solid-waffle

Multi-app repository of LangGraph + FastAPI applications, each demonstrating a different workflow pattern.

Applications

App	Pattern	Port	Description
research_assistant	Sequential chain	8000	Search (DuckDuckGo) → Summarize (Gemini) → Cite (Gemini) + SQLite history
customer_support_triage	Router + Human-in-the-loop	8001	Supervisor (structured output) → Specialist → Responder → Escalation/Handoff with checkpoints
content_creation_studio	Reflection Loop (Cycle)	8002	Writer → Critic (score <8 loop max 3) → Editor → Human Approval (interrupt_before) + SSE stream
code_assistant_team	Parallel Collaboration	8003	Planner → Send fan-out → Coder/Tester/DocsWriter (subgraphs + reducers) → Reviewer + WS/SSE

Quick Start

Each app is self-contained with its own virtual environment and dependencies.

research_assistant

cd research_assistant
pip install -r requirements.txt
cp .env.example .env  # add GOOGLE_API_KEY
uvicorn app.main:app --reload --port 8000

customer_support_triage

cd customer_support_triage
pip install -r requirements.txt
cp .env.example .env  # add GOOGLE_API_KEY (mock fallback works without)
uvicorn app.main:app --reload --port 8001

content_creation_studio

cd content_creation_studio
pip install -r requirements.txt
cp .env.example .env  # add GOOGLE_API_KEY (mock fallback works without)
uvicorn app.main:app --reload --port 8002

code_assistant_team

cd code_assistant_team
pip install -r requirements.txt
cp .env.example .env  # add GOOGLE_API_KEY (mock fallback works without)
uvicorn app.main:app --reload --port 8003

Open http://localhost:<port>/ for UI, /docs for Swagger.

Shared Stack

• FastAPI 0.141.1
• LangGraph 1.2.11
• Gemini via langchain-google-genai 4.4.0
• Pydantic 2.13.5 / pydantic-settings 2.15.0
• SQLite via aiosqlite 0.22.1 (async) or sqlite3 (sync)
• Testing: pytest 9.1.1 + httpx

See AGENTS.md for architecture conventions, adding new apps, and development guidelines.

Adding a New App

1. Create folder with snake_case name
2. Copy structure from existing app (see AGENTS.md)
3. Update requirements.txt with shared + app-specific deps
4. Implement app/graph/builder.py with build_graph()
5. Wire app/main.py (lifespan, router, static mount)
6. Document in README.md with run commands and endpoints
7. Pick unused port (8002, 8003...)

Repository Structure

solid-waffle/
├── AGENTS.md                    # Agent instructions & conventions
├── README.md                    # This file
├── research_assistant/          # Sequential workflow app
│   ├── requirements.txt
│   ├── .env.example
│   ├── README.md
│   └── app/
├── customer_support_triage/     # Router + human handoff app
│   ├── requirements.txt
│   ├── .env.example
│   ├── README.md
│   └── app/
└── content_creation_studio/     # Reflection loop app
     ├── requirements.txt
     ├── .env.example
     ├── README.md
     └── app/
 └── code_assistant_team/         # Parallel collaboration app
     ├── requirements.txt
     ├── .env.example
     ├── README.md
     └── app/

License

MIT