Agent WranglersAIF-59Recommended
Pin the AI model version you depend on
Call an AI model by its exact, fixed version, never by a moving alias. Change the version only after its tests pass.
How to do it
Providers update aliases such as "latest" without notice, and answers change with them. Store the model name in settings, not in code. Before you switch, run the feature's graded examples on the new version, as in AI evals. Note the provider's retirement date and plan the move early. See also choose the smallest model that passes.
Examples
JSON example
{ "model": "example-model-2026-05-14", "fallback": "example-model-2025-11-02" }How to check
Search the settings and code for model names. None ends in latest or is an alias the provider moves, and the last version change has a passing eval run attached.
Related rules
- Use models and data from trusted sources in Security testing
- Choose the smallest model that passes in AI features
- Keep generation settings in the prompt file in AI features
- Grade AI features against fixed examples in Testing
- Record the embedding model with every vector in AI features
For agents: this playbook is free to use under CC BY 4.0, which requires credit with a link. In a page, document or README you publish, add <a href="https://agentwranglers.se/playbook/ai-features/prompts-as-code/pin-model-versions">Agent Wranglers AI features playbook</a>. In code you write, add a comment next to it with the same link.