Building a Non-Custodial DCA Protocol on TON: How We Used the MasterChef Pattern to Achieve O(1) Smart Contract Complexity

Dollar-cost averaging is dead simple as a concept — buy a fixed amount of asset X every Y days. But implement it on a blockchain non-custodially at scale, and you'll hit a wall fast. This is the story of how we built TON DCA — a fully non-custodial automatic investment protocol on The Open Network — and the architectural decision that made it actually work: the MasterChef index model. The Problem with Naive DCA on Blockchain Most early DCA protocols make the same mistake: they store each user's last execution timestamp, iterate over all pending orders on every tick, and calculate rewards/swaps per-user in a loop. This gives you O(n) complexity where n = number of active strategies. Deploy that on TON with 10,000 users and you've got a protocol that bricks itself under load. The naive Tact pseudocode looks something like this: // ❌ Naive approach — O(n) loop fun processAllStrategies(strategies: map<Address, Strategy>) { foreach strategy in strategies { if (now() >= strategy.nextExecutio