diff --git a/cmd/server/nodes_geofilter_optin_test.go b/cmd/server/nodes_geofilter_optin_test.go
new file mode 100644
index 00000000..c96f29a2
--- /dev/null
+++ b/cmd/server/nodes_geofilter_optin_test.go
@@ -0,0 +1,79 @@
+package main
+
+import (
+	"encoding/json"
+	"net/http/httptest"
+	"testing"
+)
+
+// Regression test: configuring geo_filter alone must not change what
+// GET /api/nodes returns. Before this fix, setting geo_filter silently
+// hid every node outside the polygon that hadn't yet been re-tagged
+// foreign_advert=1 by the ingestor (which only happens on that node's
+// next ADVERT) — including the live map, which lists straight off this
+// endpoint. The filter is now opt-in via ?geoFilter=1.
+func TestHandleNodes_GeoFilterExcludedByDefault(t *testing.T) {
+	apiKey := "a-strong-api-key-for-testing"
+	srv, router, _ := setupGeoFilterServer(t, apiKey)
+	srv.setGeoFilter(&GeoFilterConfig{
+		LatMin: floatPtr(53.0), LatMax: floatPtr(59.0),
+		LonMin: floatPtr(6.0), LonMax: floatPtr(15.0),
+	})
+
+	mustExecDB(t, srv.db, `INSERT INTO nodes (public_key, name, lat, lon, foreign_advert) VALUES ('pk-inside', 'InsideNode', 55.7, 10.5, 0)`)
+	mustExecDB(t, srv.db, `INSERT INTO nodes (public_key, name, lat, lon, foreign_advert) VALUES ('pk-outside-untagged', 'OutsideUntagged', 44.4, 26.1, 0)`)
+	mustExecDB(t, srv.db, `INSERT INTO nodes (public_key, name, lat, lon, foreign_advert) VALUES ('pk-outside-tagged', 'OutsideTagged', 52.4, 10.8, 1)`)
+
+	names := func(w *httptest.ResponseRecorder) map[string]bool {
+		var body map[string]interface{}
+		if err := json.Unmarshal(w.Body.Bytes(), &body); err != nil {
+			t.Fatalf("unmarshal: %v", err)
+		}
+		nodes, ok := body["nodes"].([]interface{})
+		if !ok {
+			t.Fatal("expected nodes array")
+		}
+		out := make(map[string]bool, len(nodes))
+		for _, n := range nodes {
+			m := n.(map[string]interface{})
+			out[m["name"].(string)] = true
+		}
+		return out
+	}
+
+	t.Run("default request returns every node regardless of geo_filter", func(t *testing.T) {
+		req := httptest.NewRequest("GET", "/api/nodes?limit=50", nil)
+		w := httptest.NewRecorder()
+		router.ServeHTTP(w, req)
+		if w.Code != 200 {
+			t.Fatalf("expected 200, got %d", w.Code)
+		}
+		got := names(w)
+		for _, want := range []string{"InsideNode", "OutsideUntagged", "OutsideTagged"} {
+			if !got[want] {
+				t.Errorf("expected %s in default (unfiltered) response, got %v", want, got)
+			}
+		}
+	})
+
+	t.Run("geoFilter=1 excludes untagged out-of-polygon nodes but keeps foreign-tagged ones", func(t *testing.T) {
+		req := httptest.NewRequest("GET", "/api/nodes?limit=50&geoFilter=1", nil)
+		w := httptest.NewRecorder()
+		router.ServeHTTP(w, req)
+		if w.Code != 200 {
+			t.Fatalf("expected 200, got %d", w.Code)
+		}
+		got := names(w)
+		if !got["InsideNode"] {
+			t.Error("expected InsideNode (within polygon) to be present")
+		}
+		if !got["OutsideTagged"] {
+			t.Error("expected OutsideTagged (foreign_advert=1) to be present even though it's outside the polygon — #730")
+		}
+		if got["OutsideUntagged"] {
+			t.Error("expected OutsideUntagged (outside polygon, not yet foreign-tagged) to be excluded when geoFilter=1")
+		}
+	})
+}
+
+func floatPtr(f float64) *float64 { return &f }
diff --git a/cmd/server/openapi.go b/cmd/server/openapi.go
index afd233db..46464ecb 100644
--- a/cmd/server/openapi.go
+++ b/cmd/server/openapi.go
@@ -80,6 +80,7 @@ func routeDescriptions() map[string]routeMeta {
 			QueryParams: []paramMeta{
 				{Name: "role", Description: "Filter by node role", Type: "string"},
 				{Name: "status", Description: "Filter by status (active/stale/offline)", Type: "string"},
+				{Name: "geoFilter", Description: "Set to \"1\" to exclude nodes outside the configured geo_filter (unless foreign_advert-tagged). Opt-in — omitting it returns every node regardless of geo_filter.", Type: "string"},
 			}},
 		"GET /api/nodes/search":             {Summary: "Search nodes", Description: "Search nodes by name or public key prefix.", Tag: "nodes", QueryParams: []paramMeta{{Name: "q", Description: "Search query", Type: "string", Required: true}}},
 		"GET /api/nodes/bulk-health":        {Summary: "Bulk node health", Description: "Returns health status for all nodes in one call.", Tag: "nodes"},
diff --git a/cmd/server/routes.go b/cmd/server/routes.go
index 9f47fe9f..d56f0207 100644
--- a/cmd/server/routes.go
+++ b/cmd/server/routes.go
@@ -1426,7 +1426,16 @@ func (s *Server) handleNodes(w http.ResponseWriter, r *http.Request) {
 			}
 		}
 	}
-	if s.cfg.GeoFilter != nil {
+	// Opt-in only (?geoFilter=1): configuring geo_filter alone must not
+	// change what /api/nodes (and therefore the live map, which lists
+	// straight off this endpoint) returns by default. It used to — any node
+	// outside the polygon and not YET foreign_advert-tagged (which only
+	// happens on that node's next ADVERT after geo_filter was configured)
+	// would silently vanish from every view the moment geo_filter was set,
+	// with no per-request way to see them anyway. geo_filter's own
+	// ingestor-side tagging (and the explicit prune-geo-filter admin flow)
+	// are unaffected by this — this only gates the passive declutter view.
+	if s.cfg.GeoFilter != nil && q.Get("geoFilter") == "1" {
 		filtered := nodes[:0]
 		for _, node := range nodes {
 			// Foreign-flagged nodes (#730) are kept even when their GPS lies