claudegoodies
Skill

claude-opus-4-5-migration

From anthropics

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.

Updates model strings and prompts in a codebase to migrate to Claude Opus 4.5.

Use it when

  • Upgrading from Sonnet 4.0, Sonnet 4.5, or Opus 4.1 to Opus 4.5
  • Model strings scattered across Anthropic API, Bedrock, Vertex AI, or Azure code
  • Reports of tool overtriggering, over-engineering, or generic frontend output after switching models
  • Extended-thinking-sensitive prompts breaking after upgrading to Opus 4.5

Skip it if

  • Migrating to or from Haiku 4.5 (explicitly not handled)
  • Codebase uses the 1M context beta header (removed, not yet supported)
  • Only need a single model string swapped, no prompt review needed

Facts

Repository
anthropics/claude-code
Status
Actively maintained
Last commit
Source file
plugins/claude-opus-4-5-migration/skills/claude-opus-4-5-migration/SKILL.md

Source preview

The instructions Claude Code reads when this skill runs.

# 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`
View full source on GitHub →

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