Migrate prompts and code from Claude Sonnet 4.0, Sonnet 4.5, or Opus 4.1 to Opus 4.5. Use when the user wants to update their codebase, prompts, or API calls to use Opus 4.5. Handles model string updates and prompt adjustments for known Opus 4.5 behavioral differences. Does NOT migrate Haiku 4.5.
View on GitHubmichelabboud/claude-code
claude-opus-4-5-migration
plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration/SKILL.md
January 18, 2026
Select agents to install to:
npx add-skill https://github.com/michelabboud/claude-code/blob/main/plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration/SKILL.md -a claude-code --skill claude-opus-4-5-migrationInstallation paths:
.claude/skills/claude-opus-4-5-migration/# Opus 4.5 Migration Guide One-shot migration from Sonnet 4.0, Sonnet 4.5, or Opus 4.1 to Opus 4.5. ## Migration Workflow 1. Search codebase for model strings and API calls 2. Update model strings to Opus 4.5 (see platform-specific strings below) 3. Remove unsupported beta headers 4. Add effort parameter set to `"high"` (see `references/effort.md`) 5. Summarize all changes made 6. Tell the user: "If you encounter any issues with Opus 4.5, let me know and I can help adjust your prompts." ## Model String Updates Identify which platform the codebase uses, then replace model strings accordingly. ### Unsupported Beta Headers Remove the `context-1m-2025-08-07` beta header if present—it is not yet supported with Opus 4.5. Leave a comment noting this: ```python # Note: 1M context beta (context-1m-2025-08-07) not yet supported with Opus 4.5 ``` ### Target Model Strings (Opus 4.5) | Platform | Opus 4.5 Model String | |----------|----------------------| | Anthropic API (1P) | `claude-opus-4-5-20251101` | | AWS Bedrock | `anthropic.claude-opus-4-5-20251101-v1:0` | | Google Vertex AI | `claude-opus-4-5@20251101` | | Azure AI Foundry | `claude-opus-4-5-20251101` | ### Source Model Strings to Replace | Source Model | Anthropic API (1P) | AWS Bedrock | Google Vertex AI | |--------------|-------------------|-------------|------------------| | Sonnet 4.0 | `claude-sonnet-4-20250514` | `anthropic.claude-sonnet-4-20250514-v1:0` | `claude-sonnet-4@20250514` | | Sonnet 4.5 | `claude-sonnet-4-5-20250929` | `anthropic.claude-sonnet-4-5-20250929-v1:0` | `claude-sonnet-4-5@20250929` | | Opus 4.1 | `claude-opus-4-1-20250422` | `anthropic.claude-opus-4-1-20250422-v1:0` | `claude-opus-4-1@20250422` | **Do NOT migrate**: Any Haiku models (e.g., `claude-haiku-4-5-20251001`). ## Prompt Adjustments Opus 4.5 has known behavioral differences from previous models. **Only apply these fixes if the user explicitly requests them or reports a specific issue.** By default, just update model s