Function resolveModel

packages/runtime/src/agent/index.ts:168–241

(
  spec: ModelSpecifier,
  apiKey?: string,
)

 * @returns LanguageModel instance
 */
export function resolveModel(
  spec: ModelSpecifier,
  apiKey?: string,
): LanguageModel {
  // If already a LanguageModel instance, pass through
  if (typeof spec !== "string") {
    return spec;
  }

  // Normalize "provider/model" or "provider:model" format
  const normalized = spec.replace("/", ":").trim();
  const parts = normalized.split(":");
  const rawProvider = parts[0];
  const rest = parts.slice(1);

  if (!rawProvider) {
    throw new Error(
      `Invalid model string "${spec}". Use "openai/gpt-5", "anthropic/claude-sonnet-4.5", or "google/gemini-2.5-pro".`,
    );
  }

  const provider = rawProvider.toLowerCase();
  const model = rest.join(":").trim();

  if (!model) {
    throw new Error(
      `Invalid model string "${spec}". Use "openai/gpt-5", "anthropic/claude-sonnet-4.5", or "google/gemini-2.5-pro".`,
    );
  }

  switch (provider) {
    case "openai": {
      // Lazily create OpenAI provider
      // Use provided apiKey, or fall back to environment variable
      const openai = createOpenAI({
        apiKey: apiKey || process.env.OPENAI_API_KEY!,
      });
      // Accepts any OpenAI model id, e.g. "gpt-4o", "gpt-4.1-mini", "o3-mini"
      return openai(model);
    }

    case "anthropic": {
      // Lazily create Anthropic provider
      // Use provided apiKey, or fall back to environment variable
      const anthropic = createAnthropic({
        apiKey: apiKey || process.env.ANTHROPIC_API_KEY!,
      });
      // Accepts any Claude id, e.g. "claude-3.7-sonnet", "claude-3.5-haiku"
      return anthropic(model);
    }

    case "google":
    case "gemini":
    case "google-gemini": {
      // Lazily create Google provider
      // Use provided apiKey, or fall back to environment variable
      const google = createGoogleGenerativeAI({
        apiKey: apiKey || process.env.GOOGLE_API_KEY!,