Unclear It is not clear whether Claude Code was already sending these messages before the schema listed them.
When Claude Code runs with streaming JSON output, it prints a series of machine-readable messages. A published schema describes which message shapes are allowed. A schema is a formal description of a data format. Programs built on Claude Code, including SDK integrations, can check each message against it. The SDK is the toolkit for building programs on top of Claude Code.
The schema now includes two more message types:
- A system message with the subtype
post_turn_summary - An active goal message
Both were added to the list of messages that report on a session and to the full list of messages Claude Code can print.
If a program checks Claude Code's output against this schema, it now accepts these two messages instead of rejecting them as unknown.
It is not clear whether Claude Code was already sending these messages before the schema listed them.