specs/001-task-crud/spec.md

# Feature Specification: Task CRUD Operations

**Feature Branch**: `001-task-crud`
**Created**: 2026-01-08
**Status**: Draft
**Input**: User description: "Task CRUD Feature – Phase II Todo Web App"

## User Scenarios & Testing *(mandatory)*

### User Story 1 - View and Create Tasks (Priority: P1)

As an authenticated user, I want to view my task list and create new tasks so that I can start managing my to-do items.

**Why this priority**: This is the foundational MVP functionality. Without the ability to create and view tasks, the application has no value. This story delivers immediate user value and can be demonstrated independently.

**Independent Test**: Can be fully tested by logging in, viewing an empty task list, creating a new task with a title, and seeing it appear in the list. Delivers core value of task creation and visibility.

**Acceptance Scenarios**:

1. **Given** I am an authenticated user with no tasks, **When** I view my task list, **Then** I see an empty state message indicating no tasks exist
2. **Given** I am viewing my task list, **When** I click "Add Task" and enter a title "Buy groceries", **Then** the task appears in my list with the title and a default "not completed" status
3. **Given** I am creating a task, **When** I enter a title and optional description, **Then** both fields are saved and displayed in the task list
4. **Given** I am viewing my task list, **When** I refresh the page, **Then** all my previously created tasks are still visible (data persists)
5. **Given** I am an authenticated user, **When** I view my task list, **Then** I only see tasks that I created (not other users' tasks)

---

### User Story 2 - Update and Complete Tasks (Priority: P2)

As an authenticated user, I want to edit my tasks and mark them as complete so that I can update task details and track my progress.

**Why this priority**: After creating tasks, users need to update them as requirements change and mark them complete to track progress. This builds on P1 and adds essential task management capabilities.

**Independent Test**: Can be tested by creating a task (from P1), editing its title or description, and toggling its completion status. Delivers progress tracking value.

**Acceptance Scenarios**:

1. **Given** I have a task "Buy groceries", **When** I click edit and change the title to "Buy groceries and milk", **Then** the updated title is saved and displayed
2. **Given** I have a task with a description, **When** I edit the description, **Then** the updated description is saved
3. **Given** I have an incomplete task, **When** I click the checkbox to mark it complete, **Then** the task is visually marked as completed
4. **Given** I have a completed task, **When** I click the checkbox again, **Then** the task is marked as incomplete
5. **Given** I am editing a task, **When** I cancel the edit, **Then** the original task details remain unchanged

---

### User Story 3 - Delete Tasks (Priority: P3)

As an authenticated user, I want to delete tasks I no longer need so that my task list stays clean and relevant.

**Why this priority**: Task deletion is important for list maintenance but not critical for initial value delivery. Users can work around missing deletion by marking tasks complete.

**Independent Test**: Can be tested by creating a task (from P1), deleting it, and verifying it no longer appears in the list. Delivers list management value.

**Acceptance Scenarios**:

1. **Given** I have a task in my list, **When** I click the delete button, **Then** the task is removed from my list
2. **Given** I have deleted a task, **When** I refresh the page, **Then** the deleted task does not reappear
3. **Given** I am about to delete a task, **When** I am prompted for confirmation, **Then** I can confirm or cancel the deletion
4. **Given** I have multiple tasks, **When** I delete one task, **Then** only that specific task is removed and others remain

---

### User Story 4 - Filter and Sort Tasks (Priority: P4)

As an authenticated user, I want to filter tasks by completion status and sort them so that I can focus on relevant tasks.

**Why this priority**: Filtering and sorting improve usability but are not essential for core task management. Users can manually scan their list initially.

**Independent Test**: Can be tested by creating multiple tasks with different completion statuses, applying filters (show all/active/completed), and verifying the correct subset is displayed. Delivers organization value.

**Acceptance Scenarios**:

1. **Given** I have both completed and incomplete tasks, **When** I select "Active" filter, **Then** I only see incomplete tasks
2. **Given** I have both completed and incomplete tasks, **When** I select "Completed" filter, **Then** I only see completed tasks
3. **Given** I have multiple tasks, **When** I select "All" filter, **Then** I see all tasks regardless of completion status
4. **Given** I have multiple tasks, **When** I sort by creation date (newest first), **Then** tasks are displayed with most recent at the top
5. **Given** I have applied a filter, **When** I refresh the page, **Then** the filter preference is maintained

---

### Edge Cases

- What happens when a user tries to create a task with an empty title?
- What happens when a user tries to create a task with a title exceeding 200 characters?
- What happens when a user tries to create a task with a description exceeding 1000 characters?
- How does the system handle concurrent updates to the same task from multiple browser tabs?
- What happens when the backend API is unavailable during task operations?
- How does the system handle special characters or emojis in task titles and descriptions?
- What happens when a user tries to access another user's task directly via URL manipulation?

## Requirements *(mandatory)*

### Functional Requirements

- **FR-001**: System MUST allow authenticated users to create tasks with a title (1-200 characters, required) and description (0-1000 characters, optional)
- **FR-002**: System MUST display all tasks belonging to the authenticated user in a list view
- **FR-003**: System MUST allow users to edit the title and description of their existing tasks
- **FR-004**: System MUST allow users to toggle the completion status of their tasks (completed/incomplete)
- **FR-005**: System MUST allow users to delete their tasks with confirmation
- **FR-006**: System MUST persist all task data to the database with automatic timestamps (created_at, updated_at)
- **FR-007**: System MUST enforce data isolation - users can only view, edit, and delete their own tasks
- **FR-008**: System MUST validate task title length (1-200 characters) and reject invalid submissions
- **FR-009**: System MUST validate task description length (0-1000 characters) and reject invalid submissions
- **FR-010**: System MUST provide filtering options: All tasks, Active tasks (incomplete), Completed tasks
- **FR-011**: System MUST provide sorting options: by creation date (newest/oldest first)
- **FR-012**: System MUST display task metadata: creation timestamp, last updated timestamp
- **FR-013**: System MUST provide visual distinction between completed and incomplete tasks
- **FR-014**: System MUST handle API errors gracefully with user-friendly error messages
- **FR-015**: System MUST maintain responsive design across mobile, tablet, and desktop viewports

### Assumptions

- Authentication and JWT token management are handled by a separate authentication feature (Spec 2)
- The frontend receives a valid JWT token from the authentication system
- The backend has middleware to verify JWT tokens and extract user identity
- Database connection and configuration are already established
- The user ID is available from the authenticated session/token

### Key Entities

- **Task**: Represents a to-do item with the following attributes:
  - Unique identifier (system-generated)
  - Title (1-200 characters, required)
  - Description (0-1000 characters, optional)
  - Completion status (boolean: completed/incomplete)
  - Owner (reference to the user who created it)
  - Creation timestamp (automatically set)
  - Last updated timestamp (automatically updated)
  - Relationships: Belongs to one User

- **User**: Represents an authenticated user (defined in authentication spec)
  - Unique identifier
  - Relationships: Has many Tasks

## Success Criteria *(mandatory)*

### Measurable Outcomes

- **SC-001**: Users can create a new task in under 10 seconds from clicking "Add Task" to seeing it in their list
- **SC-002**: Users can view their complete task list with all tasks loading and displaying within 2 seconds
- **SC-003**: Users can edit a task and see the updated information reflected immediately (within 1 second of saving)
- **SC-004**: Users can mark a task as complete and see the visual change instantly (within 500ms)
- **SC-005**: Users can delete a task and see it removed from the list within 1 second
- **SC-006**: System correctly isolates user data - 100% of API requests return only the authenticated user's tasks
- **SC-007**: System handles 100 concurrent users performing task operations without errors or data corruption
- **SC-008**: 95% of task operations (create, update, delete, complete) succeed on first attempt without errors
- **SC-009**: Users can successfully complete all core task operations (create, view, update, complete, delete) on mobile devices with touch interactions
- **SC-010**: System maintains data integrity - 100% of created tasks persist correctly and are retrievable after page refresh

### User Experience Outcomes

- **SC-011**: Users can understand how to create, edit, and delete tasks without external documentation
- **SC-012**: Error messages clearly communicate what went wrong and how to fix it (e.g., "Title must be between 1 and 200 characters")
- **SC-013**: The interface provides immediate visual feedback for all user actions (loading states, success confirmations, error alerts)
- **SC-014**: Users can distinguish between completed and incomplete tasks at a glance through clear visual indicators

## Out of Scope

The following items are explicitly excluded from this specification:

- User authentication and authorization implementation (covered in separate authentication spec)
- JWT token generation, validation, and refresh logic (covered in authentication spec)
- User registration and login flows (covered in authentication spec)
- Task sharing or collaboration features
- Task categories, tags, or labels
- Task due dates or reminders
- Task priority levels
- Task attachments or file uploads
- Task comments or notes beyond the description field
- Task history or audit trail
- Bulk operations (delete multiple tasks, mark multiple complete)
- Task search functionality
- Task export/import features
- Chatbot or AI-powered task suggestions
- Deployment configuration or environment setup
- Advanced UI animations or transitions beyond standard interactions

## Dependencies

- **Authentication System**: This feature requires a functioning authentication system that provides JWT tokens and user identity
- **Database**: Requires Neon PostgreSQL database to be provisioned and accessible
- **Backend Framework**: Requires FastAPI backend with SQLModel ORM configured
- **Frontend Framework**: Requires Next.js 16+ with App Router configured

## Technical Constraints

- **Frontend**: Must use Next.js 16+ (App Router), TypeScript, Tailwind CSS
- **Backend**: Must use Python FastAPI with SQLModel ORM
- **Database**: Must use Neon Serverless PostgreSQL
- **API Design**: Must follow REST principles with JSON request/response format
- **Authentication**: All task endpoints must require valid JWT token in Authorization header
- **Code Generation**: All implementation must be generated via Claude Code referencing this specification
- **File Structure**: Must follow monorepo organization with frontend/ and backend/ directories

## References

This specification should be referenced during implementation planning and task generation:

- `@specs/001-task-crud/spec.md` (this file)
- `@specs/001-task-crud/plan.md` (to be created by `/sp.plan`)
- `@specs/001-task-crud/tasks.md` (to be created by `/sp.tasks`)
- `@specs/001-task-crud/contracts/` (API endpoint contracts to be defined in planning phase)