Five ideas.

A category is a small TypeScript interface in @openagentry/core. host, db, auth, llm, wiki, repo, storage, email, domain are the v0 categories.

// @openagentry/core — categories are TypeScript interfaces.
export interface DatabaseAdapter {
  readonly category: 'db';
  readonly id: string;
  createInstance(opts): Promise<DatabaseInstance>;
  destroyInstance(i, confirm): Promise<void>;
  connectionString(i, env): Promise<string>;
  exportState(i): Promise<DatabaseStateBundle>;
  importState(b): Promise<DatabaseInstance>;
}

Methods are total. Every failure throws a structured AgentryError with a stable code, a phase, and a one-line suggestedFix.

An adapter is an npm package whose default export satisfies a category interface. Adapter packages also declare an openagentry manifest block (type, category, id, capabilities, envVars, protocolVersion).

// @openagentry/adapter-db-neon — an adapter is an npm package whose
// default export satisfies the category interface.
import db from '@openagentry/adapter-db-neon';
// → DatabaseAdapter — category: 'db', id: 'neon'

await db.createInstance({ name: 'app-prod', region: 'aws-us-east-1', engine: 'postgres' });

The CLI reads the manifest at registration time. It never imports anything from the package beyond the default export.

The CLI reads .agentry/workspace.json, resolves each listed package from the workspace node_modules, validates its manifest, and registers its default export. Plugins are loaded in declaration order.

// .agentry/workspace.json
{
  "plugins": [
    "@openagentry/adapter-llm-cli",
    "@openagentry/adapter-llm-aigateway",
    "@openagentry/adapter-wiki-fs"
  ],
  "defaultEnv": "dev"
}

Failures during load are collected, not thrown. agentry capabilities reports them under loadErrors so you can register what works and fix what doesn't.

Most adapters use a lazy-default pattern: the default export is always a frozen object with category and id, but env reads happen on first method call. The package imports cleanly without env set; calls fail with a structured error at use-site.

// adapter-db-neon: the default export is a frozen shape.
// Calling a method reads NEON_API_KEY on first use.
import db from '@openagentry/adapter-db-neon';
// → DatabaseAdapter — works to import without env set.

await db.createInstance({ name: 'app', ... });
// → throws AgentryError({ code: 'E_NEON_AUTH', ... }) if NEON_API_KEY is missing.

Three adapters (auth-nextauth, llm-cli, wiki-fs) use eager-but-never-null because their env defaults always resolve to something. The construct-or-null pattern is gone.

useAdapter(category) returns the last-registered adapter for that category. Multiple adapters in the same category are fine — change the default by reordering workspace.json. No app-code change.

// app.ts — useAdapter returns whichever adapter was registered last
// for the category. With three llm adapters declared, the last one wins.
import { useAdapter } from '@openagentry/core';

const llm = useAdapter('llm');
// → llm-aigateway, the last entry in workspace.json's plugins array

// Reorder workspace.json to switch defaults — no app code change.

agentry capabilities --json surfaces both the default (categories[cat]) and the full registered list (adaptersByCategory[cat]).