fix(websub): handle empty channels map in mapWebSubAPIModelToAPI

platform-api/src/internal/service/websub_api.go

@@ -414,7 +414,7 @@ func mapWebSubAPIModelToAPI(m *model.WebSubAPI, apiUtil *utils.APIUtil) *api.Web
 		Transport:         transport,
 		Context:           m.Configuration.Context,
 		Upstream:          mapUpstreamModelToAPI(&m.Configuration.Upstream),
-		Channels:          *mapWebSubChannelsModelToAPI(m.Configuration.Channels),
+		Channels:          mapWebSubChannelsModelToAPI(m.Configuration.Channels),
 		AllChannels:       mapWebSubAllChannelPoliciesModelToAPI(m.Configuration.AllChannels),
 		SubscriptionPlans: subscriptionPlans,
 		CreatedAt:         utils.TimePtr(m.CreatedAt),
@@ -465,10 +465,10 @@ func mapWebSubAllChannelPoliciesAPIToModel(in *api.WebSubAllChannelPolicies) *mo
 }
 
 // mapWebSubChannelsModelToAPI converts the model channel map to the API channel map.
-func mapWebSubChannelsModelToAPI(in map[string]model.WebSubChannel) *map[string]api.WebSubChannel {
-	if len(in) == 0 {
-		return nil
-	}
+// It always returns a non-nil map so callers that embed the result by value
+// (api.WebSubAPI.Channels is a value-type map) do not panic when the input is
+// empty or nil.
+func mapWebSubChannelsModelToAPI(in map[string]model.WebSubChannel) map[string]api.WebSubChannel {
 	out := make(map[string]api.WebSubChannel, len(in))
 	for name, ch := range in {
 		out[name] = api.WebSubChannel{
@@ -478,7 +478,7 @@ func mapWebSubChannelsModelToAPI(in map[string]model.WebSubChannel) *map[string]
 			OnMessageDelivery: mapEventPoliciesModelToAPI(ch.OnMessageDelivery),
 		}
 	}
-	return &out
+	return out
 }
 
 // mapEventPoliciesModelToAPI converts model event policies to API.

platform-api/src/internal/service/websub_api_test.go

@@ -491,3 +491,61 @@ func TestWebSubAPI_NilPoliciesHandled(t *testing.T) {
 		t.Errorf("expected nil for nil input, got %v", got)
 	}
 }
+
+// TestWebSubAPI_MapModelToAPI_EmptyChannelsDoesNotPanic guards the nil-pointer
+// dereference reported in #1995. Previously mapWebSubChannelsModelToAPI
+// returned nil for empty/nil channel maps and the caller dereferenced that nil
+// pointer when assigning to api.WebSubAPI.Channels (a value-type map). The Get,
+// List, and Update return paths panicked for any WebSub API stored with an
+// empty channels map.
+func TestWebSubAPI_MapModelToAPI_EmptyChannelsDoesNotPanic(t *testing.T) {
+	tests := []struct {
+		name string
+		in   map[string]model.WebSubChannel
+	}{
+		{name: "nil channel map", in: nil},
+		{name: "empty channel map", in: map[string]model.WebSubChannel{}},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			defer func() {
+				if r := recover(); r != nil {
+					t.Fatalf("mapWebSubAPIModelToAPI panicked: %v", r)
+				}
+			}()
+
+			m := &model.WebSubAPI{
+				Handle:  "test",
+				Name:    "test",
+				Version: "v1",
+				Configuration: model.WebSubAPIConfiguration{
+					Channels: tc.in,
+				},
+			}
+
+			got := mapWebSubAPIModelToAPI(m, &utils.APIUtil{})
+			if got == nil {
+				t.Fatal("expected non-nil WebSubAPI result")
+			}
+			if got.Channels == nil {
+				t.Errorf("expected non-nil Channels map, got nil")
+			}
+			if len(got.Channels) != 0 {
+				t.Errorf("expected empty Channels map, got %d entries", len(got.Channels))
+			}
+		})
+	}
+}
+
+// TestWebSubAPI_MapChannelsModelToAPI_NeverReturnsNil ensures the helper itself
+// always returns a usable (non-nil) map so callers do not need a nil guard
+// before assigning the result to a value-type map field.
+func TestWebSubAPI_MapChannelsModelToAPI_NeverReturnsNil(t *testing.T) {
+	if got := mapWebSubChannelsModelToAPI(nil); got == nil {
+		t.Errorf("expected non-nil map for nil input, got nil")
+	}
+	if got := mapWebSubChannelsModelToAPI(map[string]model.WebSubChannel{}); got == nil {
+		t.Errorf("expected non-nil map for empty input, got nil")
+	}
+}