# Buchhaltung — Remaining Features Implementation Plan

## Context

The Buchhaltung system has core CRUD, transfers, bank statements, Haushaltsplan, and PDF export implemented. Three features from the original design doc remain:

1. **Budget Delegation Freigaben** — authorizes a user to spend against a budget account (distinct from the existing transaction-approval freigaben)
2. **Split Booking Dialog** — book a pending transaction into N parts across different budget accounts
3. **Sub-Budget Flow** — create budget delegation Freigaben from approved plan positions

---

## Task Dependency Graph

```
T1: Migration 083 (budget_freigaben)    T2: Migration 084 (split_gruppe_id)
        |                                        |
        v                                        v
T3: Backend budget freigaben CRUD        T4: Backend split booking endpoint
        |                                        |
        +------------+                           v
        |            |                   T7: Frontend BookingDialog
        v            v
T5: Backend plan→   T6: Frontend budget
    freigabe endpoint    freigaben tab + sidebar
        |            |
        +-----+------+
              v
T8: Frontend plan position → freigabe action
```

---

## Tasks

### T1 — Migration 083: `buchhaltung_budget_freigaben` table
**Teammate**: database | **blockedBy**: none

Create `backend/src/database/migrations/083_buchhaltung_budget_freigaben.sql`:
```sql
CREATE TABLE IF NOT EXISTS buchhaltung_budget_freigaben (
  id               SERIAL PRIMARY KEY,
  konto_id         INT           NOT NULL REFERENCES buchhaltung_konten(id) ON DELETE CASCADE,
  user_id          UUID          NOT NULL REFERENCES users(id) ON DELETE CASCADE,
  beschreibung     TEXT,
  betrag_limit     NUMERIC(12,2),
  planposition_id  INT           REFERENCES buchhaltung_planpositionen(id) ON DELETE SET NULL,
  aktiv            BOOLEAN       NOT NULL DEFAULT TRUE,
  erstellt_von     UUID          REFERENCES users(id) ON DELETE SET NULL,
  created_at       TIMESTAMPTZ   NOT NULL DEFAULT NOW()
);
CREATE INDEX idx_budget_freigaben_konto ON buchhaltung_budget_freigaben(konto_id);
CREATE INDEX idx_budget_freigaben_user ON buchhaltung_budget_freigaben(user_id);
```

### T2 — Migration 084: Add `split_gruppe_id` to transaktionen
**Teammate**: database | **blockedBy**: none

Create `backend/src/database/migrations/084_buchhaltung_split_gruppe.sql`:
```sql
ALTER TABLE buchhaltung_transaktionen
  ADD COLUMN IF NOT EXISTS split_gruppe_id UUID;
CREATE INDEX IF NOT EXISTS idx_buch_trans_split_gruppe
  ON buchhaltung_transaktionen(split_gruppe_id) WHERE split_gruppe_id IS NOT NULL;
```

### T3 — Backend: Budget Freigaben CRUD
**Teammate**: backend | **blockedBy**: T1

**Files**: `buchhaltung.service.ts`, `buchhaltung.controller.ts`, `buchhaltung.routes.ts`

Service functions (add before export block ~line 1937):
- `listBudgetFreigaben(filters: { konto_id?, user_id? })` — JOIN users + konten for display names
- `getMyBudgetFreigaben(userId)` — active freigaben for current user
- `createBudgetFreigabe(data, erstelltVon)` — INSERT
- `updateBudgetFreigabe(id, data, userId)` — UPDATE beschreibung/betrag_limit
- `deactivateBudgetFreigabe(id, userId)` — SET aktiv=false

Routes (add BEFORE `/:id` catch-all routes):
```
GET    /budget-freigaben      manage_accounts   listBudgetFreigaben
GET    /budget-freigaben/my   buchhaltung:view  getMyBudgetFreigaben
POST   /budget-freigaben      manage_accounts   createBudgetFreigabe
PATCH  /budget-freigaben/:id  manage_accounts   updateBudgetFreigabe
DELETE /budget-freigaben/:id  manage_accounts   deactivateBudgetFreigabe
```

### T4 — Backend: Split Booking Endpoint
**Teammate**: backend | **blockedBy**: T2

**Files**: `buchhaltung.service.ts`, `buchhaltung.controller.ts`

Modify `bookTransaktion(id, userId, splits?)`:
- No splits → existing behavior (unchanged)
- With splits `Array<{ betrag, konto_id, bankkonto_id? }>`:
  1. Validate sum equals original betrag
  2. BEGIN transaction
  3. Generate UUID `split_gruppe_id`
  4. Mark original as `status='gebucht'`, set `split_gruppe_id`
  5. INSERT N new booked transactions copying fields from original but with split-specific betrag/konto_id/bankkonto_id, same `split_gruppe_id`
  6. Budget alert check per split konto
  7. Audit: `logAudit(id, 'split_gebucht', { splits, split_gruppe_id }, userId)`

Controller: read optional `req.body.splits`, pass to service.

### T5 — Backend: Plan Position → Freigabe Endpoint
**Teammate**: backend | **blockedBy**: T3

**Files**: `buchhaltung.service.ts`, `buchhaltung.controller.ts`, `buchhaltung.routes.ts`

New function `createBudgetFreigabeFromPlanposition(posId, { user_id, betrag_limit?, beschreibung? }, erstelltVon)`:
- Fetch planposition, verify konto_id exists
- Default betrag_limit to sum of budget_gwg + budget_anlagen + budget_instandhaltung
- Call `createBudgetFreigabe` with `planposition_id` set

Route: `POST /planung/positionen/:posId/freigabe` — manage_accounts

### T6 — Frontend: Budget Freigaben Tab + Sidebar
**Teammate**: frontend | **blockedBy**: T3

**Files**: `buchhaltung.types.ts`, `buchhaltung.ts`, `Buchhaltung.tsx`, `Sidebar.tsx`

Types:
- `BudgetFreigabe` — id, konto_id, user_id, beschreibung, betrag_limit, planposition_id, aktiv, konto_bezeichnung, user_name
- `BudgetFreigabeFormData` — konto_id, user_id, beschreibung?, betrag_limit?

Service: `getBudgetFreigaben`, `getMyBudgetFreigaben`, `createBudgetFreigabe`, `updateBudgetFreigabe`, `deleteBudgetFreigabe`

Buchhaltung.tsx:
- Add tab 3 "Freigaben" (visible only with `manage_accounts`)
- Table: Konto, Benutzer, Beschreibung, Betrag-Limit, Status, Aktionen
- Create/Edit dialog with Konto select, User select, Betrag-Limit, Beschreibung
- Pattern: follow TransaktionenTab Table+Dialog structure

Sidebar.tsx (~line 155): add `{ text: 'Freigaben', path: '/buchhaltung?tab=3' }` to buchhaltung subItems

### T7 — Frontend: Split Booking Dialog
**Teammate**: frontend | **blockedBy**: T4

**Files**: `buchhaltung.types.ts`, `buchhaltung.ts`, `Buchhaltung.tsx`

Types: add `SplitRow { betrag: number; konto_id: number; bankkonto_id?: number }`

Service: update `buchenTransaktion(id, splits?)` to POST body with optional splits array

Buchhaltung.tsx:
- Add `BookingDialog` component (inline):
  - Shows transaction details (betrag, beschreibung)
  - "Einfach buchen" button for simple booking (no splits)
  - "Aufteilen" toggle reveals split rows
  - Each row: betrag input, konto select, bankkonto select, remove button
  - "Zeile hinzufuegen" button
  - Sum validation with remaining amount display
  - "Buchen" button
- Replace buchen IconButton click: open BookingDialog instead of direct mutation
- Update `buchenMut` to accept `{ id, splits? }`

### T8 — Frontend: Plan Position → Freigabe Action
**Teammate**: frontend | **blockedBy**: T5, T6

**Files**: `buchhaltung.ts`, `HaushaltsplanDetail.tsx`

Service: add `createBudgetFreigabeFromPosition(posId, { user_id, betrag_limit?, beschreibung? })`

HaushaltsplanDetail.tsx:
- Add "Freigabe erstellen" IconButton per position row (only when canManage && pos.konto_id set)
- Dialog: User select (fetch members), Betrag-Limit (pre-filled from position total), Beschreibung (pre-filled from position name)
- Pattern: follow existing position edit dialog

---

## Teammate Assignments

| Teammate | Tasks | Mode |
|----------|-------|------|
| database | T1, T2 | bypassPermissions |
| backend | T3, T4, T5 | bypassPermissions |
| frontend | T6, T7, T8 | bypassPermissions |

## Verification

1. Migration: check tables exist via backend startup logs
2. Backend: test budget-freigaben CRUD via curl/frontend
3. Frontend: verify Freigaben tab renders, BookingDialog opens on buchen click
4. Split booking: create pending transaction, open dialog, add split rows, book
5. Plan→Freigabe: open HaushaltsplanDetail, click freigabe button on position with konto_id