@executioncontrolprotocol/core

Runtime-agnostic ECP core: fluent workflow API, environment builder, registry, in-memory executor, encode/decode/patch/invoke, and Fluent rendering.

This package has no Node or browser I/O on its main entry. Host-specific compile and file loading live on subpaths (see below).

Main entry (@executioncontrolprotocol/core)

Use for:

• Building environments: environment(), extension(), runtime(), policy()
• Operational APIs on Ecp after await env.init(): run, encode, decode, patch, validate, describe, search, invoke, terminate
• Workflow authoring: workflow(), step(), .accepts() / .returns(), parallel(), etc.
• Fluent output: ecp.encode(manifest).as("fluent") (no @executioncontrolprotocol/format-fluent extension)

Do not import Node built-ins from the main barrel. Bundlers (Vite, etc.) should resolve only @executioncontrolprotocol/core for browser apps.

import { workflow, step, ref } from "@executioncontrolprotocol/core"

const manifest = workflow("Weekly brief")
  .accepts({ type: "object", properties: { prompt: { type: "string" } }, required: ["prompt"] })
  .returns({ type: "object", properties: { echo: { type: "object" } } })
  .run([step("@executioncontrolprotocol/test.echo", "Echo").with({ value: ref("prompt") }).as("echo")])
  .toManifest()

Host subpaths

| Subpath | Host | Purpose | | ------- | ---- | ------- | | @executioncontrolprotocol/core/node | Node | Re-exports @executioncontrolprotocol/core/loaders + @executioncontrolprotocol/core/compile | | @executioncontrolprotocol/core/compile | Node | compileWorkflowSource, compileHarnessArtifactSource (intent/reply TS), temp-file module eval | | @executioncontrolprotocol/core/loaders | Node | File I/O for CLI and Node apps | | @executioncontrolprotocol/core/browser | Browser | Authoring subset: builders, validate, Fluent encode, browser-safe compileWorkflowSource + compileHarnessArtifactSource (esbuild-wasm + blob import) |

CLI and @executioncontrolprotocol/node import @executioncontrolprotocol/core/compile and @executioncontrolprotocol/core/loaders directly—not the main barrel.

Why compile is here (not on runtime hosts): harnesses must compile Fluent/TS artifacts without importing @executioncontrolprotocol/node or @executioncontrolprotocol/browser. Same APIs; Node vs browser entry (or "browser" condition on ./compile). Hosts may re-export for convenience.

Environment vs Ecp

| Environment (builder) | Ecp (after init()) | | ----------------------- | ---------------------- | | withRuntime, withExtensions, withPolicies | run, encode, decode, patch, validate, invoke | | init() | describe, search, terminate |

Related packages

• @executioncontrolprotocol/node — Node runtime, process env, secrets, re-exports Node compile
• @executioncontrolprotocol/browser — Browser runtime, registry, session config (not the demo app)
• @executioncontrolprotocol/types — Protocol types and JSON Schema outputs

See AGENTS.md for monorepo commands and extension rules.