llm-compat

SDK-agnostic model compatibility, routing, and request normalization helpers for LLM applications.

This package is intentionally not a full LLM SDK. It helps applications keep using OpenAI SDK, Vercel AI SDK, fetch, or custom clients while sharing model compatibility behavior.

Scope

llm-compat handles:

• model pattern matching and capability lookup
• provider/base URL detection
• route-table model resolution
• usage/env config resolution
• max_tokens / max_completion_tokens / max_output_tokens normalization
• fixed-temperature and rejected-stop cleanup
• provider-specific reasoning/thinking shapes for OpenAI, OpenRouter, DeepSeek, GLM, and Qwen-style no-think prompts

It does not handle:

• client creation
• streaming abstraction
• message conversion
• tool calling abstraction
• OAuth
• cost tracking

Basic Usage

npm install llm-compat

import { normalizeChatRequest, resolveModelProfile } from 'llm-compat';

const profile = resolveModelProfile({ model: 'gpt-5.4', baseURL: process.env.OPENAI_BASE_URL });

const request = normalizeChatRequest(
  {
    model: 'gpt-5.4',
    messages: [{ role: 'user', content: 'Hello' }],
    max_tokens: 1000,
    temperature: 0.7,
  },
  profile,
  { thinking: 'disabled' },
);

Usage Env Resolver

import { createPrefixedUsageDefinition, resolveUsageConfig } from 'llm-compat';

const usage = resolveUsageConfig({
  usage: 'fast',
  env: process.env,
  defaults: {
    model: process.env.MODEL,
    apiKey: process.env.OPENAI_API_KEY,
    baseURL: process.env.OPENAI_BASE_URL,
  },
  usages: {
    fast: createPrefixedUsageDefinition(['APP_FAST', 'FAST']),
  },
});

Route Table Resolver

import { resolveModelRoute } from 'llm-compat';

const resolved = resolveModelRoute({
  model: 'openrouter-gemini-3-pro',
  routes: [
    {
      models: 'openrouter-*',
      stripProviderPrefix: true,
      endpoint: {
        baseURL: '$OPENROUTER_BASE_URL',
        apiKey: '$OPENROUTER_API_KEY',
      },
    },
  ],
  env: process.env,
});

Status

0.x is experimental. APIs may change while internal applications migrate.