feat: enhance Safew error handling and polling mechanism

- Added error_msg field to safewAPIResponse for better error descriptions.
- Updated safewErrorDescription function to include error_msg in the output.
- Introduced a new test to verify that error messages are included in Safew error descriptions.
- Improved the polling mechanism in the Watcher to handle conflicts and ensure no overlapping polls occur.

internal/safew/watcher_test.go

@@ -3,6 +3,7 @@ package safew
 import (
 	"context"
 	"errors"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -13,7 +14,7 @@ func TestRefreshMergesAndAdvancesOffset(t *testing.T) {
 	st := NewMemStore()
 	poll := func(token string, offset int64, timeout int) ([]adapter.SafewChat, int64, error) {
 		if timeout != 0 {
-			t.Fatalf("timeout=%d", timeout)
+			return nil, offset, nil
 		}
 		if offset != 0 {
 			t.Fatalf("offset=%d", offset)
@@ -36,6 +37,7 @@ func TestRefreshMergesAndAdvancesOffset(t *testing.T) {
 	if off != 11 {
 		t.Fatalf("offset=%d", off)
 	}
+	w.Stop()
 }
 
 func TestRefreshAuthError(t *testing.T) {
@@ -50,6 +52,44 @@ func TestRefreshAuthError(t *testing.T) {
 	if _, ok := err.(*adapter.SafewAuthError); !ok {
 		t.Fatalf("%T", err)
 	}
+	w.Stop()
+}
+
+type alwaysLockStore struct{ *MemStore }
+
+func (a *alwaysLockStore) TrySafewPollLock(context.Context, string, time.Duration) (bool, error) {
+	return true, nil
+}
+
+func (a *alwaysLockStore) UnlockSafewPoll(context.Context, string) error { return nil }
+
+func TestRefreshAndEnsureDoNotOverlapPolls(t *testing.T) {
+	st := &alwaysLockStore{MemStore: NewMemStore()}
+	var inflight int32
+	var overlap int32
+	poll := func(token string, offset int64, timeout int) ([]adapter.SafewChat, int64, error) {
+		n := atomic.AddInt32(&inflight, 1)
+		if n > 1 {
+			atomic.AddInt32(&overlap, 1)
+		}
+		time.Sleep(40 * time.Millisecond)
+		atomic.AddInt32(&inflight, -1)
+		return []adapter.SafewChat{{ID: "1", Type: "group", Title: "g"}}, offset + 1, nil
+	}
+	w := NewWatcher(st, poll)
+	w.bgIdle = 20 * time.Millisecond
+	ctx := context.Background()
+	errCh := make(chan error, 1)
+	go func() { errCh <- w.Refresh(ctx, "tok") }()
+	w.Ensure("tok")
+	if err := <-errCh; err != nil {
+		t.Fatal(err)
+	}
+	time.Sleep(80 * time.Millisecond)
+	w.Stop()
+	if atomic.LoadInt32(&overlap) > 0 {
+		t.Fatalf("overlapping getUpdates: %d", overlap)
+	}
 }
 
 func TestEnsurePollsInBackground(t *testing.T) {
@@ -57,7 +97,7 @@ func TestEnsurePollsInBackground(t *testing.T) {
 	got := make(chan int, 1)
 	w := NewWatcher(st, func(token string, offset int64, timeout int) ([]adapter.SafewChat, int64, error) {
 		if timeout != 30 {
-			return nil, offset, errors.New("not background")
+			return nil, offset, nil
 		}
 		select {
 		case got <- timeout:
@@ -74,3 +114,10 @@ func TestEnsurePollsInBackground(t *testing.T) {
 	}
 	w.Stop()
 }
+
+func TestPollConflictIsRetryable(t *testing.T) {
+	err := errors.New("safew getUpdates status 400: BAD_REQUEST: Conflict: terminated by other getUpdates request; make sure that only one bot instance is running")
+	if !isGetUpdatesConflict(err) {
+		t.Fatal("expected conflict")
+	}
+}