Systems

Cross-package architectural systems. Each one spans multiple packages and is documented here as a single concept rather than as a set of unrelated package pages.

System	What it is	Page
Ivy runtime	The instruction-based rendering engine that replaced View Engine in v9. Lives in packages/core/src/render3/.	ivy-runtime
Template compiler	The pipeline from .html source to Ivy instructions: @angular/compiler, ngtsc, the linker.	template-compiler
Change detection	How Angular schedules and runs ticks — zone-based and zoneless modes. Spans core and the schedulers.	change-detection
Dependency injection	The hierarchical injector tree, the bloom-filter element injector, and provider scopes.	dependency-injection
Hydration	Reusing server-rendered DOM at client boot. Spans core, platform-server, and platform-browser.	hydration

These systems are the deep magic. A change in one usually requires coordinated changes in others.