feat: create "providers" package

[davidturnbull]

Summary

This PR refactors provider management across the Lingo.dev monorepo by consolidating scattered provider-specific code into two new shared packages: @lingo.dev/providers and @lingo.dev/config.

What Changed

For Users:

• No breaking changes - all existing i18n.json configurations continue to work as before
• More consistent error messages when provider API keys are missing
• Better support for adding new AI providers in the future

For Developers:

• Created @lingo.dev/providers package that centralizes:
  • Provider factory (createProviderClient())
  • Provider metadata (API key env vars, config keys, documentation links)
  • API key resolution logic
  • Custom error types (ProviderKeyMissingError, ProviderAuthFailedError, UnsupportedProviderError)
  • Supported providers: OpenAI, Anthropic, Google, Groq, Mistral, Ollama, OpenRouter
• Created @lingo.dev/config package for RC file management:
  • getRcConfig() - reads from ~/.lingodotdevrc
  • saveRcConfig() - writes to ~/.lingodotdevrc
• Removed duplicate provider code from CLI and compiler packages
• Reduced bundle sizes by removing redundant AI SDK dependencies from individual packages

Packages Modified

• packages/cli/ - Uses new provider factory and config package
• packages/compiler/ - Uses new provider factory and config package
• packages/spec/ - Enhanced provider type definitions
• packages/config/ - NEW - RC file management
• packages/providers/ - NEW - Centralized provider logic

Files Changed

34 files changed: +1,016 insertions, -741 deletions

Key changes:

• New packages: config and providers
• Removed files: compiler/src/utils/llm-api-key.ts, compiler/src/utils/rc.ts
• New test files: routing tests for CLI and compiler packages
• Updated: provider routing logic in CLI and compiler

Testing Instructions

Prerequisites

pnpm install
pnpm build

Test 1: Run Unit Tests

Providers package:

cd packages/providers
pnpm test

CLI provider routing:

cd packages/cli
pnpm test providers-routing

Compiler provider routing:

cd packages/compiler
pnpm test providers-routing

Test 2: Test CLI with Different Providers

Configure a provider in your i18n.json:

{
  "provider": {
    "id": "openai",
    "model": "gpt-4o",
    "prompt": "Translate professionally"
  }
}

Set the corresponding API key:

export OPENAI_API_KEY="your-key"
# or use the config command:
node packages/cli/bin/cli.mjs config set llm.openaiApiKey "your-key"

Run localization:

node packages/cli/bin/cli.mjs run

Test with other providers by changing id to: anthropic, google, groq, mistral, ollama, or openrouter

Test 3: Test Compiler with Different Providers

The compiler is used via bundler integration (Vite, Next.js, etc.). Test with a demo project:

Using Vite demo:

cd demo/vite-project

Configure the compiler in vite.config.ts with a specific provider:

lingoCompiler.vite({
  sourceRoot: "src",
  targetLocales: ["es", "fr"],
  models: {
    es: "openai:gpt-4o",
    fr: "anthropic:claude-3-5-sonnet-20241022"
  }
})(viteConfig)

Set API keys and run the dev server:

export OPENAI_API_KEY="your-key"
export ANTHROPIC_API_KEY="your-key"
pnpm dev

The compiler will validate provider API keys on startup and show clear error messages if any are missing.

Test other demo projects:

# Next.js demo
cd demo/next-app
pnpm dev

# React Router demo
cd demo/react-router-app
pnpm dev

# AdonisJS demo
cd demo/adonisjs
pnpm dev

Test 4: Verify Error Handling

CLI - Test missing API key:

unset OPENAI_API_KEY
node packages/cli/bin/cli.mjs run
# Should see clear message about missing OPENAI_API_KEY with instructions

Compiler - Test missing API key:

cd demo/vite-project
unset OPENAI_API_KEY
pnpm dev
# Compiler should exit with helpful error message showing how to set the key

Test 5: Config Commands

Test RC file operations:

node packages/cli/bin/cli.mjs config set llm.openaiApiKey "test-key"
node packages/cli/bin/cli.mjs config get llm.openaiApiKey
# Should output: test-key

node packages/cli/bin/cli.mjs config set llm.anthropicApiKey "another-key"
node packages/cli/bin/cli.mjs config get llm.anthropicApiKey
# Should output: another-key

Test 6: Full Regression

Run all tests:

pnpm test

Build all packages:

pnpm build

Migration Notes

No migration required - this is a non-breaking internal refactoring.

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