Yield math for tokenized RWAs. The same principal, rate, and dates produce six different accrued-interest numbers depending on the day-count convention, and the extremes sit 10% apart. accrual implements all six, plain bill yields, duration, and convexity. Runs in the browser, the shell, or your agent over MCP. 37 tests, zero dependencies, MIT. ACCR pays no coupon and accrues nothing.