Terminology

Use the left column in prose and the right column in code. Several names on the left are words other frameworks use for something different, which is exactly why they are listed.

Term used here	Name in the code
Provider registry	ProviderRegistry for registration, Inject() and app.resolve for resolution, app.diagnostics() for the view
Provider	what app.provide registers; keyed by a type or a Protocol
Dependency injection	Annotated[T, Inject()], with Scope.APP, Scope.REQUEST, Scope.TRANSIENT
Module	an application package plus a composition root. There is no runtime "module" object to register
Plugin	a Plugin subclass: name, api_version, requires, config_type, register, and optional start and stop
Extension module	a plugin distributed as an installable package
Workflow	Workflow, Step, StepContext, WorkflowExecutor
Intent	a structured call validated against the closed JSON Schema subset
Agent	something you compose: a ToolSet plus the workflow engine
Model capability	ModelCapabilities, enforced through AIUnsupportedCapabilityError before any call
Capability	ambiguous, and avoided here. It means a declared model capability, or what a plugin provides — never a registry of runtime-discovered implementations
Startup and shutdown	app.start() and app.stop(), or async with app.lifespan()

Two terms that are not interchangeable

A module is not a plugin. A module is how you organise an application's own code: a package with a composition root. A plugin is how someone else's code extends an application, through a declared contract. The runtime loads plugins and knows nothing about "modules".

A registry is not a container. app.provide runs while the application is being composed, and choosing an implementation is a decision the application makes then — not a lookup the runtime performs per request. There is no way to resolve a provider by writing its name in a parameter, which is why a misspelled contract is a type error rather than a surprise at runtime.