# LLM API User Guide

Internal LLM Chat API Documentation

> This internal API allows authorized users to interact with a local Large Language Model (LLM). The system uses Basic Authentication and provides endpoints to list available models and generate chat completions.

## Servers

http://X.X.X.X:8000

## Security Schemes

basicAuth

## Authentication
- Method: HTTP Basic Authentication
- Users: Predefined in the users dictionary
- Access control:
Users in the blocked group are denied access
- Only users in admin or user groups can access /v1/chat/completions

## GET / — Health Check

- Description: Verify that the API is running.
- Auth Required: ❌ No

Response Example:
> { "message": "FastAPI is running" }

## GET /v1/models — List Available Models
- Description: Retrieve the list of LLM models registered with the local Ollama backend.
- Auth Required: ✅ Yes (Basic Auth)

Response Example:

{
  "object": "list",
  "data": [
    {
      "id": "gemma:2b",
      "object": "model",
      "owned_by": "ollama",
      "root": "sha256:abc123..."
    }
  ]
}

Errors:

- 401 Unauthorized: Invalid or missing credentials
- 500 Internal Server Error: Ollama backend unreachable

## POST /v1/chat/completions — Generate Chat Completion
Description: Submit a prompt (text and/or image) to the LLM and receive a response.

Auth Required: ✅ Yes (Basic Auth)
Permissions: Only admin or user group members
Request Body (application/json):

{
  "model": "gemma:2b",
  "messages": [
    {
      "role": "user",
      "content": "Tell me about the solar system."
    }
  ],
  "temperature": 0.7,
  "top_p": 0.9,
  "max_tokens": 1024,
  "stream": false
}

Errors:
- 400 Bad Request: No valid user input provided
- 401 Unauthorized: Invalid credentials
- 403 Forbidden: Group not allowed
- 422 Unprocessable Entity: Model returned nothing
- 500 Internal Server Error: Ollama call failed

## Chat Logging
All completed interactions are stored in daily .jsonl log files:

- Format: chat_log_YYYY-MM-DD.jsonl
- Logged fields:
- Timestamp
- Session ID
- User
- Input & Response messages