Handle bundled collection poster failures gracefully

- Log poster store/update failures instead of aborting collection sync
- Preallocate matched collection replacements using the active limit

internal/api/handlers/library_collections.go

@@ -130,7 +130,14 @@ func (h *LibraryCollectionHandler) storeBundledTemplatePoster(
 		posterPath,
 	)
 	if err != nil || !stored {
-		return false, storedPath, thumbhash, err
+		if err != nil {
+			slog.Warn("failed to store bundled template poster",
+				"collection_id", collectionID,
+				"poster_path", posterPath,
+				"error", err,
+			)
+		}
+		return false, storedPath, thumbhash, nil
 	}
 
 	notAutoGenerated := false
@@ -144,7 +151,13 @@ func (h *LibraryCollectionHandler) storeBundledTemplatePoster(
 		input.PosterFromTemplate = &fromTemplate
 	}
 	if err := h.repo.Update(ctx, input); err != nil {
-		return false, "", "", fmt.Errorf("updating bundled poster path: %w", err)
+		slog.Warn("failed to persist bundled template poster",
+			"collection_id", collectionID,
+			"poster_path", posterPath,
+			"stored_path", storedPath,
+			"error", err,
+		)
+		return false, "", "", nil
 	}
 	return true, storedPath, thumbhash, nil
 }

internal/api/handlers/user_collection_imports.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"io/fs"
+	"log/slog"
 	"net/http"
 	"strings"
 	"time"
@@ -270,7 +271,14 @@ func (h *UserCollectionImportHandler) storeBundledTemplatePoster(
 		posterPath,
 	)
 	if err != nil || !stored {
-		return err
+		if err != nil {
+			slog.Warn("failed to store bundled user collection poster",
+				"collection_id", collection.ID,
+				"poster_path", posterPath,
+				"error", err,
+			)
+		}
+		return nil
 	}
 
 	if err := store.UpdateCollection(r.Context(), userstore.UpdateCollectionInput{
@@ -279,7 +287,13 @@ func (h *UserCollectionImportHandler) storeBundledTemplatePoster(
 		PosterURL:        &storedPath,
 		PosterThumbhash:  &thumbhash,
 	}); err != nil {
-		return fmt.Errorf("persisting template poster: %w", err)
+		slog.Warn("failed to persist bundled user collection poster",
+			"collection_id", collection.ID,
+			"poster_path", posterPath,
+			"stored_path", storedPath,
+			"error", err,
+		)
+		return nil
 	}
 	collection.PosterURL = storedPath
 	collection.PosterThumbhash = thumbhash

internal/usercollections/sync.go

@@ -243,8 +243,12 @@ func (s *Service) filterByLibraries(ctx context.Context, matched []userstore.Col
 // content_id for each, and produces deduped, position-numbered replacements
 // plus an unmatched count. Shared by all three source backends.
 func resolveMatchedWithLimit(total int, limit *int, resolve func(i int) string) ([]userstore.CollectionItemReplacement, int, int) {
-	matched := make([]userstore.CollectionItemReplacement, 0, total)
-	seen := make(map[string]struct{}, total)
+	capacity := total
+	if limit != nil && *limit > 0 && *limit < total {
+		capacity = *limit
+	}
+	matched := make([]userstore.CollectionItemReplacement, 0, capacity)
+	seen := make(map[string]struct{}, capacity)
 	unmatched := 0
 	scanned := 0
 	for i := 0; i < total; i++ {