Add Abacus vendor for ChatLLM models with static model list

[ksylvan]

Add Abacus vendor for ChatLLM models with static model list

Summary

This PR adds support for the Abacus AI provider to the OpenAI-compatible plugin, including a new static model list mechanism for providers that don't support dynamic model discovery.

Related Issues

Closes #1800

Files Changed

.vscode/settings.json

• Added two new dictionary entries: "kimi" and "qwen" to the cSpell.words array
• These additions support spell-checking for new model names and providers referenced in the codebase

internal/plugins/ai/openai_compatible/providers_config.go

• Added new Abacus provider configuration to ProviderMap
• Introduced getStaticModels() method to handle static model lists
• Modified ListModels() method to check for static model list prefix ("static:")
• Added fmt package import for error formatting

internal/plugins/ai/openai_compatible/providers_config_test.go

• Added test case for the new Abacus provider to verify it exists in the provider map

Code Changes

Static Model List Mechanism

The most significant change is the introduction of a static model list handler in ListModels():

// If a custom models URL is provided, handle it
if c.modelsURL != "" {
    // Check for static model list
    if strings.HasPrefix(c.modelsURL, "static:") {
        return c.getStaticModels(c.modelsURL)
    }
    // ... existing code for dynamic model fetching
}

This enables providers to specify a static list of models using a special static: prefix instead of requiring an API endpoint for model discovery.

New getStaticModels Method

A new method was added to retrieve predefined model lists:

func (c *Client) getStaticModels(modelsKey string) ([]string, error) {
    switch modelsKey {
    case "static:abacus":
        return []string{
            "route-llm",
            "gpt-4o-2024-11-20",
            // ... 50+ additional models
        }, nil
    default:
        return nil, fmt.Errorf("unknown static model list: %s", modelsKey)
    }
}

Abacus Provider Configuration

Added new provider entry in ProviderMap:

"Abacus": {
    Name:                "Abacus",
    BaseURL:             "https://routellm.abacus.ai/v1/",
    ModelsURL:           "static:abacus",
    ImplementsResponses: false,
},

Reason for Changes

The changes were made to:

1. Support Abacus AI provider: Integrate Abacus AI's RouteLL M service which provides access to multiple AI models through a unified API
2. Handle providers without model discovery APIs: Some providers don't expose a /models endpoint or have non-standard model listing mechanisms. The static model list approach provides a fallback solution
3. Maintain code consistency: Abacus follows the same pattern as other OpenAI-compatible providers in the codebase

Impact of Changes

Positive Impacts

• Users can now access 50+ AI models through the Abacus AI provider, including models from OpenAI, Anthropic, Meta, Google, Alibaba, DeepSeek, and others
• The static model list mechanism is extensible and can be reused for other providers that don't support dynamic model discovery
• No breaking changes to existing functionality

Potential Issues

1. Model list maintenance: The static model list needs manual updates when Abacus adds or removes models. This could lead to outdated model references if not maintained regularly
2. No validation: The code doesn't validate whether the static models are actually available through the Abacus API at runtime
3. Hardcoded models: Having 50+ hardcoded model names increases the binary size slightly and creates a maintenance burden
4. Error handling: If a user tries to use a model from the static list that Abacus no longer supports, they'll receive an error at request time rather than during model listing

Test Plan

1. Unit test coverage: Added test case in providers_config_test.go verifying the Abacus provider exists in the provider map
2. Manual testing should include:
   • Selecting the Abacus provider and verifying the static model list is returned
   • Attempting to use various models from the static list with actual API calls
   • Verifying error handling when an invalid static key is provided
3. Integration testing: Test the complete flow of selecting Abacus provider, choosing a model, and making API requests

Additional Notes

• The Abacus provider uses ImplementsResponses: false, which means it follows the legacy response handling approach
• Future enhancement: Could implement a hybrid approach that tries dynamic discovery first and falls back to the static list