Module history 

Append-only view of a session’s chat history.

The core Phase A invariant is that [Session::messages] is the pure record of what happened and is never mutated by compression, experimental dedup / snippet strategies, or pairing repair. This module provides a typestate-style wrapper, History, whose only mutating method is append — making it a compile-time error for a new caller to acquire a &mut Vec<Message> and rewrite the buffer in place.

Scope

This is a foundation for the visibility tightening described in the refactor plan. The public [Session::messages] field stays pub for now so the crate keeps building across every caller (19 files, ~51 usages at the time of this refactor). New code paths should reach for [Session::history] instead. Future PRs can tighten messages to pub(crate) — each remaining direct-mutation site then surfaces as a compile error and is migrated onto this typestate.

Examples

use codetether_agent::session::Session;

let session = Session::new().await.unwrap();
let view = session.history();
assert!(view.is_empty());

use codetether_agent::provider::{ContentPart, Message, Role};
use codetether_agent::session::history::History;

let mut buf: Vec<Message> = Vec::new();
let mut history = History::new(&mut buf);
history.append(Message {
    role: Role::User,
    content: vec![ContentPart::Text {
        text: "hello".to_string(),
    }],
});
assert_eq!(history.view().len(), 1);

Structs

History

Append-only handle to a chat-history buffer.