zendriver 0.2.6

Async-first, undetectable browser automation via the Chrome DevTools Protocol
Documentation 
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//! Per-frame isolated-world execution-context cache.
//!
//! Shared between [`crate::tab::Tab`] (main-frame eval) and
//! [`crate::frame::Frame`] (per-frame eval). Holds the discovered main frame
//! id (cached after the first `Page.getFrameTree` round-trip) and the
//! `executionContextId` returned by `Page.createIsolatedWorld` (cached
//! after first use; invalidated when Chrome reports
//! "Cannot find context with specified id", typically after a navigation
//! destroys the previous context).
//!
//! Pre-P4 this lived as a private type inside `tab.rs`. P4 promotes it to
//! a shared module so [`crate::frame::Frame`] can carry its own per-frame
//! cache without duplicating the struct definition. The visibility stays
//! `pub(crate)` — neither the cache nor its fields are part of the public
//! API.

/// Cache of the discovered main-frame id + the executionContextId for that
/// frame's `zendriver-eval` isolated world.
///
/// Both fields start `None`; the first call to
/// [`crate::tab::Tab::ensure_isolated_world`] populates them in one
/// round-trip pair (`Page.getFrameTree` then `Page.createIsolatedWorld`).
/// Subsequent calls short-circuit on the cached `context_id`.
///
/// When [`crate::tab::Tab::evaluate`] catches Chrome's `-32000 Cannot find
/// context with specified id` error, it sets `context_id = None` (leaving
/// `main_frame_id` intact since the frame is still around) and retries —
/// the next `ensure_isolated_world` call re-runs `Page.createIsolatedWorld`
/// only, skipping the `Page.getFrameTree` round-trip.
#[derive(Default, Debug)]
pub(crate) struct IsolatedWorldCache {
    pub(crate) main_frame_id: Option<String>,
    pub(crate) context_id: Option<i64>,
}