How do I defineoverride model shortcuts aliases

Aliases come from agents.defaults.models.<modelId>.alias. Example:
{
agents: {
defaults: {
model: { primary: "anthropic/claude-opus-4-5" },
models: {
"anthropic/claude-opus-4-5": { alias: "opus" },
"anthropic/claude-sonnet-4-5": { alias: "sonnet" },
"anthropic/claude-haiku-4-5": { alias: "haiku" },
},
},
},
}
Then /model sonnet (or /<alias> when supported) resolves to that model ID.