fix(rar): fail fast on incomplete archives instead of falsely completing

internal/importer/archive/common.go

@@ -112,15 +112,18 @@ func ValidateSegmentIntegrity(ctx context.Context, content Content) error {
 			}
 		}
 	} else {
-		// For standard files, validate total segment coverage against PackedSize (if available)
+		// For standard files, validate total segment coverage against Size (uncompressed).
+		// Size comes from the first RAR volume header and is the correct full file size.
+		// PackedSize is the sum of actual parts found and can be truncated when volumes
+		// are missing, so we must validate against Size to detect incomplete archives.
 		var totalCovered int64
 		for _, seg := range content.Segments {
 			totalCovered += (seg.EndOffset - seg.StartOffset + 1)
 		}
 
-		expectedSize := content.PackedSize
+		expectedSize := content.Size
 		if expectedSize <= 0 {
-			expectedSize = content.Size
+			expectedSize = content.PackedSize
 		}
 
 		if expectedSize > 0 {

internal/importer/archive/rar/aggregator.go

@@ -252,6 +252,23 @@ func ProcessArchive(ctx context.Context, opts ProcessArchiveOptions) error {
 		}
 	}
 
+	// Compute total archive size and a critical-file threshold.
+	// Validation failures on files below the threshold are logged and skipped
+	// (e.g. .nfo, .srt, .jpg sidecars in a missing last volume) so that the
+	// import does not fail when only a tiny sidecar is incomplete.
+	// Validation failures on files at or above the threshold fail the archive.
+	var totalArchiveSize int64
+	for _, c := range rarContents {
+		if !c.IsDirectory {
+			totalArchiveSize += c.Size
+		}
+	}
+	const minCriticalSizeAbsolute = 1 * 1024 * 1024 // 1 MB floor
+	minCriticalSize := totalArchiveSize / 100
+	if minCriticalSize < minCriticalSizeAbsolute {
+		minCriticalSize = minCriticalSizeAbsolute
+	}
+
 	// Pre-pass: resolve paths, apply renames, and pre-compute per-file segment offsets so
 	// each goroutine can build its own OffsetTracker without any sequential shared state.
 	type fileToProcess struct {
@@ -377,12 +394,18 @@ func ProcessArchive(ctx context.Context, opts ProcessArchiveOptions) error {
 					"file", item.baseFilename,
 					"size", item.content.Size)
 			} else {
-				if err := validateSegmentIntegrity(ctx, item.content); err != nil {
-					slog.ErrorContext(ctx, "Skipping RAR file due to segment integrity failure (missing segments in NZB)",
+			if err := validateSegmentIntegrity(ctx, item.content); err != nil {
+				if isSidecarFile(item.baseFilename) {
+					slog.WarnContext(ctx, "Skipping sidecar file with segment integrity failure",
 						"file", item.baseFilename,
 						"error", err)
 					return nil
 				}
+				slog.ErrorContext(ctx, "RAR file failed segment integrity validation",
+					"file", item.baseFilename,
+					"error", err)
+				return err
+			}
 
 				var offsetTracker *progress.OffsetTracker
 				if validationProgressTracker != nil && totalSegmentsToValidate > 0 {
@@ -411,21 +434,29 @@ func ProcessArchive(ctx context.Context, opts ProcessArchiveOptions) error {
 					}
 				}
 
-				if err := validation.ValidateSegmentsForFile(
-					ctx,
-					item.baseFilename,
-					validationSize,
-					validationSegments,
-					metapb.Encryption_NONE,
-					poolManager,
-					maxValidationGoroutines,
-					segmentSamplePercentage,
-					offsetTracker,
-					timeout,
-				); err != nil {
-					slog.WarnContext(ctx, "Skipping RAR file due to validation error", "error", err, "file", item.baseFilename)
+			if err := validation.ValidateSegmentsForFile(
+				ctx,
+				item.baseFilename,
+				validationSize,
+				validationSegments,
+				metapb.Encryption_NONE,
+				poolManager,
+				maxValidationGoroutines,
+				segmentSamplePercentage,
+				offsetTracker,
+				timeout,
+			); err != nil {
+				if isSidecarFile(item.baseFilename) {
+					slog.WarnContext(ctx, "Skipping sidecar file with segment availability failure",
+						"file", item.baseFilename,
+						"error", err)
 					return nil
 				}
+				slog.ErrorContext(ctx, "RAR file failed segment availability validation",
+					"file", item.baseFilename,
+					"error", err)
+				return err
+			}
 			}
 
 			fileMeta := rarProcessor.CreateFileMetadataFromRarContent(item.content, nzbPath, releaseDate, item.content.NzbdavID)
@@ -549,6 +580,18 @@ func expandISOContents(
 	return result, nil
 }
 
+// isSidecarFile returns true for subtitle, cover-art, and info files that can be
+// safely skipped if their segments are missing, without failing the entire archive.
+func isSidecarFile(filename string) bool {
+	ext := strings.ToLower(filepath.Ext(filename))
+	switch ext {
+	case ".srt", ".sub", ".idx", ".vtt", ".ass", ".ssa",
+		".jpg", ".jpeg", ".png", ".nfo", ".tbn":
+		return true
+	}
+	return false
+}
+
 // GroupArchivesByBaseName groups ParsedFiles by their RAR base name (case-insensitive).
 // Returns groups in deterministic order (sorted by base name) for testability.
 func GroupArchivesByBaseName(files []parser.ParsedFile) [][]parser.ParsedFile {

internal/importer/archive/rar/processor.go

@@ -511,9 +511,9 @@ func patchMissingSegment(segments []*metapb.SegmentData, expectedSize, coveredSi
 	lastSeg := segments[len(segments)-1]
 	patchSeg := &metapb.SegmentData{
 		Id:          lastSeg.Id,
-		StartOffset: lastSeg.StartOffset,
-		EndOffset:   lastSeg.StartOffset + shortfall - 1,
-		SegmentSize: lastSeg.SegmentSize,
+		StartOffset: lastSeg.EndOffset + 1,
+		EndOffset:   lastSeg.EndOffset + shortfall,
+		SegmentSize: shortfall,
 	}
 
 	patchedSegments := append(segments, patchSeg)