{"version":"2.1.281","anchor":"bundled-model-preset-config-chat-preset-thinking-effort-for","canonical_anchor":"bundled-model-catalog-adds-claude-opus-5-5-opus-55-whi","heading":"Opus 5.5 becomes the Opus choice in the model picker, defaulting to medium effort","tier":"use","area":"Models","url":"https:\/\/changelogs.core-directive.com\/v\/2.1.281\/e\/bundled-model-preset-config-chat-preset-thinking-effort-for","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.281","markdown":"### Opus 5.5 becomes the Opus choice in the model picker, defaulting to medium effort\n\nThe bundled model catalog now puts claude-opus-5-5 (Opus 5.5) in the Opus picker slot with medium thinking effort, and the in-app release notes announce it\n\n**Unclear.** The evidence fits both a reordered list with a new Opus 5.5 entry and a renamed existing entry, and it does not say where the `chat` preset is used.\n\n**What**\n\nClaude Opus 5.5, model id `claude-opus-5-5`, now fills the Opus slot in the model catalog bundled with Claude Code. The catalog is the built-in list of models the model picker offers, and this build carries catalog version 994. The in-app release notes describe the same change.\n\n- The in-app release notes now start with a `## 2.1.280` section. Its first line says Claude Opus 5.5 (`claude-opus-5-5`) was added and is now the default Opus model. There is no `## 2.1.281` section in this build.\n\n- The picker's quick-select entry with short name \"Opus\" and description \"For complex tasks\" now points to `claude-opus-5-5` \/ \"Opus 5.5\". Before, it pointed to `claude-opus-5` \/ \"Opus 5\".\n\n- The static model table shows the display name \"Opus 5.5\", and there is a Vertex region environment variable named `VERTEX_REGION_CLAUDE_5_5_OPUS`.\n\n- The per-model thinking defaults (`thinking_by_model`) now list `claude-opus-5-5` on every surface. Thinking effort is how much work the model puts into a reply before answering.\n\n- On the `cc` surface and in the \"chat\" preset, `claude-opus-5-5` gets effort \"medium\", while `claude-opus-5` keeps \"high\".\n\n- A bundled `model_selector_state` sample for `cc` and `ccd` shows the same switch to medium, although its top-level model is still `claude-opus-5`.\n\n- In the catalog's `claude-opus-5-5` entry, the recommended \"Default\" badge in the effort options moved from High to Medium. The same badge move happened for `claude-fable-5-1` under the \"chat\" selector config.\n\n- A separate list that uses `effort_and_mode` gains a `claude-opus-5` entry with effort \"high\" and mode \"auto\", placed just before `claude-opus-4-8`.\n\n**Why**\n\nPicking Opus in the model picker now selects Opus 5.5, and it starts at medium effort rather than high. The catalog's own effort text says higher effort gives more thorough responses but takes longer and uses your limits faster. If replies feel less thorough than they did with Opus 5, check the effort setting.\n\n- Area: Models\n- Names: `claude-opus-5-5`\n- Tier: Use it now\n- Useful: 5\/5\n- Signal: 4\/5"}