feat: scaffold go backend foundation

internal/httpapi/handler.go

@@ -0,0 +1,47 @@
+package httpapi
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"tutor/internal/config"
+	"tutor/internal/workflows"
+)
+
+type Handler struct {
+	cfg    config.Config
+	runner workflows.Runner
+}
+
+func NewHandler(cfg config.Config, runner workflows.Runner) Handler {
+	return Handler{
+		cfg:    cfg,
+		runner: runner,
+	}
+}
+
+func (h Handler) Routes() http.Handler {
+	mux := http.NewServeMux()
+	mux.HandleFunc("GET /healthz", h.health)
+	return mux
+}
+
+func (h Handler) health(w http.ResponseWriter, _ *http.Request) {
+	writeJSON(w, http.StatusOK, healthResponse{
+		Status:      "ok",
+		Environment: h.cfg.Environment,
+		ModelKey:    h.cfg.ModelKey,
+	})
+}
+
+type healthResponse struct {
+	Status      string `json:"status"`
+	Environment string `json:"environment"`
+	ModelKey    string `json:"model_key"`
+}
+
+func writeJSON(w http.ResponseWriter, status int, value any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(value)
+}

internal/httpapi/handler_test.go

@@ -0,0 +1,42 @@
+package httpapi
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"tutor/internal/config"
+	"tutor/internal/workflows"
+)
+
+func TestHealth(t *testing.T) {
+	cfg := config.Config{
+		Environment: "test",
+		ModelKey:    "deepseek-v4-flash",
+	}
+	handler := NewHandler(cfg, workflows.NewStubRunner())
+
+	req := httptest.NewRequest(http.MethodGet, "/healthz", nil)
+	rec := httptest.NewRecorder()
+
+	handler.Routes().ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status = %d, want %d", rec.Code, http.StatusOK)
+	}
+
+	var body healthResponse
+	if err := json.NewDecoder(rec.Body).Decode(&body); err != nil {
+		t.Fatalf("decode health response: %v", err)
+	}
+	if body.Status != "ok" {
+		t.Fatalf("body.Status = %q", body.Status)
+	}
+	if body.Environment != "test" {
+		t.Fatalf("body.Environment = %q", body.Environment)
+	}
+	if body.ModelKey != "deepseek-v4-flash" {
+		t.Fatalf("body.ModelKey = %q", body.ModelKey)
+	}
+}