Generate a single comprehensive sequence diagram for the following function:

Module: {module_name}
Description: {module_description}
Tech Stack: {tech_stack}

Function: {function_name}
Description: {function_description}

Features:
{features}

User Stories:
{user_stories}

Selected Mermaid Diagram:
{mermaid_diagram}

{custom_instructions}

Please analyze the provided information and generate ONE sequence diagram that includes:

1. Core Components:
   - Frontend/UI
   - Backend API
   - Database
   - External Services (if any)

2. Main Flow:
   - Primary success path
   - Key operations and data flow
   - Service interactions

3. Alternative Flows (using alt/opt):
   - Error scenarios
   - Validation failures
   - Edge cases
   - Different user paths

4. Subflows (using rect):
   - Group related operations
   - Show parallel processes
   - Highlight specific features

Requirements:
1. Create ONE comprehensive diagram that includes all flows
2. Use rect to group related operations
3. Use alt/opt for different scenarios
4. Use loop for repetitive operations
5. Add notes for complex logic
6. Include activation boxes for long-running operations
7. Use clear participant definitions
8. Show proper message direction with arrows

Format your response as follows:

# Comprehensive Sequence Flow
Brief description of the overall functionality and included flows

```mermaid
sequenceDiagram
    %% Participants
    participant FE as Frontend
    participant API as Backend API
    participant DB as Database
    [Additional participants as needed]

    %% Main Flow
    rect rgb(200, 220, 240)
        Note over FE,DB: Main Flow
        [Main success path]
    end

    %% Alternative Scenarios
    alt [Condition]
        [Alternative flow]
    else [Other condition]
        [Other flow]
    end

    %% Feature-specific Subflows
    rect rgb(220, 240, 200)
        Note over FE,DB: [Feature Name]
        [Feature-specific flow]
    end
```

Note: Create a single, comprehensive diagram that shows all flows and scenarios within the same diagram using proper grouping and alternative paths.