---
title: keys
sidebarTitle: keys
---

# `fastmcp.server.tasks.keys`


Task key management for SEP-1686 background tasks.

Task keys encode security scoping and metadata in the Docket key format:
    {session_id}:{client_task_id}:{task_type}:{component_identifier}

This format provides:
- Session-based security scoping (prevents cross-session access)
- Task type identification (tool/prompt/resource)
- Component identification (name or URI for result conversion)


## Functions

### `build_task_key` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/tasks/keys.py#L15" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
build_task_key(session_id: str, client_task_id: str, task_type: str, component_identifier: str) -> str
```


Build Docket task key with embedded metadata.

Format: {session_id}:{client_task_id}:{task_type}:{component_identifier}

The component_identifier is URI-encoded to handle special characters (colons, slashes, etc.).

**Args:**
- `session_id`: Session ID for security scoping
- `client_task_id`: Client-provided task ID
- `task_type`: Type of task ("tool", "prompt", "resource")
- `component_identifier`: Tool name, prompt name, or resource URI

**Returns:**
- Encoded task key for Docket

**Examples:**

>>> build_task_key("session123", "task456", "tool", "my_tool")
'session123:task456:tool:my_tool'
>>> build_task_key("session123", "task456", "resource", "file://data.txt")
'session123:task456:resource:file%3A%2F%2Fdata.txt'


### `parse_task_key` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/tasks/keys.py#L47" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
parse_task_key(task_key: str) -> dict[str, str]
```


Parse Docket task key to extract metadata.

**Args:**
- `task_key`: Encoded task key from Docket

**Returns:**
- Dict with keys: session_id, client_task_id, task_type, component_identifier

**Examples:**

>>> parse_task_key("session123:task456:tool:my_tool")
{'session_id': 'session123', 'client_task_id': 'task456',
 'task_type': 'tool', 'component_identifier': 'my_tool'}
>>> parse_task_key("session123:task456:resource:file%3A%2F%2Fdata.txt")
{'session_id': 'session123', 'client_task_id': 'task456',
 'task_type': 'resource', 'component_identifier': 'file://data.txt'}


### `get_client_task_id_from_key` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/tasks/keys.py#L80" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_client_task_id_from_key(task_key: str) -> str
```


Extract just the client task ID from a task key.

**Args:**
- `task_key`: Full encoded task key

**Returns:**
- Client-provided task ID (second segment)

