Function decode_frame 

pub fn decode_frame(
    buf: &[u8],
    max_frame: usize,
) -> Result<Option<(ObsEnvelope, usize)>, Error>

Decode one length-prefixed envelope from buf.

Returns Ok(None) when the buffer is too short to contain a full length + payload; otherwise returns the decoded envelope and the number of bytes consumed. Caller is responsible for draining consumed bytes.

max_frame bounds the declared length — anything larger is treated as a framing error (a well-behaved emitter never produces envelopes that big; crossing the limit usually means the stream is desynchronised).

Errors

Returns io::ErrorKind::InvalidData when the declared length exceeds max_frame or when buffa decoding fails.