Trait Engine 

pub trait Engine {
    // Required methods
    fn open(&mut self, url: &str) -> EngineResult<PageHandle>;
    fn close(&mut self, page: PageHandle) -> EngineResult<()>;
    fn snapshot(&mut self, page: PageHandle) -> EngineResult<Tree>;
    fn act(
        &mut self,
        page: PageHandle,
        target: ActTarget,
        action: Action,
    ) -> EngineResult<()>;
    fn wait(
        &mut self,
        page: PageHandle,
        cond: WaitCondition,
        budget: Duration,
    ) -> EngineResult<()>;
    fn capture(
        &mut self,
        page: PageHandle,
        scope: CaptureScope,
    ) -> EngineResult<PathBuf>;
    fn layout(
        &mut self,
        page: PageHandle,
        refs: &[Ref],
    ) -> EngineResult<Vec<LayoutBox>>;
    fn set_viewport(
        &mut self,
        page: PageHandle,
        viewport: Viewport,
    ) -> EngineResult<()>;
    fn save_auth(&mut self, page: PageHandle) -> EngineResult<AuthBlob>;
    fn load_auth(
        &mut self,
        page: PageHandle,
        blob: &AuthBlob,
    ) -> EngineResult<()>;
    fn capabilities(&self) -> EngineCapabilities;

    // Provided methods
    fn console_entries(
        &mut self,
        _page: PageHandle,
    ) -> EngineResult<Vec<ConsoleEntry>> { ... }
    fn network_entries(
        &mut self,
        _page: PageHandle,
    ) -> EngineResult<Vec<NetworkEntry>> { ... }
    fn request_detail(
        &mut self,
        _page: PageHandle,
        _seq: u64,
    ) -> EngineResult<Option<RequestDetail>> { ... }
    fn eval_js(
        &mut self,
        _page: PageHandle,
        _expr: &str,
    ) -> EngineResult<EvalResult> { ... }
    fn storage(
        &mut self,
        _page: PageHandle,
        _scope: StorageScope,
    ) -> EngineResult<Vec<StorageEntry>> { ... }
    fn cookie_events(
        &mut self,
        _page: PageHandle,
    ) -> EngineResult<Vec<CookieEvent>> { ... }
    fn cursor_op(
        &mut self,
        _page: PageHandle,
        _op: CursorOp,
        _mode: InputMode,
    ) -> EngineResult<()> { ... }
    fn scripts(&mut self, _page: PageHandle) -> EngineResult<Vec<ScriptEntry>> { ... }
    fn script_source(
        &mut self,
        _page: PageHandle,
        _seq: u64,
    ) -> EngineResult<Option<ScriptSource>> { ... }
    fn dom(
        &mut self,
        _page: PageHandle,
        _r: Ref,
        _extra_props: &[String],
    ) -> EngineResult<Option<DomDetail>> { ... }
    fn performance(
        &mut self,
        _page: PageHandle,
    ) -> EngineResult<PerformanceMetrics> { ... }
}

The browser engine, as the daemon sees it.

All methods are synchronous from the daemon’s perspective. The runtime layer dispatches calls onto a dedicated thread that owns the platform run loop; implementations should assume they are running on that thread.

Required Methods

fn open(&mut self, url: &str) -> EngineResult<PageHandle>

Open a fresh page navigated to url.

fn close(&mut self, page: PageHandle) -> EngineResult<()>

Close a page. Idempotent — closing a closed page is a no-op.

fn snapshot(&mut self, page: PageHandle) -> EngineResult<Tree>

Snapshot the a11y tree at page.

fn act( &mut self, page: PageHandle, target: ActTarget, action: Action, ) -> EngineResult<()>

Perform action on target at page.

fn wait( &mut self, page: PageHandle, cond: WaitCondition, budget: Duration, ) -> EngineResult<()>

Wait for cond at page until satisfied or budget elapses.

fn capture( &mut self, page: PageHandle, scope: CaptureScope, ) -> EngineResult<PathBuf>

Take a screenshot. Returns the path on disk where the image was written.

fn layout( &mut self, page: PageHandle, refs: &[Ref], ) -> EngineResult<Vec<LayoutBox>>

Compute layout boxes for refs at page.

fn set_viewport( &mut self, page: PageHandle, viewport: Viewport, ) -> EngineResult<()>

Set the viewport at page. Triggers a re-baseline for the next snapshot.

fn save_auth(&mut self, page: PageHandle) -> EngineResult<AuthBlob>

Snapshot cookies/storage for page as an opaque AuthBlob.

fn load_auth(&mut self, page: PageHandle, blob: &AuthBlob) -> EngineResult<()>

Apply a previously saved AuthBlob to page.

fn capabilities(&self) -> EngineCapabilities

Capabilities the daemon should advertise for this engine.

Provided Methods

fn console_entries( &mut self, _page: PageHandle, ) -> EngineResult<Vec<ConsoleEntry>>

Snapshot the always-captured console ring buffer for page. Default impl returns empty (engines without console capture).

fn network_entries( &mut self, _page: PageHandle, ) -> EngineResult<Vec<NetworkEntry>>

Snapshot the always-captured network ring buffer for page. Default impl returns empty (engines without network capture).

fn request_detail( &mut self, _page: PageHandle, _seq: u64, ) -> EngineResult<Option<RequestDetail>>

Look up the full detail (headers + bodies) for a single captured network request. Returns None if the seq isn’t in the buffer. Default impl returns None.

fn eval_js( &mut self, _page: PageHandle, _expr: &str, ) -> EngineResult<EvalResult>

Evaluate expr in main world. Default impl returns EvalResult::Thrown { kind: "NotImplemented", ... }.

fn storage( &mut self, _page: PageHandle, _scope: StorageScope, ) -> EngineResult<Vec<StorageEntry>>

List storage entries for the requested scope.

fn cookie_events(&mut self, _page: PageHandle) -> EngineResult<Vec<CookieEvent>>

List cookie store ADD/REMOVE events observed since the page opened. Engines without a cookie-changed observer (Windows, the stub) return an empty vec or ENGINE_UNSUPPORTED via their capability flag.

fn cursor_op( &mut self, _page: PageHandle, _op: CursorOp, _mode: InputMode, ) -> EngineResult<()>

Coordinate-addressed cursor operation. Backends that don’t implement native input dispatch fall through to the default ENGINE_UNSUPPORTED here; agents see ! ENGINE_UNSUPPORTED on the wire and can switch to ref-based vs act instead.

fn scripts(&mut self, _page: PageHandle) -> EngineResult<Vec<ScriptEntry>>

List scripts loaded by the page.

fn script_source( &mut self, _page: PageHandle, _seq: u64, ) -> EngineResult<Option<ScriptSource>>

Source of one script by seq. Returns None if the seq isn’t in the script registry.

fn dom( &mut self, _page: PageHandle, _r: Ref, _extra_props: &[String], ) -> EngineResult<Option<DomDetail>>

Outer HTML + computed styles for a ref. Caller-requested computed properties land in extra_props; the engine merges them with its default property set. Returns None for unknown refs.

fn performance(&mut self, _page: PageHandle) -> EngineResult<PerformanceMetrics>

Web Vitals + heap + DOM stats. Returns zero-filled defaults if the engine can’t measure them.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl Engine for WpeBackend