Providers

Providers are how the SDK talks to an actual LLM vendor. This page covers what's registered and working today, the IProvider contract every vendor integration implements, and how to write and register your own.

Overview

A provider is any object implementing IProvider: a name, a capabilities object declaring which optional features it supports, and generate/generateStream methods. Agent depends only on this interface, never on a vendor SDK, so swapping providers is a matter of changing one string or one constructor call — nothing else in your application changes.

Providers are resolved by name through a registry (defaultProviderRegistry), so adding a new one never requires modifying existing code — you register a factory function under a name, and every Agent that references that name by string picks it up.

Note — Only two of the six provider names the SDK's types declare are actually registered: "openai" and "openrouter". Passing any of the other four ("anthropic", "gemini", "ollama", "groq") as an Agent's provider typechecks — ProviderName is a union of all six strings — but throws ConfigurationError ("Unknown provider") at Agent construction time. See Troubleshooting if you hit this.

OpenAI

Overview

The OpenAI integration talks to the POST /chat/completions endpoint over native fetch, with no vendor SDK dependency.

Installation

No separate installation — it ships as part of aniki-sdk and is registered automatically the first time you resolve a provider by name.

Configuration

import { Agent } from "aniki-sdk"; const agent = new Agent({  name: "Assistant",  instructions: "You are a helpful assistant.",  model: "gpt-4o-mini",  provider: "openai",});

Or construct the provider directly for more control (a custom base URL, an injected HTTP client for testing, and so on):

import { OpenAIProvider } from "aniki-sdk"; const provider = new OpenAIProvider({  apiKey: process.env.OPENAI_API_KEY ?? "",  baseURL: "https://api.openai.com/v1", // optional; this is already the default  timeout: 30_000, // optional; milliseconds});

API keys

Resolved from, in order: an explicit ProviderConfig.apiKey, the SDK's global Aniki config (only when it targets this same provider), then the OPENAI_API_KEY environment variable. If none of these resolve, ConfigurationError is thrown at Agent/provider construction time — never mid-run. See Configuration resolution below for the full precedence rule.

Supported models

Any model identifier your OpenAI account has access to — the SDK passes model through unchanged and never validates it.

Streaming support

Yes. capabilities.streaming is true.

Tool calling support

No, not end-to-end, despite Runner fully implementing the tool-calling loop. OpenAIProvider.capabilities.toolCalling is false, and the request builder silently drops any tools you attach to an agent — it never reaches OpenAI's wire format. Attaching tools to an OpenAI-backed agent produces a run that never calls a tool, with no error raised. See Tools for the full explanation and the working alternative (MockProvider, or your own IProvider).

Limitations

• No tool calling (above).
• No native structured output — structured output works, but it's prompt-driven, not a provider feature. See Generating Text.
• Generation parameters (temperature, maxTokens, ...) are supported by OpenAIRequestBuilder, but there's no way to set them through Agent/Runner today. See Generating Text.

Example

import { Agent, Runner } from "aniki-sdk"; const agent = new Agent({  name: "Assistant",  instructions: "You are a helpful assistant.",  model: "gpt-4o-mini",  provider: "openai",}); const result = await new Runner().run(agent, { message: "Hi" });console.log(result.content);

OpenRouter

OpenRouter is registered as a built-in provider too — it reuses OpenAIProvider against OpenRouter's OpenAI-wire-compatible endpoint, so everything above (streaming support, the tool- calling limitation, generation-parameter limitation) applies to it identically. Configure it the same way, with provider: "openrouter" and an OPENROUTER_API_KEY.

Declared but not implemented

"anthropic", "gemini", "ollama", and "groq" are valid ProviderName values and each has an environment variable mapped for it (ANTHROPIC_API_KEY, GEMINI_API_KEY, OLLAMA_API_KEY, GROQ_API_KEY), but none of them has a registered factory. Using one throws ConfigurationError at construction time — no request is ever sent.

The provider abstraction

Every provider — built-in or custom — implements this contract:

interface IProvider {  readonly name: string;  readonly capabilities: {    readonly streaming: boolean;    readonly toolCalling: boolean;    readonly structuredOutput: boolean;  };  generate(request: ProviderRequest): Promise<ProviderResponse>;  generateStream(request: ProviderRequest): AsyncIterable<ProviderStreamChunk>;}

(ProviderRequest, ProviderResponse, and ProviderStreamChunk are exported from aniki-sdk too — see the custom-provider example below for how they're used in practice.)

capabilities isn't decorative — Runner.stream checks capabilities.streaming before opening a stream, and throws StreamingNotSupportedError synchronously if it's false.

Writing and registering a custom provider

A minimal provider only needs to implement generate and generateStream. This one returns a canned response without making a real network call, which makes it a convenient pattern for a local model server or an internal gateway:

import { Agent, ProviderFactory, Runner, defaultProviderRegistry } from "aniki-sdk";import type { IProvider, ProviderRequest, ProviderResponse, ProviderStreamChunk } from "aniki-sdk"; class EchoProvider implements IProvider {  readonly name = "echo";  readonly capabilities = { streaming: true, toolCalling: false, structuredOutput: false };   async generate(request: ProviderRequest): Promise<ProviderResponse> {    const lastMessage = request.messages[request.messages.length - 1];    return {      content: `Echo: ${lastMessage?.content ?? ""}`,      model: request.model,    };  }   async *generateStream(request: ProviderRequest): AsyncIterable<ProviderStreamChunk> {    const lastMessage = request.messages[request.messages.length - 1];    yield { delta: `Echo: ${lastMessage?.content ?? ""}`, finishReason: "stop" };  }} defaultProviderRegistry.register("echo", () => new EchoProvider()); const agent = new Agent({  name: "Assistant",  instructions: "You are a helpful assistant.",  model: "n/a",  provider: ProviderFactory.create("echo"), // Agent.provider only accepts the six built-in  //                                           ProviderName strings or an IProvider instance,  //                                           so a custom name is resolved to an instance first.}); const result = await new Runner().run(agent, { message: "Hi" });console.log(result.content); // "Echo: Hi"

defaultProviderRegistry.register(name, factory) throws ConfigurationError if name is already registered — registration is one-time, not an overwrite. Note that Agent.provider's type only accepts the six built-in ProviderName strings or an IProvider instance — a custom provider name isn't part of that union, so you resolve it through ProviderFactory.create(name) (or defaultProviderRegistry.resolve(name)(config) directly) and pass the resulting instance.

Switching providers

Because Agent.provider accepts either a registered name or an already-constructed IProvider instance, switching providers for an existing agent is a one-line change:

// By name, resolved through the registry:const agent = new Agent({ /* ... */, provider: "openai" }); // Or with an explicitly constructed instance, e.g. for a non-default configuration:const provider = new OpenAIProvider({ apiKey: "sk-...", baseURL: "https://my-gateway.example" });const agentWithCustomBaseURL = new Agent({ /* ... */, provider });

Configuration resolution

When you resolve a provider by name (via ProviderFactory.create, which is what happens when you pass a string as Agent.provider), its ProviderConfig is resolved in this precedence order, highest first:

1. An explicit ProviderConfig passed directly to ProviderFactory.create.
2. The global Aniki configuration set via Aniki.configure(...) — only when global.provider or global.defaultProvider equals the provider name being resolved.
3. The provider's PROVIDER_API_KEY_ENV_VAR environment variable (for apiKey only).

If no API key is found from any of these sources for a known provider name, ConfigurationError is thrown immediately — at Agent construction time, not on the first runner.run call.

API Reference

See IProvider, OpenAIProvider, ProviderFactory, and ProviderRegistry in the API Reference.

Related Pages

• Generating Text
• Tools
• Error Handling
• Troubleshooting