Maraca: FastPass and presentation lifetimes (0.8.0)
Maraca retains one shared RMT scheduler authority. Jobs waiting for paint, idle or scheduler.postTask no longer occupy its execution slot. Once ready, they rejoin priority selection. Native priorities, cooperative continuations, cancellation and timeouts are preserved.
Demand-driven diagnostics
runtime.subscribe(listener) still receives full immutable snapshots. A publication creates at most one full snapshot, shared by its full-snapshot subscribers. runtime.subscribeEvents(listener) receives an immutable lifecycle event containing type, generation and event-specific fields, without a snapshot wrapper. runtime.snapshot() remains a synchronous, current, full read.
No full subscribers means no automatic full snapshots. Errors, recovery state, counters and immutable lastEvent data remain available. Installing the DEV API does not create continuous snapshot demand. The browser bridge and Material scaffold DEV API use events; a diagnostic tool can explicitly request snapshots afterward. Late attachment, disconnect and reconnect do not require rebooting.
FastPass authoring
action showReports {
execution fastpass
effect navigation "#reports"
}
action dismissPanel {
execution fastpass
effect close surface panel
}
action focusNavigation {
execution fastpass
effect focus surface navigation
}Navigation also accepts a declared input, e.g. input path string followed by effect navigation input.path. Close and focus require named surfaces. Existing event bindings and dispatchCommand() recognize these declarations; dispatchCommand() keeps its Promise contract.
const runtime = createMaracaPlanRuntime({
...ports,
fastPassActions: [{
id: 'shell.navigate', scope: 'main',
effects: [{ kind: 'navigation', path: { kind: 'reference', path: 'input.path' } }]
}]
});
await runtime.boot();
const job = runtime.dispatchFastPass('shell.navigate', { path: '#reports' });
const result = await job.result;The cancellable job uses user-blocking on the shared scheduler and bypasses the business-command Promise chain. Navigation and focus coalesce by scope; the default scope is the runtime. Repeated close is idempotent. Replaced jobs are cancelled, reject their result like other RMT jobs, and are never replayed as ordinary commands.
Navigation/focus use navigationAdapter.navigate and focusAdapter.focus. Close first validates the Surface Controller, then uses the PresentationEffectPort. Custom presentation ports need setSurfaceHidden(id, hidden) for FastPass Close. Ports acknowledge the applied shell intent immediately; loading and animation are separate lifecycle work. Older commands retain ordered model commits while stale presentation commits and navigation/focus effects are discarded.
Compiler and runtime share validation. Reducers, status/result state, data sources, services, streams, resources, custom effects and chained business commands are forbidden. FastPass does not accelerate model transactions or preempt synchronous JavaScript. The default cooperative budget is 8 ms; exceeding it emits a diagnostic.
FastPass navigation accepts local relative routes and fragments only. Absolute URLs (including HTTP(S)), protocol-relative URLs, executable schemes, control characters, backslashes and encoded route syntax that changes scheme or origin are rejected. Literal targets are checked by the compiler and action registration; resolved input targets are checked before any shell effect is scheduled, including when a custom navigation adapter is supplied. Rejection uses xtend.maraca.fastpass.unsafe-navigation at dispatch. The default browser adapter also validates targets and resolves them against the current HTTP(S) Location, independently of document <base> elements. External navigation must use a separately controlled application capability.
Abort boundaries
Managed surfaces expose runtime.getSurfaceBoundary(id); omitting the ID returns the root boundary. External renderers can import createMaracaAbortBoundary({ id, parent }) from @ccslabs/xtend/maraca/plan-runtime.
The contract provides capture(), isCurrent(token), invalidate(reason), dispose() and the current signal. setActive(false) also prevents new presentation work; reactivation starts a fresh epoch. run(work, token) settles obsolete work as { ok: false, status: 'superseded' }. commit(work, token) guards a synchronous mutation. scheduleCommit(scheduler, work, token, request) checks again after scheduling and removes pending work on invalidation.
const boundary = runtime.getSurfaceBoundary('panel');
const token = boundary.capture();
const response = await kernel.runtime.requestUiCompute(envelope, {
abortBoundary: boundary, presentationToken: token
});
if (response.status === 'superseded') return;
await boundary.scheduleCommit(kernel.scheduler, () => {
renderer.commit(buildCommit(response));
}, token);Tokens stay on the main thread. They are independent of model versions and worker request generations. Check after a response and immediately before DOM/chart commits, including fallback paths. Supersession must never trigger a synchronous rendering fallback.
Managed boundaries follow successful close, hide, minimize/collapse, route departure, target replacement, data reprojection and disposal. Recreating the same surface ID does not revive old tokens. Failed atomic lifecycle operations leave the boundary unchanged. Hydration receives metadata.surfaces containing each island's id, boundary, token, signal and isCurrent(), plus a root guard. Custom hydrators must carry these guards across async work and check before resource/DOM commits.
Shared prewarming can keep valid cached data and component definitions. Business imports and services retain their own ownership. Cancellation settles and removes only the affected UI worker request, leaving the shared worker available. Guards cannot preempt synchronous code or prevent mutations by an external adapter that ignores them.
See demos/xtendrmt/maraca-fastpass/ for native RMT authoring. The maraca-responsiveness and rmt-kernel-scheduler suites cover ordering and suppressed commits deterministically; browser checks supplement them with visible shell response measurements.
The extended public runtime and presentation adapter use xtend.maraca.plan-runtime.v3 and xtend.rmt.presentation-effect-adapter.v2, following the repository’s major-only schema policy. Existing methods retain their behavior. The additive authoring contract is published in xtend-maraca/fastpass.schema.json; the released RMT v2 document schema stays unchanged.