Enabling legacy Claude models in Claude Code
Problem / Context
Claude Code's model picker only exposes current-generation models (Opus 4.6, Sonnet 4.6, Haiku 4.5). Users wanting older model versions like Opus 4.5 for testing, comparison, or personal preference had no obvious UI path to select them � the dropdown does not list legacy models even when they are still available via the API.
Solution
The fix requires Claude Code's own settings file (~/.claude/settings.json), not VS Code's settings.json. Add an env block with two keys: ANTHROPIC_CUSTOM_MODEL_OPTION set to the model ID to expose, and ANTHROPIC_CUSTOM_MODEL_OPTION_NAME set to the display name for the picker. Critical: use the model alias (e.g. claude-opus-4-5) not deprecated snapshot IDs. The old snapshot claude-opus-4-5-20250514 returns "model may not exist or you may not have access" � the current alias is claude-opus-4-5. After adding the config, reload VS Code; the custom model appears at the bottom of the /model picker. A common mistake is putting the env block in VS Code's own settings.json (claudeCode.env) � this does not work. It must go in Claude Code's own settings at ~/.claude/settings.json.
Implementation
json// Add this block inside ~/.claude/settings.json
{
"env": {
"ANTHROPIC_CUSTOM_MODEL_OPTION": "claude-opus-4-5",
"ANTHROPIC_CUSTOM_MODEL_OPTION_NAME": "Opus 4.5"
}
}Result
Opus 4.5 now selectable in Claude Code's model picker across both desktop and laptop. Confirmed working after initial failed attempts with wrong model ID and wrong config file location.