claude-opus-4-5-migration_skill

Overview

This skill migrates prompts, model strings, and related API calls from Claude Sonnet 4.0, Sonnet 4.5, or Opus 4.1 to Opus 4.5. It automates code searches and replacements, removes unsupported beta headers, and prepares prompts for known Opus 4.5 behavioral differences. It does not migrate Haiku models.

How this skill works

The skill scans your codebase for platform-specific model strings and replaces them with the correct Opus 4.5 identifiers for Anthropic, AWS Bedrock, Google Vertex AI, or Azure. It removes unsupported 1M context beta headers, adds the recommended effort parameter, and can optionally apply targeted prompt adjustments for known behavioral differences when you request them. Finally, it summarizes all changes and gives a short troubleshooting follow-up message.

When to use it

• You need to upgrade model strings in an existing codebase from Sonnet 4.0/4.5 or Opus 4.1 to Opus 4.5.
• You want an automated pass to remove unsupported beta headers and add the effort parameter.
• You want a safe default migration that updates only model identifiers by default.
• You want optional prompt tuning for Opus 4.5 behavioral differences when encountering issues.

Best practices

• Back up your codebase or work on a feature branch before running the migration.
• Run the migration first with model-string-only mode, then request prompt adjustments only if you see issues.
• Leave a comment where the unsupported context-1m beta header is removed to document the change.
• Integrate any prompt snippets into existing XML tags or prompt structure rather than appending them blindly.
• Test end-to-end flows (tooling, file writes, UI generation) after migration to catch overtriggering or over-engineering.

Example use cases

• Replace Anthropic API model strings like claude-sonnet-4-20250514 with claude-opus-4-5-20251101 across a repo.
• Update AWS Bedrock or Google Vertex AI model identifiers to their Opus 4.5 equivalents.
• Remove context-1m-2025-08-07 beta headers and add a comment noting the unsupported header.
• Enable effort:"high" in API calls to take advantage of Opus 4.5 effort tuning.
• Apply targeted prompt edits to reduce tool overtriggering after observing excessive tool calls.