chenhg5/cc-connect · error

googlechat: invalid preview handle type %T

Error message

googlechat: invalid preview handle type %T

What it means

This error is returned by UpdateMessage when the `handle` argument passed to it is not a *previewHandle — the concrete type returned by SendPreviewStart. The engine is expected to pass the handle from SendPreviewStart through unchanged (it implements core.MessageUpdater); anything else (replyContext, a string, nil, a handle from another platform) fails this type assertion. The %T verb reports the actual received type to aid debugging.

Source

Thrown at platform/googlechat/streaming.go:81

}

// buildUpdateRequest builds the PATCH URL and JSON body to update a message's text.
func buildUpdateRequest(msgName, content string) (string, []byte, error) {
	u := chatAPIBase + msgName + "?updateMask=text"
	b, err := json.Marshal(map[string]any{"text": content})
	if err != nil {
		return "", nil, fmt.Errorf("googlechat: marshal update body: %w", err)
	}
	return u, b, nil
}

// UpdateMessage patches the preview message text in place. The engine passes the
// handle returned by SendPreviewStart (not the reply context). Implements
// core.MessageUpdater.
func (p *Platform) UpdateMessage(ctx context.Context, handle any, content string) error {
	h, ok := handle.(*previewHandle)
	if !ok {
		return fmt.Errorf("googlechat: invalid preview handle type %T", handle)
	}
	url, body, err := buildUpdateRequest(h.name, content)
	if err != nil {
		return err
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodPatch, url, bytes.NewReader(body))
	if err != nil {
		return fmt.Errorf("googlechat: build update request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	resp, err := p.doRequest(req)
	if err != nil {
		return err
	}
	if _, err := io.Copy(io.Discard, resp.Body); err != nil {
		_ = resp.Body.Close()
		return fmt.Errorf("googlechat: drain update response body: %w", err)
	}

View on GitHub (pinned to 4000b2338a)

Solutions

1. Always pass the exact value returned by SendPreviewStart to UpdateMessage, unmodified
2. Do not construct or substitute handles manually — *previewHandle is an unexported, platform-specific type
3. If storing handles, keep them per-platform and keyed as the engine returns them
4. Check the %T value in the error to identify which wrong type is being passed

Example fix

// before
handle := rctx // wrong: reply context, not the preview handle
err := p.UpdateMessage(ctx, handle, text)
// after
handle, err := p.SendPreviewStart(ctx, rctx, initialText)
if err != nil { return err }
err = p.UpdateMessage(ctx, handle, text)

// caller-side pre-check
if _, ok := handle.(*googlechat.Platform) == false && handle == nil {
    // only pass the exact value returned by SendPreviewStart
}

func isPreviewHandle(handle any) bool {
    _, ok := handle.(interface{ matches(*previewHandle) bool })
    return ok // or, within package: _, ok := handle.(*previewHandle); return ok
}

if err := p.UpdateMessage(ctx, handle, text); err != nil {
    if strings.Contains(err.Error(), "invalid preview handle type") {
        return fmt.Errorf("UpdateMessage requires the value returned by SendPreviewStart, got %v", err)
    }
    return err
}

When it happens

Trigger: UpdateMessage(ctx, handle, content) is called with a value whose dynamic type is not *googlechat.previewHandle: a cached reply context, a plain string message name, a nil interface, or a preview handle produced by a different platform adapter.

Common situations: Custom engine code or plugins that store the reply context instead of the SendPreviewStart return value; mixing handles across platforms (e.g. a feishu handle routed to googlechat); a refactor that changed the handle type without updating all call sites; passing nil after a failed SendPreviewStart.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• googlechat: parse create response: %w
• googlechat: create response missing message name
• googlechat: build update request: %w
• bridge: invalid reply context type %T
• bridge: invalid reply context

AI-assisted analysis of chenhg5/cc-connect@4000b2338a (2026-09-06). Data as JSON: /api/errors/0dc79bc10ffa1a36. Report an issue: GitHub.