diff --git a/internal/hub/hub_test.go b/internal/hub/hub_test.go
new file mode 100644
index 0000000..e5d4cad
--- /dev/null
+++ b/internal/hub/hub_test.go
@@ -0,0 +1,108 @@
+package hub
+
+import "testing"
+
+func TestScopeMatches_EmptyScope(t *testing.T) {
+	// empty scope matches everything — no filters means no restrictions
+	s := Scope{}
+	e := Event{Type: EventPacketObservation, IATA: "YVR", PayloadType: 4}
+	if !scopeMatches(s, e) {
+		t.Error("empty scope should match all events")
+	}
+}
+
+func TestScopeMatches_EventFilter(t *testing.T) {
+	s := Scope{Events: []EventType{EventNodeUpdate}}
+	if !scopeMatches(s, Event{Type: EventNodeUpdate, IATA: "YVR"}) {
+		t.Error("expected nodeUpdate to match")
+	}
+	if scopeMatches(s, Event{Type: EventPacketObservation, IATA: "YVR"}) {
+		t.Error("expected packetObservation not to match")
+	}
+}
+
+func TestScopeMatches_IATAFilter(t *testing.T) {
+	s := Scope{Events: []EventType{EventPacketObservation}, IATAs: []string{"YVR", "YYJ"}}
+	if !scopeMatches(s, Event{Type: EventPacketObservation, IATA: "YVR"}) {
+		t.Error("expected YVR to match")
+	}
+	if scopeMatches(s, Event{Type: EventPacketObservation, IATA: "YYC"}) {
+		t.Error("expected YYC not to match")
+	}
+}
+
+func TestScopeMatches_RegionIATAs(t *testing.T) {
+	s := Scope{Events: []EventType{EventPacketObservation}, RegionIATAs: []string{"YYJ"}}
+	if !scopeMatches(s, Event{Type: EventPacketObservation, IATA: "YYJ"}) {
+		t.Error("expected YYJ to match via RegionIATAs")
+	}
+	if scopeMatches(s, Event{Type: EventPacketObservation, IATA: "YVR"}) {
+		t.Error("expected YVR not to match")
+	}
+}
+
+func TestScopeMatches_IATAandRegionIATAUnion(t *testing.T) {
+	// IATAs and RegionIATAs are OR'd together
+	s := Scope{
+		Events:      []EventType{EventPacketObservation},
+		IATAs:       []string{"YVR"},
+		RegionIATAs: []string{"YYJ"},
+	}
+	if !scopeMatches(s, Event{Type: EventPacketObservation, IATA: "YVR"}) {
+		t.Error("expected YVR to match via IATAs")
+	}
+	if !scopeMatches(s, Event{Type: EventPacketObservation, IATA: "YYJ"}) {
+		t.Error("expected YYJ to match via RegionIATAs")
+	}
+	if scopeMatches(s, Event{Type: EventPacketObservation, IATA: "YYC"}) {
+		t.Error("expected YYC not to match")
+	}
+}
+
+func TestScopeMatches_PayloadTypeFilter(t *testing.T) {
+	s := Scope{Events: []EventType{EventPacketObservation}, PayloadTypes: []uint8{4}}
+	if !scopeMatches(s, Event{Type: EventPacketObservation, PayloadType: 4}) {
+		t.Error("expected payload type 4 to match")
+	}
+	if scopeMatches(s, Event{Type: EventPacketObservation, PayloadType: 5}) {
+		t.Error("expected payload type 5 not to match")
+	}
+}
+
+func TestScopeMatches_ChannelHashFilter(t *testing.T) {
+	s := Scope{Events: []EventType{EventChannelMessage}, ChannelHashes: []string{"ab"}}
+	if !scopeMatches(s, Event{Type: EventChannelMessage, ChannelHash: "ab"}) {
+		t.Error("expected channel hash ab to match")
+	}
+	if scopeMatches(s, Event{Type: EventChannelMessage, ChannelHash: "cd"}) {
+		t.Error("expected channel hash cd not to match")
+	}
+}
+
+func TestScopeMatches_AllFiltersPass(t *testing.T) {
+	s := Scope{
+		Events:       []EventType{EventPacketObservation},
+		IATAs:        []string{"YVR"},
+		PayloadTypes: []uint8{4},
+	}
+	e := Event{Type: EventPacketObservation, IATA: "YVR", PayloadType: 4}
+	if !scopeMatches(s, e) {
+		t.Error("expected all-matching event to pass")
+	}
+}
+
+func TestScopeMatches_OneFilterFails(t *testing.T) {
+	s := Scope{
+		Events:       []EventType{EventPacketObservation},
+		IATAs:        []string{"YVR"},
+		PayloadTypes: []uint8{4},
+	}
+	// wrong IATA
+	if scopeMatches(s, Event{Type: EventPacketObservation, IATA: "YYC", PayloadType: 4}) {
+		t.Error("expected wrong IATA to fail")
+	}
+	// wrong payload type
+	if scopeMatches(s, Event{Type: EventPacketObservation, IATA: "YVR", PayloadType: 5}) {
+		t.Error("expected wrong payload type to fail")
+	}
+}