{"version":"2.1.283","anchor":"refusal-fallback-for-claude-opus-5-5-now-covers-the-frontier","canonical_anchor":"refusal-fallback-for-claude-opus-5-5-now-covers-the-frontier","heading":"Opus 5.5 can fall back to Opus 5 for one more refusal type","tier":"notice","area":"Models","url":"https:\/\/changelogs.core-directive.com\/v\/2.1.283\/e\/refusal-fallback-for-claude-opus-5-5-now-covers-the-frontier","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.283","markdown":"### Opus 5.5 can fall back to Opus 5 for one more refusal type\n\nWhen claude-opus-5-5 refuses a request in the frontier_llm category, Claude Code can now fall back to claude-opus-5\n\n**Unclear.** Whether the refusal fallback feature itself is switched on for everyone is not settled.\n\n**What**\n\nClaude Code keeps a list of which model to fall back to when the session's model refuses a request in a given category. For sessions on claude-opus-5-5, that list now includes the frontier_llm category, which falls back to claude-opus-5. Before, only the bio and cyber categories had fallbacks. The default list gains the same entry.\n\n**Why**\n\nIf you use Opus 5.5 and hit this kind of refusal, Claude Code may now retry on Opus 5 instead of stopping at the refusal.\n\n- Area: Models\n- Names: `claude-opus-5-5`, `claude-opus-5`\n- Tier: You'll notice\n- Useful: 3\/5\n- Signal: 4\/5"}