task-dependency-patterns

# Task Dependency Patterns

## Overview

Claude Code 2.1.16 introduces a native Task Management System with four tools:
- **TaskCreate**: Create new tasks with subject, description, and activeForm
- **TaskUpdate**: Update status (pending → in_progress → completed), set dependencies
- **TaskGet**: Retrieve full task details including blockers
- **TaskList**: View all tasks with status and dependency summary

Tasks enable structured work tracking, parallel coordination, and clear progress visibility.

## When to Use

- Breaking down complex multi-step implementations
- Coordinating parallel work across multiple files
- Tracking progress on large features
- Managing dependencies between related changes
- Providing visibility into work status

## Key Patterns

### 1. Task Decomposition

Break complex work into atomic, trackable units:

```
Feature: Add user authentication

Tasks:
#1. [pending] Create User model
#2. [pending] Add auth endpoints (blockedBy: #1)
#3. [pending] Implement JWT tokens (blockedBy: #2)
#4. [pending] Add auth middleware (blockedBy: #3)
#5. [pending] Write integration tests (blockedBy: #4)
```

### 2. Dependency Chains

Use `addBlockedBy` to create execution order:

```json
// Task #3 cannot start until #1 and #2 complete
{"taskId": "3", "addBlockedBy": ["1", "2"]}
```

### 3. Status Workflow

```
pending → in_progress → completed
   ↓           ↓
(unblocked)  (active)

pending/in_progress → deleted (CC 2.1.20)
```

- **pending**: Task created but not started
- **in_progress**: Actively being worked on
- **completed**: Work finished and verified
- **deleted**: Task removed (CC 2.1.20) - permanently removes the task

### Task Deletion (CC 2.1.20)

CC 2.1.20 adds `status: "deleted"` to permanently remove tasks:

```json
// Delete a task
{"taskId": "3", "status": "deleted"}
```

**When to delete:**
- Orphaned tasks whose blockers have all failed
- Tasks superseded by a different approach
- Duplicate tasks created in error
- Tasks from a cancelled pipe