{"version":"2.1.219","anchor":"model-downgrade-chain-and-effort-tables-know-about-opus-5","canonical_anchor":"model-downgrade-chain-and-effort-tables-know-about-opus-5","heading":"Model-downgrade chain and effort tables know about Opus 5","tier":"notice","area":"Models","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.219\/e\/model-downgrade-chain-and-effort-tables-know-about-opus-5","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.219","markdown":"### Model-downgrade chain and effort tables know about Opus 5\n\nModel fallbacks and reasoning-effort settings now handle Opus 5, stepping down to Opus 4.8 when needed.\n\n**What**\n\nThe stepwise \"older model\" resolver and the reasoning-effort tables were extended for Opus 5, so downgrades and effort selection land on the right model.\n\n**Details**\n\n- an Opus 5 name now steps down to Opus 4.8\n- a `fable-5` name resolves to Opus 5 instead of Opus 4.8\n- the reasoning-effort configuration table gained a `claude-opus-5` entry\n- the set of models on the special effort path now contains both `claude-opus-4-8` and `claude-opus-5`\n\n**Evidence**\n\n`if (t.includes(\"opus-5\") || t.includes(\"opus_5\"))`\n\n- Area: Models\n- Names: `claude-opus-5`\n- Tier: You'll notice\n- Useful: 3\/5\n- Signal: 0\/5"}