Function hasDesyncedTargetArgs

src/compute-engine/rubi/rubi-utils.ts:2529–2533

True if the tree carries a target head at 2+ DISTINCT arguments — the * signature of a desynchronized within-pair reflection (`csc[θ]·csc[θ+π/2]` * from `csc[θ]·sec[θ]`). A pure-source reflection lands every target on the SAME * `arg+π/2`, so this stays false; a genuine `csc·sec` mix trips it and

(e: Expression)

  if (TO_INERT[e.operator] !== undefined) return true;
  return e.ops?.some(hasActiveTrig) ?? false;
}

/** True if any node carries an INERT trig head (`sin`/`cos`/…). Underlies
 * Rubi's `InertTrigFreeQ` (the working-form purity test that gates many
 * Chapter-4 dispatch rules). */
function hasInertTrig(e: Expression): boolean {
  if (TO_ACTIVE[e.operator] !== undefined) return true;
  return e.ops?.some(hasInertTrig) ?? false;