@effected/schemastore

Publish Effect Schemas as SchemaStore-shaped Draft-07 JSON Schema documents. Core effect already generates JSON Schema (Schema.toJsonSchemaDocument) and lowers it to Draft-07 (JsonSchema.toDocumentDraft07); this package owns what SchemaStore and the editors expect around that output — the publication shape, the hosted identity a document is published under, the keyword-family gate, catalog entries, lints, versioning, canonical JSON and content-comparing file IO — and the effected schema command runs all of it from one config file.

Pre-1.0.0. This package is part of the @effected/* kit, built on stable Effect v4 (effect ~4.1.0) and still in 0.x development. Stable Effect makes a kit 1.0.0 possible, not automatic. To keep your effect and @effect/* versions on the line the kit is built and tested against, install @effected/pnpm-plugin-effected.

Stability: unstable. This package's API surface is not yet considered complete and may change across 0.x releases. Pin an exact version — even a package marked stable before 1.0.0 can introduce a breaking change by accident, and an exact pin turns that into a type-check error rather than a runtime surprise. Full policy: release strategy.

Install

Two roles: this library is a regular dependency of the application that publishes a schema (its code reads the schema's identity at runtime), and @effected/plugin is a devDependency that provides the effected schema command, which builds and checks the documents.

pnpm add @effected/schemastore effect
pnpm add -D @effected/plugin

Requires Node.js >=24.11.0. ESM-only. effect v4 is the only peer; @effected/semver (version ordering) is the only runtime dependency. There is no validation engine here — SchemaValidator is a contract, and the shipped ajv strict-mode engine is AjvValidator in @effected/engine/schema — so importing this package at runtime never installs or bundles ajv.

How the two packages fit together

The pattern has three parts. The application declares each schema's hosted identity once, next to the schema, and reads the $schema URL it writes into its own output from it. The config file hands the same values to defineConfig. The command derives every path, $id and catalog URL from them, so nothing is spelled twice.

// src/schema/output.ts — the application
import { HostedSchema } from "@effected/schemastore";
import { Schema } from "effect";

export const OUTPUT_SCHEMA_VERSION = "5.2";

export const OutputSchemaIdentity = HostedSchema.github({
  repo: "savvy-web/silk-release-action",
  path: "schemas",
  name: "silk-release-action.output",
  versions: [OUTPUT_SCHEMA_VERSION],
});

// Every payload the application emits names the document it was written against.
export const ReleaseOutput = Schema.Struct({
  $schema: Schema.Literal(OutputSchemaIdentity.$id),
  status: Schema.Literals(["released", "skipped"]),
});

// schemastore.config.ts — the config
import { defineConfig } from "@effected/schemastore";
import { OutputSchemaIdentity, ReleaseOutput } from "./src/schema/output.js";

export default defineConfig({
  name: "silk-release-action",
  outputDir: "schemas",
  schemas: {
    [OutputSchemaIdentity.name]: { schema: ReleaseOutput, hosted: OutputSchemaIdentity },
  },
});

{
  "scripts": {
    "schema:build": "effected schema build",
    "schema:check": "effected schema check"
  }
}

effected schema build writes schemas/5.2/silk-release-action.output-5.2.json with $id equal to OutputSchemaIdentity.$id, closed objects (additionalProperties: false), and the $schema literal the application asserts. effected schema check is the CI gate: it fails when a build would write anything. Bumping the version is one constant. Everything the command does — the drift policy, the published flag, frozen labels, the catalog file, exit codes — is documented on the tool's page.

HostedSchema.github({ repo, branch?, path?, ... }) serves files raw from a repository (branch defaults to main); HostedSchema.schemastore({ name, ... }) publishes to SchemaStore ($id on json.schemastore.org, the catalog URL on www.schemastore.org, flat layout); HostedSchema.custom({ baseUrl, ... }) takes any https:// directory as a string or URL. Each validates the identity — current must be one of versions, two spellings of one label are refused — and throws a plain Error naming the reason. $id, url and fileName answer the current document; idFor, urlFor and fileNameFor answer any advertised version. Versioned files carry SchemaStore's -<version> suffix by default; when the version directory should name the file alone (schemas/6.0/output.json, natural when the repository already names the tool), pass appendVersion: false — it needs the "versioned" layout, since under "flat" every version would share one file name. A consumer test pins target.path === \${outputDir}/${identity.fileName}`to catch a swappedhosted:` the CLI cannot see.

Using the library directly

Everything the command composes is exported, for a program that needs one piece or wants to drive the pipeline itself.

StoreDocument.fromSchema runs the assembly for one schema — 2020-12 generation, Draft-07 lowering, the #/definitions → #/$defs rewrite and the keyword-family gate — so every $ref in a built document resolves against its $defs pool:

import { StoreDocument } from "@effected/schemastore";
import { Effect, Schema } from "effect";

const Config = Schema.Struct({ name: Schema.String });

const program = Effect.gen(function* () {
  const document = yield* StoreDocument.fromSchema(Config, {
    $id: "https://example.com/config.schema.json",
  });
  return yield* Effect.fromResult(document.serializeResult());
});
// { "$schema": "http://json-schema.org/draft-07/schema#", "$id": "…", "type": "object", …, "additionalProperties": false }

Objects are closed by default — a published document is a contract, and this package does not follow core's open default. jsonSchema: { onExcessProperty: "ignore" } on one target (or one defineConfig entry) reopens that document.

SchemaPipeline.run(targets) is the emit loop over a target manifest — generate, lint, validate, gate, write — requiring SchemaFile and SchemaValidator in R. Provide the file service and an engine at the edge; the engine is @effected/engine/schema's:

import { SchemaFile, SchemaPipeline, SchemaTarget } from "@effected/schemastore";
import { AjvValidator } from "@effected/engine/schema";
import * as NodeServices from "@effect/platform-node/NodeServices";
import { Effect, Layer, Schema } from "effect";

const targets = [
  SchemaTarget.make({
    schema: Schema.Struct({ name: Schema.String }),
    $id: "https://example.com/config.schema.json",
    path: "schemas/config.schema.json",
  }),
];

const program = SchemaPipeline.run(targets).pipe(
  Effect.provide(Layer.mergeAll(SchemaFile.layer, AjvValidator.layer).pipe(Layer.provide(NodeServices.layer))),
);

run is two-phase and all-or-nothing across targets: every target is generated, gated and — for a pinned version — classified against its predecessor before any file is written. A blocking finding fails with SchemaGateError; a contract change on a pinned, published version fails with SchemaContractChangeError carrying the nextVersion to publish under instead (contractChanges: "allow" classifies and reports only). check is the same walk with no writes. Findings are values, never logs, and the gating predicate (blocking) is yours to replace.

What the library owns

• HostedSchema — a schema's hosted identity (github, schemastore, custom), deriving $id, the catalog URL and the file name for the current or any advertised version.
• defineConfig — the schemastore.config.ts contract: validated with one Schema.Struct per level (a typo'd key is named, every issue on an entry reported at once), a required config name (the base name of its catalog slice), every path and URL derived from the entry key and its identity, an optional catalog.name display name (defaulting to the key, unique within the config) that renames the catalog entry and nothing else, frozen labels resolved, a branded result the CLI recognises.
• StoreDocument — assembly: fromSchema / fromSchemaResult, the draft07 constructor for hand-built documents, the flat toJson() publication shape, serializeResult(), DRAFT_07_META_SCHEMA.
• KeywordFamilies — the one registry of declared non-standard keyword families (the vscode five, x-taplo, x-tombi-, x-intellij-, and the house x-ai- machine-annotation namespace). Anything outside it fails fromSchema with UndeclaredAnnotationKeyError; nothing is silently dropped.
• SchemaVersioning / SchemaVersion — one-to-three-component version labels, Order, latest, isPinned, next, and the fileName / schemaUrl / catalogUrls derivations.
• CatalogEntry — the catalog.json entry as a Schema.Class, assemble for both catalog modes, and the fileMatch hygiene lint.
• DocumentLint — the total structural lint (UnresolvedRef, UnknownKeyword, DepthExceeded, DescriptionWithoutUrl, …), findings as values.
• SchemaValidator — the validation contract: noop switches it off, makeTest / layerTest are the doubles; ValidationFinding and SchemaValidatorError are its values. The engine is AjvValidator in @effected/engine/schema.
• DocumentDiff — classify two documents as "none" / "annotations" / "contract", the signal for whether a change needs a new version.
• DriftPolicy — the lifecycle rule the CLI applies: published documents are held to a tolerance (strict / semantic / allow), unpublished ones regenerate in place.
• SchemaPipeline — the emit loop: run / check, runOne / checkOne, the gate and the contract guard.
• SchemaFile — write-if-changed IO over core FileSystem / Path, comparing by parsed content so a formatter that owns the file's text does not churn it; check is the non-writing half.
• CanonicalJson — the deterministic serializer (insertion order, tabs, one trailing newline, typed failures) and equals, the one content-equality rule.

License

MIT