SubagentStart
A Claude Code hook event, read out of the shipped bundle. No mined inventory carries it: everything below comes from what this site has written about it.
When a subagent is spawned
Anthropic's own wording. Read off Hooks reference, captured 2026-10-22.
In the changelogs
4Releases whose published page names SubagentStart.
-
v2.1.275
SubagentStop hook event
A SubagentStop hook now fires when a subagent finishes, alongside the existing SubagentStart hook
found in this entry's text
-
v2.1.265
Subagent spawn now threads request shape (foreground/background) and carries hook context across resumed skill-loaded turns
Subagent spawning now tracks foreground/background request shape and carries hook context through resumed skill-loading turns
found in this entry's text
-
v2.1.199
Hook additionalContext: Structured JSON Output
found in this entry's text
-
v2.1.63
SubagentStart / SubagentStop Hook Event Descriptions
found in this entry's text
First cited
0No release's published evidence quotes this name. The ledger indexes the Evidence lines of every changelog on this site, so this says nobody here has ever quoted it; it says nothing about how old the name is.
Presence across releases
0The miner has never read a build containing this name. It is here because a changelog entry of ours names it, which is evidence that it existed and not evidence of which releases carried it. The inventory starts at v2.1.138 and everything older than that was never mined.
Read out of the published npm bundle release by release, and out of Anthropic's own documentation as this site captured it. Nothing on this page is a description anybody here wrote about what the hook event does. All hook events.