What probably matters to youSection of the release
What
Messages produced by compaction are now marked synthetic in SDK and stream-json output, so consumers can filter them out alongside meta and transcript-only messages.
Details
The serialiser now calls a shared helper instead of computing the flag inline from meta and transcript-only checks.
A local-command result that trims to an empty string after its stdout and stderr wrappers are stripped now returns nothing instead of emitting an empty assistant message.
Evidence
isCompactSummary
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
