{"version":"2.1.247","anchor":"a-model-capability-toggle-tengu-willow-tern","canonical_anchor":"a-model-capability-toggle-tengu-willow-tern","heading":"A model-capability toggle, tengu_willow_tern","tier":"soon","area":"Model Config","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.247\/e\/a-model-capability-toggle-tengu-willow-tern","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.247","markdown":"### A model-capability toggle, tengu_willow_tern\n\nA new toggle applies only to models advertising an opus 5 prompt bundle capability.\n\n**What**\n\nA 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.\n\n**Details**\n\n- Non-boolean client-data values are ignored, with a warning logged once.\n- What the toggle switches on beyond the prompt bundle is not evident from the added code.\n\n**Evidence**\n\n`tengu_willow_tern`\n\n- Flag `tengu_willow_tern`: Off in both readings (read for one account on one subscription tier against v2.1.247; this account: off, anonymous baseline: off, compiled default: not a boolean we can read)\n- Area: Model Config\n- Names: `CLAUDE_CODE_WILLOW_TERN`, `tengu_willow_tern`\n- Tier: Nothing to try yet\n- Useful: 2\/5\n- Signal: 5\/5\n- Present in the build but not switched on"}