wavetermdev/waveterm · error

file part missing mimetype

Error message

file part missing mimetype

What it means

A file-type message part reached convertFileAIMessagePart without a MimeType. The converter needs the mimetype to route the part to image, PDF, text, or directory handling, so a missing one is rejected outright. This is an input validation error, not a network error.

Source

Thrown at pkg/aiusechat/openai/openai-convertmessage.go:329

		}
		if chatOpts.ChatId != "" {
			req.Header.Set("X-Wave-ChatId", chatOpts.ChatId)
		}
		req.Header.Set("X-Wave-Version", wavebase.WaveVersion)
		req.Header.Set("X-Wave-APIType", uctypes.APIType_OpenAIResponses)
		req.Header.Set("X-Wave-RequestType", chatOpts.GetWaveRequestType())
	}

	return req, nil
}

// convertFileAIMessagePart converts a file AIMessagePart to OpenAI format
func convertFileAIMessagePart(part uctypes.AIMessagePart) (*OpenAIMessageContent, error) {
	if part.Type != uctypes.AIMessagePartTypeFile {
		return nil, fmt.Errorf("convertFileAIMessagePart expects 'file' type, got '%s'", part.Type)
	}
	if part.MimeType == "" {
		return nil, fmt.Errorf("file part missing mimetype")
	}

	// Handle different file types
	switch {
	case strings.HasPrefix(part.MimeType, "image/"):
		imageUrl, err := aiutil.ExtractImageUrl(part.Data, part.URL, part.MimeType)
		if err != nil {
			return nil, err
		}

		return &OpenAIMessageContent{
			Type:       "input_image",
			ImageUrl:   imageUrl,
			Filename:   part.FileName,
			PreviewUrl: part.PreviewUrl,
		}, nil

	case part.MimeType == "application/pdf":

View on GitHub (pinned to a4447c1563)

Solutions

1. Set part.MimeType explicitly (e.g. "image/png", "application/pdf", "text/plain") before sending the message
2. Use http.DetectContentType on the file bytes to infer the mimetype when unknown
3. Validate message parts (type + mimetype + data/url present) before calling the chat API

Example fix

// before
part := uctypes.AIMessagePart{Type: uctypes.AIMessagePartTypeFile, FileName: "report.pdf"}
// after
part := uctypes.AIMessagePart{Type: uctypes.AIMessagePartTypeFile, FileName: "report.pdf", MimeType: "application/pdf", Data: pdfBytes}

if part.Type == uctypes.AIMessagePartTypeFile && part.MimeType == "" {
    part.MimeType = http.DetectContentType(part.Data) // infer from bytes
}
if part.MimeType == "" { return errors.New("file part missing mimetype") }

func hasMimetype(p uctypes.AIMessagePart) bool {
    return p.Type == uctypes.AIMessagePartTypeFile && p.MimeType != ""
}

When it happens

Trigger: Adding an AIMessagePart with Type 'file' but leaving MimeType empty (e.g. attached a file from disk without detecting its content type); APIs/paths that build parts from user upload metadata lacking a content-type header.

Common situations: Attachments uploaded through custom frontends that don't set MIME types; files with unrecognized extensions where mime detection returned empty; copying part-construction code and omitting MimeType.

Related errors

• convertFileAIMessagePart expects 'file' type, got '%s'
• invalid AIMessage: %w
• file part missing url
• file part missing mediaType
• invalid data URL format

AI-assisted analysis of wavetermdev/waveterm@a4447c1563 (2026-09-01). Data as JSON: /api/errors/efeb8a62ccfba654. Report an issue: GitHub.