{"version":"2.1.257","anchor":"claude-fable-5-1-model-wiring-vertex-region-gate","canonical_anchor":"claude-fable-5-1-model-wiring-vertex-region-gate","heading":"claude-fable-5-1 model added, gated behind renamed fable51 flag","tier":"soon","area":"Models","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.257\/e\/claude-fable-5-1-model-wiring-vertex-region-gate","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.257","markdown":"### claude-fable-5-1 model added, gated behind renamed fable51 flag\n\nclaude-fable-5-1 is wired up with its own Vertex region, and fallback lists now gate on a fable51 check.\n\nA new model id `claude-fable-5-1` and its Vertex region constant `VERTEX_REGION_CLAUDE_FABLE_5_1` were added. The opus\/haiku fallback-list builders now check feature gate `fable51` (replacing the previous `fable5` check) before appending the model via `WZe()`.\n\n- Area: Models\n- Names: `claude-fable-5-1`\n- Tier: Nothing to try yet\n- Useful: 4\/5\n- Signal: 4\/5\n- Present in the build but not switched on"}