diff --git a/internal/tester/delivery/rest/handlers.go b/internal/tester/delivery/rest/handlers.go
index e926057..b9a5edb 100644
--- a/internal/tester/delivery/rest/handlers.go
+++ b/internal/tester/delivery/rest/handlers.go
@@ -2,6 +2,7 @@ package rest
 
 import (
 	"git.sch9.ru/new_gate/ms-tester/internal/tester"
+	"git.sch9.ru/new_gate/ms-tester/pkg"
 	testerv1 "git.sch9.ru/new_gate/ms-tester/proto/tester/v1"
 	"github.com/gofiber/fiber/v2"
 )
@@ -29,7 +30,7 @@ func (h *TesterHandlers) ListProblems(c *fiber.Ctx) error {
 func (h *TesterHandlers) CreateContest(c *fiber.Ctx) error {
 	id, err := h.contestsUC.CreateContest(c.Context(), "Название контеста")
 	if err != nil {
-		return err
+		return c.SendStatus(pkg.ToREST(err))
 	}
 
 	return c.JSON(testerv1.CreateContestResponse{
@@ -40,7 +41,7 @@ func (h *TesterHandlers) CreateContest(c *fiber.Ctx) error {
 func (h *TesterHandlers) DeleteContest(c *fiber.Ctx, id int32) error {
 	err := h.contestsUC.DeleteContest(c.Context(), id)
 	if err != nil {
-		return err
+		return c.SendStatus(pkg.ToREST(err))
 	}
 
 	return c.SendStatus(fiber.StatusOK)
@@ -49,7 +50,7 @@ func (h *TesterHandlers) DeleteContest(c *fiber.Ctx, id int32) error {
 func (h *TesterHandlers) GetContest(c *fiber.Ctx, id int32) error {
 	contest, err := h.contestsUC.ReadContestById(c.Context(), id)
 	if err != nil {
-		return err
+		return c.SendStatus(pkg.ToREST(err))
 	}
 
 	return c.JSON(testerv1.GetContestResponse{
@@ -65,7 +66,7 @@ func (h *TesterHandlers) GetContest(c *fiber.Ctx, id int32) error {
 func (h *TesterHandlers) DeleteParticipant(c *fiber.Ctx, id int32, params testerv1.DeleteParticipantParams) error {
 	err := h.contestsUC.DeleteParticipant(c.Context(), params.ParticipantId)
 	if err != nil {
-		return err
+		return c.SendStatus(pkg.ToREST(err))
 	}
 
 	return c.SendStatus(fiber.StatusOK)
@@ -74,7 +75,7 @@ func (h *TesterHandlers) DeleteParticipant(c *fiber.Ctx, id int32, params tester
 func (h *TesterHandlers) AddParticipant(c *fiber.Ctx, id int32, params testerv1.AddParticipantParams) error {
 	id, err := h.contestsUC.AddParticipant(c.Context(), id, params.UserId)
 	if err != nil {
-		return err
+		return c.SendStatus(pkg.ToREST(err))
 	}
 
 	return c.JSON(testerv1.AddParticipantResponse{
@@ -85,7 +86,7 @@ func (h *TesterHandlers) AddParticipant(c *fiber.Ctx, id int32, params testerv1.
 func (h *TesterHandlers) DeleteTask(c *fiber.Ctx, id int32, params testerv1.DeleteTaskParams) error {
 	err := h.contestsUC.DeleteTask(c.Context(), params.TaskId)
 	if err != nil {
-		return err
+		return c.SendStatus(pkg.ToREST(err))
 	}
 
 	return c.SendStatus(fiber.StatusOK)
@@ -94,7 +95,7 @@ func (h *TesterHandlers) DeleteTask(c *fiber.Ctx, id int32, params testerv1.Dele
 func (h *TesterHandlers) AddTask(c *fiber.Ctx, id int32, params testerv1.AddTaskParams) error {
 	id, err := h.contestsUC.AddTask(c.Context(), id, params.ProblemId)
 	if err != nil {
-		return err
+		return c.SendStatus(pkg.ToREST(err))
 	}
 
 	return c.SendStatus(fiber.StatusNotImplemented)
@@ -103,7 +104,7 @@ func (h *TesterHandlers) AddTask(c *fiber.Ctx, id int32, params testerv1.AddTask
 func (h *TesterHandlers) CreateProblem(c *fiber.Ctx) error {
 	id, err := h.problemsUC.CreateProblem(c.Context(), "Название задачи")
 	if err != nil {
-		return err
+		return c.SendStatus(pkg.ToREST(err))
 	}
 
 	return c.JSON(testerv1.CreateProblemResponse{
@@ -114,7 +115,7 @@ func (h *TesterHandlers) CreateProblem(c *fiber.Ctx) error {
 func (h *TesterHandlers) DeleteProblem(c *fiber.Ctx, id int32) error {
 	err := h.problemsUC.DeleteProblem(c.Context(), id)
 	if err != nil {
-		return err
+		return c.SendStatus(pkg.ToREST(err))
 	}
 
 	return c.SendStatus(fiber.StatusOK)
@@ -124,7 +125,7 @@ func (h *TesterHandlers) DeleteProblem(c *fiber.Ctx, id int32) error {
 func (h *TesterHandlers) GetProblem(c *fiber.Ctx, id int32) error {
 	problem, err := h.problemsUC.ReadProblemById(c.Context(), id)
 	if err != nil {
-		return err
+		return c.SendStatus(pkg.ToREST(err))
 	}
 
 	return c.JSON(
diff --git a/internal/tester/repository/error.go b/internal/tester/repository/error.go
index cdd4408..53b33a0 100644
--- a/internal/tester/repository/error.go
+++ b/internal/tester/repository/error.go
@@ -1,23 +1,27 @@
 package repository
 
 import (
+	"database/sql"
 	"errors"
-	"git.sch9.ru/new_gate/ms-tester/pkg/utils"
+	"git.sch9.ru/new_gate/ms-tester/pkg"
 	"github.com/jackc/pgerrcode"
 	"github.com/jackc/pgx/v5/pgconn"
 )
 
-func handlePgErr(err error) error {
+func handlePgErr(err error, op string) error {
 	var pgErr *pgconn.PgError
-	if !errors.As(err, &pgErr) {
-		return utils.StorageError(err, utils.ErrUnknown, "unexpected error from postgres")
+	if errors.As(err, &pgErr) {
+		if pgerrcode.IsIntegrityConstraintViolation(pgErr.Code) {
+			return pkg.Wrap(pkg.ErrBadInput, err, op, pgErr.Message)
+		}
+		if pgerrcode.IsNoData(pgErr.Code) {
+			return pkg.Wrap(pkg.ErrNotFound, err, op, pgErr.Message)
+		}
 	}
-	if pgerrcode.IsIntegrityConstraintViolation(pgErr.Code) {
-		// TODO: probably should specify which constraint
-		return utils.StorageError(err, utils.ErrConflict, pgErr.Message)
+
+	if errors.Is(err, sql.ErrNoRows) {
+		return pkg.Wrap(pkg.ErrNotFound, err, op, "no rows found")
 	}
-	if pgerrcode.IsNoData(pgErr.Code) {
-		return utils.StorageError(err, utils.ErrNotFound, pgErr.Message)
-	}
-	return utils.StorageError(err, utils.ErrUnimplemented, "unimplemented error")
+
+	return pkg.Wrap(pkg.ErrUnhandled, err, op, "unexpected error")
 }
diff --git a/internal/tester/repository/pg_contests_repository.go b/internal/tester/repository/pg_contests_repository.go
index 6cc5ca1..406cb90 100644
--- a/internal/tester/repository/pg_contests_repository.go
+++ b/internal/tester/repository/pg_contests_repository.go
@@ -22,11 +22,13 @@ func NewContestRepository(db *sqlx.DB, logger *zap.Logger) *ContestRepository {
 const createContestQuery = "INSERT INTO contests (title) VALUES (?) RETURNING id"
 
 func (r *ContestRepository) CreateContest(ctx context.Context, title string) (int32, error) {
+	const op = "ContestRepository.CreateContest"
+
 	query := r.db.Rebind(createContestQuery)
 
 	rows, err := r.db.QueryxContext(ctx, query, title)
 	if err != nil {
-		return 0, handlePgErr(err)
+		return 0, handlePgErr(err, op)
 	}
 
 	defer rows.Close()
@@ -34,7 +36,7 @@ func (r *ContestRepository) CreateContest(ctx context.Context, title string) (in
 	rows.Next()
 	err = rows.Scan(&id)
 	if err != nil {
-		return 0, handlePgErr(err)
+		return 0, handlePgErr(err, op)
 	}
 
 	return id, nil
@@ -43,11 +45,13 @@ func (r *ContestRepository) CreateContest(ctx context.Context, title string) (in
 const readContestByIdQuery = "SELECT * from contests WHERE id=? LIMIT 1"
 
 func (r *ContestRepository) ReadContestById(ctx context.Context, id int32) (*models.Contest, error) {
+	const op = "ContestRepository.ReadContestById"
+
 	var contest models.Contest
 	query := r.db.Rebind(readContestByIdQuery)
 	err := r.db.GetContext(ctx, &contest, query, id)
 	if err != nil {
-		return nil, handlePgErr(err)
+		return nil, handlePgErr(err, op)
 	}
 	return &contest, nil
 }
@@ -55,10 +59,12 @@ func (r *ContestRepository) ReadContestById(ctx context.Context, id int32) (*mod
 const deleteContestQuery = "DELETE FROM contests WHERE id=?"
 
 func (r *ContestRepository) DeleteContest(ctx context.Context, id int32) error {
+	const op = "ContestRepository.DeleteContest"
+
 	query := r.db.Rebind(deleteContestQuery)
 	_, err := r.db.ExecContext(ctx, query, id)
 	if err != nil {
-		return handlePgErr(err)
+		return handlePgErr(err, op)
 	}
 
 	return nil
@@ -67,17 +73,19 @@ func (r *ContestRepository) DeleteContest(ctx context.Context, id int32) error {
 const addTaskQuery = "INSERT INTO tasks (problem_id, contest_id, position) VALUES (?, ?,COALESCE(SELECT MAX(position) FROM task WHERE contest_id = ? ,0) + 1) RETURNING id"
 
 func (r *ContestRepository) AddTask(ctx context.Context, contestId int32, problem_id int32) (int32, error) {
+	const op = "ContestRepository.AddTask"
+
 	query := r.db.Rebind(addTaskQuery)
 	rows, err := r.db.QueryxContext(ctx, query, problem_id, contestId, contestId)
 	if err != nil {
-		return 0, handlePgErr(err)
+		return 0, handlePgErr(err, op)
 	}
 	defer rows.Close()
 	var id int32
 	rows.Next()
 	err = rows.Scan(&id)
 	if err != nil {
-		return 0, handlePgErr(err)
+		return 0, handlePgErr(err, op)
 	}
 	return id, nil
 }
@@ -85,10 +93,12 @@ func (r *ContestRepository) AddTask(ctx context.Context, contestId int32, proble
 const deleteTaskQuery = "DELETE FROM tasks WHERE id=?"
 
 func (r *ContestRepository) DeleteTask(ctx context.Context, taskId int32) error {
+	const op = "ContestRepository.DeleteTask"
+
 	query := r.db.Rebind(deleteTaskQuery)
 	_, err := r.db.ExecContext(ctx, query, taskId)
 	if err != nil {
-		return handlePgErr(err)
+		return handlePgErr(err, op)
 	}
 	return nil
 }
@@ -96,11 +106,13 @@ func (r *ContestRepository) DeleteTask(ctx context.Context, taskId int32) error
 const addParticipantQuery = "INSERT INTO participants (user_id ,contest_id, name) VALUES (?, ?, ?) RETURNING id"
 
 func (r *ContestRepository) AddParticipant(ctx context.Context, contestId int32, userId int32) (int32, error) {
+	const op = "ContestRepository.AddParticipant"
+
 	query := r.db.Rebind(addParticipantQuery)
 	name := ""
 	rows, err := r.db.QueryxContext(ctx, query, contestId, userId, name)
 	if err != nil {
-		return 0, handlePgErr(err)
+		return 0, handlePgErr(err, op)
 	}
 	defer rows.Close()
 	var id int32
@@ -115,10 +127,12 @@ func (r *ContestRepository) AddParticipant(ctx context.Context, contestId int32,
 const deleteParticipantQuery = "DELETE FROM participants WHERE id=?"
 
 func (r *ContestRepository) DeleteParticipant(ctx context.Context, participantId int32) error {
+	const op = "ContestRepository.DeleteParticipant"
+
 	query := r.db.Rebind(deleteParticipantQuery)
 	_, err := r.db.ExecContext(ctx, query, participantId)
 	if err != nil {
-		return handlePgErr(err)
+		return handlePgErr(err, op)
 	}
 	return nil
 }
diff --git a/internal/tester/repository/pg_problems_repository.go b/internal/tester/repository/pg_problems_repository.go
index 6c66414..8758481 100644
--- a/internal/tester/repository/pg_problems_repository.go
+++ b/internal/tester/repository/pg_problems_repository.go
@@ -22,10 +22,12 @@ func NewProblemRepository(db *sqlx.DB, logger *zap.Logger) *ProblemRepository {
 const createProblemQuery = "INSERT INTO problems (title) VALUES (?) RETURNING id"
 
 func (r *ProblemRepository) CreateProblem(ctx context.Context, title string) (int32, error) {
+	const op = "ProblemRepository.CreateProblem"
+
 	query := r.db.Rebind(createProblemQuery)
 	rows, err := r.db.QueryxContext(ctx, query, title)
 	if err != nil {
-		return 0, handlePgErr(err)
+		return 0, handlePgErr(err, op)
 	}
 
 	defer rows.Close()
@@ -33,7 +35,7 @@ func (r *ProblemRepository) CreateProblem(ctx context.Context, title string) (in
 	rows.Next()
 	err = rows.Scan(&id)
 	if err != nil {
-		return 0, handlePgErr(err)
+		return 0, handlePgErr(err, op)
 	}
 
 	return id, nil
@@ -42,11 +44,13 @@ func (r *ProblemRepository) CreateProblem(ctx context.Context, title string) (in
 const readProblemQuery = "SELECT * from problems WHERE id=? LIMIT 1"
 
 func (r *ProblemRepository) ReadProblemById(ctx context.Context, id int32) (*models.Problem, error) {
+	const op = "ProblemRepository.ReadProblemById"
+
 	var problem models.Problem
 	query := r.db.Rebind(readProblemQuery)
 	err := r.db.GetContext(ctx, &problem, query, id)
 	if err != nil {
-		return nil, handlePgErr(err)
+		return nil, handlePgErr(err, op)
 	}
 	return &problem, nil
 }
@@ -54,10 +58,12 @@ func (r *ProblemRepository) ReadProblemById(ctx context.Context, id int32) (*mod
 const deleteProblemQuery = "DELETE FROM problems WHERE id=?"
 
 func (r *ProblemRepository) DeleteProblem(ctx context.Context, id int32) error {
+	const op = "ProblemRepository.DeleteProblem"
+
 	query := r.db.Rebind(deleteProblemQuery)
 	_, err := r.db.ExecContext(ctx, query, id)
 	if err != nil {
-		return handlePgErr(err)
+		return handlePgErr(err, op)
 	}
 
 	return nil
diff --git a/main.go b/main.go
index 950e3cc..0aaf32e 100644
--- a/main.go
+++ b/main.go
@@ -6,7 +6,7 @@ import (
 	"git.sch9.ru/new_gate/ms-tester/internal/tester/delivery/rest"
 	problemsRepository "git.sch9.ru/new_gate/ms-tester/internal/tester/repository"
 	testerUseCase "git.sch9.ru/new_gate/ms-tester/internal/tester/usecase"
-	"git.sch9.ru/new_gate/ms-tester/pkg/external/postgres"
+	"git.sch9.ru/new_gate/ms-tester/pkg"
 	testerv1 "git.sch9.ru/new_gate/ms-tester/proto/tester/v1"
 	"github.com/gofiber/fiber/v2"
 	fiberlogger "github.com/gofiber/fiber/v2/middleware/logger"
@@ -34,7 +34,7 @@ func main() {
 	}
 
 	logger.Info("connecting to postgres")
-	db, err := postgres.NewPostgresDB(cfg.PostgresDSN)
+	db, err := pkg.NewPostgresDB(cfg.PostgresDSN)
 	if err != nil {
 		panic(err)
 	}
diff --git a/pkg/aws-s3-client.go b/pkg/aws-s3-client.go
new file mode 100644
index 0000000..c1caffe
--- /dev/null
+++ b/pkg/aws-s3-client.go
@@ -0,0 +1 @@
+package pkg
diff --git a/pkg/errors.go b/pkg/errors.go
new file mode 100644
index 0000000..6efa146
--- /dev/null
+++ b/pkg/errors.go
@@ -0,0 +1,37 @@
+package pkg
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+)
+
+var (
+	NoPermission       = errors.New("no permission")
+	ErrUnauthenticated = errors.New("unauthenticated")
+	ErrUnhandled       = errors.New("unhandled")
+	ErrNotFound        = errors.New("not found")
+	ErrBadInput        = errors.New("bad input")
+	ErrInternal        = errors.New("internal")
+)
+
+func Wrap(basic error, err error, op string, msg string) error {
+	return errors.Join(basic, err, fmt.Errorf("during %s: %s", op, msg))
+}
+
+func ToREST(err error) int {
+	switch {
+	case errors.Is(err, ErrUnauthenticated):
+		return http.StatusUnauthorized
+	case errors.Is(err, ErrBadInput):
+		return http.StatusBadRequest
+	case errors.Is(err, ErrNotFound):
+		return http.StatusNotFound
+	case errors.Is(err, ErrInternal):
+		return http.StatusInternalServerError
+	case errors.Is(err, NoPermission):
+		return http.StatusForbidden
+	}
+
+	return http.StatusInternalServerError
+}
diff --git a/pkg/external/aws/client.go b/pkg/external/aws/client.go
deleted file mode 100644
index a1f9c0e..0000000
--- a/pkg/external/aws/client.go
+++ /dev/null
@@ -1 +0,0 @@
-package aws
diff --git a/pkg/external/pandoc/client.go b/pkg/pandoc-client.go
similarity index 98%
rename from pkg/external/pandoc/client.go
rename to pkg/pandoc-client.go
index af2427a..75a4adf 100644
--- a/pkg/external/pandoc/client.go
+++ b/pkg/pandoc-client.go
@@ -1,4 +1,4 @@
-package pandoc
+package pkg
 
 import (
 	"bytes"
diff --git a/pkg/external/postgres/client.go b/pkg/postgres-client.go
similarity index 97%
rename from pkg/external/postgres/client.go
rename to pkg/postgres-client.go
index b959972..d8b74a9 100644
--- a/pkg/external/postgres/client.go
+++ b/pkg/postgres-client.go
@@ -1,4 +1,4 @@
-package postgres
+package pkg
 
 import (
 	_ "github.com/jackc/pgx/v5/stdlib"
diff --git a/pkg/external/rabbitmq/client.go b/pkg/rabbitmq-client.go
similarity index 88%
rename from pkg/external/rabbitmq/client.go
rename to pkg/rabbitmq-client.go
index 09732fa..9d30d48 100644
--- a/pkg/external/rabbitmq/client.go
+++ b/pkg/rabbitmq-client.go
@@ -1,4 +1,4 @@
-package rabbitmq
+package pkg
 
 import amqp "github.com/rabbitmq/amqp091-go"
 
diff --git a/pkg/utils/errors.go b/pkg/utils/errors.go
deleted file mode 100644
index 98bd286..0000000
--- a/pkg/utils/errors.go
+++ /dev/null
@@ -1,132 +0,0 @@
-package utils
-
-import (
-	"errors"
-	"fmt"
-	"go.uber.org/zap/zapcore"
-	"runtime"
-)
-
-type code uint8
-
-const (
-	ErrValidationFailed code = 1
-	ErrInternal         code = 2
-	ErrExternal         code = 3
-	ErrNoPermission     code = 4
-	ErrUnknown          code = 5
-	ErrDeadlineExceeded code = 6
-	ErrNotFound         code = 7
-	ErrAlreadyExists    code = 8
-	ErrConflict         code = 9
-	ErrUnimplemented    code = 10
-	ErrBadInput         code = 11
-	ErrUnauthenticated  code = 12
-)
-
-func (c code) String() string {
-	switch {
-	case errors.Is(c, ErrValidationFailed):
-		return "validation error"
-	case errors.Is(c, ErrInternal):
-		return "internal error"
-	case errors.Is(c, ErrExternal):
-		return "external error"
-	case errors.Is(c, ErrNoPermission):
-		return "permission error"
-	case errors.Is(c, ErrUnknown):
-		return "unknown error"
-	case errors.Is(c, ErrDeadlineExceeded):
-		return "deadline error"
-	case errors.Is(c, ErrNotFound):
-		return "not found error"
-	case errors.Is(c, ErrAlreadyExists):
-		return "already exists error"
-	case errors.Is(c, ErrConflict):
-		return "conflict error"
-	case errors.Is(c, ErrUnimplemented):
-		return "unimplemented error"
-	case errors.Is(c, ErrBadInput):
-		return "bad input error"
-	}
-
-	panic("unimplemented")
-}
-
-func (c code) Error() string {
-	return c.String()
-}
-
-type layer uint8
-
-const (
-	LayerTransport layer = 1
-	LayerService   layer = 2
-	LayerStorage   layer = 3
-)
-
-func (l layer) String() string {
-	switch l {
-	case LayerTransport:
-		return "transport"
-	case LayerService:
-		return "service"
-	case LayerStorage:
-		return "storage"
-	}
-
-	panic("unimplemented")
-}
-
-func location(skip int) string {
-	_, file, line, _ := runtime.Caller(skip)
-	return fmt.Sprintf("%s:%d", file, line)
-}
-
-type Error struct {
-	src   error
-	layer layer
-	code  code
-	msg   string
-	loc   string
-}
-
-func wrap(src error, layer layer, class code, msg string, loc string) *Error {
-	return &Error{
-		src:   src,
-		layer: layer,
-		code:  class,
-		msg:   msg,
-		loc:   loc,
-	}
-}
-
-func (e *Error) Unwrap() []error {
-	return []error{e.src, e.code}
-}
-
-func (e *Error) Error() string {
-	return fmt.Sprintf("%s: %s", e.code.String(), e.msg)
-}
-
-func (e *Error) MarshalLogObject(encoder zapcore.ObjectEncoder) error {
-	if e.src != nil {
-		encoder.AddString("src", e.src.Error())
-	}
-	encoder.AddString("layer", e.layer.String())
-	encoder.AddString("code", e.code.String())
-	encoder.AddString("msg", e.msg)
-	return nil
-}
-
-func TransportError(src error, code code, msg string) error {
-	return wrap(src, LayerTransport, code, msg, location(2))
-}
-
-func ServiceError(src error, code code, msg string) error {
-	return wrap(src, LayerService, code, msg, location(2))
-}
-
-func StorageError(src error, code code, msg string) error {
-	return wrap(src, LayerStorage, code, msg, location(2))
-}
diff --git a/pkg/utils/utils.go b/pkg/utils/utils.go
deleted file mode 100644
index 8492339..0000000
--- a/pkg/utils/utils.go
+++ /dev/null
@@ -1,33 +0,0 @@
-package utils
-
-import (
-	"google.golang.org/protobuf/types/known/timestamppb"
-	"time"
-)
-
-func AsTimeP(t time.Time) *time.Time {
-	return &t
-}
-
-func AsInt32P(v int32) *int32 {
-	return &v
-}
-
-func AsStringP(str string) *string {
-	return &str
-}
-
-func TimeP(t *timestamppb.Timestamp) *time.Time {
-	if t == nil {
-		return nil
-	}
-	tt := t.AsTime()
-	return &tt
-}
-
-func TimestampP(t *time.Time) *timestamppb.Timestamp {
-	if t == nil {
-		return nil
-	}
-	return timestamppb.New(*t)
-}
diff --git a/pkg/external/valkey/client.go b/pkg/valkey-client.go
similarity index 93%
rename from pkg/external/valkey/client.go
rename to pkg/valkey-client.go
index c5a4900..87e4681 100644
--- a/pkg/external/valkey/client.go
+++ b/pkg/valkey-client.go
@@ -1,4 +1,4 @@
-package valkey
+package pkg
 
 import "github.com/valkey-io/valkey-go"