tengu_willow_tern gates behaviour for models with the opus_5_prompt_bundle capability and compiles off; CLAUDE_CODE_WILLOW_TERN overrides.
A new toggle that applies only to models advertising the opus_5_prompt_bundle capability. It reads CLAUDE_CODE_WILLOW_TERN first, then a boolean tengu_willow_tern key in client data, then the flag, whose compiled fallback is off.
- Non-boolean client-data values are ignored, with a warning logged once.
- What the toggle switches on beyond the prompt bundle is not evident from the added code.
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
tengu_willow_tern Off in both readingsThe flag server returned off for the account this site reads and for the anonymous baseline. A reading of off cannot rule out a rollout these two readings sit outside of.
This account: off · anonymous baseline: off · compiled default in v2.1.247: not a boolean we can read
Read once, for one account on one subscription tier, against v2.1.247. It isn't a statement about your account. What a flag value here can and cannot tell you
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
New in this build: CLAUDE_CODE_WILLOW_TERN