EchoHub/auriondocs/Code/src/EchoHub.Core/Models/Attachment.cs.md

Attachment

File: src/EchoHub.Core/Models/Attachment.cs
Kind: class

public class Attachment

Represents a file attached to a message (such as an image, audio, or any file), enabling a message to carry zero or more attachments alongside its text content. The Attachment entity associates a downloadable resource with its parent Message via MessageId and, optionally, Message, while storing the attachment's URL (Url), filename (FileName), size (FileSize), type (Kind), and an optional ASCII preview (AsciiPreview).

Remarks

Attachments decouple media from the textual content of a message, allowing the system to manage downloads, permissions, and encryption independently from the message body. The AsciiPreview provides a lightweight visual cue for image attachments, and its presence is influenced by how media is encrypted at rest or within channel scopes. The AttachmentKind helps callers distinguish among images, audio, and other file types to apply appropriate handling.

Notes

• The Url is a relative download path (for example, /api/files/{fileId}); clients should prefix it with the API base URL when constructing a full link.
• The AsciiPreview is null for non-image attachments and is stored encrypted at rest in encrypted channels.
• The FileSize is the number of bytes stored for the attachment and may reflect ciphertext size when encryption is enabled.