Under the hoodTier: how much it should matter to you
3Useful: my rating, 1 to 5
5Signal: worth watching, 1 to 5
CompactionArea: what it touches
Internal ChangesKind: in v2.1.248,
What probably matters to youSection of the release
What
The bundled API client adds a compaction content block and streaming compaction deltas, deprecating its own client-side compaction control in favour of the server doing it, and gains sessions and threads, vaults and credentials, skills and versions, and MCP tunnels and certificates, each behind its own beta header. This is library surface inside the bundle; none of it is a Claude Code feature on its own.
Details
Message creation now warns when thinking.type=enabled is combined with the newer models.
Evidence
edits: [{ type: "compact_20260112" }]
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
