fix(openai): route copilot Gemini preview models to chat endpoint

sdk/api/handlers/openai/endpoint_compat.go

@@ -1,6 +1,9 @@
 package openai
 
-import "github.com/router-for-me/CLIProxyAPI/v6/internal/registry"
+import (
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/registry"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/thinking"
+)
 
 const (
 	openAIChatEndpoint      = "/chat/completions"
@@ -12,6 +15,12 @@ func resolveEndpointOverride(modelName, requestedEndpoint string) (string, bool)
 		return "", false
 	}
 	info := registry.GetGlobalRegistry().GetModelInfo(modelName, "")
+	if info == nil {
+		baseModel := thinking.ParseSuffix(modelName).ModelName
+		if baseModel != "" && baseModel != modelName {
+			info = registry.GetGlobalRegistry().GetModelInfo(baseModel, "")
+		}
+	}
 	if info == nil || len(info.SupportedEndpoints) == 0 {
 		return "", false
 	}

sdk/api/handlers/openai/endpoint_compat_test.go

@@ -0,0 +1,29 @@
+package openai
+
+import (
+	"testing"
+
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/registry"
+)
+
+func TestResolveEndpointOverride_StripsThinkingSuffix(t *testing.T) {
+	const clientID = "test-endpoint-compat-suffix"
+	reg := registry.GetGlobalRegistry()
+	reg.RegisterClient(clientID, "github-copilot", []*registry.ModelInfo{
+		{
+			ID:                 "test-gemini-chat-only",
+			SupportedEndpoints: []string{openAIChatEndpoint},
+		},
+	})
+	t.Cleanup(func() {
+		reg.UnregisterClient(clientID)
+	})
+
+	override, ok := resolveEndpointOverride("test-gemini-chat-only(high)", openAIResponsesEndpoint)
+	if !ok {
+		t.Fatalf("expected endpoint override to be resolved")
+	}
+	if override != openAIChatEndpoint {
+		t.Fatalf("override endpoint = %q, want %q", override, openAIChatEndpoint)
+	}
+}