# Custom Task Status Creation Endpoint Implementation

## Overview
Implemented the POST endpoint for creating custom task statuses in projects. This allows coordinators and admins to define project-specific task statuses beyond the built-in system statuses.

## Implementation Details

### Endpoint
- **Route**: `POST /projects/{project_id}/task-statuses`
- **Status Code**: 201 Created
- **Authorization**: Requires coordinator or admin role

### Features Implemented

#### 1. Status Name Uniqueness Validation
- Validates that the status name is unique within the project
- Case-insensitive comparison to prevent duplicates like "In Review" and "in review"
- Checks against both existing custom statuses and system statuses
- Returns 409 Conflict if duplicate found

#### 2. Auto-Assign Color from Palette
- Defines a default color palette with 10 distinct colors:
  - Purple (#8B5CF6)
  - Pink (#EC4899)
  - Teal (#14B8A6)
  - Orange (#F97316)
  - Cyan (#06B6D4)
  - Lime (#84CC16)
  - Violet (#A855F7)
  - Rose (#F43F5E)
  - Sky (#22D3EE)
  - Yellow (#FACC15)
- Automatically assigns the first unused color from the palette
- If all colors are used, cycles back through the palette
- Users can override by providing a custom color in hex format

#### 3. Unique Status ID Generation
- Generates unique IDs using UUID4 with format: `custom_{8-char-hex}`
- Example: `custom_0c7ba931`
- Ensures no ID collisions

#### 4. JSON Column Updates
- Uses SQLAlchemy's `flag_modified()` to properly track changes to JSON columns
- Ensures database updates are persisted correctly

#### 5. Status Ordering
- Automatically assigns order based on existing statuses
- New statuses are appended to the end (max_order + 1)
- Maintains consistent ordering for UI display

### Request Schema
```json
{
  "name": "Ready for Review",
  "color": "#8B5CF6"  // Optional - auto-assigned if not provided
}
```

### Response Schema
```json
{
  "message": "Custom task status 'Ready for Review' created successfully",
  "status": {
    "id": "custom_0c7ba931",
    "name": "Ready for Review",
    "color": "#EC4899",
    "order": 3,
    "is_default": false
  },
  "all_statuses": {
    "statuses": [...],  // All custom statuses
    "system_statuses": [...],  // Built-in system statuses
    "default_status_id": "not_started"
  }
}
```

### Validation Rules

#### Name Validation (via Pydantic schema)
- Minimum length: 1 character
- Maximum length: 50 characters
- Whitespace is trimmed
- Cannot be empty after trimming

#### Color Validation (via Pydantic schema)
- Must be valid hex color code format: `#RRGGBB`
- Example: `#FF5733`
- Normalized to uppercase
- Optional field

### Error Responses

#### 404 Not Found
```json
{
  "detail": "Project not found"
}
```

#### 409 Conflict - Duplicate Name
```json
{
  "detail": "Status with name 'Ready for Review' already exists in this project"
}
```

#### 409 Conflict - System Status Name
```json
{
  "detail": "Status name 'In Progress' conflicts with a system status"
}
```

#### 422 Unprocessable Entity - Validation Error
```json
{
  "detail": "1 validation error for CustomTaskStatusCreate\nname\n  String should have at least 1 character..."
}
```

## Testing

### Test Results
All validation and functionality tests passed:

1. ✅ Create status without color (auto-assigned from palette)
2. ✅ Create status with custom color
3. ✅ Reject duplicate status names (409 Conflict)
4. ✅ Reject empty status names (422 Validation Error)
5. ✅ Reject invalid color formats (422 Validation Error)
6. ✅ Reject system status name conflicts (409 Conflict)
7. ✅ Proper ordering of statuses
8. ✅ Unique ID generation
9. ✅ JSON column updates with flag_modified

### Test Files
- `backend/test_create_custom_task_status.py` - Comprehensive test suite
- `backend/test_custom_status_validation.py` - Validation-focused tests

## Database Schema
The custom task statuses are stored in the `projects.custom_task_statuses` JSON column:

```json
[
  {
    "id": "custom_review",
    "name": "In Review",
    "color": "#8B5CF6",
    "order": 0,
    "is_default": false
  },
  {
    "id": "custom_blocked",
    "name": "Blocked",
    "color": "#DC2626",
    "order": 1,
    "is_default": false
  }
]
```

## Requirements Satisfied
- ✅ Requirement 1.2: Create new custom task status
- ✅ Requirement 1.3: Validate status name uniqueness within project
- ✅ Requirement 1.4: Auto-assign color from palette if not provided

## Next Steps
The following endpoints still need to be implemented:
- PUT endpoint for updating custom status (Task 5)
- DELETE endpoint for deleting custom status (Task 6)
- PATCH endpoint for reordering statuses (Task 7)
