Struct RenderCache 

pub struct RenderCache {
    pub chat: ChatState,
    pub wrapped_line_cache: FxHashMap<u64, Vec<Line<'static>>>,
    pub theme: Theme,
    pub hostname: String,
    pub username: String,
    pub version: String,
    /* private fields */
}

Transient render-layer state that lives across frames but isn’t reducer state. Owned by app::run_interactive; passed as &mut to render() per frame.

Contents are pure memoization + UI affordances (scroll position, wrapped-line cache, theme choice). Nothing here affects what the reducer sees or what ends up on disk — the cache can be dropped and rebuilt from &State at any time.

Fields

chat: ChatState

wrapped_line_cache: FxHashMap<u64, Vec<Line<'static>>>

Per-message render cache: (content, theme, width) hash → fully wrapped, role-prefixed assistant lines, so committed messages aren’t re-parsed or re-wrapped every frame (#134).

theme: Theme

hostname: String

Host + user for the status bar’s user@host:cwd line, injected once at startup so StatusWidget::render doesn’t hit the environment on every frame (#55). Process-constant, so caching here is exact. The shell reads the environment and passes the result to RenderCache::new; render itself never does, which is what keeps this module a pure function of its inputs.

username: String

version: String

App version for the status footer. Defaults to the compile-time crate version; the snapshot suite pins it (like hostname/username) so pinned frames survive release bumps.

Implementations

impl RenderCache

pub fn new(hostname: String, username: String) -> Self

hostname and username are parameters rather than environment reads because this module is covered by the layering guard: a std::env call anywhere under src/render is impurity in a tree that is supposed to be a pure function of State. The shell resolves them once at startup (app::run::host_identity); the snapshot and bench rigs pass pinned literals, which is how their frames stay byte-stable across machines.