feat: add drawer cash in/out adjustments with balance reconciliation

- New drawer_adjustment table (type: cash_in/cash_out, amount, reason)
- POST/GET /drawer/:id/adjustments endpoints
- Drawer close calculation now includes adjustments: expected = opening + sales + cash_in - cash_out
- DrawerAdjustmentSchema for input validation
- 5 new tests (44 total POS tests passing)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/backend/src/db/migrations/0042_drawer-adjustments.sql

@@ -0,0 +1,14 @@
+DO $$ BEGIN
+  CREATE TYPE "adjustment_type" AS ENUM ('cash_in', 'cash_out');
+EXCEPTION WHEN duplicate_object THEN NULL;
+END $$;
+
+CREATE TABLE IF NOT EXISTS "drawer_adjustment" (
+  "id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+  "drawer_session_id" uuid NOT NULL REFERENCES "drawer_session"("id"),
+  "type" "adjustment_type" NOT NULL,
+  "amount" numeric(10, 2) NOT NULL,
+  "reason" text NOT NULL,
+  "created_by" uuid NOT NULL REFERENCES "user"("id"),
+  "created_at" timestamp with time zone DEFAULT now() NOT NULL
+);

packages/backend/src/db/migrations/meta/_journal.json

@@ -295,6 +295,13 @@
       "when": 1775580000000,
       "tag": "0041_app_settings",
       "breakpoints": true
+    },
+    {
+      "idx": 42,
+      "version": "7",
+      "when": 1775590000000,
+      "tag": "0042_drawer-adjustments",
+      "breakpoints": true
     }
   ]
 }

packages/backend/src/db/schema/pos.ts

@@ -68,6 +68,8 @@ export const discounts = pgTable('discount', {
   updatedAt: timestamp('updated_at', { withTimezone: true }).notNull().defaultNow(),
 })
 
+export const adjustmentTypeEnum = pgEnum('adjustment_type', ['cash_in', 'cash_out'])
+
 export const drawerSessions = pgTable('drawer_session', {
   id: uuid('id').primaryKey().defaultRandom(),
   locationId: uuid('location_id').references(() => locations.id),
@@ -86,6 +88,20 @@ export const drawerSessions = pgTable('drawer_session', {
   closedAt: timestamp('closed_at', { withTimezone: true }),
 })
 
+export const drawerAdjustments = pgTable('drawer_adjustment', {
+  id: uuid('id').primaryKey().defaultRandom(),
+  drawerSessionId: uuid('drawer_session_id')
+    .notNull()
+    .references(() => drawerSessions.id),
+  type: adjustmentTypeEnum('type').notNull(),
+  amount: numeric('amount', { precision: 10, scale: 2 }).notNull(),
+  reason: text('reason').notNull(),
+  createdBy: uuid('created_by')
+    .notNull()
+    .references(() => users.id),
+  createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
+})
+
 export const transactions = pgTable('transaction', {
   id: uuid('id').primaryKey().defaultRandom(),
   locationId: uuid('location_id').references(() => locations.id),

packages/backend/src/routes/v1/drawer.ts

@@ -1,5 +1,5 @@
 import type { FastifyPluginAsync } from 'fastify'
-import { PaginationSchema, DrawerOpenSchema, DrawerCloseSchema } from '@lunarfront/shared/schemas'
+import { PaginationSchema, DrawerOpenSchema, DrawerCloseSchema, DrawerAdjustmentSchema } from '@lunarfront/shared/schemas'
 import { DrawerService } from '../../services/drawer.service.js'
 
 export const drawerRoutes: FastifyPluginAsync = async (app) => {
@@ -35,6 +35,23 @@ export const drawerRoutes: FastifyPluginAsync = async (app) => {
     return reply.send(session)
   })
 
+  app.post('/drawer/:id/adjustments', { preHandler: [app.authenticate, app.requirePermission('pos.edit')] }, async (request, reply) => {
+    const { id } = request.params as { id: string }
+    const parsed = DrawerAdjustmentSchema.safeParse(request.body)
+    if (!parsed.success) {
+      return reply.status(400).send({ error: { message: 'Validation failed', details: parsed.error.flatten(), statusCode: 400 } })
+    }
+    const adjustment = await DrawerService.addAdjustment(app.db, id, parsed.data, request.user.id)
+    request.log.info({ drawerSessionId: id, type: parsed.data.type, amount: parsed.data.amount, userId: request.user.id }, 'Drawer adjustment')
+    return reply.status(201).send(adjustment)
+  })
+
+  app.get('/drawer/:id/adjustments', { preHandler: [app.authenticate, app.requirePermission('pos.view')] }, async (request, reply) => {
+    const { id } = request.params as { id: string }
+    const adjustments = await DrawerService.getAdjustments(app.db, id)
+    return reply.send({ data: adjustments })
+  })
+
   app.get('/drawer/:id', { preHandler: [app.authenticate, app.requirePermission('pos.view')] }, async (request, reply) => {
     const { id } = request.params as { id: string }
     const session = await DrawerService.getById(app.db, id)

packages/backend/src/services/drawer.service.ts

@@ -1,8 +1,8 @@
-import { eq, and, count, sum, type Column } from 'drizzle-orm'
+import { eq, and, count, sum, sql, type Column } from 'drizzle-orm'
 import type { PostgresJsDatabase } from 'drizzle-orm/postgres-js'
-import { drawerSessions, transactions } from '../db/schema/pos.js'
+import { drawerSessions, drawerAdjustments, transactions } from '../db/schema/pos.js'
 import { ConflictError, NotFoundError } from '../lib/errors.js'
-import type { DrawerOpenInput, DrawerCloseInput, PaginationInput } from '@lunarfront/shared/schemas'
+import type { DrawerOpenInput, DrawerCloseInput, DrawerAdjustmentInput, PaginationInput } from '@lunarfront/shared/schemas'
 import { withPagination, withSort, paginatedResponse } from '../utils/pagination.js'
 
 export const DrawerService = {
@@ -47,9 +47,20 @@ export const DrawerService = {
         )
       )
 
-    const cashIn = parseFloat(cashTotals?.total ?? '0') + parseFloat(cashTotals?.rounding ?? '0')
+    // Calculate net drawer adjustments (cash_in adds, cash_out subtracts)
+    const [adjTotals] = await db
+      .select({
+        cashIn: sql<string>`coalesce(sum(case when ${drawerAdjustments.type} = 'cash_in' then ${drawerAdjustments.amount} else 0 end), 0)`,
+        cashOut: sql<string>`coalesce(sum(case when ${drawerAdjustments.type} = 'cash_out' then ${drawerAdjustments.amount} else 0 end), 0)`,
+      })
+      .from(drawerAdjustments)
+      .where(eq(drawerAdjustments.drawerSessionId, sessionId))
+
+    const salesCashIn = parseFloat(cashTotals?.total ?? '0') + parseFloat(cashTotals?.rounding ?? '0')
+    const adjCashIn = parseFloat(adjTotals?.cashIn ?? '0')
+    const adjCashOut = parseFloat(adjTotals?.cashOut ?? '0')
     const openingBalance = parseFloat(session.openingBalance)
-    const expectedBalance = openingBalance + cashIn
+    const expectedBalance = openingBalance + salesCashIn + adjCashIn - adjCashOut
     const closingBalance = input.closingBalance
     const overShort = closingBalance - expectedBalance
 
@@ -93,6 +104,31 @@ export const DrawerService = {
     return session ?? null
   },
 
+  async addAdjustment(db: PostgresJsDatabase<any>, sessionId: string, input: DrawerAdjustmentInput, createdBy: string, approvedBy?: string) {
+    const session = await this.getById(db, sessionId)
+    if (!session) throw new NotFoundError('Drawer session')
+    if (session.status === 'closed') throw new ConflictError('Cannot adjust a closed drawer')
+
+    const [adjustment] = await db
+      .insert(drawerAdjustments)
+      .values({
+        drawerSessionId: sessionId,
+        type: input.type,
+        amount: input.amount.toString(),
+        reason: input.reason,
+        createdBy,
+      })
+      .returning()
+    return adjustment
+  },
+
+  async getAdjustments(db: PostgresJsDatabase<any>, sessionId: string) {
+    return db
+      .select()
+      .from(drawerAdjustments)
+      .where(eq(drawerAdjustments.drawerSessionId, sessionId))
+  },
+
   async list(db: PostgresJsDatabase<any>, params: PaginationInput) {
     const sortableColumns: Record<string, Column> = {
       opened_at: drawerSessions.openedAt,