diff --git a/internal/hermesadapter/server.go b/internal/hermesadapter/server.go
index 202f5ce..49a9620 100644
--- a/internal/hermesadapter/server.go
+++ b/internal/hermesadapter/server.go
@@ -111,7 +111,7 @@ func NewServer(client rpcClient) *Server {
 		providerID:     strings.TrimSpace(shared.EnvOrDefault("HERMES_ADAPTER_PROVIDER_ID", defaultProviderID)),
 		providerLabel:  strings.TrimSpace(shared.EnvOrDefault("HERMES_ADAPTER_PROVIDER_LABEL", defaultLabel)),
 		allowedOrigins: parseAllowedOrigins(strings.TrimSpace(shared.EnvOrDefault("HERMES_ADAPTER_ALLOWED_ORIGINS", "https://xworkmate.svc.plus,http://localhost:*,http://127.0.0.1:*"))),
-		upstreamMethod: strings.TrimSpace(shared.EnvOrDefault("HERMES_ADAPTER_UPSTREAM_METHOD", "")),
+		upstreamMethod: strings.TrimSpace(shared.EnvOrDefault("HERMES_ADAPTER_UPSTREAM_METHOD", "session.start")),
 		sessionRunner: func(ctx context.Context, model, prompt, workingDirectory string) (string, error) {
 			return shared.RunProviderCommand(
 				ctx,
diff --git a/internal/hermesadapter/server_test.go b/internal/hermesadapter/server_test.go
index ad5bbda..1d634b0 100644
--- a/internal/hermesadapter/server_test.go
+++ b/internal/hermesadapter/server_test.go
@@ -95,6 +95,7 @@ func TestHandleRPCSessionStartReturnsUpstreamResult(t *testing.T) {
 func TestHandleSessionStartFallsBackToPromptRunner(t *testing.T) {
 	stub := &stubClient{initResult: initializeResult{ProtocolVersion: 1}}
 	server := NewServer(stub)
+	server.upstreamMethod = ""
 	server.sessionRunner = func(ctx context.Context, model, prompt, workingDirectory string) (string, error) {
 		if workingDirectory != "/tmp/demo" {
 			t.Fatalf("expected workingDirectory /tmp/demo, got %q", workingDirectory)
@@ -119,6 +120,13 @@ func TestHandleSessionStartFallsBackToPromptRunner(t *testing.T) {
 	}
 }
 
+func TestNewServerDefaultsHermesToUpstreamSessionStart(t *testing.T) {
+	server := NewServer(&stubClient{})
+	if got := server.upstreamMethod; got != "session.start" {
+		t.Fatalf("expected default upstream method session.start, got %q", got)
+	}
+}
+
 func TestHandleWebSocketCapabilities(t *testing.T) {
 	server := NewServer(&stubClient{initResult: initializeResult{ProtocolVersion: 1}})
 	httpServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {