DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.
Hook event payloads now include agent_type and agent_id fields, providing context about whether the hook fired from a subagent and which agent type triggered it. This allows hook scripts to behave differently based on agent context.
Evidence
Hook schema (search for "Agent type name", "Subagent identifier")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.