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?
The MCP client SDK can now be switched between v1 and v2 via an environment variable or feature flag.
MCP_SDK_GENERATION=v2 claude ... # force SDK v2
MCP_SDK_GENERATION=v1 claude ... # force SDK v1 (default)- Default is v1 unless the
tengu_brindle_causewayfeature flag is active - Invalid values are ignored with a warning:
"MCP_SDK_GENERATION=X is invalid; expected 'v1' or 'v2' — ignoring" - A runtime tripwire catches mismatches between the selected generation and the loaded module
- The selection source (env/growthbook/default) is logged and reported via telemetry
New env var and generation selector (search for "MCP_SDK_GENERATION")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
Related
Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.