type-registry-effect

Fetch, cache, and resolve TypeScript type definitions from npm packages for use with Twoslash and other documentation tooling that needs type-aware code samples.

Features

• Composable Effect programs with typed errors and explicit service requirements
• Disk-based caching with XDG Base Directory compliance and TTL support
• Virtual file system generation compatible with @typescript/vfs and Twoslash
• Module resolution via package.json exports, typesVersions, and legacy fields
• Concurrent package loading with graceful degradation on partial failures
• Built-in Effect Metrics (counters and timers) for cache hits, load durations, and batch operations

Installation

npm install type-registry-effect effect @effect/platform

See docs/guides/getting-started.md for peer dependency details.

Quick Start

import { TypeRegistry, PackageSpec } from "type-registry-effect";
import { NodeLayer } from "type-registry-effect/node";
import { Effect } from "effect";

const program = TypeRegistry.getVFS([
  new PackageSpec({ name: "zod", version: "3.23.8" }),
  new PackageSpec({ name: "@effect/schema", version: "0.79.0" }),
]);

const vfs = await Effect.runPromise(Effect.provide(program, NodeLayer));

Documentation

For detailed guides, architecture, and API reference, see docs/.

License

MIT