chore: move budget backend to proper DI

server/tests/unit/mcp/resources.test.ts

@@ -1,7 +1,10 @@
 /**
  * Unit tests for MCP resources (resources.ts).
- * Tests all 7 legacy-registrar resources via InMemoryTransport + Client
- * (trek://categories moved to the DI-discovered CategoriesMcp — see
+ * Tests all 6 legacy-registrar resources via InMemoryTransport + Client
+ * (trek://trips/{tripId}/budget, .../budget/per-person and
+ * .../budget/settlement moved to the DI-discovered BudgetMcp — see
+ * tools-budget.test.ts and tools-budget-advanced.test.ts;
+ * trek://categories moved to the DI-discovered CategoriesMcp — see
  * tools-categories.test.ts; trek://trips/{tripId}/todos moved to TodoMcp —
  * see tools-todos.test.ts; trek://trips/{tripId}/packing and .../packing/bags
  * moved to PackingMcp — see tools-packing.test.ts;
@@ -48,7 +51,7 @@ vi.mock('../../../src/websocket', () => ({ broadcast: vi.fn() }));
 import { createTables } from '../../../src/db/schema';
 import { runMigrations } from '../../../src/db/migrations';
 import { resetTestDb } from '../../helpers/test-db';
-import { createUser, createTrip, createPlace, addTripMember, createBudgetItem, createReservation, createCollabNote, createBucketListItem, createVisitedCountry } from '../../helpers/factories';
+import { createUser, createTrip, createPlace, addTripMember, createReservation, createCollabNote, createBucketListItem, createVisitedCountry } from '../../helpers/factories';
 import { createMcpHarness, parseResourceResult, type McpHarness } from '../../helpers/mcp-harness';
 
 beforeAll(() => {
@@ -186,32 +189,9 @@ describe('Resource: trek://trips/{tripId}/places', () => {
   });
 });
 
-describe('Resource: trek://trips/{tripId}/budget', () => {
-  it('returns budget items for a trip', async () => {
-    const { user } = createUser(testDb);
-    const trip = createTrip(testDb, user.id);
-    createBudgetItem(testDb, trip.id, { name: 'Hotel', category: 'Accommodation', total_price: 200 });
-
-    await withHarness(user.id, async (harness) => {
-      const result = await harness.client.readResource({ uri: `trek://trips/${trip.id}/budget` });
-      const items = parseResourceResult(result) as any[];
-      expect(items).toHaveLength(1);
-      expect(items[0].name).toBe('Hotel');
-    });
-  });
-
-  it('returns access denied for unauthorized trip', async () => {
-    const { user } = createUser(testDb);
-    const { user: other } = createUser(testDb);
-    const trip = createTrip(testDb, other.id);
-
-    await withHarness(user.id, async (harness) => {
-      const result = await harness.client.readResource({ uri: `trek://trips/${trip.id}/budget` });
-      const data = parseResourceResult(result) as any;
-      expect(data.error).toBeTruthy();
-    });
-  });
-});
+// The trek://trips/{tripId}/budget resource moved to the DI-discovered
+// src/nest/budget/budget.mcp.ts — its cases live in tools-budget.test.ts (the
+// registry attaches via registerTools, which this withTools:false harness skips).
 
 // The trek://trips/{tripId}/packing and .../packing/bags resources moved to the
 // DI-discovered PackingMcp — see tools-packing.test.ts.

server/tests/unit/mcp/tools-budget.test.ts

@@ -36,7 +36,7 @@ import { createTables } from '../../../src/db/schema';
 import { runMigrations } from '../../../src/db/migrations';
 import { resetTestDb } from '../../helpers/test-db';
 import { createUser, createTrip, createBudgetItem, addTripMember } from '../../helpers/factories';
-import { createMcpHarness, parseToolResult, type McpHarness } from '../../helpers/mcp-harness';
+import { createMcpHarness, parseToolResult, parseResourceResult, type McpHarness } from '../../helpers/mcp-harness';
 
 beforeAll(() => {
   createTables(testDb);
@@ -304,3 +304,35 @@ describe('Tool: delete_budget_item', () => {
     });
   });
 });
+
+// ---------------------------------------------------------------------------
+// Resource: trek://trips/{tripId}/budget (moved from the legacy resources.ts
+// registrar to the DI-discovered BudgetMcp — attached via the nest-mcp registry)
+// ---------------------------------------------------------------------------
+
+describe('Resource: trek://trips/{tripId}/budget', () => {
+  it('returns budget items for a trip', async () => {
+    const { user } = createUser(testDb);
+    const trip = createTrip(testDb, user.id);
+    createBudgetItem(testDb, trip.id, { name: 'Hotel', category: 'Accommodation', total_price: 200 });
+
+    await withHarness(user.id, async (h) => {
+      const result = await h.client.readResource({ uri: `trek://trips/${trip.id}/budget` });
+      const items = parseResourceResult(result) as { name: string }[];
+      expect(items).toHaveLength(1);
+      expect(items[0].name).toBe('Hotel');
+    });
+  });
+
+  it('returns access denied for unauthorized trip', async () => {
+    const { user } = createUser(testDb);
+    const { user: other } = createUser(testDb);
+    const trip = createTrip(testDb, other.id);
+
+    await withHarness(user.id, async (h) => {
+      const result = await h.client.readResource({ uri: `trek://trips/${trip.id}/budget` });
+      const data = parseResourceResult(result) as { error?: string };
+      expect(data.error).toBeTruthy();
+    });
+  });
+});

server/tests/unit/nest/budget.service.calc.test.ts

@@ -1,3 +1,12 @@
+/**
+ * Settlement-math and FX-freeze unit tests for BudgetService over a prepare-stub
+ * DB mock. Moved 1:1 from the legacy tests/unit/services/budgetService.test.ts
+ * (same cases, incl. the #1335/#1445/#1426 pins); the SUT is now the folded
+ * BudgetService with a constructor-injected ExchangeRatesService stub (was a
+ * path mock of the deleted exchange-rates.bridge), and the raw settlement
+ * update is exercised as applySettlementUpdate (the no-freeze write the REST
+ * updateSettlement wraps).
+ */
 import { describe, it, expect, vi, beforeEach } from 'vitest';
 
 // ── DB mock setup ────────────────────────────────────────────────────────────
@@ -11,17 +20,33 @@ const mockDb = vi.hoisted(() => {
         run: vi.fn(),
       })),
     },
+    closeDb: () => {},
+    reinitialize: () => {},
+    getPlaceWithTags: () => null,
     canAccessTrip: vi.fn(() => true),
+    isOwner: () => false,
   };
 });
 
 vi.mock('../../../src/db/database', () => mockDb);
+vi.mock('../../../src/websocket', () => ({ broadcast: vi.fn() }));
 
-const mockRates = vi.hoisted(() => ({ getRates: vi.fn() }));
-vi.mock('../../../src/nest/budget/exchange-rates.bridge', () => mockRates);
+const mockRates = { getRates: vi.fn() };
 
-import { calculateSettlement, updateSettlement, freezeForeignRate } from '../../../src/services/budgetService';
+import { BudgetService } from '../../../src/nest/budget/budget.service';
+import { DatabaseService } from '../../../src/nest/database/database.service';
+import type { PermissionsService } from '../../../src/nest/permissions/permissions.service';
+import type { ExchangeRatesService } from '../../../src/nest/budget/exchange-rates.service';
 import type { BudgetItem, BudgetItemMember, BudgetItemPayer } from '../../../src/types';
+import type Database from 'better-sqlite3';
+
+const permissionsStub = { checkPermission: vi.fn(() => true) } as unknown as PermissionsService;
+
+const budget = new BudgetService(
+  new DatabaseService(mockDb.db as unknown as Database.Database),
+  permissionsStub,
+  mockRates as unknown as ExchangeRatesService,
+);
 
 // ── Helpers ──────────────────────────────────────────────────────────────────
 // Who actually paid is recorded as explicit payers (budget_item_payers); members
@@ -85,14 +110,14 @@ beforeEach(() => {
 describe('calculateSettlement', () => {
   it('returns empty balances and flows when trip has no items', () => {
     setupDb([], [], []);
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     expect(result.balances).toEqual([]);
     expect(result.flows).toEqual([]);
   });
 
   it('returns no flows when there are items but no members', () => {
     setupDb([makeItem(1, 100)], [], [makePayer(1, 1, 100, 'alice')]);
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     expect(result.flows).toEqual([]);
   });
 
@@ -102,7 +127,7 @@ describe('calculateSettlement', () => {
       [makeMember(1, 1, 'alice'), makeMember(1, 2, 'bob')],
       [],
     );
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     expect(result.flows).toEqual([]);
   });
 
@@ -113,7 +138,7 @@ describe('calculateSettlement', () => {
       [makeMember(1, 1, 'alice'), makeMember(1, 2, 'bob')],
       [makePayer(1, 1, 100, 'alice')],
     );
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     const alice = result.balances.find(b => b.user_id === 1)!;
     const bob = result.balances.find(b => b.user_id === 2)!;
     expect(alice.balance).toBe(50);
@@ -131,7 +156,7 @@ describe('calculateSettlement', () => {
       [makeMember(1, 1, 'alice'), makeMember(1, 2, 'bob'), makeMember(1, 3, 'carol')],
       [makePayer(1, 1, 90, 'alice')],
     );
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     const alice = result.balances.find(b => b.user_id === 1)!;
     const bob = result.balances.find(b => b.user_id === 2)!;
     const carol = result.balances.find(b => b.user_id === 3)!;
@@ -148,7 +173,7 @@ describe('calculateSettlement', () => {
       [makeMember(1, 1, 'alice'), makeMember(1, 2, 'bob'), makeMember(1, 3, 'carol')],
       [makePayer(1, 1, 20, 'alice'), makePayer(1, 2, 20, 'bob'), makePayer(1, 3, 20, 'carol')],
     );
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     for (const b of result.balances) {
       expect(Math.abs(b.balance)).toBeLessThanOrEqual(0.01);
     }
@@ -162,7 +187,7 @@ describe('calculateSettlement', () => {
       [makeMember(1, 1, 'alice'), makeMember(1, 2, 'bob')],
       [makePayer(1, 1, 100, 'alice')],
     );
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     const flow = result.flows[0];
     expect(flow.from.username).toBe('bob');   // debtor
     expect(flow.to.username).toBe('alice');   // creditor
@@ -175,7 +200,7 @@ describe('calculateSettlement', () => {
       [makeMember(1, 1, 'alice'), makeMember(1, 2, 'bob'), makeMember(1, 3, 'carol')],
       [makePayer(1, 1, 10, 'alice')],
     );
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     for (const b of result.balances) {
       const str = b.balance.toString();
       const decimals = str.includes('.') ? str.split('.')[1].length : 0;
@@ -200,7 +225,7 @@ describe('calculateSettlement', () => {
       ],
       [makePayer(1, 1, 100, 'alice'), makePayer(2, 2, 60, 'bob')],
     );
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     const alice = result.balances.find(b => b.user_id === 1)!;
     const bob = result.balances.find(b => b.user_id === 2)!;
     expect(alice.balance).toBe(20);
@@ -219,7 +244,7 @@ describe('calculateSettlement', () => {
       }
       return { all: vi.fn(() => []), get: vi.fn(), run: vi.fn() };
     });
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     const alice = result.balances.find(b => b.user_id === 1)!;
     const bob = result.balances.find(b => b.user_id === 2)!;
     expect(bob.balance).toBe(30);
@@ -238,7 +263,7 @@ describe('calculateSettlement', () => {
       [makeMember(1, 1, 'alice'), makeMember(1, 2, 'bob')],
       [makePayer(1, 1, 110, 'alice')],
     );
-    const result = calculateSettlement(1, { base: 'EUR', tripCurrency: 'EUR', rates: { EUR: 1, USD: 1.2 } });
+    const result = budget.calculateSettlement(1, { base: 'EUR', tripCurrency: 'EUR', rates: { EUR: 1, USD: 1.2 } });
     const bob = result.balances.find(b => b.user_id === 2)!;
     // 110 / 1.1 = 100 EUR; Bob owes half = 50 (frozen). With the live 1.2 it would be ~45.83.
     expect(bob.balance).toBeCloseTo(-50, 2);
@@ -250,7 +275,7 @@ describe('calculateSettlement', () => {
       [makeMember(1, 1, 'alice'), makeMember(1, 2, 'bob')],
       [makePayer(1, 1, 120, 'alice')],
     );
-    const result = calculateSettlement(1, { base: 'EUR', tripCurrency: 'EUR', rates: { EUR: 1, USD: 1.2 } });
+    const result = budget.calculateSettlement(1, { base: 'EUR', tripCurrency: 'EUR', rates: { EUR: 1, USD: 1.2 } });
     const bob = result.balances.find(b => b.user_id === 2)!;
     // 120 / 1.2 (live) = 100 EUR; Bob owes 50 — unchanged behaviour for pre-#1335 rows.
     expect(bob.balance).toBeCloseTo(-50, 2);
@@ -267,7 +292,7 @@ describe('calculateSettlement', () => {
       [makePayer(1, 1, 100, 'alice')],
       [makeSettlementRow(1, 2, 1, 62.5, 'USD', 1.25)],
     );
-    const result = calculateSettlement(1, { base: 'USD', tripCurrency: 'EUR', rates: { USD: 1, EUR: 0.5 } });
+    const result = budget.calculateSettlement(1, { base: 'USD', tripCurrency: 'EUR', rates: { USD: 1, EUR: 0.5 } });
     const bob = result.balances.find(b => b.user_id === 2)!;
     expect(bob.balance).toBeCloseTo(0, 2); // settled — no residual re-opens
   });
@@ -282,7 +307,7 @@ describe('calculateSettlement', () => {
       [makePayer(1, 1, 100, 'alice')],
       [makeSettlementRow(1, 2, 1, 62.5, null, 1)],
     );
-    const result = calculateSettlement(1, { base: 'USD', tripCurrency: 'EUR', rates: { USD: 1, EUR: 0.5 } });
+    const result = budget.calculateSettlement(1, { base: 'USD', tripCurrency: 'EUR', rates: { USD: 1, EUR: 0.5 } });
     const bob = result.balances.find(b => b.user_id === 2)!;
     // settleToTrip(62.5) = 62.5 * 0.5 = 31.25 EUR; balance -50 + 31.25 = -18.75 EUR → reopens.
     expect(Math.abs(bob.balance)).toBeGreaterThan(1);
@@ -300,7 +325,7 @@ describe('calculateSettlement', () => {
       [makeMember(1, 1, 'alice'), makeMember(1, 2, 'bob'), makeMember(1, 3, 'carol')],
       [makePayer(1, 1, 45, 'alice'), makePayer(1, 2, 45, 'bob')],
     );
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     const balance = (uid: number) => result.balances.find(b => b.user_id === uid)!.balance;
 
     expect(balance(1)).toBeCloseTo(15, 2);
@@ -316,7 +341,7 @@ describe('calculateSettlement', () => {
       [makeMember(1, 1, 'alice'), makeMember(1, 2, 'bob')],
       [makePayer(1, 1, 70, 'alice'), makePayer(1, 2, 30, 'bob')],
     );
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     const balance = (uid: number) => result.balances.find(b => b.user_id === uid)!.balance;
 
     expect(balance(1)).toBeCloseTo(20, 2);
@@ -340,7 +365,7 @@ describe('calculateSettlement', () => {
         makePayer(2, 2, 25, 'bob'), makePayer(2, 3, 30, 'carol'),
       ],
     );
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     const sum = result.balances.reduce((a, b) => a + b.balance, 0);
 
     expect(sum).toBeCloseTo(0, 2);
@@ -354,7 +379,7 @@ describe('calculateSettlement', () => {
       [makeMember(1, 1, 'alice'), makeMember(1, 2, 'bob'), makeMember(1, 3, 'carol')],
       [makePayer(1, 1, 33.34, 'alice'), makePayer(1, 2, 33.34, 'bob'), makePayer(1, 3, 33.33, 'carol')],
     );
-    const result = calculateSettlement(1);
+    const result = budget.calculateSettlement(1);
     const sum = result.balances.reduce((a, b) => a + b.balance, 0);
 
     expect(sum).toBeCloseTo(0, 2);
@@ -375,7 +400,7 @@ describe('freezeForeignRate', () => {
     });
     mockRates.getRates.mockResolvedValue({ EUR: 1, USD: 1.25 });
     const data: { currency?: string | null; exchange_rate?: number } = { currency: 'usd' };
-    await freezeForeignRate(1, data);
+    await budget.freezeForeignRate(1, data);
     expect(mockRates.getRates).toHaveBeenCalledWith('EUR');
     expect(data.exchange_rate).toBe(1.25);
   });
@@ -384,14 +409,14 @@ describe('freezeForeignRate', () => {
     mockDb.db.prepare.mockImplementation((sql: string) =>
       sql.includes('FROM trips') ? tripRow('EUR') : { get: vi.fn(), all: vi.fn(() => []), run: vi.fn() });
     const data: { currency?: string | null; exchange_rate?: number } = { currency: 'EUR' };
-    await freezeForeignRate(1, data);
+    await budget.freezeForeignRate(1, data);
     expect(mockRates.getRates).not.toHaveBeenCalled();
     expect(data.exchange_rate).toBeUndefined();
   });
 
   it('respects an explicit exchange_rate from the caller', async () => {
     const data: { currency?: string | null; exchange_rate?: number } = { currency: 'USD', exchange_rate: 2 };
-    await freezeForeignRate(1, data);
+    await budget.freezeForeignRate(1, data);
     expect(mockRates.getRates).not.toHaveBeenCalled();
     expect(data.exchange_rate).toBe(2);
   });
@@ -401,7 +426,7 @@ describe('freezeForeignRate', () => {
       sql.includes('FROM trips') ? tripRow('EUR') : { get: vi.fn(), all: vi.fn(() => []), run: vi.fn() });
     mockRates.getRates.mockResolvedValue(null);
     const data: { currency?: string | null; exchange_rate?: number } = { currency: 'USD' };
-    await freezeForeignRate(1, data);
+    await budget.freezeForeignRate(1, data);
     expect(data.exchange_rate).toBeUndefined();
   });
 
@@ -412,7 +437,7 @@ describe('freezeForeignRate', () => {
       return { get: vi.fn(), all: vi.fn(() => []), run: vi.fn() };
     });
     const data: { currency?: string | null; exchange_rate?: number } = { currency: 'USD' };
-    await freezeForeignRate(1, data, 9);
+    await budget.freezeForeignRate(1, data, 9);
     expect(mockRates.getRates).not.toHaveBeenCalled();
     expect(data.exchange_rate).toBeUndefined();
   });
@@ -422,7 +447,7 @@ describe('freezeForeignRate', () => {
       sql.includes('FROM trips') ? tripRow('EUR') : { get: vi.fn(), all: vi.fn(() => []), run: vi.fn() });
     const data: { currency?: string | null; exchange_rate?: number } = { currency: 'USD' };
     // the settlement already holds USD — pass it as existingCurrency → keep the frozen rate
-    await freezeForeignRate(1, data, undefined, 'USD');
+    await budget.freezeForeignRate(1, data, undefined, 'USD');
     expect(mockRates.getRates).not.toHaveBeenCalled();
     expect(data.exchange_rate).toBeUndefined();
   });
@@ -432,14 +457,14 @@ describe('freezeForeignRate', () => {
       sql.includes('FROM trips') ? tripRow('EUR') : { get: vi.fn(), all: vi.fn(() => []), run: vi.fn() });
     mockRates.getRates.mockResolvedValue({ EUR: 1, USD: 1.25 });
     const data: { currency?: string | null; exchange_rate?: number } = { currency: 'USD' };
-    await freezeForeignRate(1, data, undefined, 'GBP'); // was GBP → now USD → re-freeze
+    await budget.freezeForeignRate(1, data, undefined, 'GBP'); // was GBP → now USD → re-freeze
     expect(data.exchange_rate).toBe(1.25);
   });
 });
 
-// ── updateSettlement ──────────────────────────────────────────────────────────
+// ── applySettlementUpdate (the raw no-freeze write behind updateSettlement) ──
 
-describe('updateSettlement', () => {
+describe('applySettlementUpdate', () => {
   it('returns null when the settlement is not in the trip', () => {
     mockDb.db.prepare.mockImplementation((sql: string) => {
       if (sql.includes('SELECT id FROM budget_settlements')) {
@@ -447,7 +472,7 @@ describe('updateSettlement', () => {
       }
       return { get: vi.fn(), all: vi.fn(() => []), run: vi.fn() };
     });
-    expect(updateSettlement(7, 1, { from_user_id: 2, to_user_id: 1, amount: 10 })).toBeNull();
+    expect(budget.applySettlementUpdate(7, 1, { from_user_id: 2, to_user_id: 1, amount: 10 })).toBeNull();
   });
 
   it('updates the row (rounded to cents) and returns the refreshed settlement', () => {
@@ -467,7 +492,7 @@ describe('updateSettlement', () => {
       return { get: vi.fn(), all: vi.fn(() => []), run: vi.fn() };
     });
 
-    const res = updateSettlement(7, 1, { from_user_id: 2, to_user_id: 1, amount: 10.126 });
+    const res = budget.applySettlementUpdate(7, 1, { from_user_id: 2, to_user_id: 1, amount: 10.126 });
     // from, to, rounded amount, currency-flag(0)/value(null), rate-flag(null)/value(1), id.
     // No currency/exchange_rate passed → both CASE guards keep the existing columns.
     expect(run).toHaveBeenCalledWith(2, 1, 10.13, 0, null, null, 1, 7);

server/tests/unit/nest/budget.service.db.test.ts

@@ -1,6 +1,9 @@
 /**
- * DB-backed unit tests for budgetService trip-scoping (BUDGET-SVC-DB-001+).
+ * DB-backed unit tests for BudgetService trip-scoping (BUDGET-SVC-DB-001+).
  * Uses a real in-memory SQLite DB so the SQL WHERE clauses are exercised.
+ * BUDGET-SVC-DB-001 through 014 moved 1:1 from the legacy
+ * tests/unit/services/budgetServiceDb.test.ts; 015–018 pin the budget.bridge
+ * delegation (the bridge instance runs over the same mocked db Proxy).
  */
 import { describe, it, expect, vi, beforeAll, beforeEach, afterAll } from 'vitest';
 
@@ -27,23 +30,43 @@ vi.mock('../../../src/config', () => ({
   ENCRYPTION_KEY: 'a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6a7b8c9d0e1f2a3b4c5d6a7b8c9d0e1f2',
   updateJwtSecret: () => {},
 }));
+vi.mock('../../../src/websocket', () => ({ broadcast: vi.fn() }));
 
 // Frozen snapshot of the rates in play in #1543 (rates[X] = units of X per 1 base).
-const RATES: Record<string, Record<string, number>> = {
-  RUB: { RUB: 1, USD: 0.013042, EUR: 0.011412 },
-  EUR: { EUR: 1, USD: 1.1429, RUB: 87.63 },
-};
-vi.mock('../../../src/nest/budget/exchange-rates.bridge', () => ({
-  getRates: vi.fn(async (base: string) => RATES[base.toUpperCase()] ?? null),
+const { RATES } = vi.hoisted(() => ({
+  RATES: {
+    RUB: { RUB: 1, USD: 0.013042, EUR: 0.011412 },
+    EUR: { EUR: 1, USD: 1.1429, RUB: 87.63 },
+  } as Record<string, Record<string, number>>,
+}));
+// Constructor-injected since the fold; the class is mocked at the module path so
+// the budget.bridge instance (which news up its own ExchangeRatesService) sees
+// the same deterministic rates as the SUT.
+vi.mock('../../../src/nest/budget/exchange-rates.service', () => ({
+  ExchangeRatesService: class {
+    async getRates(base: string) {
+      return RATES[base.toUpperCase()] ?? null;
+    }
+  },
 }));
 
 import { createTables } from '../../../src/db/schema';
 import { runMigrations } from '../../../src/db/migrations';
 import { resetTestDb } from '../../helpers/test-db';
 import { createUser, createTrip } from '../../helpers/factories';
-import { createBudgetItem, updateBudgetItem, updateMembers, toggleMemberPaid, calculateSettlement, rebaseTripCurrency } from '../../../src/services/budgetService';
+import { BudgetService } from '../../../src/nest/budget/budget.service';
+import { DatabaseService } from '../../../src/nest/database/database.service';
+import { PermissionsService } from '../../../src/nest/permissions/permissions.service';
+import { ExchangeRatesService } from '../../../src/nest/budget/exchange-rates.service';
+import * as bridge from '../../../src/nest/budget/budget.bridge';
 import { createGuest, deleteGuest } from '../../../src/services/tripService';
 
+const budget = new BudgetService(
+  new DatabaseService(testDb),
+  new PermissionsService(new DatabaseService(testDb)),
+  new ExchangeRatesService(),
+);
+
 beforeAll(() => {
   createTables(testDb);
   runMigrations(testDb);
@@ -77,7 +100,7 @@ describe('deleting a member re-splits their expenses (#1553)', () => {
     const { user: owner } = createUser(testDb);
     const trip = createTrip(testDb, owner.id);
     const guests = ['G1', 'G2', 'G3'].map(n => createGuest(trip.id, n, owner.id).member);
-    const item = createBudgetItem(trip.id, {
+    const item = budget.createBudgetItem(trip.id, {
       name: 'Dinner', total_price: 400,
       member_ids: [owner.id, ...guests.map(g => g.id)],
     });
@@ -97,7 +120,7 @@ describe('deleting a member re-splits their expenses (#1553)', () => {
     const trip = createTrip(testDb, owner.id);
     const guest = createGuest(trip.id, 'G1', owner.id).member;
     // No member rows — `persons` is just a number someone typed.
-    const item = createBudgetItem(trip.id, { name: 'Rental', total_price: 300, persons: 6 });
+    const item = budget.createBudgetItem(trip.id, { name: 'Rental', total_price: 300, persons: 6 });
 
     deleteGuest(trip.id, guest.id);
 
@@ -108,7 +131,7 @@ describe('deleting a member re-splits their expenses (#1553)', () => {
     const { user: owner } = createUser(testDb);
     const trip = createTrip(testDb, owner.id);
     const guest = createGuest(trip.id, 'G1', owner.id).member;
-    const item = createBudgetItem(trip.id, { name: 'Taxi', total_price: 50, member_ids: [guest.id] });
+    const item = budget.createBudgetItem(trip.id, { name: 'Taxi', total_price: 50, member_ids: [guest.id] });
 
     deleteGuest(trip.id, guest.id);
 
@@ -120,12 +143,12 @@ describe('deleting a member re-splits their expenses (#1553)', () => {
     const { user: owner } = createUser(testDb);
     const trip = createTrip(testDb, owner.id);
     const guest = createGuest(trip.id, 'G1', owner.id).member;
-    const item = createBudgetItem(trip.id, { name: 'Dinner', total_price: 200, member_ids: [owner.id, guest.id] });
+    const item = budget.createBudgetItem(trip.id, { name: 'Dinner', total_price: 200, member_ids: [owner.id, guest.id] });
 
     deleteGuest(trip.id, guest.id);
 
     // A client that loaded before the deletion still sends the guest back (#1553).
-    const updated = updateBudgetItem(item.id, trip.id, { member_ids: [owner.id, guest.id] });
+    const updated = budget.updateBudgetItem(item.id, trip.id, { member_ids: [owner.id, guest.id] });
 
     expect(updated!.members.map(m => m.user_id)).toEqual([owner.id]);
     expect(personsOf(item.id)).toBe(1);
@@ -135,10 +158,10 @@ describe('deleting a member re-splits their expenses (#1553)', () => {
     const { user: owner } = createUser(testDb);
     const trip = createTrip(testDb, owner.id);
     const guest = createGuest(trip.id, 'G1', owner.id).member;
-    const item = createBudgetItem(trip.id, { name: 'Drinks', total_price: 60, member_ids: [owner.id, guest.id] });
+    const item = budget.createBudgetItem(trip.id, { name: 'Drinks', total_price: 60, member_ids: [owner.id, guest.id] });
 
     deleteGuest(trip.id, guest.id);
-    const result = updateMembers(item.id, trip.id, [owner.id, guest.id]);
+    const result = budget.updateMembers(item.id, trip.id, [owner.id, guest.id]);
 
     expect(result!.members.map(m => m.user_id)).toEqual([owner.id]);
     expect(personsOf(item.id)).toBe(1);
@@ -149,10 +172,10 @@ describe('toggleMemberPaid trip-scoping', () => {
   it('BUDGET-SVC-DB-001: toggles paid for an item that belongs to the given trip', () => {
     const { user } = createUser(testDb);
     const trip = createTrip(testDb, user.id, { title: 'Trip A' });
-    const item = createBudgetItem(trip.id, { name: 'Hotel', total_price: 100 });
-    updateMembers(item.id, trip.id, [user.id]);
+    const item = budget.createBudgetItem(trip.id, { name: 'Hotel', total_price: 100 });
+    budget.updateMembers(item.id, trip.id, [user.id]);
 
-    const member = toggleMemberPaid(item.id, trip.id, user.id, true);
+    const member = budget.toggleMemberPaid(item.id, trip.id, user.id, true);
 
     expect(member).not.toBeNull();
     expect(paidFlag(item.id, user.id)).toBe(1);
@@ -162,11 +185,11 @@ describe('toggleMemberPaid trip-scoping', () => {
     const { user } = createUser(testDb);
     const tripA = createTrip(testDb, user.id, { title: 'Trip A' });
     const tripB = createTrip(testDb, user.id, { title: 'Trip B' });
-    const itemB = createBudgetItem(tripB.id, { name: 'Foreign expense', total_price: 50 });
-    updateMembers(itemB.id, tripB.id, [user.id]);
+    const itemB = budget.createBudgetItem(tripB.id, { name: 'Foreign expense', total_price: 50 });
+    budget.updateMembers(itemB.id, tripB.id, [user.id]);
 
     // Caller passes a trip they can access (A) but the item lives in trip B.
-    const member = toggleMemberPaid(itemB.id, tripA.id, user.id, true);
+    const member = budget.toggleMemberPaid(itemB.id, tripA.id, user.id, true);
 
     expect(member).toBeNull();
     expect(paidFlag(itemB.id, user.id)).toBe(0); // unchanged
@@ -180,7 +203,7 @@ describe('calculateSettlement custom splits', () => {
     const trip = createTrip(testDb, alice.id, { title: 'Trip' });
 
     // 100 total, custom split: Alice owes 90, Bob owes 10. Alice paid the whole bill.
-    createBudgetItem(trip.id, {
+    budget.createBudgetItem(trip.id, {
       name: 'Dinner',
       payers: [{ user_id: alice.id, amount: 100 }],
       members: [
@@ -189,7 +212,7 @@ describe('calculateSettlement custom splits', () => {
       ],
     });
 
-    const result = calculateSettlement(trip.id);
+    const result = budget.calculateSettlement(trip.id);
 
     // Alice paid 100 but owes 90 → net +10 (creditor); Bob owes 10 → net -10 (debtor).
     // With the equal-split bug both owe 50, so the flow would be 50 instead of 10.
@@ -214,9 +237,9 @@ function seedIssue1543Trip(tripCurrency: string) {
 
   // 9 000 ₽ nobody has paid yet, 9 000 ₽ paid by me, and $100 paid by me. The USD row
   // carries the rate frozen at entry time: units of USD per 1 RUB.
-  createBudgetItem(trip.id, { name: 'Проезд обратно', total_price: 9000, currency: 'RUB', members });
-  createBudgetItem(trip.id, { name: 'Проезд туда', currency: 'RUB', payers: [{ user_id: me.id, amount: 9000 }], members });
-  createBudgetItem(trip.id, {
+  budget.createBudgetItem(trip.id, { name: 'Проезд обратно', total_price: 9000, currency: 'RUB', members });
+  budget.createBudgetItem(trip.id, { name: 'Проезд туда', currency: 'RUB', payers: [{ user_id: me.id, amount: 9000 }], members });
+  budget.createBudgetItem(trip.id, {
     name: 'test', currency: 'USD', exchange_rate: 0.013042,
     payers: [{ user_id: me.id, amount: 100 }], members,
   });
@@ -227,7 +250,7 @@ describe('calculateSettlement with a foreign-currency expense (#1543)', () => {
   it('BUDGET-SVC-DB-004: nets in the trip currency instead of inflating the foreign share ~27x', () => {
     const { trip, me, danil, serega } = seedIssue1543Trip('RUB');
 
-    const result = calculateSettlement(trip.id, { base: 'RUB', tripCurrency: 'RUB', rates: RATES.RUB });
+    const result = budget.calculateSettlement(trip.id, { base: 'RUB', tripCurrency: 'RUB', rates: RATES.RUB });
     const balanceOf = (id: number) => result.balances.find(b => b.user_id === id)!.balance;
 
     // Total spend is 9 000 + 9 000 + $100 (≈7 668 ₽), so each of the three owes a third
@@ -248,7 +271,7 @@ describe('calculateSettlement with a foreign-currency expense (#1543)', () => {
     const { trip, danil } = seedIssue1543Trip('RUB');
 
     // Same trip, viewed in EUR: every balance is the RUB one converted once, at the end.
-    const inEur = calculateSettlement(trip.id, { base: 'EUR', tripCurrency: 'RUB', rates: RATES.EUR });
+    const inEur = budget.calculateSettlement(trip.id, { base: 'EUR', tripCurrency: 'RUB', rates: RATES.EUR });
     const danilEur = inEur.balances.find(b => b.user_id === danil.id)!.balance;
 
     const shareRub = (18000 + 100 / RATES.RUB.USD) / 3;
@@ -269,11 +292,11 @@ describe('rebaseTripCurrency', () => {
 
     // An expense that inherits the trip's base (currency NULL), one booked in USD, and
     // one already in the incoming currency.
-    const implicit = createBudgetItem(trip.id, { name: 'Implicit', total_price: 100, members }) as { id: number };
-    const usd = createBudgetItem(trip.id, { name: 'USD', total_price: 100, currency: 'USD', exchange_rate: 1.1429, members }) as { id: number };
-    const rub = createBudgetItem(trip.id, { name: 'RUB', total_price: 9000, currency: 'RUB', exchange_rate: 87.63, members }) as { id: number };
+    const implicit = budget.createBudgetItem(trip.id, { name: 'Implicit', total_price: 100, members }) as { id: number };
+    const usd = budget.createBudgetItem(trip.id, { name: 'USD', total_price: 100, currency: 'USD', exchange_rate: 1.1429, members }) as { id: number };
+    const rub = budget.createBudgetItem(trip.id, { name: 'RUB', total_price: 9000, currency: 'RUB', exchange_rate: 87.63, members }) as { id: number };
 
-    await rebaseTripCurrency(trip.id, 'RUB');
+    await budget.rebaseTripCurrency(trip.id, 'RUB');
 
     // The implicit row really held euros, so it is stamped EUR rather than silently
     // becoming 100 ₽, and every rate is re-anchored to the new base.
@@ -290,15 +313,15 @@ describe('rebaseTripCurrency', () => {
     testDb.prepare("UPDATE trips SET currency = 'EUR' WHERE id = ?").run(trip.id);
     const members = [{ user_id: alice.id }, { user_id: bob.id }];
 
-    createBudgetItem(trip.id, { name: 'Hotel', payers: [{ user_id: alice.id, amount: 100 }], members });
-    createBudgetItem(trip.id, { name: 'Dinner', currency: 'USD', exchange_rate: 1.1429, payers: [{ user_id: bob.id, amount: 60 }], members });
+    budget.createBudgetItem(trip.id, { name: 'Hotel', payers: [{ user_id: alice.id, amount: 100 }], members });
+    budget.createBudgetItem(trip.id, { name: 'Dinner', currency: 'USD', exchange_rate: 1.1429, payers: [{ user_id: bob.id, amount: 60 }], members });
 
-    const before = calculateSettlement(trip.id, { base: 'EUR', tripCurrency: 'EUR', rates: RATES.EUR });
+    const before = budget.calculateSettlement(trip.id, { base: 'EUR', tripCurrency: 'EUR', rates: RATES.EUR });
 
-    await rebaseTripCurrency(trip.id, 'RUB');
+    await budget.rebaseTripCurrency(trip.id, 'RUB');
     testDb.prepare("UPDATE trips SET currency = 'RUB' WHERE id = ?").run(trip.id);
 
-    const after = calculateSettlement(trip.id, { base: 'RUB', tripCurrency: 'RUB', rates: RATES.RUB });
+    const after = budget.calculateSettlement(trip.id, { base: 'RUB', tripCurrency: 'RUB', rates: RATES.RUB });
 
     for (const b of before.balances) {
       const rub = after.balances.find(x => x.user_id === b.user_id)!.balance;
@@ -322,7 +345,7 @@ describe('rebaseTripCurrency', () => {
     const jpy = priced(1500, 'JPY');
     const free = priced(null, null);
 
-    await rebaseTripCurrency(trip.id, 'JPY');
+    await budget.rebaseTripCurrency(trip.id, 'JPY');
 
     const placeRow = (id: number) =>
       testDb.prepare('SELECT price, currency FROM places WHERE id = ?')
@@ -340,10 +363,61 @@ describe('rebaseTripCurrency', () => {
     const { user } = createUser(testDb);
     const trip = createTrip(testDb, user.id, { title: 'Trip' });
     testDb.prepare("UPDATE trips SET currency = 'EUR' WHERE id = ?").run(trip.id);
-    const item = createBudgetItem(trip.id, { name: 'Implicit', total_price: 100, members: [{ user_id: user.id }] }) as { id: number };
+    const item = budget.createBudgetItem(trip.id, { name: 'Implicit', total_price: 100, members: [{ user_id: user.id }] }) as { id: number };
 
-    await rebaseTripCurrency(trip.id, 'EUR');
+    await budget.rebaseTripCurrency(trip.id, 'EUR');
 
     expect(itemRow(item.id)).toEqual({ currency: null, exchange_rate: 1 });
   });
 });
+
+describe('budget.bridge delegation', () => {
+  it('BUDGET-SVC-DB-015: listBudgetItems returns the hydrated list through the bridge', () => {
+    const { user } = createUser(testDb);
+    const trip = createTrip(testDb, user.id);
+    const item = budget.createBudgetItem(trip.id, { name: 'Hotel', total_price: 100, member_ids: [user.id] });
+
+    const items = bridge.listBudgetItems(trip.id);
+
+    expect(items.map(i => i.id)).toEqual([item.id]);
+    expect(items[0].members.map(m => m.user_id)).toEqual([user.id]);
+  });
+
+  it('BUDGET-SVC-DB-016: removeUserFromBudgetItems re-derives persons through the bridge', () => {
+    const { user: owner } = createUser(testDb);
+    const { user: other } = createUser(testDb, { username: 'other' });
+    const trip = createTrip(testDb, owner.id);
+    const item = budget.createBudgetItem(trip.id, { name: 'Dinner', total_price: 80, member_ids: [owner.id, other.id] });
+
+    bridge.removeUserFromBudgetItems(other.id);
+
+    const row = testDb.prepare('SELECT persons FROM budget_items WHERE id = ?').get(item.id) as { persons: number | null };
+    expect(row.persons).toBe(1);
+  });
+
+  it('BUDGET-SVC-DB-017: rebaseTripCurrency pins the implicit currency through the bridge', async () => {
+    const { user } = createUser(testDb);
+    const trip = createTrip(testDb, user.id);
+    testDb.prepare("UPDATE trips SET currency = 'EUR' WHERE id = ?").run(trip.id);
+    const item = budget.createBudgetItem(trip.id, { name: 'Implicit', total_price: 100, members: [{ user_id: user.id }] });
+
+    await bridge.rebaseTripCurrency(trip.id, 'RUB');
+
+    const row = testDb.prepare('SELECT currency, exchange_rate FROM budget_items WHERE id = ?').get(item.id) as { currency: string | null; exchange_rate: number };
+    expect(row).toEqual({ currency: 'EUR', exchange_rate: RATES.RUB.EUR });
+  });
+
+  it('BUDGET-SVC-DB-018: linkBudgetItemToReservation stamps the reservation id through the bridge', () => {
+    const { user } = createUser(testDb);
+    const trip = createTrip(testDb, user.id);
+    const reservationId = Number(testDb
+      .prepare("INSERT INTO reservations (trip_id, title, type) VALUES (?, 'Flight', 'flight')")
+      .run(trip.id).lastInsertRowid);
+
+    const item = bridge.linkBudgetItemToReservation(trip.id, reservationId, { name: 'Flight', total_price: 200 });
+
+    expect(item.reservation_id).toBe(reservationId);
+    const row = testDb.prepare('SELECT reservation_id FROM budget_items WHERE id = ?').get(item.id) as { reservation_id: number | null };
+    expect(row.reservation_id).toBe(reservationId);
+  });
+});

server/tests/unit/nest/budget.service.test.ts

@@ -1,11 +1,27 @@
+/**
+ * Seam tests for the folded BudgetService: the permission/broadcast edges, the
+ * controller-facing composite methods (create/update/settlement wrappers that
+ * freeze the FX rate before the raw write — incl. the #1445 stored-currency
+ * thread-through) and the wrapper-only syncReservationPrice SQL. The SQL-heavy
+ * paths themselves are covered by budget.service.db.test.ts (real :memory: DB)
+ * and budget.service.calc.test.ts (settlement math over a prepare-stub mock).
+ */
 import { describe, it, expect, vi, beforeEach } from 'vitest';
 
-// Mock the data + side-effect dependencies the wrapper reaches into directly.
+// Mock the data + side-effect dependencies the service reaches into directly.
 const { dbMock } = vi.hoisted(() => {
   const stmt = { get: vi.fn(), all: vi.fn(() => []), run: vi.fn() };
   return { dbMock: { prepare: vi.fn(() => stmt), _stmt: stmt } };
 });
-vi.mock('../../../src/db/database', () => ({ db: dbMock, closeDb: () => {}, reinitialize: () => {} }));
+const { canAccessTrip } = vi.hoisted(() => ({ canAccessTrip: vi.fn() }));
+vi.mock('../../../src/db/database', () => ({
+  db: dbMock,
+  closeDb: () => {},
+  reinitialize: () => {},
+  canAccessTrip,
+  getPlaceWithTags: () => null,
+  isOwner: () => false,
+}));
 import { db as dbConn } from '../../../src/db/database';
 import { DatabaseService } from '../../../src/nest/database/database.service';
 import type { PermissionsService } from '../../../src/nest/permissions/permissions.service';
@@ -16,35 +32,11 @@ vi.mock('../../../src/websocket', () => ({ broadcast }));
 const checkPermission = vi.fn(() => true);
 const permissionsStub = { checkPermission } as unknown as PermissionsService;
 
-// Constructor-injected stub since the exchange-rates fold (was a path mock of
-// the deleted services/exchangeRateService).
+// Constructor-injected ExchangeRatesService stub (as in the pre-fold wrapper).
 import type { ExchangeRatesService } from '../../../src/nest/budget/exchange-rates.service';
 const getRates = vi.fn();
 const exchangeRatesStub = { getRates } as unknown as ExchangeRatesService;
 
-const { budget } = vi.hoisted(() => ({
-  budget: {
-    verifyTripAccess: vi.fn(),
-    listBudgetItems: vi.fn(),
-    getPerPersonSummary: vi.fn(),
-    calculateSettlement: vi.fn(),
-    freezeForeignRate: vi.fn(),
-    createBudgetItem: vi.fn(),
-    updateBudgetItem: vi.fn(),
-    deleteBudgetItem: vi.fn(),
-    updateMembers: vi.fn(),
-    toggleMemberPaid: vi.fn(),
-    setItemPayers: vi.fn(),
-    listSettlements: vi.fn(() => []),
-    createSettlement: vi.fn(),
-    updateSettlement: vi.fn(),
-    deleteSettlement: vi.fn(),
-    reorderBudgetItems: vi.fn(),
-    reorderBudgetCategories: vi.fn(),
-  },
-}));
-vi.mock('../../../src/services/budgetService', () => budget);
-
 import { BudgetService } from '../../../src/nest/budget/budget.service';
 
 function svc() {
@@ -57,10 +49,10 @@ beforeEach(() => {
 });
 
 describe('BudgetService', () => {
-  it('verifyTripAccess delegates to the legacy service', () => {
-    budget.verifyTripAccess.mockReturnValue({ id: 5, user_id: 2 });
+  it('verifyTripAccess resolves through canAccessTrip (services/tripAccess)', () => {
+    canAccessTrip.mockReturnValue({ id: 5, user_id: 2 });
     expect(svc().verifyTripAccess('5', 2)).toEqual({ id: 5, user_id: 2 });
-    expect(budget.verifyTripAccess).toHaveBeenCalledWith('5', 2);
+    expect(canAccessTrip).toHaveBeenCalledWith('5', 2);
   });
 
   it('canEdit forwards the ownership flag when the user owns the trip', () => {
@@ -80,70 +72,91 @@ describe('BudgetService', () => {
     expect(broadcast).toHaveBeenCalledWith('5', 'budget:created', { item: { id: 1 } }, 'sock');
   });
 
-  it('list / perPersonSummary delegate', () => {
-    budget.listBudgetItems.mockReturnValue([{ id: 1 }]);
-    expect(svc().list('5')).toEqual([{ id: 1 }]);
-    budget.getPerPersonSummary.mockReturnValue([{ userId: 1 }]);
-    expect(svc().perPersonSummary('5')).toEqual([{ userId: 1 }]);
+  it('list / perPersonSummary resolve through the folded SQL methods', () => {
+    const s = svc();
+    const listSpy = vi.spyOn(s, 'listBudgetItems').mockReturnValue([{ id: 1 }] as never);
+    expect(s.list('5')).toEqual([{ id: 1 }]);
+    expect(listSpy).toHaveBeenCalledWith('5');
+    const summarySpy = vi.spyOn(s, 'getPerPersonSummary').mockReturnValue([{ userId: 1 }] as never);
+    expect(s.perPersonSummary('5')).toEqual([{ userId: 1 }]);
+    expect(summarySpy).toHaveBeenCalledWith('5');
   });
 
   describe('settlement', () => {
     it('upper-cases the explicit base and forwards the rates', async () => {
+      const s = svc();
+      const calcSpy = vi.spyOn(s, 'calculateSettlement').mockReturnValue({ transfers: [] } as never);
       getRates.mockResolvedValue({ USD: 1.1 });
-      budget.calculateSettlement.mockReturnValue({ transfers: [] });
-      await svc().settlement('5', 'usd', 'EUR');
+      await s.settlement('5', 'usd', 'EUR');
       expect(getRates).toHaveBeenCalledWith('USD');
-      expect(budget.calculateSettlement).toHaveBeenCalledWith('5', { base: 'USD', rates: { USD: 1.1 }, tripCurrency: 'EUR' });
+      expect(calcSpy).toHaveBeenCalledWith('5', { base: 'USD', rates: { USD: 1.1 }, tripCurrency: 'EUR' });
     });
 
     it('falls back to the trip currency when no base is given', async () => {
+      const s = svc();
+      const calcSpy = vi.spyOn(s, 'calculateSettlement').mockReturnValue({ transfers: [] } as never);
       getRates.mockResolvedValue(null);
-      await svc().settlement('5', undefined, 'gbp');
+      await s.settlement('5', undefined, 'gbp');
       expect(getRates).toHaveBeenCalledWith('GBP');
-      expect(budget.calculateSettlement).toHaveBeenCalledWith('5', { base: 'GBP', rates: null, tripCurrency: 'gbp' });
+      expect(calcSpy).toHaveBeenCalledWith('5', { base: 'GBP', rates: null, tripCurrency: 'gbp' });
     });
 
     it('falls back to EUR when neither base nor trip currency is present', async () => {
+      const s = svc();
+      const calcSpy = vi.spyOn(s, 'calculateSettlement').mockReturnValue({ transfers: [] } as never);
       getRates.mockResolvedValue(null);
-      await svc().settlement('5', undefined, '');
+      await s.settlement('5', undefined, '');
       expect(getRates).toHaveBeenCalledWith('EUR');
-      expect(budget.calculateSettlement).toHaveBeenCalledWith('5', { base: 'EUR', rates: null, tripCurrency: '' });
+      expect(calcSpy).toHaveBeenCalledWith('5', { base: 'EUR', rates: null, tripCurrency: '' });
     });
   });
 
-  it('create / update / remove / members / paid / payers delegate', async () => {
-    await svc().create('5', { name: 'Hotel' } as never);
-    expect(budget.createBudgetItem).toHaveBeenCalledWith('5', { name: 'Hotel' });
-    await svc().update('9', '5', { name: 'X' });
-    expect(budget.updateBudgetItem).toHaveBeenCalledWith('9', '5', { name: 'X' });
-    svc().remove('9', '5');
-    expect(budget.deleteBudgetItem).toHaveBeenCalledWith('9', '5');
-    svc().updateMembers('9', '5', [2, 3]);
-    expect(budget.updateMembers).toHaveBeenCalledWith('9', '5', [2, 3]);
-    svc().toggleMemberPaid('9', '5', '2', true);
-    expect(budget.toggleMemberPaid).toHaveBeenCalledWith('9', '5', '2', true);
-    svc().setPayers('9', '5', [{ user_id: 2, amount: 10 }]);
-    expect(budget.setItemPayers).toHaveBeenCalledWith('9', '5', [{ user_id: 2, amount: 10 }]);
+  it('create / update freeze the FX rate before the raw write', async () => {
+    const s = svc();
+    const freezeSpy = vi.spyOn(s, 'freezeForeignRate').mockResolvedValue();
+    const createSpy = vi.spyOn(s, 'createBudgetItem').mockReturnValue({ id: 1 } as never);
+    await s.create('5', { name: 'Hotel' });
+    expect(freezeSpy).toHaveBeenCalledWith('5', { name: 'Hotel' });
+    expect(createSpy).toHaveBeenCalledWith('5', { name: 'Hotel' });
+
+    const updateSpy = vi.spyOn(s, 'updateBudgetItem').mockReturnValue({ id: 9 } as never);
+    await s.update('9', '5', { name: 'X' });
+    // the item id is threaded through so an unchanged-currency edit keeps the frozen rate
+    expect(freezeSpy).toHaveBeenCalledWith('5', { name: 'X' }, '9');
+    expect(updateSpy).toHaveBeenCalledWith('9', '5', { name: 'X' });
   });
 
-  it('settlement ledger + reorder delegate', async () => {
-    svc().listSettlements('5');
-    expect(budget.listSettlements).toHaveBeenCalledWith('5');
-    // createSettlement freezes the FX rate (await) before delegating.
-    await svc().createSettlement('5', { from_user_id: 1, to_user_id: 2, amount: 10 }, 3);
-    expect(budget.freezeForeignRate).toHaveBeenCalledWith('5', { from_user_id: 1, to_user_id: 2, amount: 10 });
-    expect(budget.createSettlement).toHaveBeenCalledWith('5', { from_user_id: 1, to_user_id: 2, amount: 10 }, 3);
-    budget.listSettlements.mockReturnValue([{ id: 7, currency: 'USD' }] as never);
-    await svc().updateSettlement('7', '5', { from_user_id: 1, to_user_id: 2, amount: 12, currency: 'USD' });
-    // the settlement's stored currency is threaded through so an unchanged-currency edit keeps the frozen rate (#1445)
-    expect(budget.freezeForeignRate).toHaveBeenCalledWith('5', { from_user_id: 1, to_user_id: 2, amount: 12, currency: 'USD' }, undefined, 'USD');
-    expect(budget.updateSettlement).toHaveBeenCalledWith('7', '5', { from_user_id: 1, to_user_id: 2, amount: 12, currency: 'USD' });
-    svc().deleteSettlement('7', '5');
-    expect(budget.deleteSettlement).toHaveBeenCalledWith('7', '5');
-    svc().reorderItems('5', [3, 1]);
-    expect(budget.reorderBudgetItems).toHaveBeenCalledWith('5', [3, 1]);
-    svc().reorderCategories('5', ['food', 'fun']);
-    expect(budget.reorderBudgetCategories).toHaveBeenCalledWith('5', ['food', 'fun']);
+  it('remove / setPayers resolve through the folded SQL methods', () => {
+    const s = svc();
+    const deleteSpy = vi.spyOn(s, 'deleteBudgetItem').mockReturnValue(true);
+    expect(s.remove('9', '5')).toBe(true);
+    expect(deleteSpy).toHaveBeenCalledWith('9', '5');
+
+    const payersSpy = vi.spyOn(s, 'setItemPayers').mockReturnValue({ id: 9 } as never);
+    s.setPayers('9', '5', [{ user_id: 2, amount: 10 }]);
+    expect(payersSpy).toHaveBeenCalledWith('9', '5', [{ user_id: 2, amount: 10 }]);
+  });
+
+  describe('settlement ledger wrappers (#1445 freeze-then-write)', () => {
+    it('createSettlement freezes the FX rate (await) before the raw insert', async () => {
+      const s = svc();
+      const freezeSpy = vi.spyOn(s, 'freezeForeignRate').mockResolvedValue();
+      const insertSpy = vi.spyOn(s, 'insertSettlement').mockReturnValue({ id: 7 } as never);
+      await s.createSettlement('5', { from_user_id: 1, to_user_id: 2, amount: 10 }, 3);
+      expect(freezeSpy).toHaveBeenCalledWith('5', { from_user_id: 1, to_user_id: 2, amount: 10 });
+      expect(insertSpy).toHaveBeenCalledWith('5', { from_user_id: 1, to_user_id: 2, amount: 10 }, 3);
+    });
+
+    it('updateSettlement threads the stored currency through the freeze', async () => {
+      const s = svc();
+      const freezeSpy = vi.spyOn(s, 'freezeForeignRate').mockResolvedValue();
+      vi.spyOn(s, 'listSettlements').mockReturnValue([{ id: 7, currency: 'USD' }] as never);
+      const applySpy = vi.spyOn(s, 'applySettlementUpdate').mockReturnValue({ id: 7 } as never);
+      await s.updateSettlement('7', '5', { from_user_id: 1, to_user_id: 2, amount: 12, currency: 'USD' });
+      // the settlement's stored currency is threaded through so an unchanged-currency edit keeps the frozen rate (#1445)
+      expect(freezeSpy).toHaveBeenCalledWith('5', { from_user_id: 1, to_user_id: 2, amount: 12, currency: 'USD' }, undefined, 'USD');
+      expect(applySpy).toHaveBeenCalledWith('7', '5', { from_user_id: 1, to_user_id: 2, amount: 12, currency: 'USD' });
+    });
   });
 
   describe('syncReservationPrice', () => {

server/tests/unit/nest/exchange-rates.service.test.ts

@@ -4,9 +4,10 @@
  * dedicated tests; the budget-domain fold moved it inside the src/nest/**
  * coverage gate. 001–012 pin the fetch/cache behavior (including the parity
  * quirks kept on purpose: `|| 'EUR'` falsy coercion, stale-cache fallback, the
- * `>1 keys` failure heuristic); 019 pins the exchange-rates.bridge delegation
- * and the module-scoped cache shared between the DI instance and the bridge
- * instance; 021–022 pin the post-fold quirk fixes (AbortSignal timeout,
+ * `>1 keys` failure heuristic); 019 pins the module-scoped cache shared across
+ * instances (the DI singleton and the budget.bridge instance wrap one feed —
+ * originally pinned via the exchange-rates.bridge, deleted with the budget
+ * fold); 021–022 pin the post-fold quirk fixes (AbortSignal timeout,
  * response-size cap, logged failures). 013–018 and 020 covered the dead
  * convertWithRates export and were removed with it in the quirk fixes.
  *
@@ -15,7 +16,6 @@
  */
 import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
 import { ExchangeRatesService } from '../../../src/nest/budget/exchange-rates.service';
-import { getRates as bridgeGetRates } from '../../../src/nest/budget/exchange-rates.bridge';
 
 const TTL_MS = 6 * 60 * 60 * 1000; // mirrors the service's 6h TTL
 
@@ -139,13 +139,14 @@ describe('ExchangeRatesService.getRates', () => {
   });
 });
 
-describe('exchange-rates.bridge', () => {
-  it('FX-SVC-019: getRates delegates and shares the module-scoped cache with the DI instance', async () => {
+describe('cross-instance cache sharing', () => {
+  it('FX-SVC-019: a second instance (the budget.bridge shape) serves the module-scoped cache', async () => {
     // Prime the cache through the DI-style instance…
     const primed = await svc.getRates('AUD');
     expect(fetchMock).toHaveBeenCalledTimes(1);
-    // …then the bridge (its own instance) must serve the same cached feed.
-    expect(await bridgeGetRates('AUD')).toBe(primed);
+    // …then a separately-constructed instance (as budget.bridge news up) must
+    // serve the same cached feed instead of refetching.
+    expect(await new ExchangeRatesService().getRates('AUD')).toBe(primed);
     expect(fetchMock).toHaveBeenCalledTimes(1);
   });
 });

server/tests/unit/nest/reservations.service.test.ts

@@ -37,10 +37,9 @@ vi.mock('../../../src/websocket', () => ({ broadcast }));
 const checkPermission = vi.fn(() => true);
 const permissionsStub = { checkPermission } as unknown as PermissionsService;
 
-const { budget } = vi.hoisted(() => ({
-  budget: { createBudgetItem: vi.fn(), updateBudgetItem: vi.fn(), deleteBudgetItem: vi.fn(), linkBudgetItemToReservation: vi.fn() },
-}));
-vi.mock('../../../src/services/budgetService', () => budget);
+// Constructor-injected since the budget fold (was a path mock of the deleted
+// services/budgetService).
+const budget = { createBudgetItem: vi.fn(), updateBudgetItem: vi.fn(), deleteBudgetItem: vi.fn(), linkBudgetItemToReservation: vi.fn() };
 
 const { notif } = vi.hoisted(() => ({ notif: { send: vi.fn().mockResolvedValue(undefined) } }));
 vi.mock('../../../src/services/notificationService', () => notif);
@@ -52,9 +51,10 @@ import { createUser, createTrip, createReservation, createBudgetItem, createPlac
 import { DatabaseService } from '../../../src/nest/database/database.service';
 import type { PermissionsService } from '../../../src/nest/permissions/permissions.service';
 import { ReservationsService } from '../../../src/nest/reservations/reservations.service';
+import type { BudgetService } from '../../../src/nest/budget/budget.service';
 import * as bridge from '../../../src/nest/reservations/reservations.bridge';
 
-const svc = new ReservationsService(new DatabaseService(testDb), permissionsStub);
+const svc = new ReservationsService(new DatabaseService(testDb), permissionsStub, budget as unknown as BudgetService);
 
 beforeAll(() => { createTables(testDb); runMigrations(testDb); });
 beforeEach(() => {

server/tests/unit/nest/trips.service.test.ts

@@ -27,17 +27,18 @@ const { tripSvc } = vi.hoisted(() => ({
 }));
 vi.mock('../../../src/services/tripService', () => tripSvc);
 vi.mock('../../../src/services/placeService', () => ({ listPlaces: () => [] }));
-vi.mock('../../../src/services/budgetService', () => ({
-  listBudgetItems: () => [],
-  rebaseTripCurrency: vi.fn(async () => {}),
-}));
 import { TripsService } from '../../../src/nest/trips/trips.service';
 import type { TodoService } from '../../../src/nest/todo/todo.service';
 import type { PackingService } from '../../../src/nest/packing/packing.service';
 import type { FilesService } from '../../../src/nest/files/files.service';
 import type { ReservationsService } from '../../../src/nest/reservations/reservations.service';
 import type { DaysService } from '../../../src/nest/days/days.service';
-import { rebaseTripCurrency } from '../../../src/services/budgetService';
+import type { BudgetService } from '../../../src/nest/budget/budget.service';
+
+// Constructor-injected since the budget fold (was a path mock of the deleted
+// services/budgetService).
+const rebaseTripCurrency = vi.fn(async () => {});
+const budgetStub = { listBudgetItems: () => [], rebaseTripCurrency } as unknown as BudgetService;
 
 const todoStub = { listItems: () => [] } as unknown as TodoService;
 const packingListItems = vi.fn(() => []);
@@ -45,7 +46,7 @@ const packingStub = { listItems: packingListItems } as unknown as PackingService
 const filesStub = { listFiles: () => [] } as unknown as FilesService;
 const reservationsStub = { list: () => [] } as unknown as ReservationsService;
 const daysStub = { list: () => ({ days: [1] }), listAccommodations: () => [] } as unknown as DaysService;
-function svc() { return new TripsService(new DatabaseService(dbConn), todoStub, packingStub, filesStub, reservationsStub, daysStub, permissionsStub); }
+function svc() { return new TripsService(new DatabaseService(dbConn), todoStub, packingStub, filesStub, reservationsStub, daysStub, permissionsStub, budgetStub); }
 beforeEach(() => vi.clearAllMocks());
 
 describe('TripsService (wrapper delegation + bundle/copy/notify helpers)', () => {

server/tests/unit/plugins/plugin-host-deps.factory.test.ts

@@ -56,6 +56,9 @@ const budgetStub = {
     return id === '404' ? null : { id: Number(id), trip_id: Number(tid), ...input };
   },
   remove(id: string, _tid: string) { return id !== '404'; },
+  // The listCostsForTrip/listCostsForUser closures inject this since the budget
+  // fold (was the legacy listBudgetItems path import).
+  listBudgetItems: vi.fn(() => []),
 } as unknown as BudgetService;
 
 // Edit permission — flip per test to exercise the gates (constructor-injected
@@ -124,16 +127,6 @@ const assignmentsStub = {
   placeExists: vi.fn((placeId: number) => placeId === 7),
   getAssignmentForTrip: vi.fn((id: number) => (id === 99 ? undefined : { id, day_id: 3 })),
 } as unknown as AssignmentsService;
-// The extra named exports satisfy the real reservations.service.ts module (now
-// loaded un-mocked as a factory constructor dep); its instance is stubbed, so
-// these are never called.
-vi.mock('../../../src/services/budgetService', () => ({
-  listBudgetItems: vi.fn(() => []),
-  createBudgetItem: vi.fn(),
-  updateBudgetItem: vi.fn(),
-  deleteBudgetItem: vi.fn(),
-  linkBudgetItemToReservation: vi.fn(),
-}));
 // Packing is a constructor-injected stub (same behaviors as the old path mock).
 const packingStub = {
   listItems: vi.fn((tid: number | string, userId?: number) => [{ id: 1, trip_id: tid, name: 'Socks', _uid: userId }]),