wavetermdev/waveterm · error

error encoding osc message (AdaptMsgChToPty): %w

Error message

error encoding osc message (AdaptMsgChToPty): %w

What it means

AdaptMsgChToPty wraps each channel message in a Wave OSC escape sequence via EncodeWaveOSCBytes before writing to the pty. This error means the OSC encoding step failed for a message, before any bytes were written.

Source

Thrown at pkg/wshutil/wshrpcio.go:53

			return fmt.Errorf("error writing to output (AdaptOutputChToStream): %w", err)
		}
		// write trailing newline
		if _, err := output.Write([]byte{'\n'}); err != nil {
			drain = true
			return fmt.Errorf("error writing trailing newline to output (AdaptOutputChToStream): %w", err)
		}
	}
	return nil
}

func AdaptMsgChToPty(outputCh chan []byte, oscEsc string, output io.Writer) error {
	if len(oscEsc) != 5 {
		panic("oscEsc must be 5 characters")
	}
	for msg := range outputCh {
		barr, err := EncodeWaveOSCBytes(oscEsc, msg)
		if err != nil {
			return fmt.Errorf("error encoding osc message (AdaptMsgChToPty): %w", err)
		}
		if _, err := output.Write(barr); err != nil {
			return fmt.Errorf("error writing osc message (AdaptMsgChToPty): %w", err)
		}
	}
	return nil
}

View on GitHub (pinned to a4447c1563)

Solutions

1. Reduce the message size before sending it through outputCh.
2. Chunk large payloads into multiple smaller messages.
3. Avoid routing bulk data (file reads, large command output) through the OSC message channel.
4. Check message origin upstream and cap payload size there.

Example fix

// before
outputCh <- largePayload // may exceed 64MB
// after
for _, chunk := range chunkBytes(largePayload, 1<<20) {
    outputCh <- chunk
}

if len(msg) > 64*1024*1024 {
    return errors.New("message exceeds OSC encoding limit")
}

if err := AdaptMsgChToPty(ch, oscEsc, pty); err != nil {
    if strings.Contains(err.Error(), "input data too large") {
        return handleOversizedPayload()
    }
    return err
}

When it happens

Trigger: EncodeWaveOSCBytes(oscEsc, msg) returns an error for a message coming off outputCh — practically, when the message exceeds the 64 MB maxSize limit (the oscEsc length is validated by panic at function entry, so encoding failures are effectively size failures).

Common situations: A huge RPC payload (e.g. a large file read result) is routed to terminal output and exceeds the 64 MB OSC limit.

Understand the failure class

Background: payload too large / request exceeds maximum size: why libraries cap bytes and how to fix oversize payloads — this error's family across 50 libraries.

Related errors

• input data too large
• failed to decode base64 data: %w
• oscNum must be 5 characters
• beginning of file
• procinfo: process not found

AI-assisted analysis of wavetermdev/waveterm@a4447c1563 (2026-09-01). Data as JSON: /api/errors/6ea347b83a103a36. Report an issue: GitHub.