Unclear It is not clear which connections turn the strict mode on.
Some of Claude Code's connections use SSE (server-sent events), a way for a server to keep one connection open and stream updates over it. That connection has a new optional strict mode, called requireStreamEvidence. It is off by default. When it is on, Claude Code treats the connection as failed if both of these are true:
- the reply is not marked as an event stream
- the reply has no header from the session service
In that case it logs that a proxy or gateway may have answered instead of the real server.
The connection also now records the time the server reports in its reply when it first connects.
On some networks a proxy, a company gateway or a hotel-style login page answers in place of the real server. Without this check Claude Code could treat that reply as a working connection. This makes Remote Control and other remote connections fail clearly in that situation instead of quietly misbehaving.
It is not clear which connections turn the strict mode on.