# Claude Opus 4.5 Migration > Has your agent move code and prompts from Sonnet 4.x or Opus 4.1 to Claude Opus 4.5, from model strings to prompt fixes. Anthropic's own Claude Code plugin for moving a codebase from Claude Sonnet 4, Sonnet 4.5 or Opus 4.1 to Claude Opus 4.5. It's a single skill: ask your agent to migrate, and it finds your model strings and API calls, updates them and sums up what it changed. What it does - Searches your codebase for model strings and API calls - Swaps in the Opus 4.5 model string for the Claude API, AWS Bedrock, Google Vertex AI or Azure AI Foundry - Removes the 1M-context beta header, which the skill says Opus 4.5 doesn't support yet, and leaves a comment saying why - Adds the effort parameter, set to high - Lists every change it made Prompt fixes, only when you ask Opus 4.5 behaves differently from earlier models, so the skill carries fixes for known issues. By default it only updates model strings; it applies these when you ask or report the problem: - Tools called too often: it softens forceful wording such as "CRITICAL" or "You MUST" in tool instructions - Extra files and abstractions: it adds a snippet that keeps solutions minimal - Fixes proposed without reading the code: it adds a snippet that has the model read the files first - Generic-looking frontend output: it adds a frontend design snippet - Trouble with the word "think" when extended thinking is off: it swaps in words like "consider" or "evaluate" How to install it In Claude Code, run /plugin marketplace add anthropics/claude-code, then /plugin install claude-opus-4-5-migration@claude-code-plugins. Then ask "Migrate my codebase to Opus 4.5". Good to know - It leaves Haiku models alone. - It targets Opus 4.5 only, not newer Claude models. - If anything feels off after the move, keep using the skill to adjust your prompts. - Type: Skill - Made by: Anthropic - Category: AI & agents - Formats: Skills - Version: 734cac2 - Source: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration - Page: https://pluginboard.ai/skills/anthropic-opus-4-5-migration ## Works with - ChatGPT - Claude - Gemini - GitHub Copilot - Cursor - Claude Code - Codex - Antigravity - Gemini CLI - Replit - OpenClaw - OpenCode - Hermes Agent ## Install ### ChatGPT In ChatGPT: Download the claude-opus-4-5-migration folder and zip it, then Plugins → Skills → Create → Upload from your computer. Business and Enterprise plans. View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ### Claude In Claude (web or desktop): Download the claude-opus-4-5-migration folder and zip the folder itself, then upload it in Customize → Skills. View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ### Gemini In Gemini: Download the claude-opus-4-5-migration folder, then at gemini.google.com click Customize → Skills → Create → Upload and pick the folder (or a .zip of it). View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ### GitHub Copilot Run in your terminal: ```shell npx -y degit anthropics/claude-code/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ~/.copilot/skills/claude-opus-4-5-migration ``` View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ### Cursor Run in your terminal: ```shell npx -y degit anthropics/claude-code/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ~/.cursor/skills/claude-opus-4-5-migration ``` View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ### Claude Code Run in your terminal: ```shell npx -y degit anthropics/claude-code/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ~/.claude/skills/claude-opus-4-5-migration ``` View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration Or as a Claude Code plugin: ```text /plugin marketplace add anthropics/claude-code /plugin install claude-opus-4-5-migration@claude-code-plugins ``` ### Codex Run in your terminal: ```shell npx -y degit anthropics/claude-code/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ~/.agents/skills/claude-opus-4-5-migration ``` View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ### Antigravity In Antigravity: Copy the claude-opus-4-5-migration folder into ~/.gemini/config/skills (Antigravity app and IDE) or ~/.gemini/antigravity-cli/skills (Antigravity CLI). View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ### Gemini CLI Run in your terminal: ```shell npx -y degit anthropics/claude-code/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ~/.gemini/skills/claude-opus-4-5-migration ``` View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ### Replit Run in your terminal: ```shell npx -y degit anthropics/claude-code/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration .agents/skills/claude-opus-4-5-migration ``` View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ### OpenClaw Run in your terminal: ```shell npx -y degit anthropics/claude-code/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ~/.openclaw/skills/claude-opus-4-5-migration ``` View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ### OpenCode Run in your terminal: ```shell npx -y degit anthropics/claude-code/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ~/.config/opencode/skills/claude-opus-4-5-migration ``` View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ### Hermes Agent Run in your terminal: ```shell npx -y degit anthropics/claude-code/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration ~/.hermes/skills/claude-opus-4-5-migration ``` View the folder on GitHub: https://github.com/anthropics/claude-code/tree/HEAD/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration --- From Pluginboard (https://pluginboard.ai).