Function buildLlmConfig

scripts/agent_config.ts:401–431

(
  modelHandle: string,
  models: LettaModel[],
  currentConfig: LlmConfig | undefined,
)

 * precedence over the current value.
 */
export function buildLlmConfig(
  modelHandle: string,
  models: LettaModel[],
  currentConfig: LlmConfig | undefined,
): LlmConfig {
  const slashIdx = modelHandle.indexOf('/');
  const providerName = slashIdx > 0 ? modelHandle.substring(0, slashIdx) : undefined;
  const modelName = slashIdx > 0 ? modelHandle.substring(slashIdx + 1) : modelHandle;

  const modelInfo = findModel(models, modelHandle);

  // Spread current config to preserve settings, then override model fields
  const config: LlmConfig = {
    ...(currentConfig || {}),
    model: modelName,
    handle: modelHandle,
    provider_name: providerName || modelInfo?.provider_type || currentConfig?.provider_name,
    model_endpoint_type: modelInfo?.provider_type || currentConfig?.model_endpoint_type,
  };

  // LETTA_CONTEXT_WINDOW env var overrides the current value
  const envContextWindow = process.env.LETTA_CONTEXT_WINDOW;
  if (envContextWindow) {
    const parsed = parseInt(envContextWindow, 10);
    if (!isNaN(parsed) && parsed > 0) {
      config.context_window = parsed;
    }
  }

  return config;
}

/**
 * Update agent's model configuration via the llm_config PATCH.