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NomAI

🧠 AI-Powered Nutrition Intelligence Platform

Analyze food, chat with AI, plan weekly diets, and receive real-time nutrition insights.

📱 Mobile App: Download / View Repository

FastAPI Python Gemini Firebase Exa DuckDuckGo Deploy on Railway

⚡ Overview

NomAI is a powerful AI Agent that brings nutrition and food intelligence to life. Whether you're analyzing meals through images, chatting with an AI nutrition assistant, or generating personalized weekly diet plans — NomAI handles the heavy lifting with a sophisticated multi-step LLM pipeline backed by real-time web research.

✨ Features

Feature Description
🧠 AI Nutrition Analysis Analyze food from images or text descriptions with a 3-step pipeline: food extraction → web search → LLM synthesis
💬 Conversational AI Chatbot LangChain-powered agent that understands dietary preferences, allergies, and health goals
🍽️ Weekly Diet Planner Generate 7-day personalized meal plans with carb cycling, variety tracking, and macro targets
🔄 Meal Alternatives Get 5 AI-suggested alternative meals respecting your dietary profile
📊 Nutrition Tracking Mark meals as eaten, update plans on the fly, and track diet history
🔗 Dual LLM Support Seamlessly switch between Google Gemini and OpenRouter (Claude) providers
🌐 Web-Grounded Analysis Nutrition data enriched with web search results from Exa or DuckDuckGo
🛢️ Firestore Persistence Chat history and diet plans stored in Google Firestore

Deploy on Railway

🏗️ Architecture

graph TD
    Client["🖥️ Client (Mobile / Web)"]
    Main["main.py — FastAPI App"]
    
    Client --> Main

    Main --> NutritionRouter["/api/v1/nutrition"]
    Main --> ChatRouter["/api/v1/users"]
    Main --> AgentRouter["/api/v1/chat"]
    Main --> DietRouter["/api/v1/diet"]

    NutritionRouter --> NutritionServiceV2
    AgentRouter --> LangChainAgent["🤖 LangChain Agent"]
    LangChainAgent --> AgentTools["Tools: analyse_image\nanalyse_food_description"]
    AgentTools --> NutritionServiceV2
    ChatRouter --> ChatFirestore
    DietRouter --> DietService

    NutritionServiceV2 --> FoodExtractor["FoodExtractorService"]
    NutritionServiceV2 --> SearchService
    NutritionServiceV2 --> LLMProvider["LLM Provider\n(Gemini / OpenRouter)"]
    DietService --> LLMProvider
    DietService --> DietFirestoreDB["DietFirestore"]

    FoodExtractor --> LLMProvider
    SearchService --> ExaAPI["🔍 Exa / DuckDuckGo"]

    ChatFirestore --> Firestore["🔥 Firestore DB"]
    DietFirestoreDB --> Firestore
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🔌 API Endpoints

🥗 Nutrition — /api/v1/nutrition

Method Path Description
POST /analyze Analyze nutrition from a food image (URL required)
POST /analyze-by-description Analyze nutrition from a text description

🤖 AI Agent Chat — /api/v1/chat

Method Path Description
POST /messages Send a message and receive AI nutrition analysis with tool calls

💬 Chat History — /api/v1/users

Method Path Description
GET / Get chat messages for a user (paginated)
PATCH /log-status Update the isAddedToLogs flag for a message

🍽️ Diet Plans — /api/v1/diet

Method Path Description
POST / Generate a new weekly diet plan
GET /{user_id} Get the active weekly diet
GET /{user_id}/history Get diet history (paginated)
POST /{user_id}/suggest-alternatives Suggest 5 alternative meals
PUT /{user_id}/{day_index}/meals/{meal_type} Update a specific meal
PATCH /{user_id}/meals/eaten Mark a meal as eaten / not eaten
GET /{user_id}/diet/{diet_id} Get a specific diet by ID
POST /{user_id}/diet/{diet_id}/copy Copy a past diet as new active diet

🧠 AI Agent Decision Flow

NomAI's conversational brain operates as a ReAct Agent (Reasoning + Acting). It doesn't just respond; it thinks, selects tools, and iterates until it has the best answer.

graph TD
    User["👤 User Input\n(Chat/Image)"] --> Context["📋 Context Builder\n(Preferences + Allergies + Goals)"]
    Context --> Brain["🧠 LLM Controller\n(ReAct State Graph)"]
    
    Brain --> Decision{"Is this food-related?"}
    
    Decision -- "No / Simple Q&A" --> Direct["💬 Direct Friendly Answer"]
    Decision -- "Yes / Needs Analysis" --> ToolSelection["🛠️ Tool Selection"]
    
    ToolSelection -- "Image Provided" --> ToolA["📸 analyse_image"]
    ToolSelection -- "Text Description" --> ToolB["📝 analyse_food_description"]
    
    ToolA --> Pipe["🧪 Nutrition Pipeline"]
    ToolB --> Pipe
    
    Pipe --> Observation["🔍 Tool Observation\n(Structured Nutrition Data)"]
    Observation --> Brain
    
    Brain --> Final["🎁 Final Personalized Response\n(Friendly Answer + Data)"]
    Final --> Firestore["🔥 Sync to Firestore"]
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The State Graph (ReAct Pattern)

NomAI maintains a Message State that evolves during a single request:

  1. State Init: User message + System prompt (Personalized Profile).
  2. Reasoning: The LLM analyzes the intent. If it sees food, it pauses and emits a tool_call.
  3. Acting: The system executes the analyse_image or analyse_food_description tool.
  4. Observation: The tool's output (nutrients, calories, fiber) is appended to the message list.
  5. Finalization: The LLM reads the tool's findings and crafts a warm, personalized message (e.g., "This burger looks delicious, Pavel! It has 650 calories, but keep an eye on the sodium...").

🚀 Deployment

NomAI supports two easy deployment options: Google Cloud Platform (GCP) or Railway.

☁️ Option 1: GCP (Cloud Run)

NomAI is architected for the cloud, utilizing a fully automated CI/CD pipeline on Google Cloud Platform (GCP).

graph LR
    Dev["💻 Developer\nPush to GitHub"] --> CB["⚙️ Google Cloud Build"]

    subgraph "CI/CD Pipeline"
        CB --> Build["🐳 Docker Build\n(Dockerfile.api)"]
        Build --> AR["📦 Artifact Registry\n(Docker Image)"]
        AR --> Deploy["🚀 Cloud Run\n(Managed Serverless)"]
    end

    Deploy --> Public["🌐 Public API Endpoints\n(https://nomai-service-...)"]

    subgraph "Infrastructure"
        Firebase["🔥 Firestore\n(NoSQL DB)"]
        Secret["🔒 Secret Manager\n(API Keys)"]
    end

    Deploy -.-> Firebase
    Deploy -.-> Secret
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🚂 Option 2: Railway (One-Click Template)

One-click deployment to Railway with built-in environment variable management and template setup.

Deploy on Railway

🚂 One-Click Railway Template Deployment

  1. Click the button above — This opens Railway with the NomAI template pre-loaded
  2. Connect your GitHub repository to enable automatic deployments
  3. Configure Environment Variables in the Railway dashboard:
Variable Description Required
FIREBASE_CREDENTIALS_JSON Full Firebase service account JSON string ⬜
GOOGLE_API_KEY Google Gemini API key (If openrouter is used then can skip this ) ✅
EXA_API_KEY Exa search API key (optional if not using DuckDuckGo) ⬜
SEARCH_PROVIDER exa or duckduckgo ✅
PROVIDER_TYPE gemini or openrouter ✅
GEMINI_MODEL Gemini model name (auto-switches when PROVIDER_TYPE=gemini) ⬜
OPENROUTER_MODEL OpenRouter model name (auto-switches when PROVIDER_TYPE=openrouter) ⬜
OPENROUTER_API_KEY OpenRouter API key (if using openrouter) ⬜
AGENT_MODEL Agent model for LangChain if provider is gemini then put gemini model else openrouter model (default: openai/gpt-4o-mini) ✅

Model Auto-Switching: When PROVIDER_TYPE=gemini, the system uses GEMINI_MODEL (default: gemini-2.0-flash). When PROVIDER_TYPE=openrouter, it uses OPENROUTER_MODEL (default: google/gemini-3.1-flash-lite-preview).

The Firebase Credentials are loaded 3 ways , on the local machine via direct service.json file , on the GCP it does n't require service.json file , on non Google provider like railway , we load the service.json file via key FIREBASE_CREDENTIALS_JSON.

  1. Deploy — Railway auto-detects Python, installs dependencies via uv, and starts uvicorn main:app
  2. Custom Domain (optional) — Add a custom domain in Railway service settings

Railway Features

  • ✅ Automatic HTTPS/SSL
  • ✅ GitHub integration for auto-deploy on push
  • ✅ Environment variable management
  • ✅ Built-in logs and monitoring
  • ✅ Free tier available

Production Stack

  • Containerization: uv-optimized Python 3.13 slim image for fast builds and minimal footprint.
  • Orchestration: Managed via cloudbuild.yaml in infra/cloudbuild/ (GCP).
  • Hosting: Google Cloud Run for autoscaling serverless execution (GCP) or Railway for managed deployment.
  • Registry: Google Artifact Registry for secure container storage (GCP).

NomAI uses a sophisticated 3-step pipeline for accurate, web-grounded nutrition analysis:

graph LR
    A["📸 Multi-modal Input\n(Image + Prompt)"] --> B["Step 1\nFood Identification"]
    B --> C["Step 2\nWeb Grounding"]
    C --> D["Step 3\nMultimodal Synthesis"]
    D --> E["📊 Structured\nNutrition Response"]
    
    B -.- B1["Lightweight LLM identifies\nfood items & generates\nenriched search queries"]
    C -.- C1["Exa / DuckDuckGo\nfinds USDA, FDA, or\nbrand-specific data"]
    D -.- D1["Powerful Multimodal LLM\ncombines Actual Image +\nWeb Data + User Prompt"]
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Step Purpose Service
1. Food Identification Lightweight LLM detects food items and generates enriched queries for search FoodExtractorService
2. Web Grounding Executes targeted searches (Exa/DDG) to find authoritative nutritional facts SearchService
3. Multimodal Synthesis Final LLM combines Actual Image + Web Results + User Prompt for the result GeminiProvider / OpenRouterProvider
4. Client Delivery Returns highly accurate, fact-checked structured data to the user FastAPI Response

📅 Diet Plan Generation Flow

Generating a weekly diet plan is a multi-stage process that balances nutritional targets, metabolic variety (carb cycling), and food diversity.

graph TD
    Input["📥 DietInput Payload\n(Macros + Preferences + Goals)"] --> Calc["⚖️ Target Calculator"]
    
    Calc --> Patterns["🔄 Carb Cycling Logic\n(Mon-Sun Pattern: 0, -15, -10, -15, +10, -10, +15)"]
    
    Patterns --> Loop["🔁 7-Day Generation Loop"]
    
    subgraph "Per-Day Iteration"
        DayPrompt["📝 Prompt Builder\n(Day Context + Used Foods)"] --> LLMCall["🤖 LLM Provider\n(Gemini / OpenRouter)"]
        LLMCall --> DailyClean["🧹 Data Cleaning\n(Remove concerns/alternatives)"]
        DailyClean --> Variety["🥗 Update Used Foods\n(Track variety for next days)"]
    end
    
    Loop --> DayPrompt
    Variety -- "Next Day" --> Loop
    
    Variety -- "End Loop" --> Aggregator["📊 Weekly Aggregator\n(Sum Macros & Totals)"]
    Aggregator --> Firestore["🔥 Firestore Storage\n(users/{userId}/diet/{dietId})"]
    Firestore --> Final["✅ WeeklyDietOutput\n(Sent to Client)"]
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Key Stages

  1. Payload Intake: Receives targets (Calories, P/C/F), dietary restrictions (Vegan, Keto, etc.), and health goals.
  2. Carb Cycling Pattern: Instead of flat targets, the system applies a pattern (e.g., lower carbs on Mon/Thu, higher carbs on Fri/Sun) to prevent metabolic adaptation.
  3. Sequential Variety Loop: The system generates one day at a time, feeding the list of used_foods from previous days back into the next prompt to ensure you don't eat the same thing every day.
  4. Final Aggregation: Calculates the total weekly impact and persists the plan as "active" in Firestore.

🌍 Web Grounding Infrastructure

NomAI utilizes a modular search architecture to ground AI responses in real-world data. It supports multiple search backends that can be toggled via environment variables.

graph TD
    Pipeline["🧪 Nutrition Pipeline"] --> Router["🔍 SearchService (Router)"]
    
    Router --> Env{"SEARCH_PROVIDER\nEnv Var"}
    
    Env -- "exa" --> Exa["🚀 ExaSearchProvider"]
    Env -- "duckduckgo" --> DDG["🦆 DuckDuckGoSearchProvider"]
    
    Exa --> ExaAPI["Exa AI API\n(Authoritative / Linked Data)"]
    DDG --> DDG_Library["DDGS Library\n(Global Web Search)"]
    
    ExaAPI --> Results["📊 Normalized SearchResults\n(Title, URL, Snippet, Score)"]
    DDG_Library --> Results
    
    Results --> Pipeline
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🤖 LLM Provider Strategy

NomAI supports multiple LLM backends via a strategy pattern:

classDiagram
    class LLMProvider {
        <<abstract>>
        +generate_from_text(prompt, schema)
        +generate_from_image(prompt, image_bytes, schema)
    }
    class GeminiProvider {
        +Google Gemini API
        +Structured output support
        +Native vision capabilities
    }
    class OpenRouterProvider {
        +OpenRouter API
        +Claude, GPT, etc.
        +JSON schema validation
    }
    LLMProvider <|-- GeminiProvider
    LLMProvider <|-- OpenRouterProvider
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Switch providers with a single environment variable: PROVIDER_TYPE=gemini or PROVIDER_TYPE=openrouter.

📂 Project Structure

nomai-backend/
├── app/
│   ├── agent/                  # LangChain AI agent
│   ├── config/                 # App settings
│   ├── endpoints/              # API route handlers
│   ├── exceptions/             # Custom exception hierarchy
│   ├── middleware/             # FastAPI middleware
│   ├── models/                 # Pydantic data models
│   ├── services/               # Business logic layer
│   └── utils/                  # Helpers and shared utilities
├── infra/                      # Infrastructure as Code
│   ├── cloudbuild/             # GCP Cloud Build configs
│   └── docker/                 # Dockerfile.api
├── main.py                     # App entrypoint
├── pyproject.toml              # Dependencies (uv)
└── railway.json                # Railway deployment config

⚠️ Error Handling

NomAI uses a comprehensive exception hierarchy with 18 standardized error codes:

graph TD
    Base["BaseNomAIException"]
    Base --> V["ValidationException (400)"]
    Base --> I["ImageProcessingException (400/413)"]
    Base --> N["NutritionAnalysisException (400/422)"]
    Base --> E["ExternalServiceException (502)"]
    Base --> C["ConfigurationException (503)"]
    Base --> R["RateLimitException (429)"]
    Base --> B["BusinessLogicException (400)"]
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🚀 Getting Started

1. Clone the Repository

git clone https://github.com/Pavel401/nomai-backend.git
cd nomai-backend

2. Install Dependencies

uv sync

3. Run the Server

uvicorn main:app --host 0.0.0.0 --port 8000 --reload

🔧 Environment Variables

Variable Purpose Default
PROD Production mode toggle false
PROVIDER_TYPE LLM provider (gemini / openrouter) gemini
GOOGLE_API_KEY Google Gemini API key —
GEMINI_MODEL Gemini model name (auto-used when PROVIDER_TYPE=gemini) gemini-2.0-flash
OPENROUTER_API_KEY OpenRouter API key —
OPENROUTER_MODEL OpenRouter model (auto-used when PROVIDER_TYPE=openrouter) google/gemini-3.1-flash-lite-preview
AGENT_MODEL Agent model for LangChain openai/gpt-4o-mini
SEARCH_PROVIDER Search backend (exa / duckduckgo) exa
EXA_API_KEY Exa search API key —
FIREBASE_CREDENTIALS_PATH Firebase service account JSON path —
FIREBASE_CREDENTIALS_JSON Firebase service account JSON string (for Railway) —
FIRESTORE_DATABASE_ID Firestore database ID mealai
DEBUG_MODE Enable pipeline debug logging false
HOST / PORT Server bind address 0.0.0.0 / 8000

👨‍💻 Tech Stack

Tech Use Case
FastAPI API framework
LangChain Agent orchestration & tool management
Google Gemini Primary LLM for analysis & generation
OpenRouter Alternative LLM provider (Claude, GPT, etc.)
Pydantic v2 Data validation & structured output
Firestore Chat & diet plan persistence
Exa / DuckDuckGo Web search for nutrition data grounding
Python 3.13+ Core backend language
uv Package management

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