chenhg5/cc-connect · warning

slack: update preview: %w

Error message

slack: update preview: %w

What it means

UpdateMessage calls client.UpdateMessageContext to edit the preview message via chat.update. This error wraps any failure from that API call — message not found, message_cant_update, rate limit, invalid channel/timestamp, or network error. The preview could not be edited for this throttled update tick.

Source

Thrown at platform/slack/streaming.go:54

	if err != nil {
		return nil, fmt.Errorf("slack: send preview: %w", err)
	}
	return &slackPreviewHandle{channel: rc.channel, timestamp: ts}, nil
}

// UpdateMessage edits the preview message in place. The engine passes the handle
// returned by SendPreviewStart (not the reply context). Implements
// core.MessageUpdater.
func (p *Platform) UpdateMessage(ctx context.Context, previewHandle any, content string) error {
	h, ok := previewHandle.(*slackPreviewHandle)
	if !ok {
		return fmt.Errorf("slack: invalid preview handle type %T", previewHandle)
	}
	_, _, _, err := p.client.UpdateMessageContext(ctx, h.channel, h.timestamp,
		slack.MsgOptionText(core.MarkdownToSlackMrkdwn(content), false),
	)
	if err != nil {
		return fmt.Errorf("slack: update preview: %w", err)
	}
	return nil
}

var (
	_ core.MessageUpdater = (*Platform)(nil)
	_ core.PreviewStarter = (*Platform)(nil)
)

View on GitHub (pinned to 4000b2338a)

Solutions

1. Check the wrapped error: rate_limited => rely on engine throttling/backoff; message_not_found => user deleted it, re-post or stop updating
2. Verify chat:write scope is still granted on the bot token
3. Confirm the preview message's channel/timestamp are still valid
4. Retry on transient network errors; engine throttling usually prevents persistent 429s

Example fix

// before
// preview deleted by user -> chat.update fails with message_not_found
// after
if err := p.UpdateMessage(ctx, handle, content); err != nil {
    slog.Warn("slack: preview update failed, skipping tick", "err", err)
}

if handle == nil { return errors.New("no active preview handle") }

err := p.UpdateMessage(ctx, handle, content)
var rl *slack.RateLimitedError
if errors.As(err, &rl) {
    time.Sleep(rl.RetryAfter)
    err = p.UpdateMessage(ctx, handle, content)
}
if err != nil { slog.Warn("slack: preview update failed", "err", err) } // non-fatal

When it happens

Trigger: UpdateMessageContext fails: ts/channel from the handle no longer valid, the message was deleted by a user, chat:write scope missing, Slack 429 rate limiting, or ctx cancellation.

Common situations: A user deleted the in-progress preview message while the agent streamed; Slack rate limits during long streaming responses (engine throttles, but bursts still hit); token scope changes; channel archived mid-session.

Understand the failure class

Background: "API request failed": what wrapped HTTP errors from external APIs mean and how to find the real cause — this error's family across 29 libraries.

Related errors

• slack: send preview: %w
• stream AI card: status=%d, body=%s
• slack: resolve channel name for %s: %w
• slack: invalid reply context type %T
• slack: invalid preview handle type %T

AI-assisted analysis of chenhg5/cc-connect@4000b2338a (2026-09-06). Data as JSON: /api/errors/b4a92b48494ea760. Report an issue: GitHub.