From 18f015f7fd0ce0a28572009996c688209f326d83 Mon Sep 17 00:00:00 2001
From: sb <sb@MacBook-Pro.local>
Date: Tue, 7 Jul 2026 23:08:00 +0900
Subject: [PATCH] =?UTF-8?q?feat(repayment):=20=EB=8C=80=EC=B6=9C=20?=
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- 계좌 관리 대출 폼에 '월 상환금(선택)' 입력(원리금균등)
- repayment.js: loanPayment 있으면 이자=잔액×이율, 원금=상환금-이자로 상각
  → 남은 개월수 추정 오차(±1회) 없이 은행 조회액과 일치. 미입력 시 기존 추정

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
---
 src/utils/repayment.js                  | 19 +++++++++++++++++++
 src/views/account/AccountWalletView.vue | 11 +++++++++++
 2 files changed, 30 insertions(+)

diff --git a/src/utils/repayment.js b/src/utils/repayment.js
index c44608c..04cf531 100644
--- a/src/utils/repayment.js
+++ b/src/utils/repayment.js
@@ -71,6 +71,25 @@ export function loanSchedule(w, now = currentYm(), cap = 600) {
   }
 
   // EQUAL_PAYMENT 원리금균등
+  // (0) 월 상환금(고정)이 입력돼 있으면 그대로 사용 → 이자=잔액×이율, 원금=상환금-이자 로 은행과 정확히 일치
+  const fixed = Number(w.loanPayment) || 0
+  if (fixed > 0) {
+    while (bal > 0 && rows.length < cap) {
+      const interest = Math.round(bal * r)
+      let principal = fixed - interest
+      if (principal <= 0) {
+        // 상환금이 이자에 못 미침(데이터 이상) → 더 진행 못함
+        rows.push({ label: label(y, m), principal: Math.max(0, principal), interest, total: fixed, balance: bal })
+        break
+      }
+      principal = Math.min(principal, bal)
+      bal = Math.max(0, bal - principal)
+      rows.push({ label: label(y, m), principal, interest, total: principal + interest, balance: bal })
+      ;({ y, m } = addMonths(y, m, 1))
+    }
+    return { rows, partial: false }
+  }
+
   // (1) 남은 개월수 n 산출: 최초 상환액으로 역산(loanStart 없어도 정확) → 안되면 loanStart 경과
   let n = null
   if (w.loanAmount && w.loanMonths && r > 0) {
diff --git a/src/views/account/AccountWalletView.vue b/src/views/account/AccountWalletView.vue
index cff5950..8fac133 100644
--- a/src/views/account/AccountWalletView.vue
+++ b/src/views/account/AccountWalletView.vue
@@ -62,6 +62,7 @@ const form = reactive({
   loanMethod: '',
   loanMonths: null,
   loanStart: '',
+  loanPayment: null,
 })
 const submitting = ref(false)
 const formError = ref(null)
@@ -187,6 +188,7 @@ function openCreate() {
     loanMethod: '',
     loanMonths: null,
     loanStart: '',
+    loanPayment: null,
   })
   formError.value = null
   formOpen.value = true
@@ -208,6 +210,7 @@ function openEdit(w) {
     loanMethod: w.loanMethod || '',
     loanMonths: w.loanMonths ?? null,
     loanStart: w.loanStart || '',
+    loanPayment: w.loanPayment ?? null,
   })
   formError.value = null
   formOpen.value = true
@@ -240,6 +243,7 @@ async function submit() {
     loanMethod: isLoan && form.loanMethod ? form.loanMethod : null,
     loanMonths: isLoan && form.loanMonths ? Number(form.loanMonths) : null,
     loanStart: isLoan && form.loanStart ? form.loanStart : null,
+    loanPayment: isLoan && form.loanPayment ? Number(form.loanPayment) : null,
   }
   try {
     if (editId.value) await accountApi.updateWallet(editId.value, payload)
@@ -413,6 +417,13 @@ onBeforeUnmount(destroySortables)
           <label>대출시작일
             <input v-model="form.loanStart" type="date" :disabled="submitting" />
           </label>
+          <label v-if="form.loanMethod === 'EQUAL_PAYMENT' || form.loanMethod === ''">월 상환금(선택)
+            <input v-model.number="form.loanPayment" type="number" min="0"
+              placeholder="은행 조회 고정 월납입금 (예: 697868)" :disabled="submitting" />
+          </label>
+          <p v-if="form.loanMethod === 'EQUAL_PAYMENT' || form.loanMethod === ''" class="form-hint">
+            원리금균등은 <b>월 상환금</b>을 입력하면 상환표의 원금·이자가 은행 조회액과 정확히 일치합니다. (미입력 시 잔액·개월수로 추정)
+          </p>
         </template>
 
         <p v-if="formError" class="msg error">{{ formError }}</p>