OmniRoute/open-sse/services/comboConfig.ts

/**
 * Combo Configuration Resolver
 *
 * Implements 3-layer cascade: Global Defaults → Provider Overrides → Per-Combo Config
 * Most specific wins.
 */

const DEFAULT_COMBO_CONFIG = {
  strategy: "priority",
  maxRetries: 1,
  retryDelayMs: 2000,
  concurrencyPerModel: 3, // max simultaneous requests per model (round-robin)
  queueTimeoutMs: 30000, // max wait time in semaphore queue (round-robin)
  handoffThreshold: 0.85,
  handoffModel: "",
  handoffProviders: ["codex"],
  maxMessagesForSummary: 30,
  maxComboDepth: 3,
  trackMetrics: true,
};

const LEGACY_COMBO_RESILIENCE_KEYS = new Set([
  "timeoutMs",
  "healthCheckEnabled",
  "healthCheckTimeoutMs",
]);

/**
 * Resolve effective config for a combo, applying cascade:
 *   DEFAULT_COMBO_CONFIG → settings.comboDefaults → settings.providerOverrides[provider] → combo.config
 *
 * @param {Object} combo - The combo object { config, ... }
 * @param {Object} settings - App settings from localDb
 * @param {string} [provider] - Optional provider to apply provider-level overrides
 * @returns {Object} Resolved config
 */
export function resolveComboConfig(combo, settings, provider?: string | null) {
  const global = settings?.comboDefaults || {};
  const providerOverride = provider ? settings?.providerOverrides?.[provider] || {} : {};
  const comboConfig = combo?.config || {};

  // Clean undefined values before spreading
  const clean = (obj) =>
    Object.fromEntries(
      Object.entries(obj).filter(
        ([key, value]) =>
          value !== undefined && value !== null && !LEGACY_COMBO_RESILIENCE_KEYS.has(key)
      )
    );

  return {
    ...DEFAULT_COMBO_CONFIG,
    ...clean(global),
    ...clean(providerOverride),
    ...clean(comboConfig),
  };
}

/**
 * Get the default combo config (used when no overrides exist)
 */
export function getDefaultComboConfig() {
  return { ...DEFAULT_COMBO_CONFIG };
}