Enum HostCommand 

pub enum HostCommand {
    EnqueuePendingWindowCreation {
        entry: PendingWindowCreation,
    },
    DequeuePendingWindowCreation,
    EnqueueBrowserPaneCreate {
        block_id: String,
        label: String,
    },
    TryRegisterBrowserPaneLive {
        block_id: String,
    },
    CompleteBrowserPaneCreate {
        block_id: String,
    },
    EnqueueBrowserPaneClose {
        block_id: String,
    },
    CompleteBrowserPaneClose {
        block_id: String,
    },
    DrainBrowserPaneByLabel {
        label: String,
    },
    AbortBrowserPaneCreate {
        block_id: String,
        reason: String,
    },
    RegisterBrowser {
        label: String,
        browser: Browser,
        kind: BrowserKind,
    },
    UnregisterBrowser {
        label: String,
    },
    StartDrag {
        session: DragSession,
    },
    EndDrag {
        drag_id: String,
        outcome: DragOutcome,
    },
    PoolWindowSpawnStart {
        label: String,
    },
    PoolWindowReady {
        label: String,
    },
    PoolWindowDestroyedBeforePromote {
        label: String,
    },
    PromotePoolWindow {
        label: String,
    },
    PopAndPromoteFrontPoolWindow,
    PoolDrainAll,
    BeginDrain {
        reason: QuitReason,
    },
    ConfirmDrained,
    EnqueueTopLevelWindow {
        request: TopLevelCreationRequest,
    },
    TopLevelCallbackFired {
        label: String,
    },
    TopLevelRendererTerminated {
        label: String,
        status: String,
    },
    TopLevelExternallyClosed {
        label: String,
    },
    SetWindowOpacity {
        label: String,
        opacity: f32,
    },
}

Commands handled by the host reducer.

Manual Debug impl below because RegisterBrowser carries a cef::Browser which doesn’t impl Debug.

Variants

EnqueuePendingWindowCreation

Append a pending-window-creation handoff. Producer side of the pending_window_creations queue (replaces the four direct state.pending_window_creations.lock().push_back(...) sites).

Fields

entry: PendingWindowCreation

DequeuePendingWindowCreation

Pop the head of pending_window_creations. Returns the popped entry via HostEvent::PendingWindowDequeued, or HostEvent::PendingWindowQueueEmpty if the queue was empty. Consumer side of the queue (replaces client.rs::on_after_created’s direct pop_front).

EnqueueBrowserPaneCreate

Caller (pane create code) requests a new pane lifecycle entry. Reducer inserts with Live. Reject if block_id already present.

Fields

block_id: String

label: String

TryRegisterBrowserPaneLive

PR #5 — sole pane registration entry point post-H.1.d.

Replaces pane::lifecycle::PaneStateMachine::try_register_live. Reducer generates the label internally (via next_browser_pane_label) so label assignment is atomic with the entry insert. Returns the outcome via DispatchOutput::browser_pane_register_result:

• Fresh(label): new Live entry inserted; caller posts CreateBrowserPaneTask
• AlreadyLive(label): caller should re-navigate existing browser
• Closing: caller must reject (old teardown still in flight)

Fields

block_id: String

CompleteBrowserPaneCreate

CEF on_after_created fired for a pane browser; confirm it’s Live. No-op if already Live or absent (idempotent against late callbacks).

Fields

block_id: String

EnqueueBrowserPaneClose

Caller requests pane close. Reducer flips entry to Closing and returns the entry’s label via DispatchOutput::closed_browser_pane_label iff the transition actually fired (was Live). Returns None for missing or already-Closing entries (idempotent).

Fields

block_id: String

CompleteBrowserPaneClose

CEF on_before_close fired for a pane; remove entry from map.

Fields

block_id: String

DrainBrowserPaneByLabel

PR #5 — sole label-keyed drain entry point post-H.1.d.

Replaces pane::lifecycle::PaneStateMachine::drain_by_label. Used by BrowserPaneManager::drain_closed_label when CEF’s on_before_close fires for a pane. Removes the entry whose label matches; returns the drained block_id via DispatchOutput::drained_browser_pane_block_id so the caller can also dispatch any block_id-keyed cleanup. Idempotent (None if no match).

Fields

label: String

AbortBrowserPaneCreate

Pane creation failed before reaching Live (e.g., CEF callback never fired, browser host returned 0). Reducer removes entry.

Fields

block_id: String

reason: String

RegisterBrowser

Insert browser into browsers map. Caller is on the CEF UI thread (e.g., client.rs::on_after_created). Reject (with Error) if label already present (collision indicates a bug).

Fields

label: String

browser: Browser

kind: BrowserKind

UnregisterBrowser

Remove browser from browsers map. Idempotent; no-op if absent.

Fields

label: String

StartDrag

Begin a cross-window drag session. Reject if one is already active (singleton invariant).

Fields

session: DragSession

EndDrag

End the active drag. drag_id must match the current session.

Fields

drag_id: String

outcome: DragOutcome

PoolWindowSpawnStart

Pool window spawn started. Adds label to unpromoted set; sets respawn_in_flight = true if not already.

Fields

label: String

PoolWindowReady

Frontend signaled the pool window’s renderer is fully initialized. Move from unpromoted to queue; clear respawn_in_flight.

Fields

label: String

PoolWindowDestroyedBeforePromote

Pool window was destroyed before renderer-ready (e.g., user closed it externally during pre-warm). Remove from unpromoted, clear respawn_in_flight. Reducer may emit a refill effect.

Fields

label: String

PromotePoolWindow

Promote a pool window into a user-visible top-level. Removes from queue and unpromoted, marks the corresponding BrowserHandle as is_pool: false.

Fields

label: String

PopAndPromoteFrontPoolWindow

PR #5 H.4 — atomic pop+promote front of pool queue. Returns the popped label via DispatchOutput::promoted_pool_label, or None if the queue is empty. Replaces the legacy state.window_pool.lock().pop_front() + state.unpromoted_pool_labels.lock().remove pair in promote_pool_window.

PoolDrainAll

Drain all pool windows on shutdown. Idempotent.

BeginDrain

Transition Running → Draining. Suppresses pool refills, awaits drain completion.

Fields

reason: QuitReason

ConfirmDrained

All drainable resources are gone (pool empty, browsers empty). Transition Draining → Quit.

EnqueueTopLevelWindow

Caller requests a top-level window. Reducer either:

• rejects (User-initiated + busy) with Error; caller propagates visible error to frontend.
• queues (Background) for later auto-advance.
• starts immediately (idle slot) and emits Effect::PostCreateWindow.

Fields

request: TopLevelCreationRequest

TopLevelCallbackFired

CEF on_after_created fired for label. If matches in-flight, mark Completed and advance queue. If doesn’t match (orphan from stale state), emit Effect::CloseOrphanBrowser.

Fields

label: String

TopLevelRendererTerminated

CEF on_render_process_terminated fired for the renderer process associated with label. If matches in-flight, mark Failed and advance queue.

Fields

label: String

status: String

TopLevelExternallyClosed

CEF on_before_close fired for label while still in-flight. User or external code closed the window mid-creation. Mark Failed.

Fields

label: String

SetWindowOpacity

Set per-window opacity. Reducer stores the clamped value in window_opacities; the IPC handler applies the Win32 side-effect after host_dispatch returns (pure reducer, no I/O inside).

Fields

label: String

opacity: f32

Trait Implementations

impl Clone for HostCommand

fn clone(&self) -> HostCommand

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for HostCommand

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.