Function encode_frame 

pub fn encode_frame(value: &impl Serialize) -> Result<Vec<u8>, ProtocolError>

Encode a serializable value into a length-prefixed protocol frame.

The wire format is:

• 4-byte big-endian payload length (u32)
• JSON payload bytes

Returns

Ok(Vec<u8>) on succesfull frame encoding.

Errors

Returns ProtocolError if:

• serialization fails,
• the serialized payload is too large to fit into a u32 length prefix,
• the required output buffer capacity would overflow usize.