chenhg5/cc-connect · error

slack: SendFile: invalid reply context type %T

Error message

slack: SendFile: invalid reply context type %T

What it means

Type-assertion guard in Slack SendFile: rctx is not the platform's internal replyContext struct, so the destination channel/thread for the file upload is unknown.

Source

Thrown at platform/slack/slack.go:539

// SendObservation implements core.ObserverTarget for terminal session observation.
func (p *Platform) SendObservation(ctx context.Context, channelID, text string) error {
	_, _, err := p.client.PostMessageContext(ctx, channelID,
		slack.MsgOptionText(text, false),
		slack.MsgOptionDisableLinkUnfurl(),
	)
	if err != nil {
		return fmt.Errorf("slack: send observation: %w", err)
	}
	return nil
}

// SendFile uploads and sends a generic file to the channel.
// Implements core.FileSender.
func (p *Platform) SendFile(ctx context.Context, rctx any, file core.FileAttachment) error {
	rc, ok := rctx.(replyContext)
	if !ok {
		return fmt.Errorf("slack: SendFile: invalid reply context type %T", rctx)
	}

	name := file.FileName
	if name == "" {
		name = "attachment"
	}

	_, err := p.client.UploadFileV2Context(ctx, slack.UploadFileV2Parameters{
		Reader:          bytes.NewReader(file.Data),
		FileSize:        len(file.Data),
		Filename:        name,
		Channel:         rc.channel,
		ThreadTimestamp: rc.timestamp,
	})
	if err != nil {
		return fmt.Errorf("slack: send file: %w", err)
	}
	return nil

View on GitHub (pinned to 4000b2338a)

Solutions

1. Pass a Slack-produced reply context

When it happens

Trigger: Thrown at platform/slack/slack.go:539 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of chenhg5/cc-connect@4000b2338a (2026-09-06). Data as JSON: /api/errors/9febd2b1f721e427. Report an issue: GitHub.