fix: gracefully handle deleted memos in activity service to prevent inbox crashes

server/router/api/v1/activity_service.go

@@ -34,9 +34,12 @@ func (s *APIV1Service) ListActivities(ctx context.Context, request *v1pb.ListAct
 	for _, activity := range activities {
 		activityMessage, err := s.convertActivityFromStore(ctx, activity)
 		if err != nil {
-			return nil, status.Errorf(codes.Internal, "failed to convert activity from store: %v", err)
+			// Skip activities that reference deleted memos instead of failing the entire list
+			continue
+		}
+		if activityMessage != nil {
+			activityMessages = append(activityMessages, activityMessage)
 		}
-		activityMessages = append(activityMessages, activityMessage)
 	}
 
 	return &v1pb.ListActivitiesResponse{
@@ -61,16 +64,24 @@ func (s *APIV1Service) GetActivity(ctx context.Context, request *v1pb.GetActivit
 	if err != nil {
 		return nil, status.Errorf(codes.Internal, "failed to convert activity from store: %v", err)
 	}
+	if activityMessage == nil {
+		return nil, status.Errorf(codes.NotFound, "activity references deleted content")
+	}
 	return activityMessage, nil
 }
 
 // convertActivityFromStore converts a storage-layer activity to an API activity.
 // This handles the mapping between internal activity representation and the public API,
 // including proper type and level conversions.
+// Returns nil if the activity references deleted content (to allow graceful skipping).
 func (s *APIV1Service) convertActivityFromStore(ctx context.Context, activity *store.Activity) (*v1pb.Activity, error) {
 	payload, err := s.convertActivityPayloadFromStore(ctx, activity.Payload)
 	if err != nil {
-		return nil, status.Errorf(codes.Internal, "failed to convert activity payload from store: %v", err)
+		return nil, err
+	}
+	// Skip activities that reference deleted memos
+	if payload == nil {
+		return nil, nil
 	}
 
 	// Convert store activity type to proto enum
@@ -103,6 +114,7 @@ func (s *APIV1Service) convertActivityFromStore(ctx context.Context, activity *s
 
 // convertActivityPayloadFromStore converts a storage-layer activity payload to an API payload.
 // This resolves references (e.g., memo IDs) to resource names for the API.
+// Returns nil if the activity references deleted content (to allow graceful skipping).
 func (s *APIV1Service) convertActivityPayloadFromStore(ctx context.Context, payload *storepb.ActivityPayload) (*v1pb.ActivityPayload, error) {
 	v2Payload := &v1pb.ActivityPayload{}
 	if payload.MemoComment != nil {
@@ -114,8 +126,9 @@ func (s *APIV1Service) convertActivityPayloadFromStore(ctx context.Context, payl
 		if err != nil {
 			return nil, status.Errorf(codes.Internal, "failed to get memo: %v", err)
 		}
+		// If the comment memo was deleted, skip this activity gracefully
 		if memo == nil {
-			return nil, status.Errorf(codes.NotFound, "memo does not exist")
+			return nil, nil
 		}
 
 		// Fetch the related memo (the one being commented on)
@@ -126,6 +139,10 @@ func (s *APIV1Service) convertActivityPayloadFromStore(ctx context.Context, payl
 		if err != nil {
 			return nil, status.Errorf(codes.Internal, "failed to get related memo: %v", err)
 		}
+		// If the related memo was deleted, skip this activity gracefully
+		if relatedMemo == nil {
+			return nil, nil
+		}
 
 		v2Payload.Payload = &v1pb.ActivityPayload_MemoComment{
 			MemoComment: &v1pb.ActivityMemoCommentPayload{

server/router/api/v1/test/activity_deleted_memo_test.go

@@ -0,0 +1,263 @@
+package test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	apiv1 "github.com/usememos/memos/proto/gen/api/v1"
+	v1 "github.com/usememos/memos/server/router/api/v1"
+	"github.com/usememos/memos/store"
+)
+
+// TestListActivitiesWithDeletedMemos verifies that ListActivities gracefully handles
+// activities that reference deleted memos instead of crashing the entire request.
+func TestListActivitiesWithDeletedMemos(t *testing.T) {
+	ctx := context.Background()
+	ts := NewTestService(t)
+	defer ts.Cleanup()
+
+	// Create two users - one to create memo, one to comment
+	userOne, err := ts.CreateRegularUser(ctx, "test-user-1")
+	require.NoError(t, err)
+	userOneCtx := ts.CreateUserContext(ctx, userOne.ID)
+
+	userTwo, err := ts.CreateRegularUser(ctx, "test-user-2")
+	require.NoError(t, err)
+	userTwoCtx := ts.CreateUserContext(ctx, userTwo.ID)
+
+	// Create a memo by userOne
+	memo1, err := ts.Service.CreateMemo(userOneCtx, &apiv1.CreateMemoRequest{
+		Memo: &apiv1.Memo{
+			Content:    "Original memo",
+			Visibility: apiv1.Visibility_PUBLIC,
+		},
+	})
+	require.NoError(t, err)
+	require.NotNil(t, memo1)
+
+	// Create a comment on the memo by userTwo (this will create an activity for userOne)
+	comment, err := ts.Service.CreateMemoComment(userTwoCtx, &apiv1.CreateMemoCommentRequest{
+		Name: memo1.Name,
+		Comment: &apiv1.Memo{
+			Content:    "This is a comment",
+			Visibility: apiv1.Visibility_PUBLIC,
+		},
+	})
+	require.NoError(t, err)
+	require.NotNil(t, comment)
+
+	// Verify activity was created for the comment (check from userOne's perspective - they receive the notification)
+	activities, err := ts.Service.ListActivities(userOneCtx, &apiv1.ListActivitiesRequest{})
+	require.NoError(t, err)
+	initialActivityCount := len(activities.Activities)
+	require.Greater(t, initialActivityCount, 0, "Should have at least one activity")
+
+	// Delete the original memo (this deletes the comment too)
+	_, err = ts.Service.DeleteMemo(userOneCtx, &apiv1.DeleteMemoRequest{
+		Name: memo1.Name,
+	})
+	require.NoError(t, err)
+
+	// List activities again - should succeed even though the memo is deleted
+	activities, err = ts.Service.ListActivities(userOneCtx, &apiv1.ListActivitiesRequest{})
+	require.NoError(t, err)
+	// Activities list should be empty or not contain the deleted memo activity
+	for _, activity := range activities.Activities {
+		if activity.Payload != nil && activity.Payload.GetMemoComment() != nil {
+			require.NotEqual(t, memo1.Name, activity.Payload.GetMemoComment().Memo,
+				"Activity should not reference deleted memo")
+		}
+	}
+	// After deletion, there should be fewer activities
+	require.LessOrEqual(t, len(activities.Activities), initialActivityCount-1,
+		"Should have filtered out the activity for the deleted memo")
+}
+
+// TestGetActivityWithDeletedMemo verifies that GetActivity returns a proper error
+// when trying to fetch an activity that references a deleted memo.
+func TestGetActivityWithDeletedMemo(t *testing.T) {
+	ctx := context.Background()
+	ts := NewTestService(t)
+	defer ts.Cleanup()
+
+	// Create two users
+	userOne, err := ts.CreateRegularUser(ctx, "test-user-1")
+	require.NoError(t, err)
+	userOneCtx := ts.CreateUserContext(ctx, userOne.ID)
+
+	userTwo, err := ts.CreateRegularUser(ctx, "test-user-2")
+	require.NoError(t, err)
+	userTwoCtx := ts.CreateUserContext(ctx, userTwo.ID)
+
+	// Create a memo by userOne
+	memo1, err := ts.Service.CreateMemo(userOneCtx, &apiv1.CreateMemoRequest{
+		Memo: &apiv1.Memo{
+			Content:    "Original memo",
+			Visibility: apiv1.Visibility_PUBLIC,
+		},
+	})
+	require.NoError(t, err)
+	require.NotNil(t, memo1)
+
+	// Create a comment to trigger activity creation by userTwo
+	comment, err := ts.Service.CreateMemoComment(userTwoCtx, &apiv1.CreateMemoCommentRequest{
+		Name: memo1.Name,
+		Comment: &apiv1.Memo{
+			Content:    "Comment",
+			Visibility: apiv1.Visibility_PUBLIC,
+		},
+	})
+	require.NoError(t, err)
+	require.NotNil(t, comment)
+
+	// Get the activity ID by listing activities from userOne's perspective
+	activities, err := ts.Service.ListActivities(userOneCtx, &apiv1.ListActivitiesRequest{})
+	require.NoError(t, err)
+	require.Greater(t, len(activities.Activities), 0)
+
+	activityName := activities.Activities[0].Name
+
+	// Delete the memo
+	_, err = ts.Service.DeleteMemo(userOneCtx, &apiv1.DeleteMemoRequest{
+		Name: memo1.Name,
+	})
+	require.NoError(t, err)
+
+	// Try to get the specific activity - should return NotFound error
+	_, err = ts.Service.GetActivity(userOneCtx, &apiv1.GetActivityRequest{
+		Name: activityName,
+	})
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "activity references deleted content")
+}
+
+// TestActivitiesWithPartiallyDeletedMemos verifies that when some memos are deleted,
+// other valid activities are still returned.
+func TestActivitiesWithPartiallyDeletedMemos(t *testing.T) {
+	ctx := context.Background()
+	ts := NewTestService(t)
+	defer ts.Cleanup()
+
+	// Create two users
+	userOne, err := ts.CreateRegularUser(ctx, "test-user-1")
+	require.NoError(t, err)
+	userOneCtx := ts.CreateUserContext(ctx, userOne.ID)
+
+	userTwo, err := ts.CreateRegularUser(ctx, "test-user-2")
+	require.NoError(t, err)
+	userTwoCtx := ts.CreateUserContext(ctx, userTwo.ID)
+
+	// Create two memos by userOne
+	memo1, err := ts.Service.CreateMemo(userOneCtx, &apiv1.CreateMemoRequest{
+		Memo: &apiv1.Memo{
+			Content:    "First memo",
+			Visibility: apiv1.Visibility_PUBLIC,
+		},
+	})
+	require.NoError(t, err)
+
+	memo2, err := ts.Service.CreateMemo(userOneCtx, &apiv1.CreateMemoRequest{
+		Memo: &apiv1.Memo{
+			Content:    "Second memo",
+			Visibility: apiv1.Visibility_PUBLIC,
+		},
+	})
+	require.NoError(t, err)
+
+	// Create comments on both by userTwo (creates activities for userOne)
+	_, err = ts.Service.CreateMemoComment(userTwoCtx, &apiv1.CreateMemoCommentRequest{
+		Name: memo1.Name,
+		Comment: &apiv1.Memo{
+			Content:    "Comment on first",
+			Visibility: apiv1.Visibility_PUBLIC,
+		},
+	})
+	require.NoError(t, err)
+
+	_, err = ts.Service.CreateMemoComment(userTwoCtx, &apiv1.CreateMemoCommentRequest{
+		Name: memo2.Name,
+		Comment: &apiv1.Memo{
+			Content:    "Comment on second",
+			Visibility: apiv1.Visibility_PUBLIC,
+		},
+	})
+	require.NoError(t, err)
+
+	// Should have 2 activities from userOne's perspective
+	activities, err := ts.Service.ListActivities(userOneCtx, &apiv1.ListActivitiesRequest{})
+	require.NoError(t, err)
+	require.Equal(t, 2, len(activities.Activities))
+
+	// Delete first memo
+	_, err = ts.Service.DeleteMemo(userOneCtx, &apiv1.DeleteMemoRequest{
+		Name: memo1.Name,
+	})
+	require.NoError(t, err)
+
+	// List activities - should still work and return only the second memo's activity
+	activities, err = ts.Service.ListActivities(userOneCtx, &apiv1.ListActivitiesRequest{})
+	require.NoError(t, err)
+	require.Equal(t, 1, len(activities.Activities), "Should have 1 activity remaining")
+
+	// Verify the remaining activity relates to a valid memo
+	require.NotNil(t, activities.Activities[0].Payload.GetMemoComment())
+	require.Contains(t, activities.Activities[0].Payload.GetMemoComment().RelatedMemo, "memos/")
+}
+
+// TestActivityStoreDirectDeletion tests the scenario where a memo is deleted directly
+// from the store (simulating database-level deletion or migration).
+func TestActivityStoreDirectDeletion(t *testing.T) {
+	ctx := context.Background()
+	ts := NewTestService(t)
+	defer ts.Cleanup()
+
+	user, err := ts.CreateRegularUser(ctx, "test-user")
+	require.NoError(t, err)
+	userCtx := ts.CreateUserContext(ctx, user.ID)
+
+	// Create a memo
+	memo1, err := ts.Service.CreateMemo(userCtx, &apiv1.CreateMemoRequest{
+		Memo: &apiv1.Memo{
+			Content:    "Test memo",
+			Visibility: apiv1.Visibility_PUBLIC,
+		},
+	})
+	require.NoError(t, err)
+
+	// Create a comment
+	comment, err := ts.Service.CreateMemoComment(userCtx, &apiv1.CreateMemoCommentRequest{
+		Name: memo1.Name,
+		Comment: &apiv1.Memo{
+			Content:    "Test comment",
+			Visibility: apiv1.Visibility_PUBLIC,
+		},
+	})
+	require.NoError(t, err)
+
+	// Extract memo UID from the comment name
+	commentMemoUID, err := v1.ExtractMemoUIDFromName(comment.Name)
+	require.NoError(t, err)
+
+	commentMemo, err := ts.Store.GetMemo(ctx, &store.FindMemo{
+		UID: &commentMemoUID,
+	})
+	require.NoError(t, err)
+	require.NotNil(t, commentMemo)
+
+	// Delete the comment memo directly from store (simulating orphaned activity)
+	err = ts.Store.DeleteMemo(ctx, &store.DeleteMemo{ID: commentMemo.ID})
+	require.NoError(t, err)
+
+	// List activities should still succeed even with orphaned activity
+	activities, err := ts.Service.ListActivities(userCtx, &apiv1.ListActivitiesRequest{})
+	require.NoError(t, err)
+	// Activities should be empty or not include the orphaned one
+	for _, activity := range activities.Activities {
+		if activity.Payload != nil && activity.Payload.GetMemoComment() != nil {
+			require.NotEqual(t, comment.Name, activity.Payload.GetMemoComment().Memo,
+				"Should not return activity with deleted memo")
+		}
+	}
+}