Customizing Agent Native

Rule

Start with the app's registered design system and local UI adapters, then use the public feature's props, semantic components, controller, product slots, and callbacks. If those seams are not enough, use the eject CLI to transfer the smallest supported feature into the app and make that copy app-owned. Never edit node_modules, deep-import a private source file at runtime, or patch an @agent-native/* package.

Use this order:

1. Set brand tokens with the build-time theme configuration when tokens are enough.
2. Register company components in app/design-system.ts with defineDesignSystem, then pass that definition to ToolkitProvider.
3. Configure a public feature through its semantic components, headless controller, and product-level render slots.
4. Compose app primitives behind the app's local UI adapter layer.
5. Eject the smallest feature into app-owned source.
6. Propose a new Toolkit seam when the same override is useful in two apps.

Ejection is for intentional product customization, not for hiding an upgrade failure or replacing Core runtime behavior.

Use A Company Design System

Keep the explicit, typed registration seam in app/design-system.ts:

import { defineDesignSystem } from "@agent-native/toolkit/design-system";
import {
  AcmeActionButtonAdapter,
  AcmeDialogAdapter,
} from "./design-system/acme-adapter";

export const designSystem = defineDesignSystem({
  name: "Acme",
  components: {
    ActionButton: AcmeActionButtonAdapter,
    Dialog: AcmeDialogAdapter,
  },
});

Adapters translate the semantic Toolkit contract into company component props. They are ordinary React components and may use MUI-style providers, React Aria, CSS modules, CSS-in-JS, or another styling runtime. className and style are optional interoperability hooks, not Tailwind or CVA requirements.

The contract has nine leaf components (ActionButton, IconButton, TextField, TextArea, Spinner, Skeleton, Status, Surface, Avatar) and eight behavior components (Tooltip, Menu, Popover, Dialog, Picker, Checkbox, Switch, Tabs). Picker covers select and combobox behavior, not date picking. Behavior adapters own their portal, focus, keyboard, dismissal, and stacking implementation while honoring the semantic props and portalContainer interop contract.

App product code imports standard controls from its local adapter path, usually @/components/ui/*. Do not import @agent-native/toolkit/ui/* directly from pages, routes, or domain components. That bypasses the app seam and makes a future design-system replacement incomplete. Toolkit feature packages remain valid imports; configure their presentation through the registered semantic components, controller, and product slots.

Run the published conformance kit against a complete adapter in its own CI:

import { assertDesignSystemConformance } from "@agent-native/toolkit/conformance";
import { DESIGN_SYSTEM_CONTRACT_VERSION } from "@agent-native/toolkit/design-system";

await assertDesignSystemConformance({
  adapterName: "Acme",
  components,
  contractVersion: DESIGN_SYSTEM_CONTRACT_VERSION,
});

New components and optional props are minor contract changes. Required props, removed APIs, or behavioral changes require a new contract major.

Customize A Shared Feature

Prefer feature-level headless controllers over rebuilding individual widgets. One controller must power both the Toolkit default view and every custom render path so behavior, actions, analytics, accessibility state, and error handling cannot drift. Use a product-level render slot to replace the view while keeping that controller. Eject only when the controller and slots cannot express the required product behavior.

Eject A Feature

Discover and inspect the ejection units published by installed first-party packages before changing source:

agent-native eject --list
agent-native eject inspect <unit>
agent-native eject <unit> --app <app>
agent-native eject <unit> --app <app> --apply

The command is dry-run by default. It prints the file closure, consumer import rewrites, protected package contracts, and verification commands before writing. --apply copies the package-version-matched source into the app and rewrites only imports covered by the unit manifest.

Every first-party public ejection unit must have a complete manifest. If one is missing, treat that as a framework coverage bug instead of inventing a copy recipe. For an unknown third-party package, use the emitted add-style blueprint as a starting point. Protected runtime behavior is never copied; follow the reported configuration, adapter, or extension seam instead.

Applied ejections are recorded in the committed agent-native.ejections.json, including package version, manifest digest, target hashes, and import rewrites. Use the recorded state to review drift or undo an unchanged ejection:

agent-native eject diff <unit> --app <app>
agent-native eject restore <unit> --app <app>
agent-native eject restore <unit> --app <app> --apply

Restore is hash-gated. It refuses to remove locally edited files or reverse changed imports and prints their diff instead. Keep an edited ejection as app-owned code, or reconcile those edits before restoring it.

Find The Installed Implementation

Use the source that matches the installed package version:

pnpm action docs-search --query "<component or feature>"
pnpm action source-search --query "<component or symbol>"
rg -n "<component or symbol>" node_modules/@agent-native/toolkit/src
rg -n "<component or symbol>" node_modules/@agent-native/core/corpus

• Toolkit publishes readable TypeScript under node_modules/@agent-native/toolkit/src/ for selective UI adoption.
• Core and first-party template source lives under node_modules/@agent-native/core/corpus/core/ and node_modules/@agent-native/core/corpus/templates/.
• Treat those trees as read-only references. Prefer agent-native eject so the package manifest selects the complete source closure and rewrites imports. Manual inspection is still useful for deciding whether to configure, compose, eject, or propose a shared seam.

Do not manually guess at sibling dependencies. The ejection manifest owns the required file closure and keeps protected contracts on public package imports.

Preserve The Agent-Native Contract

UI ownership may change; product contracts should not:

• Keep app operations in defineAction actions and call them through useActionQuery, useActionMutation, or another named client helper.
• Keep navigation, selection, and focused-object state visible through the existing application-state keys.
• Keep AI work in the shared agent chat instead of adding direct LLM calls.
• Keep auth, access checks, persistence, chat transport, and agent execution in Core. Do not copy those runtimes into the app.
• Keep local adapters narrow so package upgrades still improve every surface the app has not intentionally taken ownership of.
• Keep page, route, and domain code on local UI adapter imports. Never reach around the registered design system with direct Toolkit UI primitive imports.

App Shapes

• Template app: begin with app/design-system.ts, its local UI adapters, and domain UI. Use Toolkit features for repeated workspace behavior; eject only the unit being customized.
• Chat app: keep AgentChatSurface, thread state, and chat transport in Core. Compose or eject Toolkit presentation such as chat-history UI around it.
• Headless app: stay action-first while no UI is needed. When adding a UI, use the Chat template as the on-ramp or add Toolkit components without replacing the existing actions.
• Workspace: put one-app overrides in that app. Promote a local component to packages/shared only when multiple workspace apps use it.

After Ejecting

• Commit agent-native.ejections.json with the app-owned files and rewrites.
• Remove unused dependencies and imports from the ejected files.
• Keep visible text in the app's localization catalogs.
• Run the manifest verification commands plus the app's formatter, typecheck, and focused tests.
• Re-check the installed source during future package upgrades; the app-owned ejection does not receive upstream fixes automatically. Use eject diff to distinguish recorded output from subsequent local edits.

Don't

• Don't edit or import from node_modules/@agent-native/*/src at runtime.
• Don't add pnpm.overrides, patches, or resolutions for Agent Native packages.
• Don't copy Core auth, DB, action, agent-loop, or transport internals.
• Don't manually copy a first-party unit with a missing recipe; fix its manifest.
• Don't eject a full package when a prop, slot, wrapper, or smaller unit works.
• Don't fork feature state into a custom view; consume the feature's controller.

Related Skills

• agent-native-docs — version-matched docs and source lookup
• agent-native-toolkit — shared-vs-app-owned architecture boundary
• self-modifying-code — safe app source edits
• upgrade-agent-native — supported package upgrade path
• adding-a-feature — UI/action/instructions/application-state parity