Reference

Public API

Exact signatures come from generated declarations; this page identifies the public entrypoints and the job each exported symbol is meant to do.

Export Map

The package exposes three entrypoints.

Entrypoint	Purpose
`alien-middleware`	Core middleware chain, Web request context, fetch adapter, runtime filter, and shared types.
`alien-middleware/srvx`	srvx-specific context creation and fetch adapter helpers.
`alien-middleware/router`	Path and method router that can be composed as middleware.

To inspect the complete declaration surface from the package export map, run:

exports-md package.json --follow

The --follow flag includes helper declarations that appear inside exported types, which is useful for checking that declaration output has useful TSDoc.

Core Entrypoint

Import these symbols from alien-middleware.

Symbol	Kind	Use
`chain`	function	Create an empty chain or normalize an existing middleware or chain.
`MiddlewareChain`	class	Immutable middleware chain with `.use()`, `.isolate()`, `.toHandler()`, and `middlewareCount`.
`createContext`	function	Build a `RequestContext` from a Web `Request` and optional host metadata.
`toFetchHandler`	function	Adapt a `RequestHandler` into a plain fetch-compatible handler.
`filterRuntime`	function	Continue a branch only when `context.host.runtime?.name` matches.
`RequestContext`	type	Context received by middleware.
`WebRequestContext`	interface	Base context shape before plugin properties are intersected in.
`Middleware`	type	Request middleware function contract.
`RequestPlugin`	type	Object returned by middleware to extend context, env, runtime type, or response callbacks.
`RequestMiddleware`	type	Middleware function bound to a particular chain input context.
`RequestHandler`	type	Callable handler produced by a middleware chain.
`RequestHost`	type	Host metadata and lifecycle hooks used by contexts and fetch adapters.
`RequestHostFactory`	type	Per-request function that returns host metadata.
`FetchHandler`	type	Fetch-compatible request-to-response function.
`CreateContextOptions`	interface	Options accepted by `createContext`.
`ToFetchHandlerOptions`	interface	Options accepted by root and srvx `toFetchHandler` adapters.
`EnvAccessor`	type	Callable environment accessor used by `context.env`.
`ResponseCallback`	type	Callback that observes or replaces the generated response.
`MiddlewareTypes`	type	Type metadata carried by chains and handlers.
`MiddlewareContext`	type	Extract the context type produced by a chain or middleware list.
`ApplyMiddleware`	type	Compute chain metadata after appending one middleware.
`ApplyMiddlewares`	type	Compute chain metadata after applying a tuple of middleware.
`ExtractMiddleware`	type	Extract a middleware function type from a middleware or chain.
`AnyMiddleware`	type	Union of middleware functions and middleware chains.
`AnyMiddlewareChain`	type	Minimal metadata shape shared by middleware chains.
`EmptyMiddlewareChain`	type	Chain type used when no middleware has been added.

srvx Entrypoint

Import these symbols from alien-middleware/srvx.

Symbol	Kind	Use
`toFetchHandler`	function	Adapt a chain to srvx `serve({ fetch })` and copy srvx request metadata into `context.host`.
`createContextFromServerRequest`	function	Build a `RequestContext` directly from a srvx `ServerRequest`.
`SrvxRuntime`	type	Runtime metadata type exposed by srvx requests.
`SrvxRequestContext`	type	`RequestContext` specialized with srvx runtime metadata.

Use this entrypoint instead of the root adapter when the handler receives srvx ServerRequest objects.

Router Entrypoint

Import these symbols from alien-middleware/router.

Symbol	Kind	Use
`routes`	function	Create a router that can be added to a middleware chain.
`Router`	type	Callable router with overloaded `.use()` route registration.
`RouteContext`	type	Context passed to route handlers, including typed `params` and `method`.
`RouteHandler`	type	Function contract for route handlers.
`RouterContext`	type	Extract the context type accepted by a router.

Router path params are inferred through pathic. Method filters accept one method, a readonly list of methods, or '*'.

Documentation Boundary

Keep stable behavior in TSDoc near the symbol it describes. Use guides for composition patterns and examples, not for duplicating every overload. When declaration output shows an unexpected symbol, treat that as a package boundary question before documenting it as intentional API.

The API table is the star chart; the alien monolith still insists you read the declaration files.