Fix: Update endpoint selection logic for Claude models in LanguageModelServer

[bhavyaus]

No description provided.

[Copilot]

Pull request overview

This PR updates the endpoint selection logic in LanguageModelServer to handle Claude model variants (haiku, sonnet, and opus) by mapping them to version 4.5 endpoints instead of using GPT-4o-mini as a fallback for haiku models.

Changes:

• Updated model mapping logic to support Claude haiku-4.5, sonnet-4.5, and opus-4.5
• Modified fallback matching patterns for Claude models
• Removed the haiku-to-GPT-4o-mini mapping in favor of proper Claude model routing

Comments suppressed due to low confidence (3)

src/extension/agents/node/langModelServer.ts:321

• The selectEndpoint method lacks test coverage. Given that there are comprehensive tests for the adapters in this module (see openaiAdapter.spec.ts), this critical model selection logic should also have unit tests to verify the mapping and fallback behavior for different Claude model variants.

	private selectEndpoint(endpoints: readonly IChatEndpoint[], requestedModel?: string): IChatEndpoint | undefined {
		if (requestedModel) {
			// Handle model mapping
			let mappedModel = requestedModel;
			if (requestedModel.startsWith('claude-haiku')) {
				mappedModel = 'claude-haiku-4.5';
			}
			if (requestedModel.startsWith('claude-sonnet-4')) {
				mappedModel = 'claude-sonnet-4.5';
			}
			if (requestedModel.startsWith('claude-opus-4')) {
				mappedModel = 'claude-opus-4.5';
			}

			// Try to find exact match first
			let selectedEndpoint = endpoints.find(e => e.family === mappedModel || e.model === mappedModel);

			// If not found, try to find by partial match for Anthropic models
			if (!selectedEndpoint && requestedModel.startsWith('claude-haiku-4')) {
				selectedEndpoint = endpoints.find(e => e.model.includes('claude-haiku-4-5')) ?? endpoints.find(e => e.model.includes('claude'));
			} else if (!selectedEndpoint && requestedModel.startsWith('claude-sonnet-4')) {
				selectedEndpoint = endpoints.find(e => e.model.includes('claude-sonnet-4-5')) ?? endpoints.find(e => e.model.includes('claude'));
			} else if (!selectedEndpoint && requestedModel.startsWith('claude-opus-4')) {
				selectedEndpoint = endpoints.find(e => e.model.includes('claude-opus-4-5')) ?? endpoints.find(e => e.model.includes('claude'));
			}

			return selectedEndpoint;
		}

		// Use first available model if no criteria specified
		return endpoints[0];
	}

src/extension/agents/node/langModelServer.ts:311

• The model string format is inconsistent. The fallback searches for 'claude-sonnet-4-5' (with hyphens) while the mapped model is 'claude-sonnet-4.5' (with a dot). This mismatch means the partial match will likely fail. These should use the same format to ensure proper matching.

				mappedModel = 'claude-sonnet-4.5';
			}
			if (requestedModel.startsWith('claude-opus-4')) {
				mappedModel = 'claude-opus-4.5';
			}

			// Try to find exact match first
			let selectedEndpoint = endpoints.find(e => e.family === mappedModel || e.model === mappedModel);

			// If not found, try to find by partial match for Anthropic models
			if (!selectedEndpoint && requestedModel.startsWith('claude-haiku-4')) {
				selectedEndpoint = endpoints.find(e => e.model.includes('claude-haiku-4-5')) ?? endpoints.find(e => e.model.includes('claude'));
			} else if (!selectedEndpoint && requestedModel.startsWith('claude-sonnet-4')) {
				selectedEndpoint = endpoints.find(e => e.model.includes('claude-sonnet-4-5')) ?? endpoints.find(e => e.model.includes('claude'));

src/extension/agents/node/langModelServer.ts:313

• The model string format is inconsistent. The fallback searches for 'claude-opus-4-5' (with hyphens) while the mapped model is 'claude-opus-4.5' (with a dot). This mismatch means the partial match will likely fail. These should use the same format to ensure proper matching.

				mappedModel = 'claude-opus-4.5';
			}

			// Try to find exact match first
			let selectedEndpoint = endpoints.find(e => e.family === mappedModel || e.model === mappedModel);

			// If not found, try to find by partial match for Anthropic models
			if (!selectedEndpoint && requestedModel.startsWith('claude-haiku-4')) {
				selectedEndpoint = endpoints.find(e => e.model.includes('claude-haiku-4-5')) ?? endpoints.find(e => e.model.includes('claude'));
			} else if (!selectedEndpoint && requestedModel.startsWith('claude-sonnet-4')) {
				selectedEndpoint = endpoints.find(e => e.model.includes('claude-sonnet-4-5')) ?? endpoints.find(e => e.model.includes('claude'));
			} else if (!selectedEndpoint && requestedModel.startsWith('claude-opus-4')) {
				selectedEndpoint = endpoints.find(e => e.model.includes('claude-opus-4-5')) ?? endpoints.find(e => e.model.includes('claude'));

[Copilot]

There is a logic inconsistency between the model mapping and the fallback condition. Line 294 maps models starting with 'claude-haiku' to 'claude-haiku-4.5', but line 308 checks if the requestedModel starts with 'claude-haiku-4'. This means the fallback logic will never execute for models that match the mapping condition. The conditions should be aligned: either both check for 'claude-haiku' or both check for 'claude-haiku-4'.

Suggested change

	if (!selectedEndpoint && requestedModel.startsWith('claude-haiku-4')) {
	if (!selectedEndpoint && requestedModel.startsWith('claude-haiku')) {

[Copilot]

The model string format is inconsistent. The fallback searches for 'claude-haiku-4-5' (with hyphens) while the mapped model is 'claude-haiku-4.5' (with a dot). This mismatch means the partial match will likely fail. These should use the same format to ensure proper matching.

This issue also appears in the following locations of the same file:

• line 298
• line 301

See below for a potential fix:

				selectedEndpoint = endpoints.find(e => e.model.includes('claude-haiku-4.5')) ?? endpoints.find(e => e.model.includes('claude'));
			} else if (!selectedEndpoint && requestedModel.startsWith('claude-sonnet-4')) {
				selectedEndpoint = endpoints.find(e => e.model.includes('claude-sonnet-4.5')) ?? endpoints.find(e => e.model.includes('claude'));
			} else if (!selectedEndpoint && requestedModel.startsWith('claude-opus-4')) {
				selectedEndpoint = endpoints.find(e => e.model.includes('claude-opus-4.5')) ?? endpoints.find(e => e.model.includes('claude'));