home.js
+++ b/public/home.js
@@ -302,14 +302,19 @@
             <button class="mnc-btn" data-action="packets" data-key="${mn.pubkey}">View packets →</button>
           </div>
         </div>`;
-      } catch {
+      } catch (err) {
+        const is404 = err && err.message && err.message.includes('404');
+        const statusIcon = is404 ? '📡' : '❓';
+        const statusMsg = is404
+          ? 'Waiting for first advert — this node has been seen in channel messages but hasn\u2019t advertised yet'
+          : 'Could not load data';
         return `<div class="my-node-card silent" data-key="${mn.pubkey}" tabindex="0" role="button">
           <div class="mnc-header">
-            <div class="mnc-status">❓</div>
+            <div class="mnc-status">${statusIcon}</div>
             <div class="mnc-name">${escapeHtml(mn.name || truncate(mn.pubkey, 12))}</div>
             <button class="mnc-remove" data-key="${mn.pubkey}" title="Remove" aria-label="Remove ${escapeAttr(mn.name || truncate(mn.pubkey, 12))} from My Mesh">✕</button>
           </div>
-          <div class="mnc-status-text">Could not load data</div>
+          <div class="mnc-status-text">${statusMsg}</div>
         </div>`;
       }
     }));