SubagentStart API
July 14, 2026 · View on GitHub
Available when inheriting from ClaudeHooks::SubagentStart:
Runs when a subagent task starts. Use it to inject context specific to the subagent or log the start.
Input Helpers
The agent_id and agent_type common fields are populated for this event.
| Method | Description |
|---|---|
agent_id | The subagent's unique ID |
agent_type | The subagent's type |
Hook State Helpers
| Method | Description |
|---|---|
add_additional_context!(context) | Add contextual information for the subagent |
add_context!(context) | Alias for add_additional_context! |
Output Helpers
| Method | Description |
|---|---|
output.additional_context | Get the additional context that was added |
Hook Exit Codes
| Exit Code | Behavior |
|---|---|
exit 0 | Continues normally; STDOUT added as context |
exit 2 | N/A — non-blocking event |