{"version":"2.1.219","anchor":"opus-5-replaces-opus-4-8-as-the-default-opus-model","canonical_anchor":"opus-5-replaces-opus-4-8-as-the-default-opus-model","heading":"Opus 5 replaces Opus 4.8 as the default Opus model","tier":"notice","area":"Models","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.219\/e\/opus-5-replaces-opus-4-8-as-the-default-opus-model","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.219","markdown":"### Opus 5 replaces Opus 4.8 as the default Opus model\n\nOpus 5 is now the default Opus, with a 1M-context option in the model picker.\n\n**What**\n\nThe bundled model catalog gains `claude-opus-5` and the `opus` alias now points at it, so anything resolving the newest Opus resolves Opus 5 instead of Opus 4.8.\n\n**Details**\n\n- Catalog entry: display name \"Opus 5\", knowledge cutoff \"May 2026\", 1M-token context with `supports_1m_suffix`, `max_output_tokens` default 64000 and upper 128000, `pricing: \"tier_5_25\"`, `default_effort: \"high\"`, `fallback_3p: \"claude-opus-4-8\"`, `vertex_region_env_var` \"VERTEX_REGION_CLAUDE_5_OPUS\", and a new capability tag `opus_5_prompt_bundle`.\n- Provider ids ship for bedrock (`us.anthropic.claude-opus-5`), vertex, foundry, mantle (`anthropic.claude-opus-5`) and gateway. The `opus` alias resolves to claude-opus-5 for first-party, bedrock, vertex, mantle and anthropic_aws; foundry still maps to claude-opus-4-6 and gateway to claude-opus-4-7.\n- Three internal default-model constants changed from the literal \"opus48\" to \"opus5\", and the first-party preference order went from [\"opus48\",\"opus47\",\"opus46\",\"opus45\"] to [\"opus5\",\"opus48\",\"opus47\",\"opus46\",\"opus45\"]. The alias table gained `\"claude-opus-5\": \"opus5\"` and `latest_per_family.opus` moved to claude-opus-5.\n- The picker shows a plain \"Opus\" row plus an \"Opus (1M context)\" variant, and Opus 4.8 is demoted to \"Opus 4.8 \u00b7 Previous Opus version\". `OPUS_NAME` is now \"Claude Opus 5\" with the old pair kept as `PREV_OPUS_ID` \/ `PREV_OPUS_NAME`.\n- Pricing suffix lookups now query `claude-opus-5`, unrecognized-model fallbacks return \"claude-opus-5\" instead of \"claude-opus-4-8\", and `claude-fable-5` falls back to it via `fallback_3p`.\n- The catalog data is unconditional in this build; whether a row is offered still depends on the model being available for the active account and provider, which the picker checks via provider id \/ modelOverrides.\n\n**Evidence**\n\n`Opus 5 - best for everyday, complex tasks`, `Opus 5 with 1M context window - for long sessions with large codebases`, `opus_5_prompt_bundle`, `PREV_OPUS_NAME: \"Claude Opus 4.8\"`, `claude-opus-5`\n\n- Area: Models\n- Names: `opus`, `claude-opus-5`, `VERTEX_REGION_CLAUDE_5_OPUS`\n- Tier: You'll notice\n- Useful: 5\/5\n- Signal: 0\/5"}