mcp_set_servers gains a sign-in hint and waits for servers that are still connecting

What

MCP servers are outside services that give Claude Code extra tools. mcp_set_servers is a control message that a controlling program, such as the service behind a remote session, sends to tell Claude Code which MCP servers to use. It changes in two ways:

• The message gains an optional hint field that says why the set was sent, for example connector_signed_in. It is described as "a hint, not a grant": Claude Code still works out its own set of MCP servers.
• When a sign-in hint is passed, Claude Code now waits for each server to finish connecting, leaving the 'pending' state, before acting. A server that then needs sign-in ('needs-auth') is connected with the context 'MCP server set'. If the wait runs out first, it logs 'Still connecting when the wait after the sign-in hint ended, so it is not dialed again'. Before, every server needing sign-in was dialed right away.

The read_file control request, when it asks for a live reply (liveReply), now joins mcp_authenticate and mcp_status in the set of requests that are only answered live.

Why

After you sign in to a connector in a remote session, Claude Code should no longer try to connect the same server twice while it is still connecting. The hint does not give the controlling program extra power over which servers are used.