What causes "invalid rich clipboard asset count [%d]" in siyuan-note/siyuan?

Skip the call entirely when the assets slice is empty (guard with len(assets) == 0 before invoking).

invalid rich clipboard asset count [%d]

Error message

invalid rich clipboard asset count [%d]

What it means

Returned by PrepareRichClipboardAssets when the number of assets supplied in the slice is less than 1 or greater than 1024. The function performs a bounded batch copy of image assets for rich clipboard pasting and rejects empty or oversized batches up front to cap memory and I/O. The %d placeholder is filled with len(assets).

Source

Thrown at kernel/model/clipboard.go:68

	Index int
	Path  string
	Box   string
}

type RichClipboardPreparedAsset struct {
	Index int    `json:"index"`
	Path  string `json:"path"`
}

type RichClipboardPrepared struct {
	Batch  string                       `json:"batch"`
	Groups []string                     `json:"groups"`
	Assets []RichClipboardPreparedAsset `json:"assets"`
}

func PrepareRichClipboardAssets(assets []RichClipboardAsset) (ret *RichClipboardPrepared, err error) {
	if len(assets) < 1 || 1024 < len(assets) {
		return nil, fmt.Errorf("invalid rich clipboard asset count [%d]", len(assets))
	}

	batch := util.RandString(24)
	groups := map[string]struct{}{}
	copied := map[string]string{}
	ret = &RichClipboardPrepared{Batch: batch}
	defer func() {
		if err != nil {
			cleanupRichClipboardGroups(batch, groups)
		}
	}()

	for _, asset := range assets {
		if asset.Index < 0 {
			return nil, fmt.Errorf("invalid rich clipboard asset index [%d]", asset.Index)
		}

		ext := strings.ToLower(filepath.Ext(AssetPathWithoutQuery(asset.Path)))

View on GitHub (pinned to 251596fc0d)

Solutions

Skip the call entirely when the assets slice is empty (guard with len(assets) == 0 before invoking).
If the batch exceeds 1024, chunk the assets into multiple batches of <=1024 and call PrepareRichClipboardAssets per chunk.
Audit the frontend code that builds the assets array to ensure it only includes genuine image references.

Example fix

// before
prepared, err := PrepareRichClipboardAssets(assets)

// after
if len(assets) == 0 {
    return // nothing to do
}
for i := 0; i < len(assets); i += 1024 {
    end := i + 1024
    if end > len(assets) {
        end = len(assets)
    }
    prepared, err := PrepareRichClipboardAssets(assets[i:end])
    // handle prepared, err
}

Defensive patterns

Strategy: validation

Validate before calling

// Validate count before calling PrepareRichClipboardAssets
const maxRichClipboardAssets = 1024
if len(assets) == 0 || len(assets) > maxRichClipboardAssets {
    // chunk or skip
}

Type guard

func isValidRichClipboardCount(n int) bool { return n >= 1 && n <= 1024 }

Try / catch

if err != nil && strings.Contains(err.Error(), "invalid rich clipboard asset count") { /* chunk or abort */ }

Prevention

Skip the call for empty asset slices.
Chunk large pastes into batches of at most 1024 assets.
Audit the frontend asset collector to avoid oversized batches.

When it happens

Trigger: Calling PrepareRichClipboardAssets with an empty slice, or with a slice containing more than 1024 image references (e.g. pasting a document that embeds hundreds of inline images). The check is the very first guard in the function, before any disk work.

Common situations: Frontend paste handler sends an empty assets array because the clipboard contained no images; a large page copy triggers hundreds of embedded images exceeding the 1024 cap; a bug in asset collection produces a nil/empty slice.

Related errors

AI-assisted analysis of siyuan-note/siyuan@251596fc0d (2026-08-12). Data as JSON: /api/errors/74e4fc437d2023e4. Report an issue: GitHub.