W3C Context Protocol

Dependency resolution rides the platform event flow instead of a virtual container tree. A consumer dispatches a context-request event; the nearest mounted ancestor that owns the token answers through the callback.

The request

import { inject } from '@sandlada/document-context/dom'

const auth = inject('auth-service')(document.getElementById('login-btn')!)

Underneath, this dispatches a ContextRequestEvent with bubbles: true, composed: true, cancelable: true. composed: true is what lets the request cross Shadow DOM boundaries, including closed roots, because the provider answers via detail.callback without reading event.target.

Provider answers

Mounted elements listen for context-request, lazily instantiate or reuse their scoped instance, invoke callback(instance, unsubscribe), and call stopPropagation() — unless the request sets multi: true, in which case every ancestor accumulates via injectAll.

import { injectAll } from '@sandlada/document-context/dom'

const plugins = injectAll('plugin', { direction: 'topDown' })(childElement)

Streaming subscriptions

Passing subscribe: true keeps the callback alive: the provider re-invokes it on every state change until the consumer calls unsubscribe or the provider session is disposed. Disposal terminates all live streams for that provider.

Rules that prevent bugs

• Unconnected nodes cannot bubble: inject on a detached node falls back to global singletons, otherwise throws UnconnectedNodeError.
• Route caching uses WeakRef and is invalidated by ancestor-tree mutations, so virtual-list recycling never serves a stale provider.
• Async providers coalesce concurrent injectAsync calls and evict rejections for self-healing retries.