{"name":"tengu_fennel_kite_model","slug":"tengu-fennel-kite-model","family":"flag","title":"Feature flags","noun":"feature flag","description":"Default `\"\"`. A model-ID substring: when the current model's ID contains it, and the base preconditions hold (the default Anthropic API base URL or `CLAUDE_CODE_MID_CONVERSATION_SYSTEM` set, plus other provider and model checks), requests send the `mid-conversation-system-2026-04-07` beta header and message building switches to its mid-conversation-system handling. A model ID matching `CLAUDE_CODE_MID_CONVERSATION_SYSTEM` is accepted first, and a non-empty cached client-data value of the same name is used in place of the flag.","description_source":"code","described_by":{"bundle":"2.1.153","author":"claude-opus-5-5"},"presence":{"first_seen":"2.1.138","removed_in":"2.1.154","in_current_build":false,"newest_mined":"2.1.308","builds":15,"mined_builds":149,"first_cited":null},"aliases":[],"entries":[],"entries_total":0,"docs":[],"docs_total":0,"gates":[],"related":[{"name":"tengu_fennel_godwit","slug":"tengu-fennel-godwit","description":"On Opus 5, Claude is told not to spawn subagents, workflows or deep research unless you ask."}],"url":"https:\/\/changelogs.core-directive.com\/reference\/flag\/tengu-fennel-kite-model","family_url":"https:\/\/changelogs.core-directive.com\/reference\/flag.json"}