Add multi-provider AI support (local servers, OpenRouter)

[JasonDoug]

Summary

Adds support for two additional AI providers alongside the existing OpenAI integration, with no breaking changes to existing configuration.

• Local servers (Ollama, LM Studio, any OpenAI-compatible /v1 endpoint) via AI_PROVIDER=local
• OpenRouter via AI_PROVIDER=openrouter, supporting hundreds of hosted models with a single API key
• A shared app/utils/ai-provider.ts utility (getModel / getOptionsModel) replaces direct openai() calls in all three API routes, so future provider additions touch only one file

Options generation (structured output)

The multiple-choice options feature uses streamObject() with a JSON schema, which requires structured output support that not all models provide. A separate OPTIONS_PROVIDER env var lets users route options generation to a different provider than chat — e.g. use a local model for chat while keeping OpenAI for reliable structured output.

Per-provider options model vars: OPENAI_OPTIONS_MODEL, LOCAL_OPTIONS_MODEL, OPENROUTER_OPTIONS_MODEL.

Robustness

• Throws immediately with a clear message when OPENROUTER_API_KEY is missing, rather than passing "" to the SDK and failing at call time
• Warns on unrecognised AI_PROVIDER / OPTIONS_PROVIDER values (typo detection) instead of silently falling back to OpenAI
• Each provider's options model falls back only to its own provider-appropriate default — no cross-provider model name leakage

Files changed

File	Change
app/utils/ai-provider.ts	New — shared provider factory with getModel and getOptionsModel
app/api/chat/route.ts	Use getModel() instead of openai()
app/api/generate-doc/route.ts	Use getModel() instead of openai()
app/api/generate-options/route.ts	Use getOptionsModel() instead of openai()
.env.example	Full provider documentation with recommended models and examples
CLAUDE.md	Added (project guidance for Claude Code)

Configuration examples

Local (Ollama):

AI_PROVIDER=local
LOCAL_AI_BASE_URL=http://localhost:11434/v1
OPENAI_MODEL=llama3.2:latest

OpenRouter:

AI_PROVIDER=openrouter
OPENROUTER_API_KEY=sk-or-...
OPENAI_MODEL=anthropic/claude-3-5-sonnet

Mixed — local chat, OpenAI options:

AI_PROVIDER=local
OPTIONS_PROVIDER=openai
OPENAI_API_KEY=sk-...
LOCAL_AI_BASE_URL=http://localhost:11434/v1
OPENAI_MODEL=llama3.2:latest

Test plan

• AI_PROVIDER=openai — existing behaviour unchanged, all tests pass
• AI_PROVIDER=local with Ollama — chat and document generation stream correctly
• AI_PROVIDER=openrouter — chat and document generation stream correctly
• Missing OPENROUTER_API_KEY throws a clear error at request time
• OPTIONS_PROVIDER=openai while AI_PROVIDER=local — options use OpenAI, chat uses local
• Unrecognised provider value logs a warning and falls back to OpenAI
• npm test passes

🤖 Generated with Claude Code

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