---
description: "Implement FinanceDbContext with fluent entity configurations, indexes, relationships, and SQLite connection setup"
agent: "agent"
---

# Step 3: DbContext & Mappings

Create `src/Duempelkas.Infrastructure/Persistence/FinanceDbContext.cs`.

## DbSets
- `DbSet<Account> Accounts`
- `DbSet<AccountYear> AccountYears`
- `DbSet<Entry> Entries`
- `DbSet<TransferLink> TransferLinks`

## Connection
- Accept SQLite connection string via constructor options.
- Default path: `Data Source=duempelkas.db` in the app's base directory.

## Entity Configurations (use `OnModelCreating` with `IEntityTypeConfiguration<T>` or inline)

### Account
- `Name` required, max length 200.
- Cascade delete → AccountYears.

### AccountYear
- Unique index on `(AccountId, Year)`.
- `OpeningBalance` column type `decimal(18,2)`.
- Cascade delete → Entries.

### Entry
- Index on `(AccountYearId, Date)`.
- `Amount` column type `decimal(18,2)`.
- `Type` stored as int.
- Optional FK to TransferLink (`TransferLinkId`), restrict delete.

### TransferLink
- Unique index on `SourceEntryId`.
- Unique index on `TargetEntryId`.
- Relationships to SourceEntry and TargetEntry with `DeleteBehavior.Restrict`.

## Notes
- Use separate `IEntityTypeConfiguration<T>` classes in `Persistence/Configurations/`.
- Do not auto-generate migrations; the initial migration will be created manually later.