@pattern-js/core

The runtime-neutral Pattern execution engine. Plain TypeScript over Web standards (Web Streams, AbortController, fetch, crypto.subtle). One dependency: Zod.

pattern-js.dev · npm

npm install @pattern-js/core

import { Engine, type Workflow } from "@pattern-js/core";

const engine = new Engine();              // base op catalog auto-registered
engine.registerWorkflow(wf);              // validates with human-readable errors
const result = await engine.run(wf, { input: { /* trigger ports */ } });

What's inside

Types & contracts: PortSpec, OpDefinition, Workflow, Principal, hook/event/observability interfaces.
Validation: load-time checks (op/port existence, edge kind & schema compatibility, cycles, boundary pairing) with located, human-readable errors.
Scheduler: value barriers + control pulses + backpressured stream fan-out; skip propagation for branches; sub-workflow invocation.
Op catalog: constants, scalars, strings, objects, arrays (+ higher-order), control flow, data/encoding, time, crypto, http.fetch, the stream ops, WebSocket ops, hooks/events. Browse the generated reference at /docs/ops.
Boundaries: contracts + payload schemas (HTTP, WS, CLI, manual, schedule, hook, event).
Hooks & events, auth (Principal + provider chain), observability (OTLP-shaped spans), transport (in-process; pluggable).

Subpath exports: @pattern-js/core (everything), @pattern-js/core/ops, @pattern-js/core/boundaries.

Key APIs


`new Engine(opts?)`	the façade: registries, services, transport, trace fan-out
`engine.registerWorkflow(wf)`	validate + register (auto-wires `boundary.hook` / `boundary.event`)
`await engine.registerWorkflowAsync(wf)`	same, but runs the resolve phase for boundary config ports
`engine.run(wf, { trigger?, input?, params?, principal? })`	run; returns `RunResult`
`engine.registerOp(op)` / `engine.use(mod)`	extend with ops / a plugin mod
`engine.onTrace(sink)`	subscribe to telemetry
`engine.invokeHook(name, payload)` / `engine.emit(event, payload)`	extensibility
`validateWorkflow(doc, ops)` / `formatGraph(wf, ops)`	validate / render

See authoring ops, concepts, and architecture.