index.mdx

title	Kernel & Services
description	The ObjectKernel runtime — plugin host, event bus, service registry, and the versioned services.* APIs your hooks and plugins call.

Kernel & Services

The kernel is ObjectStack's runtime: it loads your metadata artifact, hosts plugins, wires up services, and enforces the lifecycle that keeps the system stable. This module documents the ObjectOS layer in practice — the System Protocol is its normative spec. If you write hooks or plugins, this is where the capability surface you call — ctx.api, ctx.getService(...), and the services.* contract they implement — is documented.

How it fits together

• The ObjectKernel boots through a strict lifecycle and exposes a service registry; everything else — data engine, auth, storage — is a service registered by a plugin.
• Events & hooks are the kernel-level extension points plugins use to react to system activity.
• Runtime services (services.*) are the stable, versioned API surface exposed to hook and action bodies:

API	Stability	What it does
services.data	stable	CRUD and queries with the caller's permission context
services.sharing	stable	buildReadFilter, canEdit, canDelete, canManageShares, grant/revoke, listShares
services.email	stable	send, sendTemplate
services.queue	stable	Background work and queues
services.settings	stable	App/environment settings
services.storage	stable	File storage
services.audit	experimental	Append-only audit sink (query history via services.data)

• Service contracts (IDataEngine, IAuthService, ICacheService, IMetadataService, IStorageService, … in packages/spec/src/contracts/) define what any implementation must provide, so services are swappable — the repo ships runtime service packages for cache, cluster, datasource, i18n, jobs, knowledge, messaging, realtime, and more.
• Cluster semantics define how the runtime behaves beyond a single node — including the per-partition locking the webhook outbox relies on.

What's in this module

Related

• Spec: System Lifecycle, Metadata Service
• Schema reference: Kernel, System, Contracts
• Neighbors: building and packaging plugins is covered in Plugins & Packages; running the kernel in production is covered in Deployment & Operations.