tengu_brindle_causeway On for this account, and not off by defaultThe flag server returned on for the one account this site reads, and nothing in this release compiles it off by default. The compiled default is shown below, and says which it is when we cannot read one: a fifth of gates compile in a string or a number rather than on or off, and most published releases have no gate table behind them at all. No client can see what the server returns for your account.
This account: on · anonymous baseline: on · compiled default in v2.1.218: on
These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.
Read once, for one account on one subscription tier, against v2.1.218. It isn't a statement about your account. What a flag value here can and cannot tell you
What's wrong with this entry?
Server-controlled rollout via tengu_brindle_causeway feature flag (default: disabled). Users can force v2 manually with MCP_SDK_GENERATION=v2.
A second generation of the MCP client SDK (v2) is fully implemented and selectable. V2 brings stateless claude.ai-proxy MCP connections with cached initialization responses to avoid a full round-trip on reconnect (Yqu/Xqu), plus module-level separation of transport concerns.
- Both v1 and v2 are fully functional; v2 is currently off by default
- The generation is selected at arm time and locked for the session
- A runtime tripwire (
MCP_TREE_IDsentinel) confirms the correct module loaded
Generation selector and tripwire (search for "MCP runtime accessor tripwire")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.