You'll notice
Mid-conversation system prompt injection on tool changes now limited to first-party provider
What
The internal check that decides whether to inject a mid-conversation system message when tools change now immediately returns false unless Claude Code is running against the first-party Anthropic provider. This means it now bails out for other providers, such as Bedrock or Vertex, before even checking the environment variable override that previously controlled this.
Why
This stops Claude Code from injecting this system message on non-first-party providers, where it presumably wasn't intended or reliable to do so.