II.
HookSurface overview
Reference · livehook-surface:claude.subagent-start
SubagentStart (Claude Code) overview
Fires when a subagent is spawned. Output limited to additionalContext visible only to the user (not the subagent or parent). Used for UI indicators / telemetry. Matchable by agent_type.
Attributes
eventName
SubagentStart (Claude Code)
displayName
SubagentStart (Claude Code)
kind
native
originVendor
Anthropic
direction
pre
blocking
false
family
observer
payloadSchema
type
object
required
- hook_event_name
- agent_type
- agent_id
- prompt
properties
hook_event_name
type
string
const
SubagentStart
agent_type
type
string
agent_id
type
string
prompt
type
string
description
Fires when a subagent is spawned. Output limited to additionalContext
visible only to the user (not the subagent or parent). Used for UI
indicators / telemetry. Matchable by agent_type.
Outgoing edges
None.
Incoming edges
exposes1
- agent-runtime-impl:claude-code.runtime@1.x·AgentRuntimeImplClaude Code Runtime (1.x)
fires_hook1
- agent-core-impl:claude-code.core@1.x·AgentCoreImplClaude Code Core (1.x)
maps_hook1
- hook-mapping:claude-subagent-start·HookMapping