## Summary
Mirror the real-estate historical-balance pattern for loan accounts.
When a loan is created with a current balance, linearly interpolate
monthly `account_balances` rows between the loan start date
(`original_amount`) and today (current balance).
## Approach
Since we don't know how the user actually paid down the loan, use simple
linear regression between two known points:
- `(start_date, original_amount)` from `loan_details`
- `(today, current_balance)` from the latest `account_balances` row
Rows are placed on the start date, the 1st of each intermediate month,
and today.
## Changes
- **`LoanBalanceGeneratorService`** — linear interpolation + upsert on
`(account_id, balance_date)` so existing rows aren't duplicated.
- **`GenerateHistoricalLoanBalancesJob`** — `ShouldQueue`, 3 tries, 10s
backoff. Takes account, original amount, start date, current balance,
from, to.
- **`Settings/AccountController::store`** (loan branch) — after creating
`loanDetail`, if a starting balance was provided: generate the last 12
months synchronously, dispatch older window to the queue when
`start_date` predates it.
- **`LoanDetailController::update`** — when the detail is first created
for an existing account, use the most recent `AccountBalance` as the
current value and apply the same sync/async split.
## Tests
- Service: interpolation, single-balance edge, future start_date, upsert
dedupe, monthly 1st placement, from/to range.
- Job: implements `ShouldQueue`, respects from/to range.
```
Tests: 8 passed (62 assertions)
```
No dependency or directory-structure changes.
## Summary
- Adds loan detail tracking (interest rate, term, start date, original
amount) to loan-type accounts, following the existing
`real_estate_details` pattern
- Implements `LoanAmortizationService` with standard amortization math
to automatically project month-to-month balance evolution
- Shows projected future balances as a dashed line on the account
balance chart, visually distinct from historical data
- Adds a scheduled command (`loans:generate-balances`) to auto-generate
monthly balance entries for loan accounts
- Includes 36 tests (10 unit for pure math, 26 feature for CRUD, API
projections, command, and authorization)
## Changes
### Backend
- **Migration**: `loan_details` table (UUID PK, unique `account_id` FK,
interest rate, term, start date, original amount)
- **LoanDetail model** + factory with `Account::loanDetail()` HasOne
relationship
- **LoanAmortizationService**: `calculateMonthlyPayment`,
`calculateRemainingBalance`, `generateProjection`, `projectFromBalance`,
`calculateRemainingMonths`, `getBalanceAtDate`
- **GenerateMonthlyLoanBalances** command: runs monthly on 1st, skips
existing entries
- **LoanDetailController**: PATCH endpoint for editing loan details from
show page
- **Settings\AccountController**: creates/updates `LoanDetail` on
store/update
- **DashboardAnalyticsController**: appends projected data points with
`projected: true` flag
- **Validation**: loan-specific rules in StoreAccountRequest and
UpdateAccountRequest
### Frontend
- **AccountForm**: loan fields (rate, term, start date, original amount)
shown when `type === 'loan'`
- **Create/Edit dialogs**: pass loan data fields in POST/PATCH payloads
- **Show page**: `LoanDetailsCard` component with edit/read modes,
computed monthly payment and remaining months
- **Balance chart**: new `ComposedChart` branch with dashed `Line`
overlay for projected data points
- **Types**: `LoanDetail` interface in `account.ts`
Víctor Falcón