Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
ArtifactsArea: what it touches
Internal ChangesKind: in v2.1.310,
Internal ChangesSection of the release
What
The prompt cache lets Claude Code reuse earlier parts of a request instead of sending them again from scratch. Requests are grouped by a key. For artifact sessions there were two groups, and there are now three:
Sessions whose tools include a particular artifact tool
Sessions where artifact MCP tools replace the built-in ones, which used to share the first group
All other sessions
Why
Requests from these two kinds of artifact session no longer share cached prompts.
