Fi-Plan

Applies an ordered list of scenario patches to a DEEP COPY of the plan (never persisted) and returns the resulting snapshot plus applied_patches. Pass plan_id to load the plan server-side (preferred — never paste plan_json); plan_json is accepted for portability. Pass summary=true for the compact view; add milestones=true for long durations to get yearly points + totals instead of every month. Patches support add_income, add_expense, add_cashflow_change, add_loan, update_loan (loan_id plus any of title, principal_amount, interest_rate, start_month, end_month, deposit_to_bank, type, ref_id, prepayments), add_fdp (fdp: { start_month, end_month, s, e, i } with s + e + i = 100 — or the legacy { amount, interest_rate, tenure } fixed-deposit shape) and set_account_balance — nested ({"op":"add_cashflow_change","change":{...}}) and flat ({cashflow_id,value,start_month,...}) forms are both accepted; the op is inferred from the fields.

Pure calculation of EMI and a month-by-month amortization schedule for a loan of amount at annual interest_rate over tenure months. Returns opening/closing balance, interest, principal and running totals per month. Pass optional prepayments to model extra principal payments beyond the EMI (each {start_month, amount, frequency: 'm'|'q'|'y'|null, step_pct?} — null frequency = one-time lump, step_pct = % the amount grows by each recurrence): the EMI stays constant, the loan shortens, and the result becomes { schedule, payoff_month, total_interest_paid, total_prepaid, interest_saved } instead of a plain array. NOTE: here start_month is loan-relative (1 = the loan's first EMI month); on a persisted loan the same fields are plan-absolute months.

Pure what-if: closes the loan at refinance_month (outstanding balance settled) and restarts it at new_rate over new_tenure months. Returns outstanding balance, old vs new EMI, remaining interest vs new total interest, interest_saved, net_savings (after optional foreclosure_charge) and breakeven_months (null when the new EMI is not lower). Read-only — to persist, update the old loan's end_month and add the new loan.

Pure calculator for one asset (no plan needed): monthly value, invested, growth, income and TDS over duration months. Pass asset parameters (principal, growth_rate, yield_rate, income_frequency, income_mode, maturity_month, sale_month, sip) — class presets are NOT applied automatically, so pass explicit rates. TDS on FD interest follows the stored rules for the assessment_year. Returns rows plus closing value and totals.