fastapi-ai-chat 0.1.0

Minimal FastAPI backend for streaming AI chat over SSE (token/done/error), compatible with ai-chat-kit

fastapi-ai-chat

Minimal FastAPI backend library for streaming AI chat over Server-Sent Events (SSE).

Designed to be wire-compatible with ai-chat-kit's React adapter:

• POST /chat/stream returns text/event-stream
• emits SSE events: token, done, error

Install

Local editable install (recommended during development):

python -m pip install -e Backend/fastapi-ai-chat

From PyPI (after you publish):

python -m pip install "fastapi-ai-chat[server]"

Run

Create a small server file (or use the included example):

python -m pip install "fastapi-ai-chat[server]"
python -m uvicorn examples.server:app --reload --port 8000

Environment variables (optional):

• OPENAI_API_KEY or FASTAPI_AI_CHAT_OPENAI_API_KEY
• ANTHROPIC_API_KEY or FASTAPI_AI_CHAT_ANTHROPIC_API_KEY
• GEMINI_API_KEY or FASTAPI_AI_CHAT_GEMINI_API_KEY
• FASTAPI_AI_CHAT_SQLITE_PATH (default: ./chat_history.sqlite3)

Streaming protocol (SSE)

The server emits frames separated by a blank line (\n\n):

• event: token with JSON: {"type":"token","token":"..."} (many times)
• event: done with JSON: {"type":"done","message":{"role":"assistant","content":"..."}, "provider":"...", "conversationId":"..."}
• event: error with JSON: {"type":"error","error":{"message":"..."}}

Test streaming:

curl -N -X POST "http://localhost:8000/chat/stream" \
  -H "Content-Type: application/json" \
  -d '{"userId":"u1","messages":[{"role":"user","content":"Hello streaming"}]}'

Selecting a model/provider

Send params.model in the request body:

• OpenAI: gpt-4.1 (default if omitted)
• Anthropic: claude-3-5-sonnet (or any model starting with claude)
• Gemini: gemini-1.5-pro (or any model starting with gemini)

If you do not configure provider keys, the backend will fall back to a deterministic mock stream unless a real model was explicitly requested.

Publish to PyPI

Build:

python -m pip install -U build twine
python -m build Backend/fastapi-ai-chat

Upload:

• Recommended: PyPI Trusted Publishing
• Or token-based:

python -m twine upload Backend/fastapi-ai-chat/dist/*