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loopctl

`src/message.rs` — the conversation data model

Everything the model ever sees is built from these types: Message, Role, MessagePart, ImageSource, ToolContent, ToolContentPart.

Key items

  • Message { role, parts } — constructors user, assistant, new; readers text_content(), tool_call_parts().
  • Role — User, Assistant, System (snake_case serde).
  • MessagePart — Text, Image, ToolCall { id, name, input }, ToolResult { call_id, name, output, is_error }; constructors text, tool_call, tool_result; predicates is_text etc., as_text().
  • ImageSource::new_base64(media_type, data) — always use the constructor; data must be raw base64 (no data-URI prefix).
  • ToolContent — Text(String) or Multipart(Vec<ToolContentPart>); From<String>/From<&str>; Display joins text parts and skips images.

Behavior notes

  • Tool results ride Role::User messages — provider convention, handled everywhere.
  • ToolCall.id ↔ ToolResult.call_id pairing is the load-bearing link; the engine stamps ids authoritatively.
  • Everything serializes with serde — this is what makes machine checkpointing work.
  • ToolResult.name defaults to "" when deserializing old data (the field came later).

Deep dive: Messages.