Struct CompactAttachment 

pub struct CompactAttachment {

    pub id: [u8; 32],
    pub key: [u8; 32],
    pub nonce: [u8; 16],
    pub size: u64,
    pub flags: AttachmentFlags,
    pub extension: Box<str>,
    pub url: Box<str>,
    pub path: Box<str>,
    pub img_meta: Option<Box<ImageMetadata>>,
    pub group_id: Option<Box<[u8; 32]>>,
    pub original_hash: Option<Box<[u8; 32]>>,
    pub webxdc_topic: Option<Box<str>>,
    pub mls_filename: Option<Box<str>>,
    pub scheme_version: Option<Box<str>>,
    pub name: String,
}

Memory-efficient attachment with binary hashes and compact strings.

Compared to the regular Attachment struct (~320+ bytes):

• id (SHA256): [u8; 32] instead of hex String (saves ~56 bytes)
• key: [u8; 32] instead of String (saves ~56 bytes)
• nonce: [u8; 16] instead of String (saves ~32 bytes)
• Bools packed into AttachmentFlags (saves padding)
• Strings use Box (saves 8 bytes each)
• Rare fields boxed (saves ~100+ bytes when None)
• Total: ~120 bytes vs ~320 bytes (62% savings!)

Fields

id: [u8; 32]

SHA256 file hash as binary (was hex String)

key: [u8; 32]

Encryption key - 32 bytes (empty = legacy derived)

nonce: [u8; 16]

Encryption nonce - 16 bytes (AES-256-GCM with 0xChat compatibility)

size: u64

File size in bytes

flags: AttachmentFlags

Packed boolean flags (downloading, downloaded)

extension: Box<str>

File extension (e.g., “png”, “mp4”)

url: Box<str>

Host URL (blossom server, etc.)

path: Box<str>

Local file path (empty if not downloaded)

img_meta: Option<Box<ImageMetadata>>

Image metadata (only for images/videos)

group_id: Option<Box<[u8; 32]>>

Legacy group ID for key derivation

original_hash: Option<Box<[u8; 32]>>

Original file hash before encryption

webxdc_topic: Option<Box<str>>

WebXDC topic (Mini Apps only - very rare)

mls_filename: Option<Box<str>>

Legacy filename for AAD

scheme_version: Option<Box<str>>

Scheme version (e.g., “mip04-v1”)

name: String

Original filename (e.g. “memories.zip”). Empty = fallback to {hash}.{ext}

Implementations

impl CompactAttachment

pub fn downloaded(&self) -> bool

pub fn downloading(&self) -> bool

pub fn set_downloaded(&mut self, value: bool)

pub fn set_downloading(&mut self, value: bool)

pub fn id_eq(&self, hex_id: &str) -> bool

Check if this attachment’s ID matches a hex string

pub fn id_hex(&self) -> String

Get file ID as hex string

pub fn key_hex(&self) -> String

Get encryption key as hex string (empty if zeros)

pub fn nonce_hex(&self) -> String

Get nonce as hex string (empty if zeros, respects original length)

pub fn from_attachment(att: &Attachment) -> Self

Convert from regular Attachment (borrowed)

pub fn from_attachment_owned(att: Attachment) -> Self

Convert from regular Attachment (owned) - zero-copy where possible

pub fn to_attachment(&self) -> Attachment

Convert back to regular Attachment

Trait Implementations

impl Clone for CompactAttachment

fn clone(&self) -> CompactAttachment

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CompactAttachment

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl DeepSize for CompactAttachment

fn deep_size(&self) -> usize