wavetermdev/waveterm · error

widget_id must be 8 characters

Error message

widget_id must be 8 characters

What it means

ResolveBlockIdFromPrefix resolves an 8-character block/widget id prefix to a full block id within a tab. It strictly validates the prefix length up front and rejects anything that is not exactly 8 characters with this literal message (the wording says widget_id but it applies to the blockIdPrefix argument).

Source

Thrown at pkg/wcore/wcore.go:131

	if err != nil {
		log.Printf("error getting object for update event: %v", err)
		return
	}
	wps.Broker.Publish(wps.WaveEvent{
		Event:  wps.Event_WaveObjUpdate,
		Scopes: []string{oref.String()},
		Data: waveobj.WaveObjUpdate{
			UpdateType: waveobj.UpdateType_Update,
			OType:      waveObj.GetOType(),
			OID:        waveobj.GetOID(waveObj),
			Obj:        waveObj,
		},
	})
}

func ResolveBlockIdFromPrefix(ctx context.Context, tabId string, blockIdPrefix string) (string, error) {
	if len(blockIdPrefix) != 8 {
		return "", fmt.Errorf("widget_id must be 8 characters")
	}

	tab, err := wstore.DBMustGet[*waveobj.Tab](ctx, tabId)
	if err != nil {
		return "", fmt.Errorf("error getting tab: %w", err)
	}

	for _, blockId := range tab.BlockIds {
		if strings.HasPrefix(blockId, blockIdPrefix) {
			return blockId, nil
		}
	}

	return "", fmt.Errorf("widget_id not found: %q", blockIdPrefix)
}

func GoSendNoTelemetryUpdate(telemetryEnabled bool) {
	go func() {

View on GitHub (pinned to a4447c1563)

Solutions

1. Pass exactly the first 8 characters of the block id
2. Trim/validate the prefix before calling: strings.TrimSpace and len check
3. If you have a full UUID, slice it: id[:8]
4. Check the caller's serialization — some paths may pass an empty string

Example fix

// before
blockId, err := wcore.ResolveBlockIdFromPrefix(ctx, tabId, fullBlockUUID)
// after
if len(fullBlockUUID) >= 8 {
    blockId, err = wcore.ResolveBlockIdFromPrefix(ctx, tabId, fullBlockUUID[:8])
}

if len(strings.TrimSpace(blockIdPrefix)) != 8 {
    return fmt.Errorf("prefix must be exactly 8 chars, got %d", len(blockIdPrefix))
}

When it happens

Trigger: Calling ResolveBlockIdFromPrefix (directly or via CreateToolUseData, getTermScrollbackOutput, or AI tool-use handlers) with a blockIdPrefix whose len() != 8 — e.g. a full 36-char UUID, an empty string, or a truncated prefix of the wrong length.

Common situations: AI/tool integrations passing a full UUID block id instead of the 8-char prefix; frontends sending user-truncated text of arbitrary length; copy/paste errors in tool call arguments.

Related errors

• input is required
• widget_id not found: %q
• invalid simple id format: %s
• Image too large (>5MB)
• Unsupported or invalid image type: ${blob.type}

AI-assisted analysis of wavetermdev/waveterm@a4447c1563 (2026-09-01). Data as JSON: /api/errors/3714e1a37541926c. Report an issue: GitHub.