@pattern-js/core

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

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.