## MODIFIED Requirements

### Requirement: FastAPI Server Configuration
The middleware server SHALL be implemented using Python FastAPI framework with comprehensive environment-based configuration supporting standalone deployment.

#### Scenario: Server startup with valid configuration
- **WHEN** the server starts with valid .env file containing all required variables (DB_HOST, DB_PORT, DB_USER, DB_PASS, DB_NAME, DIFY_API_URL, DIFY_API_KEY, AUTH_API_URL)
- **THEN** the server SHALL start successfully and accept connections on the configured BACKEND_HOST and BACKEND_PORT

#### Scenario: Server startup with missing configuration
- **WHEN** the server starts with missing required environment variables
- **THEN** the server SHALL fail to start with descriptive error message

#### Scenario: Server startup with optional configuration
- **WHEN** optional environment variables (BACKEND_PORT, DB_POOL_SIZE, etc.) are not set
- **THEN** the server SHALL use sensible defaults and start normally

### Requirement: Database Connection Pool
The middleware server SHALL maintain a configurable connection pool to the MySQL database using environment variables.

#### Scenario: Database connection success
- **WHEN** the server connects to MySQL with valid credentials from environment
- **THEN** a connection pool SHALL be established with DB_POOL_SIZE connections

#### Scenario: Database connection failure
- **WHEN** the database is unreachable
- **THEN** the server SHALL return HTTP 503 with error details for affected endpoints

### Requirement: CORS Configuration
The middleware server SHALL allow cross-origin requests from all origins to support Electron desktop application clients.

#### Scenario: CORS preflight request
- **WHEN** any client sends OPTIONS request
- **THEN** the server SHALL respond with CORS headers allowing the request (allow_origins=["*"])

## ADDED Requirements

### Requirement: Backend Server Configuration
The middleware server SHALL support configurable host and port through environment variables for flexible deployment.

#### Scenario: Custom port binding
- **WHEN** BACKEND_PORT environment variable is set to 9000
- **THEN** the server SHALL listen on port 9000

#### Scenario: Production host binding
- **WHEN** BACKEND_HOST is set to 0.0.0.0
- **THEN** the server SHALL accept connections from any network interface

#### Scenario: Default configuration
- **WHEN** BACKEND_HOST and BACKEND_PORT are not set
- **THEN** the server SHALL default to 0.0.0.0:8000

### Requirement: Timeout Configuration
The middleware server SHALL support configurable timeout values for different operations through environment variables.

#### Scenario: File upload timeout
- **WHEN** UPLOAD_TIMEOUT is set to 900000 (15 minutes)
- **THEN** file upload operations SHALL allow up to 15 minutes before timeout

#### Scenario: LLM processing timeout
- **WHEN** LLM_TIMEOUT is set to 180000 (3 minutes)
- **THEN** Dify LLM summarization operations SHALL allow up to 3 minutes before timeout

#### Scenario: Dify STT timeout
- **WHEN** DIFY_STT_TIMEOUT is set to 600000 (10 minutes)
- **THEN** Dify STT audio transcription per chunk SHALL allow up to 10 minutes before timeout

#### Scenario: Authentication timeout
- **WHEN** AUTH_TIMEOUT is set to 60000 (1 minute)
- **THEN** authentication API calls SHALL allow up to 1 minute before timeout

### Requirement: File Path Configuration
The middleware server SHALL support configurable directory paths for templates and records.

#### Scenario: Custom template directory
- **WHEN** TEMPLATE_DIR environment variable is set to /data/templates
- **THEN** Excel templates SHALL be loaded from /data/templates

#### Scenario: Custom record directory
- **WHEN** RECORD_DIR environment variable is set to /data/records
- **THEN** exported meeting records SHALL be saved to /data/records

#### Scenario: Relative path resolution
- **WHEN** directory paths are relative
- **THEN** they SHALL be resolved relative to the backend application root

### Requirement: Frontend Environment Configuration
The frontend Electron application SHALL support environment-based API URL configuration for connecting to deployed backend.

#### Scenario: Custom API URL in production build
- **WHEN** VITE_API_BASE_URL is set to http://192.168.1.100:8000/api during build
- **THEN** the built Electron app SHALL connect to http://192.168.1.100:8000/api

#### Scenario: Default API URL in development
- **WHEN** VITE_API_BASE_URL is not set
- **THEN** the frontend SHALL default to http://localhost:8000/api

### Requirement: Sidecar Whisper Configuration
The Electron frontend's Sidecar (local Whisper transcription service) SHALL support environment-based model configuration.

#### Scenario: Custom Whisper model
- **WHEN** WHISPER_MODEL environment variable is set to "large"
- **THEN** the Sidecar SHALL load the large Whisper model for transcription

#### Scenario: GPU acceleration
- **WHEN** WHISPER_DEVICE is set to "cuda" and WHISPER_COMPUTE is set to "float16"
- **THEN** the Sidecar SHALL use GPU for faster transcription

#### Scenario: Default CPU mode
- **WHEN** WHISPER_DEVICE is not set
- **THEN** the Sidecar SHALL default to CPU with int8 compute type

### Requirement: Environment Example Files
The project SHALL provide example environment files documenting all configuration options.

#### Scenario: Backend environment example
- **WHEN** developer sets up backend
- **THEN** backend/.env.example SHALL list all environment variables with descriptions and example values (without sensitive data)

#### Scenario: Frontend environment example
- **WHEN** developer sets up frontend
- **THEN** client/.env.example SHALL list all VITE_ prefixed and WHISPER_ prefixed environment variables with descriptions