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title: Plugin slots description: Shared slot registry API used by Core, React, and Solid skill: entry: true intents: [plugins, plugin, slots, registry, extensions]

Plugin slots

Plugin slots let a host define typed layout regions and let registered plugins contribute UI to those regions. The host controls layout, slot modes, context, and prop types.

This page owns the shared registry, slot, contribution, mode, and error model. Use the integration for your node type:

• Core plugin slots use BaseRenderable nodes.
• React plugin slots use ReactNode values.
• Solid plugin slots use JSX.Element values.

Slots do not discover packages, read manifests, sandbox code, grant permissions, or manage a complete application plugin lifecycle. Runtime module loading is a separate concern. See Load plugins and modules at runtime.

Concepts

• Host: Defines slot names, slot prop types, and shared context.
• Registry: Stores plugins for one renderer and resolves their contributions.
• Slot: A named region that receives typed props from the host.
• Contribution: A synchronous callback that returns the node type for one slot.
• Slot mode: Combines contribution output with host fallback UI.

Define slots and host context

Slot names map to the props that each slot receives. The registry passes one shared host context to each contribution.

import type { PluginContext } from "@opentui/core"

type AppSlots = {
  statusbar: { user: string }
  sidebar: { section: "left" | "right" }
}

interface AppContext extends PluginContext {
  appName: string
  version: string
}

The context can be any object. PluginContext is an alias for object. Extending it is optional, but a named context type gives every contribution the same contract.

Create a registry

import { createSlotRegistry } from "@opentui/core"

type AppSlots = {
  statusbar: { user: string }
  sidebar: { section: "left" | "right" }
}

const context = { appName: "my-app", version: "1.0.0" }

const registry = createSlotRegistry<string, AppSlots, typeof context>(renderer, "my-app:plugins", context)

The first type parameter, TNode, is the host node type. Use BaseRenderable for Core, ReactNode for React, or JSX.Element for Solid. The framework integrations supply this type.

createSlotRegistry is renderer-scoped. A (renderer, key) pair always returns the same registry. The key lets one renderer contain independent registries.

Another call with the same pair returns the existing registry and applies the new options through configure(). The context argument must use the same object reference. A different reference throws, even when its fields are equal.

// Correct: reuse the same object reference.
const context = { appName: "my-app" }
const reg1 = createSlotRegistry(renderer, "my-key", context)
const reg2 = createSlotRegistry(renderer, "my-key", context) // returns reg1

// Throws: this is a different object reference.
const reg3 = createSlotRegistry(renderer, "my-key", { appName: "my-app" })

Create a renderer-scoped registry while the renderer is live. The factory does not reject a destroyed renderer, and a destroy listener added after destruction does not replay. After asynchronous module loading, check renderer.isDestroyed before you create a registry or register a contribution.

Renderer destruction clears registries that were created before destruction. Clearing a registry calls each registered plugin's dispose() hook.

createCoreSlotRegistry, createReactSlotRegistry, and createSolidSlotRegistry each use a fixed key. Call createSlotRegistry directly when one renderer needs more than one registry for the same node type.

Registry options

All create*SlotRegistry functions accept an optional SlotRegistryOptions object:

Register plugins

const unregister = registry.register({
  id: "clock-plugin",
  order: 0,
  setup(ctx, renderer) {
    // Initialize resources during registration.
  },
  dispose() {
    // Release plugin resources during unregistration or registry clearing.
  },
  slots: {
    statusbar(ctx, props) {
      return `${ctx.appName}:${props.user}`
    },
  },
})

// Later, remove this plugin.
unregister()

register() returns an unregister function. Calling it removes the plugin and calls its dispose hook. A duplicate id throws. If setup throws, the registry reports the error, returns a no-op unregister function, and does not add the plugin.

Plugin interface

The Core integration also supports managed slot contributions with node ownership hooks.

Ordering

Plugins are resolved in this order:

1. order ascending (lower numbers first)
2. Registration order (earlier registrations first)
3. id lexicographic (tie-breaker)

Slot modes

Every slot mount or <Slot> component accepts a mode.

append         host clock sync
replace        clock sync
single_winner  clock

Resolve contributions

const entries = registry.resolveEntries("statusbar")
// Array<{ id: string, renderer: (ctx, props) => TNode }>

const slotRenderers = registry.resolve("statusbar")
// Array<(ctx, props) => TNode>

In this result, renderer means the slot contribution callback. It does not mean the CliRenderer instance.

Use resolveEntries when you need plugin ids alongside the callbacks. Use resolve when you only need the callbacks.

Registry methods

Error handling

Registries expose plugin error events:

registry.onPluginError((event) => {
  console.error(event.pluginId, event.phase, event.source, event.error.message)
})

You can also read and clear buffered errors:

const history = registry.getPluginErrors()
registry.clearPluginErrors()

PluginErrorReport

The reportPluginError method accepts a PluginErrorReport:

PluginErrorEvent

Next

• Core plugin slots define Core node ownership and managed contributions.
• React plugin slots define React reconciliation and failure boundaries.
• Solid plugin slots define Solid ownership and disposal.