feat(http): chi router skeleton + Google-style error response

internal/transport/http/response_test.go

@@ -0,0 +1,49 @@
+package httpx
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/yan1h/agent-coding-workflow/internal/infra/errs"
+)
+
+func TestWriteJSON(t *testing.T) {
+	rec := httptest.NewRecorder()
+	WriteJSON(rec, 200, map[string]any{"x": 1})
+	require.Equal(t, 200, rec.Code)
+	require.Equal(t, "application/json; charset=utf-8", rec.Header().Get("Content-Type"))
+
+	var body map[string]any
+	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &body))
+	require.EqualValues(t, 1, body["x"])
+}
+
+func TestWriteError_AppError(t *testing.T) {
+	rec := httptest.NewRecorder()
+	e := errs.New(errs.CodeInvalidInput, "bad").WithFields(map[string]any{"name": "required"})
+	WriteError(rec, "req-1", e)
+	require.Equal(t, 400, rec.Code)
+
+	var body map[string]any
+	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &body))
+	require.Equal(t, "invalid_input", body["code"])
+	require.Equal(t, "bad", body["message"])
+	require.Equal(t, "req-1", body["request_id"])
+	fields := body["fields"].(map[string]any)
+	require.Equal(t, "required", fields["name"])
+}
+
+func TestWriteError_GenericError_BecomesInternal(t *testing.T) {
+	rec := httptest.NewRecorder()
+	WriteError(rec, "req-2", errors.New("boom"))
+	require.Equal(t, 500, rec.Code)
+
+	var body map[string]any
+	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &body))
+	require.Equal(t, "internal", body["code"])
+	require.Equal(t, "internal server error", body["message"])
+}