> ## Documentation Index
> Fetch the complete documentation index at: https://docs.trydraft.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Ticket Dependencies

> Manage execution order with a dependency DAG

## Overview

Tickets can depend on each other via `blocked_by_ticket_id`. This creates a **directed acyclic graph (DAG)** that controls execution order.

## How Dependencies Work

* A ticket **cannot execute** until its blocker reaches `DONE`
* The planner automatically **blocks** tickets with incomplete dependencies
* When a dependency completes, blocked tickets are **auto-unblocked**

## Setting Dependencies

### Via the UI

Drag a ticket onto another to create a dependency, or use the ticket detail panel to set the "Blocked By" field.

### Via the API

```bash theme={null}
curl -X PATCH http://localhost:8000/tickets/{id} \
  -H "Content-Type: application/json" \
  -d '{"blocked_by_ticket_id": "other-ticket-id"}'
```

## Execution Order

Draft uses **Kahn's algorithm** for topological sorting to determine execution order:

1. Build a dependency graph from all tickets
2. Find tickets with no dependencies (ready to execute)
3. Execute in priority order
4. When a ticket completes, check if any blocked tickets are now unblocked

### Cycle Detection

If circular dependencies are detected, Draft falls back to the original priority order and logs a warning.

## Example

```
Ticket A: "Set up database schema"
    ↓
Ticket B: "Add API endpoints" (blocked by A)
    ↓
Ticket C: "Add frontend pages" (blocked by B)
```

Execution order: A → B → C

Ticket B won't start until A reaches `DONE`. If A becomes `BLOCKED`, B stays `BLOCKED` too.

## Best Practices

* Keep dependency chains **short** (2-3 levels max)
* Use dependencies for true **data/API dependencies**, not just priority ordering
* Let the planner handle dependency management when using autopilot