@angulus/core

Components use @Component({selector, templateUrl, styleUrl?, imports?, customElements?}). The decorator is a no-op compile-time marker; mounting an uncompiled class throws. The compiler attaches a render function with defineComponent(Class, (ctx, parent, scope) => {}, scopeId). There is no component registry, runtime template parser, or reflection.

mount(Class, host, {inputs: {name: value}}) returns {instance, scope, destroy()}. Each mount constructs a new instance. Inputs are callable read-only Input<T> values; input(default) is optional and input.required<T>() has a RequiredInput<T> type. Missing required values fail mount. They are available before the first render and mount hooks, not in the constructor or field initializers. output<T>() exposes emit(value) and subscribe(handler) (which returns an unsubscribe function). Use the compiler, not defineComponent, in ordinary application code. Public root mounts dispose automatically on non-persisted pagehide (including full-page HMR reloads). Persisted BFCache transitions retain their state. Explicit destroy() removes that listener and remains safe to call repeatedly. Application bootstrap must still dispose its router and any resources it owns outside mounts.

Checker integrations can extract contracts with InputValue<typeof instance.name> and OutputValue<typeof instance.changed>. A generated helper should prevent the value argument from widening the inferred input type: function checkInput<I extends Input<unknown>>(input: I, value: InputValue<NoInfer<I>>): void {}. Input carries __input: true; required inputs also carry __requiredInput: true.

signal(value) exposes a callable reader, .set(value), and .update(fn). computed(fn) is lazy and tracks dynamic dependencies. Ordinary fields do not become reactive. effect(fn) runs immediately, then once per microtask batch; return a cleanup function to run before reruns and disposal. Effects created in a component scope are automatically disposed. Standalone effects return a disposer. flushSync(fn?) drains queued effects synchronously. batch(fn) documents a batch: all synchronous writes already share the microtask batch. untracked(fn) suppresses dependency collection. Errors propagate; asynchronous update errors are uncaught microtask errors rather than silent failures.

Register onMount(() => cleanup?) and onDestroy(cleanup) during construction, render, or another active scope. Alternatively implement class methods onMount(): void | (() => void) and onDestroy(): void. Order: constructor, inputs and output connections, render, registered mount hooks, class mount hook. A child finishes mounting before its parent's mount hooks. Destroy disposes owned scopes, effects, listeners and rendered nodes; cleanup runs in reverse registration order. Every cleanup is attempted even if another throws. Do not assume DOM remains attached in destroy hooks. DOM creation in a compiled render is staged in a fragment; mount hooks run after the completed tree has been inserted into the host.

For advanced integration, new Scope(parent?) (or createScope) provides run(fn), add(cleanup), mount(), and idempotent dispose(). effect(fn, scope) explicitly owns an effect. A new scope defaults to the active scope. The DOM helpers (element, text, bind, listen, setProperty, ifBlock, forBlock, switchBlock, mountChild) are compiler-facing contracts. Blocks own anchored DOM ranges. Keyed rows preserve node/component identity on reorder, update item/index signals, and reject duplicate keys before changing rows. mountChild renders into the supplied parent and connects reactive input getters and output handlers. Only HTML elements are currently supported (no SVG namespace API).

Dynamic URL bindings allow relative URLs and http:, https:, mailto:, tel:, sms:, ftp:, and blob: schemes. Other explicit schemes, including javascript: and data:, throw visible errors. Dynamic srcset/imagesrcset bindings are not supported; use src. Raw HTML (innerHTML, outerHTML, srcdoc) and on* property/attribute bindings are prohibited; use template event bindings instead. These restrictions are not a substitute for application URL authorization or CSP.