feat: ModelRouter — unified OpenAI-compatible multi-source LLM gateway

- Lua adapters per upstream (transform_request/response/stream_chunk, build_headers signing hooks)
- AUTO priority routing with per-model kind (chat/image), explicit source/model routing
- Per-source concurrency caps with queueing, exponential backoff, AUTO failover
- OpenAI-compatible API: chat completions, SSE streaming, image generations, models
- Gateway key auth, web UI for adapter/source management, runtime persistence
- e2e test running the real binary against mocked upstreams

internal/lua/vm_test.go

@@ -0,0 +1,87 @@
+package lua
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestLoadBundledAdapters(t *testing.T) {
+	vm := NewVM(t.TempDir())
+	if err := vm.Start(); err != nil {
+		t.Fatalf("start: %v", err)
+	}
+	defer vm.Stop()
+	adapters := vm.ListAdapters()
+	if len(adapters) == 0 {
+		t.Fatal("no adapters loaded")
+	}
+	names := map[string]bool{}
+	for _, a := range adapters {
+		names[a.Name] = true
+	}
+	for _, want := range []string{"openai", "deepseek", "anthropic", "gemini", "ollama", "kimicode"} {
+		if !names[want] {
+			t.Errorf("missing adapter %s (got %v)", want, names)
+		}
+	}
+}
+
+func TestTransformRequest(t *testing.T) {
+	vm := NewVM(t.TempDir())
+	if err := vm.Start(); err != nil {
+		t.Fatal(err)
+	}
+	defer vm.Stop()
+	out, err := vm.Transform("openai", "transform_request", `{"model":"x","disable_thinking":true,"messages":[]}`)
+	if err != nil {
+		t.Fatalf("transform: %v", err)
+	}
+	if strings.Contains(out, "disable_thinking") {
+		t.Fatalf("disable_thinking not stripped: %s", out)
+	}
+}
+
+func TestBuildHeadersFallbackStatic(t *testing.T) {
+	vm := NewVM(t.TempDir())
+	if err := vm.Start(); err != nil {
+		t.Fatal(err)
+	}
+	defer vm.Stop()
+	hdrs, err := vm.BuildHeaders("anthropic", nil)
+	if err != nil {
+		t.Fatalf("build headers: %v", err)
+	}
+	if hdrs["anthropic-version"] != "2023-06-01" {
+		t.Fatalf("static header missing: %v", hdrs)
+	}
+}
+
+func TestBuildHeadersCustomHook(t *testing.T) {
+	vm := NewVM(t.TempDir())
+	if err := vm.Start(); err != nil {
+		t.Fatal(err)
+	}
+	defer vm.Stop()
+	hdrs, err := vm.BuildHeaders("kimicode", map[string]interface{}{
+		"timestamp": int64(12345),
+		"api_key":   "k",
+		"body":      "{}",
+		"method":    "POST",
+		"url":       "http://x/chat",
+		"source": map[string]interface{}{"meta": map[string]interface{}{
+			"app_id": "app-9", "app_secret": "s", "api_key": "k",
+		}},
+	})
+	if err != nil {
+		t.Fatalf("build headers: %v", err)
+	}
+	if hdrs["X-App-Id"] != "app-9" {
+		t.Fatalf("x-app-id = %q", hdrs["X-App-Id"])
+	}
+	if hdrs["X-App-Sign"] == "" {
+		t.Fatal("expected signature header")
+	}
+	if hdrs["X-Timestamp"] != "12345" {
+		t.Fatalf("timestamp = %q", hdrs["X-Timestamp"])
+	}
+}