bug: Anthropic assumes known models in completion make

[Sytten]

• I have looked for existing issues (including closed) about this

Bug Report

Following the change to introduce the generic builder, the make function for the CompletionModel was added. This calls Self::new which uses calculate_max_tokens. This is only meant to be used with the predefined models. Otherwise it's not flexible enough.

See #1069

Expected behavior

The generic provider should probably expect that the model passed in is not going to be one of the provided key.

[linear]

RIG-1113

[Sytten]

Also we should revert to the better code for custom, right now the custom doesnt do the starts_with so you cant pin a revision of the model:

fn calculate_max_tokens(model: &str) -> Option<u64> {
    if model.starts_with("claude-opus-4") {
        Some(32000)
    } else if model.starts_with("claude-sonnet-4") || model.starts_with("claude-3-7-sonnet") {
        Some(64000)
    } else if model.starts_with("claude-3-5-sonnet") || model.starts_with("claude-3-5-haiku") {
        Some(8192)
    } else if model.starts_with("claude-3-opus")
        || model.starts_with("claude-3-sonnet")
        || model.starts_with("claude-3-haiku")
    {
        Some(4096)
    } else {
        None
    }
}

[joshua-mo-143]

This does appear to be a bit of an issue. I'll have a look into it