This project demonstrates how to build a robust, type-safe backend using Effect, Apollo GraphQL, and Drizzle ORM.

• Functional, effectful business logic with Effect
• Type-safe database access with Drizzle ORM
• GraphQL API with Apollo Server
• SQLite as the database (file-based, easy for demos)
• Robust error handling, logging, and separation of concerns
• Branded types for type-safe IDs (see domain/ticket/schema.ts)

• domain/ - All business logic, models, schemas, errors, and branded types.
  • ticket/model.ts - Drizzle table definition for tickets.
  • ticket/schema.ts - Input validation schemas, including a branded TicketId type for type-safe IDs.
  • ticket/service.ts - Business logic (e.g., finding, creating tickets).
  • ticket/repository.ts - Database access functions.
  • errors.ts - Domain-specific error types.
• lib/ - Database setup and utilities.
  • db.ts - Sets up the SQLite/Drizzle/Effect database connection and layers.
  • utils.ts - Response helpers for GraphQL (e.g., successResponse, errorResponse).
• scripts/ - Utility scripts.
  • seed.ts - Seeds the database with demo data and creates the table if needed.
• graphql/ - GraphQL schema and resolvers.
  • schema/typeDefs.ts - GraphQL SDL schema (types, queries, mutations).
  • resolvers/index.ts - GraphQL resolvers. This is where all error handling, retries, timeouts, and mapping from domain/service results to GraphQL responses happens. The resolver layer is responsible for API robustness: it catches and logs errors, applies retry policies, handles timeouts, and translates domain/service errors into GraphQL-friendly responses.
• server.ts - App entrypoint. Sets up ApolloServer, checks DB/table existence, and starts the API.

1. Install dependencies:

   npm install

2. Seed the database:

   npm run seed

3. Start the server:

   npm run dev

To delete the database file and reseed:

npm run db:reset

• Effect (functional effects, error handling, dependency injection)
• Drizzle ORM (type-safe SQL for SQLite)
• Apollo Server (GraphQL API)
• SQLite (file-based database)
• TypeScript

Retrieves root-level tickets (tickets with no parent) with pagination support.

Input: FindAllTicketsInput { offset: Int!, limit: Int! }

Behavior:

• Returns only tickets where parentId is null (root tickets)
• Supports pagination with offset and limit parameters
• Each root ticket is enriched with its complete child tree
• Uses parallel processing to enrich multiple tickets simultaneously

Example Response:

{
  "success": true,
  "data": [
    {
      "id": "1",
      "title": "Project A - Main Project",
      "children": [
        {
          "id": "4",
          "title": "Frontend Development",
          "children": [...]
        }
      ]
    }
  ],
  "message": "📋 Retrieved 3 root tickets"
}

Retrieves a specific ticket by ID along with its complete child tree.

Input: FindTicketByIdInput { id: ID! }

Behavior:

• Finds the ticket with the specified ID
• Enriches the ticket with its complete child tree (up to 10 levels deep)
• Returns detailed information about the ticket's hierarchy
• Includes count of direct children and total descendants

Example Response:

{
  "success": true,
  "data": {
    "id": "1",
    "title": "Project A - Main Project",
    "children": [
      {
        "id": "4",
        "title": "Frontend Development",
        "children": [...]
      }
    ]
  },
  "message": "🌳 Found ticket \"Project A - Main Project\" (ID: 1) with 3 direct children and 15 total descendants"
}

Creates a new root-level ticket.

Input: CreateTicketInput { title: String!, description: String! }

Behavior:

• Creates a new ticket with the provided title and description
• Sets completed to false by default
• Sets parentId to null (creates a root ticket)
• Automatically sets createdAt and updatedAt timestamps
• Returns the newly created ticket

Example Response:

{
  "success": true,
  "data": {
    "id": "21",
    "title": "New Feature Implementation",
    "description": "Implement user authentication system",
    "completed": false,
    "parentId": null
  },
  "message": "✅ Successfully created ticket \"New Feature Implementation\" with ID: 21"
}

Toggles the completion status of a ticket and all its descendants (cascade toggle).

Input: ToggleTicketInput { id: ID!, isCompleted: Boolean! }

Behavior:

• Finds the specified ticket and toggles its completion status
• Recursively finds all child tickets in the tree
• Updates the completion status of the parent ticket and all descendants
• Uses parallel processing for efficiency when updating multiple tickets
• Returns the complete updated ticket tree

Example: Before toggle (ID: 1, isCompleted: true):

Root (ID: 1, completed: false)
├── Child (ID: 2, completed: false)
│   ├── Grandchild (ID: 3, completed: false)
│   └── Grandchild (ID: 4, completed: false)
└── Child (ID: 5, completed: false)

After toggle:

Root (ID: 1, completed: true)
├── Child (ID: 2, completed: true)
│   ├── Grandchild (ID: 3, completed: true)
│   └── Grandchild (ID: 4, completed: true)
└── Child (ID: 5, completed: true)

Example Response:

{
  "success": true,
  "data": {
    "id": "1",
    "title": "Project A - Main Project",
    "completed": true,
    "children": [...]
  },
  "message": "✅ Updated completion status for \"Project A - Main Project\" and 5 child tickets to: true"
}

Deletes a ticket and all its descendants (cascade delete).

Input: DeleteTicketInput { id: ID! }

Behavior:

• Finds the specified ticket and its complete child tree
• Deletes the parent ticket and all descendants
• Uses parallel processing for efficient deletion of multiple tickets
• Returns information about all deleted tickets

Example: Before delete (ID: 1):

Root (ID: 1)
├── Child (ID: 2)
│   ├── Grandchild (ID: 3)
│   └── Grandchild (ID: 4)
└── Child (ID: 5)

After delete:

(All tickets 1, 2, 3, 4, 5 are deleted)

Example Response:

{
  "success": true,
  "data": [
    {"deletedId": "1"},
    {"deletedId": "2"},
    {"deletedId": "3"},
    {"deletedId": "4"},
    {"deletedId": "5"}
  ],
  "message": "🗑️ Successfully deleted ticket and 4 child tickets (5 total tickets removed)"
}

Converts a child ticket to a root-level ticket by removing its parent relationship.

Input: RemoveParentInput { id: ID! }

Behavior:

• Finds the specified ticket and checks if it has a parent
• If the ticket is already a root ticket, returns it unchanged
• If the ticket has a parent, removes the parent relationship (sets parentId to null)
• The ticket and all its children become a separate root tree
• Returns the updated ticket with information about affected children

Example: Before removeParent(ID: 3):

Root (ID: 1)
├── Child (ID: 2) 
│   ├── Grandchild (ID: 3) ← This ticket
│   │   ├── Great-grandchild (ID: 4)
│   │   └── Great-grandchild (ID: 5)
│   └── Grandchild (ID: 6)

After removeParent(ID: 3):

Root (ID: 1)
├── Child (ID: 2) 
│   └── Grandchild (ID: 6)

Root (ID: 3) ← Now a root with its children
│   ├── Child(ID: 4)
│   └── Child(ID: 5)

Example Response:

{
  "success": true,
  "data": {
    "id": "3",
    "title": "Frontend Components",
    "parentId": null
  },
  "message": "✅ Successfully removed parent from ticket \"Frontend Components\" (ID: 3) along with 2 child tickets. Ticket is now a root ticket."
}

Moves a ticket and all its descendants to become children of another ticket.

Input: SetParentInput { childId: ID!, parentId: ID! }

Behavior:

• Validates that both child and parent tickets exist
• Prevents setting a ticket as its own parent
• Checks for circular relationships (prevents creating cycles in the hierarchy)
• Moves the entire subtree: the child ticket and all its descendants
• Updates the child ticket's parentId to point to the new parent
• Returns the updated child ticket with information about the new parent and total tickets moved

Validation Rules:

• Both childId and parentId must exist
• childId cannot equal parentId
• Cannot create circular relationships (e.g., A → B → C → A)

Example: Before setParent(childId: 3, parentId: 5):

Root (ID: 1)
├── Child (ID: 2)
│   └── Grandchild (ID: 3) ← This ticket and its subtree
│       ├── Great-grandchild (ID: 4)
│       └── Great-grandchild (ID: 5)

Root (ID: 6)
└── Child (ID: 7) ← Target parent

After setParent(childId: 3, parentId: 7):

Root (ID: 1)
└── Child (ID: 2)

Root (ID: 6)
└── Child (ID: 7)
    └── Grandchild (ID: 3) ← Moved here with entire subtree
        ├── Great-grandchild (ID: 4)
        └── Great-grandchild (ID: 5)

Example Response:

{
  "success": true,
  "data": {
    "id": "3",
    "title": "Frontend Components",
    "parentId": "7"
  },
  "message": "✅ Successfully moved ticket \"Frontend Components\" (ID: 3) and 2 descendants to \"Backend API\" (ID: 7)"
}

Adds multiple tickets as children to a parent ticket in a single operation.

Input: AddChildrenInput { parentId: ID!, childrenIds: [ID!]! }

Behavior:

• Validates that the parent ticket exists
• Validates that all child tickets exist
• Checks for circular relationships (prevents creating cycles in the hierarchy)
• Prevents duplicate child IDs in the input
• Checks if any child is already a child of the parent
• Moves all children to the parent using parallel processing for efficiency
• Returns information about the parent and all moved children

Validation Rules:

• parentId must exist
• All childrenIds must exist
• No duplicate IDs in childrenIds array
• Cannot create circular relationships (e.g., A → B → C → A)
• Children cannot already be children of the parent
• Maximum 50 children per operation (performance limit)

Example: Before addChildren(parentId: 5, childrenIds: [3, 7, 9]):

Root (ID: 1)
├── Child (ID: 2)
│   └── Grandchild (ID: 3) ← This ticket
│       └── Great-grandchild (ID: 4)

Root (ID: 6)
└── Child (ID: 7) ← This ticket

Root (ID: 8)
└── Child (ID: 9) ← This ticket

Root (ID: 10)
└── Child (ID: 5) ← Target parent

After addChildren(parentId: 5, childrenIds: [3, 7, 9]):

Root (ID: 1)
└── Child (ID: 2)

Root (ID: 6)

Root (ID: 8)

Root (ID: 10)
└── Child (ID: 5) ← Target parent
    ├── Child (ID: 3) ← Moved here with its subtree
    │   └── Child (ID: 4)
    ├── Child (ID: 7) ← Moved here
    └── Child (ID: 9) ← Moved here

Example Response:

{
  "success": true,
  "data": {
    "id": "5",
    "title": "Backend API",
    "parentId": "10"
  },
  "message": "✅ Successfully added 3 children (\"Frontend Components\", \"Database Design\", \"User Authentication\") to \"Backend API\" (ID: 5)"
}