diff --git a/scripts/migrations/007-contacts.ts b/scripts/migrations/007-contacts.ts
new file mode 100644
index 0000000..1492676
--- /dev/null
+++ b/scripts/migrations/007-contacts.ts
@@ -0,0 +1,15 @@
+import { ContactModel } from "@/models/contact";
+import { TransactionModel } from "@/models/transaction";
+import type { Migration } from "./types";
+
+export const migration: Migration = {
+  name: "007-contacts",
+  description: "contacts index'leri; işlemlerde cari alanları ve cari index'i",
+  async up(db) {
+    await db
+      .collection("transactions")
+      .updateMany({ contactKind: { $exists: false } }, { $set: { contactKind: null } });
+    await ContactModel.createIndexes();
+    await TransactionModel.createIndexes();
+  },
+};
diff --git a/scripts/migrations/index.ts b/scripts/migrations/index.ts
index a4e2f90..5d7850c 100644
--- a/scripts/migrations/index.ts
+++ b/scripts/migrations/index.ts
@@ -6,10 +6,11 @@ import { migration as m003 } from "./003-transactions";
 import { migration as m004 } from "./004-attachments-reconciliation";
 import { migration as m005 } from "./005-recurring";
 import { migration as m006 } from "./006-card-statements";
+import { migration as m007 } from "./007-contacts";
 import type { Migration } from "./types";
 
 /** Sıralı migration listesi. Yeni migration: dosyayı ekle ve buraya sırayla ekle. */
-export const MIGRATIONS: Migration[] = [m001, m002, m003, m004, m005, m006];
+export const MIGRATIONS: Migration[] = [m001, m002, m003, m004, m005, m006, m007];
 
 const COLLECTION = "migrations";
 
diff --git a/src/features/attachments/service.int.test.ts b/src/features/attachments/service.int.test.ts
index 94582f1..d4e7fc4 100644
--- a/src/features/attachments/service.int.test.ts
+++ b/src/features/attachments/service.int.test.ts
@@ -245,7 +245,7 @@ describe("işleme bağlama", () => {
       cakir,
       txId,
       await form({
-        accountId: detail!.account.id,
+        accountId: detail!.account!.id,
         categoryId: detail!.categoryId,
         attachmentIds: [a3.id, a4.id],
       }),
diff --git a/src/features/contacts/actions.ts b/src/features/contacts/actions.ts
new file mode 100644
index 0000000..8be7c3a
--- /dev/null
+++ b/src/features/contacts/actions.ts
@@ -0,0 +1,88 @@
+"use server";
+
+import { revalidatePath } from "next/cache";
+import { z } from "zod";
+import { tr } from "@/i18n/tr";
+import { fail, type ActionResult } from "@/lib/action-result";
+import { getHouseholdActionContext } from "@/lib/dal";
+import { contactEntrySchema, contactFormSchema } from "@/shared/schemas/contact";
+import {
+  createContact,
+  createContactEntry,
+  setContactArchived,
+  updateContact,
+  updateContactEntry,
+} from "./service";
+
+const idSchema = z.string().regex(/^[a-f0-9]{24}$/i);
+
+function fieldErrors(error: z.ZodError) {
+  const out: Record<string, string> = {};
+  for (const issue of error.issues) {
+    const key = issue.path.join(".");
+    if (key && !out[key]) out[key] = issue.message;
+  }
+  return out;
+}
+
+function revalidate() {
+  revalidatePath("/", "layout");
+}
+
+export async function saveContactAction(
+  contactId: unknown,
+  input: unknown,
+): Promise<ActionResult<unknown>> {
+  const ctx = await getHouseholdActionContext("member");
+  if (!ctx) return fail(tr.common.unauthorized);
+  const parsed = contactFormSchema.safeParse(input);
+  if (!parsed.success) return fail(tr.adminUsers.errors.checkFields, fieldErrors(parsed.error));
+  let result: ActionResult<unknown>;
+  if (contactId === null || contactId === undefined) {
+    result = await createContact(ctx.user.id, ctx.household.id, parsed.data);
+  } else {
+    const id = idSchema.safeParse(contactId);
+    if (!id.success) return fail(tr.common.notFound);
+    result = await updateContact(ctx.user.id, ctx.household.id, id.data, parsed.data);
+  }
+  if (result.ok) revalidate();
+  return result;
+}
+
+export async function setContactArchivedAction(
+  contactId: unknown,
+  archived: unknown,
+): Promise<ActionResult> {
+  const ctx = await getHouseholdActionContext("member");
+  if (!ctx) return fail(tr.common.unauthorized);
+  const id = idSchema.safeParse(contactId);
+  const a = z.boolean().safeParse(archived);
+  if (!id.success || !a.success) return fail(tr.common.notFound);
+  const result = await setContactArchived(ctx.user.id, ctx.household.id, id.data, a.data);
+  if (result.ok) revalidate();
+  return result;
+}
+
+/** Yeni hareket (transactionId boş) veya mevcut hareketi düzenle. */
+export async function saveContactEntryAction(
+  contactId: unknown,
+  transactionId: unknown,
+  input: unknown,
+): Promise<ActionResult<unknown>> {
+  const ctx = await getHouseholdActionContext("member");
+  if (!ctx) return fail(tr.common.unauthorized);
+  const parsed = contactEntrySchema.safeParse(input);
+  if (!parsed.success) return fail(tr.adminUsers.errors.checkFields, fieldErrors(parsed.error));
+  let result: ActionResult<unknown>;
+  if (transactionId) {
+    const tid = idSchema.safeParse(transactionId);
+    if (!tid.success) return fail(tr.common.notFound);
+    result = await updateContactEntry(ctx.user.id, ctx.household.id, tid.data, parsed.data);
+  } else {
+    const cid = idSchema.safeParse(contactId);
+    if (!cid.success) return fail(tr.common.notFound);
+    result = await createContactEntry(ctx.user.id, ctx.household.id, cid.data, parsed.data);
+  }
+  if (result.ok) revalidate();
+  return result;
+}
diff --git a/src/features/contacts/service.int.test.ts b/src/features/contacts/service.int.test.ts
new file mode 100644
index 0000000..f8eae1a
--- /dev/null
+++ b/src/features/contacts/service.int.test.ts
@@ -0,0 +1,272 @@
+import { afterAll, beforeAll, describe, expect, it } from "vitest";
+import { listAccounts } from "@/features/accounts/service";
+import {
+  getTransaction,
+  listTransactions,
+  updateTransaction,
+} from "@/features/transactions/service";
+import { currentMonth, getAccountStatement } from "@/features/transactions/statement";
+import { AccountModel } from "@/models/account";
+import { todayIstanbul } from "@/shared/dates";
+import { addDays } from "@/shared/recurrence";
+import {
+  contactEntrySchema,
+  contactFormSchema,
+  type ContactEntryInput,
+  type ContactFormInput,
+} from "@/shared/schemas/contact";
+import { transactionFilterSchema } from "@/shared/schemas/transaction";
+import { setupSeededDb, teardownDb } from "@/test/seeded-db";
+import {
+  countDueContacts,
+  createContact,
+  createContactEntry,
+  getContactStatement,
+  listContacts,
+  setContactArchived,
+  updateContact,
+  updateContactEntry,
+} from "./service";
+
+let ids: Awaited<ReturnType<typeof setupSeededDb>>;
+let cakir = "";
+let ayse = "";
+let emre = "";
+let zeynep = "";
+let fatma = "";
+const today = todayIstanbul();
+
+beforeAll(async () => {
+  ids = await setupSeededDb();
+  cakir = ids.household("Çakır Ailesi");
+  ayse = ids.user("ayse");
+  emre = ids.user("emre");
+  zeynep = ids.user("zeynep");
+  fatma = ids.user("fatma");
+});
+afterAll(teardownDb);
+
+const acc = (name: string) =>
+  AccountModel.findOne({ householdId: cakir, name })
+    .lean()
+    .then((a) => String(a!._id));
+const contactForm = (over: Partial<ContactFormInput> = {}) =>
+  contactFormSchema.parse({ name: "Test Kişi", openingDate: today, ...over });
+const entry = (over: Partial<ContactEntryInput>) =>
+  contactEntrySchema.parse({ kind: "lend", amount: "1000", date: today, ...over });
+
+async function balance(userId: string, accountId: string) {
+  return (await listAccounts(userId, cakir))!.accounts.find((a) => a.id === accountId)!
+    .balanceMinor!;
+}
+async function contactBalance(userId: string, id: string) {
+  return (await listContacts(userId, cakir))!.contacts.find((c) => c.id === id)!.balanceMinor;
+}
+const sums = async () =>
+  (await listTransactions(ayse, cakir, transactionFilterSchema.parse({})))!.sums;
+
+describe("cari defteri", () => {
+  let ahmet = "";
+  let lendId = "";
+
+  it("borç verme ve tahsilat: hesap bakiyeleri değişir, gelir/gider toplamlarına girmez", async () => {
+    const ziraat = await acc("Ziraat Maaş");
+    const cuzdan = await acc("Cüzdan");
+    const [zBefore, cBefore, sBefore] = [
+      await balance(ayse, ziraat),
+      await balance(ayse, cuzdan),
+      await sums(),
+    ];
+    const c = await createContact(
+      ayse,
+      cakir,
+      contactForm({ name: "Kemal Test", relation: "friend" }),
+    );
+    expect(c.ok).toBe(true);
+    ahmet = c.ok ? c.data.id : "";
+
+    const l = await createContactEntry(
+      ayse,
+      cakir,
+      ahmet,
+      entry({ accountId: ziraat, amount: "5.000" }),
+    );
+    expect(l.ok).toBe(true);
+    lendId = l.ok ? l.data.id : "";
+    await createContactEntry(
+      emre,
+      cakir,
+      ahmet,
+      entry({ kind: "collect", accountId: cuzdan, amount: "2.000" }),
+    );
+
+    expect(await balance(ayse, ziraat)).toBe(zBefore - 5_000_00);
+    expect(await balance(ayse, cuzdan)).toBe(cBefore + 2_000_00);
+    expect(await contactBalance(ayse, ahmet)).toBe(3_000_00);
+    expect(await sums()).toEqual(sBefore);
+
+    const detail = (await getTransaction(ayse, cakir, lendId))!;
+    expect(detail).toMatchObject({
+      type: "transfer",
+      contact: { kind: "lend", name: "Kemal Test" },
+    });
+    expect(detail.toAccount).toBeNull();
+  });
+
+  it("borç alma ve geri ödeme; açılış bakiyesi; ekstre yürüyen bakiye", async () => {
+    const ziraat = await acc("Ziraat Maaş");
+    const c = await createContact(
+      ayse,
+      cakir,
+      contactForm({ name: "Hasan Amca", relation: "family", openingBalance: "-1.000" }),
+    );
+    const hasan = c.ok ? c.data.id : "";
+    await createContactEntry(
+      ayse,
+      cakir,
+      hasan,
+      entry({ kind: "borrow", accountId: ziraat, amount: "10.000" }),
+    );
+    await createContactEntry(
+      ayse,
+      cakir,
+      hasan,
+      entry({ kind: "repay", accountId: ziraat, amount: "4.000" }),
+    );
+    expect(await contactBalance(ayse, hasan)).toBe(-7_000_00);
+
+    const s = (await getContactStatement(ayse, cakir, hasan))!;
+    expect(s.rows).toHaveLength(2);
+    expect(s.rows[0]!.balanceMinor).toBe(-7_000_00);
+    expect(s.rows[1]!.balanceMinor).toBe(-11_000_00);
+    expect(s.contact.balanceMinor).toBe(-7_000_00);
+
+    const list = (await listContacts(ayse, cakir))!;
+    expect(list.totals.iOweMinor).toBeGreaterThanOrEqual(7_000_00);
+    expect(list.totals.owesMeMinor).toBeGreaterThanOrEqual(3_000_00);
+  });
+
+  it("hareket düzenleme: tür değişince yön ve bakiyeler değişir; işlem formuyla düzenlenemez", async () => {
+    const ziraat = await acc("Ziraat Maaş");
+    const before = await balance(ayse, ziraat);
+    const u = await updateContactEntry(
+      ayse,
+      cakir,
+      lendId,
+      entry({ kind: "borrow", accountId: ziraat, amount: "5.000" }),
+    );
+    expect(u.ok).toBe(true);
+    expect(await balance(ayse, ziraat)).toBe(before + 10_000_00);
+    expect(await contactBalance(ayse, ahmet)).toBe(-7_000_00);
+    const d = (await getTransaction(ayse, cakir, lendId))!;
+    expect(d.account).toBeNull();
+    expect(d.toAccount?.id).toBe(ziraat);
+
+    const viaForm = await updateTransaction(ayse, cakir, lendId, {
+      type: "transfer",
+      amount: 1,
+      date: today,
+      accountId: ziraat,
+      toAccountId: await acc("Cüzdan"),
+      categoryId: null,
+      splits: [],
+      payee: "",
+      description: "",
+      tags: [],
+      installments: 1,
+      attachmentIds: [],
+    });
+    expect(viaForm.ok).toBe(false);
+  });
+
+  it("vade uyarısı: yaklaşan, geçmiş, kapalı bakiye", async () => {
+    const c = await createContact(
+      ayse,
+      cakir,
+      contactForm({
+        name: "Vade Kişi",
+        openingBalance: "500",
+        dueDate: addDays(today, 2),
+        reminderDays: 3,
+      }),
+    );
+    const id = c.ok ? c.data.id : "";
+    const before = await countDueContacts(ayse, cakir);
+    let v = (await listContacts(ayse, cakir))!.contacts.find((x) => x.id === id)!;
+    expect(v.due).toBe("upcoming");
+    await updateContact(
+      ayse,
+      cakir,
+      id,
+      contactForm({ name: "Vade Kişi", openingBalance: "500", dueDate: addDays(today, -1) }),
+    );
+    v = (await listContacts(ayse, cakir))!.contacts.find((x) => x.id === id)!;
+    expect(v.due).toBe("overdue");
+    await updateContact(
+      ayse,
+      cakir,
+      id,
+      contactForm({ name: "Vade Kişi", openingBalance: "0", dueDate: addDays(today, -1) }),
+    );
+    v = (await listContacts(ayse, cakir))!.contacts.find((x) => x.id === id)!;
+    expect(v.due).toBe("none");
+    expect(await countDueContacts(ayse, cakir)).toBe(before - 1);
+  });
+
+  it("aynı ad engellenir; arşivli cariye hareket eklenmez", async () => {
+    expect((await createContact(ayse, cakir, contactForm({ name: "kemal TEST" }))).ok).toBe(
+      false,
+    );
+    expect((await setContactArchived(ayse, cakir, ahmet, true)).ok).toBe(true);
+    expect(
+      (await createContactEntry(ayse, cakir, ahmet, entry({ accountId: await acc("Cüzdan") }))).ok,
+    ).toBe(false);
+    expect((await setContactArchived(ayse, cakir, ahmet, false)).ok).toBe(true);
+  });
+});
+
+describe("yetki ve gizlilik", () => {
+  it("izleyici yazamaz; hane dışı göremez; başka hanenin hesabı kullanılamaz", async () => {
+    expect((await createContact(zeynep, cakir, contactForm({ name: "X" }))).ok).toBe(false);
+    expect(await listContacts(fatma, cakir)).toBeNull();
+    const c = await createContact(ayse, cakir, contactForm({ name: "Hesap Testi" }));
+    const id = c.ok ? c.data.id : "";
+    const otherHousehold = String(
+      (await AccountModel.findOne({ name: "Vakıfbank Emekli" }).lean())!._id,
+    );
+    expect(
+      (await createContactEntry(ayse, cakir, id, entry({ accountId: otherHousehold }))).ok,
+    ).toBe(false);
+  });
+
+  it("yalnızca ben cari: başkası listede, ekstrede ve işlemlerde görmez; hesap ekstresinde ad gizlenir", async () => {
+    const ziraat = await acc("Ziraat Maaş");
+    const c = await createContact(
+      ayse,
+      cakir,
+      contactForm({ name: "Gizli Kişi", isPrivate: true }),
+    );
+    const id = c.ok ? c.data.id : "";
+    const e = await createContactEntry(
+      ayse,
+      cakir,
+      id,
+      entry({ accountId: ziraat, amount: "750" }),
+    );
+    const txId = e.ok ? e.data.id : "";
+
+    expect((await listContacts(emre, cakir))!.contacts.some((x) => x.id === id)).toBe(false);
+    expect(await getContactStatement(emre, cakir, id)).toBeNull();
+    expect(await getTransaction(emre, cakir, txId)).toBeNull();
+    expect((await createContactEntry(emre, cakir, id, entry({ accountId: ziraat }))).ok).toBe(
+      false,
+    );
+
+    const st = (await getAccountStatement(emre, cakir, ziraat, currentMonth()))!;
+    const row = st.rows.find((r) => r.item.id === txId)!;
+    expect(row.restricted).toBe(true);
+    expect(row.item.contact!.name).not.toBe("Gizli Kişi");
+    // Ortak hesabın bakiyesi herkes için aynı.
+    expect(await balance(emre, ziraat)).toBe(await balance(ayse, ziraat));
+  });
+});
diff --git a/src/features/contacts/service.ts b/src/features/contacts/service.ts
new file mode 100644
index 0000000..1ea817f
--- /dev/null
+++ b/src/features/contacts/service.ts
@@ -0,0 +1,441 @@
+import "server-only";
+import { Types, type PipelineStage } from "mongoose";
+import {
+  loadContext,
+  loadOwnTransaction,
+  toItem,
+  userNames,
+  type Ctx,
+  type LeanTx,
+  type TransactionListItem,
+} from "@/features/transactions/service";
+import { hasHouseholdRole } from "@/features/households/roles";
+import { tr } from "@/i18n/tr";
+import { fail, ok, type ActionResult } from "@/lib/action-result";
+import { writeAudit } from "@/lib/audit";
+import { toObjectId } from "@/lib/object-id";
+import { ContactModel } from "@/models/contact";
+import { TransactionModel } from "@/models/transaction";
+import {
+  contactDelta,
+  dueState,
+  isOutgoing,
+  type ContactRelation,
+  type DueState,
+} from "@/shared/contacts";
+import { istanbulDayStart, todayIstanbul, toIstanbulYmd } from "@/shared/dates";
+import { addDays } from "@/shared/recurrence";
+import type { ContactEntry, ContactForm } from "@/shared/schemas/contact";
+import { compareTr, foldTr } from "@/shared/search";
+
+/**
+ * Cari hesaplar (Bölüm 6.4). Okuma: viewer; yazma: member. Hareketler `transactions` içinde
+ * transferdir (`contactId`, `contactKind`): cariye çıkışta `accountId` dolu/`toAccountId` boş,
+ * cariden girişte tersi. Böylece hesap bakiyesi, ekstre ve mutabakat ek kural gerektirmez;
+ * gelir/gider raporlarına girmez.
+ */
+
+const t = tr.contacts;
+
+type ContactDoc = {
+  _id: Types.ObjectId;
+  householdId: Types.ObjectId;
+  name: string;
+  relation: ContactRelation;
+  phone: string;
+  note: string;
+  openingBalanceMinor: number;
+  openingDate: Date;
+  dueDate?: string | null;
+  reminderDays: number;
+  isPrivate: boolean;
+  ownerUserId?: Types.ObjectId | null;
+  archivedAt?: Date | null;
+  updatedAt: Date;
+};
+
+const visible = (c: ContactDoc, userId: string) => !c.isPrivate || String(c.ownerUserId) === userId;
+
+/** Cari bazında hareket toplamı (+ çıkış, − giriş) ve son hareket tarihi. */
+async function contactTotals(householdId: Types.ObjectId, contactIds?: Types.ObjectId[]) {
+  const pipeline: PipelineStage[] = [
+    {
+      $match: {
+        householdId,
+        status: "posted",
+        deletedAt: null,
+        contactId: contactIds ? { $in: contactIds } : { $type: "objectId" },
+      },
+    },
+    {
+      $group: {
+        _id: "$contactId",
+        delta: {
+          $sum: {
+            $cond: [
+              { $in: ["$contactKind", ["lend", "repay"]] },
+              "$amountMinor",
+              { $multiply: ["$amountMinor", -1] },
+            ],
+          },
+        },
+        last: { $max: "$date" },
+      },
+    },
+  ];
+  const rows = await TransactionModel.aggregate<{ _id: Types.ObjectId; delta: number; last: Date }>(
+    pipeline,
+  );
+  return new Map(rows.map((r) => [String(r._id), r]));
+}
+
+export type ContactView = {
+  id: string;
+  name: string;
+  relation: ContactRelation;
+  phone: string;
+  note: string;
+  /** + bana borçlu, − ben borçluyum. */
+  balanceMinor: number;
+  openingBalanceMinor: number;
+  openingDate: string;
+  dueDate: string | null;
+  reminderDays: number;
+  due: DueState;
+  isPrivate: boolean;
+  archived: boolean;
+  lastActivity: string | null;
+};
+
+function toView(
+  c: ContactDoc,
+  totals: Map<string, { delta: number; last: Date }>,
+  today: string,
+): ContactView {
+  const x = totals.get(String(c._id));
+  const balanceMinor = c.openingBalanceMinor + (x?.delta ?? 0);
+  return {
+    id: String(c._id),
+    name: c.name,
+    relation: c.relation,
+    phone: c.phone,
+    note: c.note,
+    balanceMinor,
+    openingBalanceMinor: c.openingBalanceMinor,
+    openingDate: toIstanbulYmd(c.openingDate),
+    dueDate: c.dueDate ?? null,
+    reminderDays: c.reminderDays,
+    due: dueState(balanceMinor, c.dueDate ?? null, c.reminderDays, today, addDays),
+    isPrivate: c.isPrivate,
+    archived: Boolean(c.archivedAt),
+    lastActivity: x?.last ? toIstanbulYmd(x.last) : null,
+  };
+}
+
+export type ContactList = {
+  contacts: ContactView[];
+  totals: { owesMeMinor: number; iOweMinor: number };
+};
+
+export async function listContacts(
+  userId: string,
+  householdId: string,
+): Promise<ContactList | null> {
+  const ctx = await loadContext(userId, householdId, "viewer");
+  if (!ctx) return null;
+  const docs = (await ContactModel.find({ householdId: ctx.m.householdId }).lean<ContactDoc[]>())
+    .filter((c) => visible(c, userId))
+    .sort((a, b) => compareTr(a.name, b.name));
+  const totals = await contactTotals(
+    ctx.m.householdId,
+    docs.map((d) => d._id),
+  );
+  const today = todayIstanbul();
+  const contacts = docs.map((c) => toView(c, totals, today));
+  let owesMeMinor = 0;
+  let iOweMinor = 0;
+  for (const c of contacts) {
+    if (c.archived) continue;
+    if (c.balanceMinor > 0) owesMeMinor += c.balanceMinor;
+    else iOweMinor += -c.balanceMinor;
+  }
+  return { contacts, totals: { owesMeMinor, iOweMinor } };
+}
+
+async function loadContact(ctx: Ctx, contactId: string, userId: string) {
+  const id = toObjectId(contactId);
+  if (!id) return null;
+  const c = await ContactModel.findOne({
+    _id: id,
+    householdId: ctx.m.householdId,
+  }).lean<ContactDoc>();
+  return c && visible(c, userId) ? c : null;
+}
+
+async function nameTaken(householdId: Types.ObjectId, name: string, exceptId?: Types.ObjectId) {
+  const key = foldTr(name);
+  const others = await ContactModel.find(
+    { householdId, archivedAt: null, ...(exceptId ? { _id: { $ne: exceptId } } : {}) },
+    { name: 1 },
+  ).lean();
+  return others.some((o) => foldTr(o.name) === key);
+}
+
+// --- Cari yazma ---
+
+export async function createContact(
+  actorId: string,
+  householdId: string,
+  input: ContactForm,
+): Promise<ActionResult<{ id: string }>> {
+  const ctx = await loadContext(actorId, householdId, "member");
+  if (!ctx) return fail(tr.common.unauthorized);
+  if (await nameTaken(ctx.m.householdId, input.name))
+    return fail(t.errors.duplicate, { name: t.errors.duplicate });
+  const actor = new Types.ObjectId(actorId);
+  const doc = await ContactModel.create({
+    householdId: ctx.m.householdId,
+    name: input.name,
+    relation: input.relation,
+    phone: input.phone,
+    note: input.note,
+    openingBalanceMinor: input.openingBalance,
+    openingDate: istanbulDayStart(input.openingDate)!,
+    dueDate: input.dueDate,
+    reminderDays: input.reminderDays,
+    isPrivate: input.isPrivate,
+    ownerUserId: input.isPrivate ? actor : null,
+    createdBy: actor,
+    updatedBy: actor,
+  });
+  return ok({ id: String(doc._id) });
+}
+
+export async function updateContact(
+  actorId: string,
+  householdId: string,
+  contactId: string,
+  input: ContactForm,
+): Promise<ActionResult> {
+  const ctx = await loadContext(actorId, householdId, "member");
+  if (!ctx) return fail(tr.common.unauthorized);
+  const c = await loadContact(ctx, contactId, actorId);
+  if (!c) return fail(tr.common.notFound);
+  if (await nameTaken(ctx.m.householdId, input.name, c._id))
+    return fail(t.errors.duplicate, { name: t.errors.duplicate });
+  // Gizlilik yalnızca sahibince (veya ortak cariyi gizlerken işlemi yapanca) belirlenir.
+  const owner = c.ownerUserId ?? (input.isPrivate ? new Types.ObjectId(actorId) : null);
+  await ContactModel.updateOne(
+    { _id: c._id, householdId: ctx.m.householdId },
+    {
+      $set: {
+        name: input.name,
+        relation: input.relation,
+        phone: input.phone,
+        note: input.note,
+        openingBalanceMinor: input.openingBalance,
+        openingDate: istanbulDayStart(input.openingDate)!,
+        dueDate: input.dueDate,
+        reminderDays: input.reminderDays,
+        isPrivate: input.isPrivate,
+        ownerUserId: input.isPrivate ? owner : null,
+        updatedBy: new Types.ObjectId(actorId),
+      },
+    },
+  );
+  return ok(undefined);
+}
+
+export async function setContactArchived(
+  actorId: string,
+  householdId: string,
+  contactId: string,
+  archived: boolean,
+): Promise<ActionResult> {
+  const ctx = await loadContext(actorId, householdId, "member");
+  if (!ctx) return fail(tr.common.unauthorized);
+  const c = await loadContact(ctx, contactId, actorId);
+  if (!c) return fail(tr.common.notFound);
+  if (!archived && (await nameTaken(ctx.m.householdId, c.name, c._id)))
+    return fail(t.errors.duplicate);
+  await ContactModel.updateOne(
+    { _id: c._id, householdId: ctx.m.householdId },
+    { $set: { archivedAt: archived ? new Date() : null, updatedBy: new Types.ObjectId(actorId) } },
+  );
+  await writeAudit({
+    action: archived ? "contact.archive" : "contact.unarchive",
+    actorId: new Types.ObjectId(actorId),
+    householdId: ctx.m.householdId,
+    targetType: "contact",
+    targetId: String(c._id),
+    diff: { name: c.name },
+  });
+  return ok(undefined);
+}
+
+// --- Cari hareketleri ---
+
+function entryFields(ctx: Ctx, contact: ContactDoc, input: ContactEntry, keepAccount?: string) {
+  const info = ctx.accountMap.get(input.accountId);
+  if (!info || info.hidden || (info.archived && input.accountId !== keepAccount)) {
+    return fail(tr.transactions.validation.accountInvalid, {
+      accountId: tr.transactions.validation.accountInvalid,
+    });
+  }
+  const date = istanbulDayStart(input.date);
+  if (!date) return fail(tr.validation.date, { date: tr.validation.date });
+  const out = isOutgoing(input.kind);
+  return ok({
+    type: "transfer" as const,
+    date,
+    accountId: out ? info.id : null,
+    toAccountId: out ? null : info.id,
+    contactId: contact._id,
+    contactKind: input.kind,
+    amountMinor: input.amount,
+    categoryId: null,
+    splits: [],
+    effectiveCategoryIds: [],
+    payeeName: "",
+    description: input.description,
+    searchText: foldTr(`${contact.name} ${input.description}`),
+  });
+}
+
+async function applyDue(contact: ContactDoc, input: ContactEntry, actor: Types.ObjectId) {
+  if (input.dueDate === undefined) return;
+  await ContactModel.updateOne(
+    { _id: contact._id },
+    {
+      $set: {
+        dueDate: input.dueDate,
+        ...(input.reminderDays !== undefined ? { reminderDays: input.reminderDays } : {}),
+        updatedBy: actor,
+      },
+    },
+  );
+}
+
+export async function createContactEntry(
+  actorId: string,
+  householdId: string,
+  contactId: string,
+  input: ContactEntry,
+): Promise<ActionResult<{ id: string }>> {
+  const ctx = await loadContext(actorId, householdId, "member");
+  if (!ctx) return fail(tr.common.unauthorized);
+  const contact = await loadContact(ctx, contactId, actorId);
+  if (!contact) return fail(tr.common.notFound);
+  if (contact.archivedAt) return fail(t.errors.archived);
+  const fields = entryFields(ctx, contact, input);
+  if (!fields.ok) return fields;
+  const actor = new Types.ObjectId(actorId);
+  const doc = await TransactionModel.create({
+    ...fields.data,
+    householdId: ctx.m.householdId,
+    status: "posted",
+    createdBy: actor,
+    updatedBy: actor,
+  });
+  await applyDue(contact, input, actor);
+  return ok({ id: String(doc._id) });
+}
+
+export async function updateContactEntry(
+  actorId: string,
+  householdId: string,
+  transactionId: string,
+  input: ContactEntry,
+): Promise<ActionResult> {
+  const ctx = await loadContext(actorId, householdId, "member");
+  if (!ctx) return fail(tr.common.unauthorized);
+  const tx = await loadOwnTransaction(ctx, transactionId);
+  if (!tx?.contactId) return fail(tr.common.notFound);
+  const contact = await loadContact(ctx, String(tx.contactId), actorId);
+  if (!contact) return fail(tr.common.notFound);
+  const keep = String(tx.accountId ?? tx.toAccountId ?? "");
+  const fields = entryFields(ctx, contact, input, keep);
+  if (!fields.ok) return fields;
+  const d = fields.data;
+  const balanceChanged =
+    d.amountMinor !== tx.amountMinor ||
+    d.date.getTime() !== new Date(tx.date).getTime() ||
+    String(d.accountId ?? "") !== String(tx.accountId ?? "") ||
+    String(d.toAccountId ?? "") !== String(tx.toAccountId ?? "");
+  const actor = new Types.ObjectId(actorId);
+  await TransactionModel.updateOne(
+    { _id: tx._id, householdId: ctx.m.householdId },
+    {
+      $set: {
+        ...d,
+        updatedBy: actor,
+        ...(balanceChanged ? { reconciledAccountIds: [] } : {}),
+      },
+    },
+  );
+  await applyDue(contact, input, actor);
+  return ok(undefined);
+}
+
+// --- Ekstre ---
+
+export type ContactStatementRow = {
+  item: TransactionListItem;
+  deltaMinor: number;
+  balanceMinor: number;
+};
+
+export type ContactStatement = {
+  contact: ContactView;
+  /** Yeniden eskiye. */
+  rows: ContactStatementRow[];
+  canWrite: boolean;
+};
+
+export async function getContactStatement(
+  userId: string,
+  householdId: string,
+  contactId: string,
+): Promise<ContactStatement | null> {
+  const ctx = await loadContext(userId, householdId, "viewer");
+  if (!ctx) return null;
+  const contact = await loadContact(ctx, contactId, userId);
+  if (!contact) return null;
+  const txs = (await TransactionModel.find({
+    householdId: ctx.m.householdId,
+    contactId: contact._id,
+    status: "posted",
+    deletedAt: null,
+  })
+    .sort({ date: 1, createdAt: 1 })
+    .limit(5000)
+    .lean()) as unknown as LeanTx[];
+  const names = await userNames(txs.map((x) => x.createdBy as Types.ObjectId));
+  let balance = contact.openingBalanceMinor;
+  const rows = txs.map((x): ContactStatementRow => {
+    const deltaMinor = contactDelta(x.contactKind!, x.amountMinor);
+    balance += deltaMinor;
+    const item = toItem(ctx, x, names);
+    // Başkasının gizli hesabıyla yapılan hareket: hesap adı gizlenir.
+    for (const a of [item.account, item.toAccount])
+      if (a && ctx.accountMap.get(a.id)?.hidden) a.name = tr.transactions.list.hiddenAccount;
+    return { item, deltaMinor, balanceMinor: balance };
+  });
+  const totals = new Map([
+    [
+      String(contact._id),
+      { delta: balance - contact.openingBalanceMinor, last: txs.at(-1)?.date ?? null },
+    ],
+  ]) as Map<string, { delta: number; last: Date }>;
+  return {
+    contact: toView(contact, totals, todayIstanbul()),
+    rows: rows.reverse(),
+    canWrite: hasHouseholdRole(ctx.m.role, "member"),
+  };
+}
+
+/** Dashboard: vadesi geçmiş veya yaklaşan (hatırlatma penceresindeki) cari sayısı. */
+export async function countDueContacts(userId: string, householdId: string): Promise<number> {
+  const list = await listContacts(userId, householdId);
+  return list?.contacts.filter((c) => !c.archived && c.due !== "none").length ?? 0;
+}
diff --git a/src/features/recurring/service.int.test.ts b/src/features/recurring/service.int.test.ts
index f912a0d..14af846 100644
--- a/src/features/recurring/service.int.test.ts
+++ b/src/features/recurring/service.int.test.ts
@@ -196,7 +196,7 @@ describe("kural ve planlı kayıtlar", () => {
       type: "expense",
       amount: 777_00,
       date: d.date,
-      accountId: d.account.id,
+      accountId: d.account!.id,
       toAccountId: null,
       categoryId: d.categoryId,
       splits: [],
diff --git a/src/features/recurring/service.ts b/src/features/recurring/service.ts
index a83101b..39aea8e 100644
--- a/src/features/recurring/service.ts
+++ b/src/features/recurring/service.ts
@@ -376,7 +376,8 @@ export async function confirmOccurrence(
     ctx.m.householdId,
     tx.payeeName ?? "",
     tx.type,
-    tx.accountId,
+    // Planlı kayıtlar cari hareketi değildir; kaynak hesap her zaman dolu.
+    tx.accountId!,
     tx.categoryId ?? null,
   );
   await TransactionModel.updateOne(
diff --git a/src/features/transactions/service.int.test.ts b/src/features/transactions/service.int.test.ts
index d273661..6f5947e 100644
--- a/src/features/transactions/service.int.test.ts
+++ b/src/features/transactions/service.int.test.ts
@@ -383,7 +383,7 @@ describe("filtreler", () => {
     );
     expect(byAccount!.total).toBeGreaterThan(0);
     expect(
-      byAccount!.items.every((i) => i.toAccount?.id === cuzdan || i.account.id === cuzdan),
+      byAccount!.items.every((i) => i.toAccount?.id === cuzdan || i.account!.id === cuzdan),
     ).toBe(true);
   });
 
diff --git a/src/features/transactions/service.ts b/src/features/transactions/service.ts
index 6d8db53..50e4999 100644
--- a/src/features/transactions/service.ts
+++ b/src/features/transactions/service.ts
@@ -13,10 +13,12 @@ import { writeAudit } from "@/lib/audit";
 import { getDb } from "@/lib/db/mongo";
 import { toObjectId } from "@/lib/object-id";
 import { AccountModel } from "@/models/account";
+import { ContactModel } from "@/models/contact";
 import { CategoryModel } from "@/models/category";
 import { PayeeModel } from "@/models/payee";
 import { TransactionModel } from "@/models/transaction";
 import type { AccountType } from "@/shared/accounts";
+import type { ContactEntryKind } from "@/shared/contacts";
 import { allowedAttachmentKinds } from "@/shared/attachments";
 import type { IconKey, Swatch } from "@/shared/appearance";
 import { installmentSchedule } from "@/shared/card-periods";
@@ -68,7 +70,7 @@ export async function loadContext(
   const m = await resolveMembership(userId, householdId, minRole);
   if (!m) return null;
   await postDueInstallments(m.householdId);
-  const [accounts, categories] = await Promise.all([
+  const [accounts, categories, contacts] = await Promise.all([
     AccountModel.find({ householdId: m.householdId })
       .select({ name: 1, type: 1, archivedAt: 1, isPrivate: 1, ownerUserId: 1, icon: 1, color: 1 })
       .lean(),
@@ -84,6 +86,9 @@ export async function loadContext(
         ancestors: 1,
       })
       .lean(),
+    ContactModel.find({ householdId: m.householdId })
+      .select({ name: 1, isPrivate: 1, ownerUserId: 1, archivedAt: 1 })
+      .lean(),
   ]);
   const accountMap = new Map<string, AccountInfo>(
     accounts.map((a) => [
@@ -126,18 +131,39 @@ export async function loadContext(
     ]),
   );
   const hiddenAccountIds = [...accountMap.values()].filter((a) => a.hidden).map((a) => a.id);
-  return { m, accountMap, categoryMap, hiddenAccountIds, flatCategories: flat };
+  const contactMap = new Map(
+    contacts.map((c) => [
+      String(c._id),
+      {
+        id: c._id,
+        name: c.name,
+        archived: Boolean(c.archivedAt),
+        hidden: Boolean(c.isPrivate) && String(c.ownerUserId) !== userId,
+      },
+    ]),
+  );
+  const hiddenContactIds = [...contactMap.values()].filter((c) => c.hidden).map((c) => c.id);
+  return {
+    m,
+    accountMap,
+    categoryMap,
+    contactMap,
+    hiddenAccountIds,
+    hiddenContactIds,
+    flatCategories: flat,
+  };
 }
 
 export type Ctx = NonNullable<Awaited<ReturnType<typeof loadContext>>>;
 
-/** Gizli hesaplara dokunan işlemleri dışlayan temel filtre. */
+/** Gizli hesaplara veya gizli carilere dokunan işlemleri dışlayan temel filtre. */
 export function baseFilter(ctx: Ctx): Record<string, unknown> {
   const f: Record<string, unknown> = { householdId: ctx.m.householdId, deletedAt: null };
   if (ctx.hiddenAccountIds.length) {
     f.accountId = { $nin: ctx.hiddenAccountIds };
     f.toAccountId = { $nin: ctx.hiddenAccountIds };
   }
+  if (ctx.hiddenContactIds.length) f.contactId = { $nin: ctx.hiddenContactIds };
   return f;
 }
 
@@ -221,7 +247,7 @@ function checkCategory(
 }
 
 type Existing = {
-  accountId: Types.ObjectId;
+  accountId?: Types.ObjectId | null;
   toAccountId?: Types.ObjectId | null;
   categoryId?: Types.ObjectId | null;
   splits?: { categoryId: Types.ObjectId }[];
@@ -238,7 +264,7 @@ export function buildDoc(
   const accountId = checkAccount(
     ctx,
     input.accountId,
-    existing ? String(existing.accountId) : null,
+    existing?.accountId ? String(existing.accountId) : null,
   );
   if (!accountId)
     return fail(t.validation.accountInvalid, { accountId: t.validation.accountInvalid });
@@ -445,6 +471,8 @@ export async function updateTransaction(
   const current = await loadOwnTransaction(ctx, transactionId);
   if (!current) return fail(tr.common.notFound);
   if (current.isAdjustment) return fail(t.adjustmentReadOnly);
+  // Cari hareketi cari sayfasındaki formla düzenlenir (tür ve yön cariye özgü).
+  if (current.contactId) return fail(t.contactEditHint);
   const built = buildDoc(ctx, input, current);
   if (!built.ok) return built;
   const d = built.data as {
@@ -467,7 +495,7 @@ export async function updateTransaction(
     d.type !== current.type ||
     d.amountMinor !== current.amountMinor ||
     d.date.getTime() !== new Date(current.date).getTime() ||
-    !d.accountId.equals(current.accountId) ||
+    String(d.accountId) !== String(current.accountId ?? "") ||
     String(d.toAccountId ?? "") !== String(current.toAccountId ?? "");
   try {
     await mongoose.connection.transaction(async (session) => {
@@ -567,8 +595,11 @@ export type TransactionListItem = {
   status: TransactionStatus;
   date: string;
   amountMinor: number;
-  account: { id: string; name: string };
+  /** Kaynak hesap; cariden girişte (borç alma, tahsilat) null. */
+  account: { id: string; name: string } | null;
   toAccount: { id: string; name: string } | null;
+  /** Cari transferi: kişi ve hareket türü. */
+  contact: { id: string; name: string; kind: ContactEntryKind } | null;
   category: { id: string; name: string; path: string; icon: IconKey; color: Swatch } | null;
   splitCount: number;
   payeeName: string;
@@ -629,7 +660,7 @@ export function toItem(ctx: Ctx, tx: LeanTx, names: Map<string, string>): Transa
     status: tx.status,
     date: toIstanbulYmd(tx.date),
     amountMinor: tx.amountMinor,
-    account: acc(tx.accountId)!,
+    account: acc(tx.accountId),
     toAccount: acc(tx.toAccountId),
     category: cat
       ? { id: String(cat.id), name: cat.name, path: cat.path, icon: cat.icon, color: cat.color }
@@ -642,6 +673,14 @@ export function toItem(ctx: Ctx, tx: LeanTx, names: Map<string, string>): Transa
     attachmentCount: tx.attachmentCount ?? 0,
     isAdjustment: Boolean(tx.isAdjustment),
     reconciledAccountIds: (tx.reconciledAccountIds ?? []).map(String),
+    contact:
+      tx.contactId && tx.contactKind
+        ? {
+            id: String(tx.contactId),
+            name: ctx.contactMap.get(String(tx.contactId))?.name ?? "—",
+            kind: tx.contactKind,
+          }
+        : null,
     installment: tx.installment?.planId
       ? {
           planId: String(tx.installment.planId),
@@ -836,7 +875,11 @@ export async function exportTransactions(
     } else {
       out.push({
         ...common,
-        category: r.isAdjustment ? t.adjustment : categoryPath(r.categoryId),
+        category: r.isAdjustment
+          ? t.adjustment
+          : r.contactId && r.contactKind
+            ? `${tr.contacts.contact}: ${ctx.contactMap.get(String(r.contactId))?.name ?? ""} (${tr.contacts.kinds[r.contactKind]})`
+            : categoryPath(r.categoryId),
         note: "",
         amountMinor: sign(r.type) * r.amountMinor,
       });
diff --git a/src/features/transactions/statement.ts b/src/features/transactions/statement.ts
index c77f193..950ddca 100644
--- a/src/features/transactions/statement.ts
+++ b/src/features/transactions/statement.ts
@@ -201,7 +201,10 @@ export async function getAccountStatement(
   const effects = rowsAsc.map((tx) => {
     const item = toItem(ctx, tx, names);
     const counterpart = tx.type === "transfer" ? [item.account, item.toAccount] : [];
-    const restricted = counterpart.some((a) => a && ctx.accountMap.get(a.id)?.hidden);
+    const hiddenContact = Boolean(item.contact && ctx.contactMap.get(item.contact.id)?.hidden);
+    if (hiddenContact && item.contact) item.contact.name = tr.transactions.list.hiddenContact;
+    const restricted =
+      hiddenContact || counterpart.some((a) => a && ctx.accountMap.get(a.id)?.hidden);
     if (restricted) {
       // Gizli karşı hesabın adı sızmasın.
       for (const a of counterpart) {
diff --git a/src/models/audit-log.ts b/src/models/audit-log.ts
index d333a01..fae2046 100644
--- a/src/models/audit-log.ts
+++ b/src/models/audit-log.ts
@@ -28,6 +28,8 @@ export const AUDIT_ACTIONS = [
   "transaction.delete",
   "transaction.restore",
   "recurring.delete",
+  "contact.archive",
+  "contact.unarchive",
 ] as const;
 export type AuditAction = (typeof AUDIT_ACTIONS)[number];
 
diff --git a/src/models/contact.ts b/src/models/contact.ts
new file mode 100644
index 0000000..a07fa7d
--- /dev/null
+++ b/src/models/contact.ts
@@ -0,0 +1,41 @@
+import { model, models, Schema, type InferSchemaType, type Model } from "mongoose";
+import { CONTACT_RELATIONS } from "@/shared/contacts";
+
+/**
+ * Cari kişi (Bölüm 6.4). Hareketler `transactions` içinde transfer olarak tutulur (`contactId`);
+ * bakiye: açılış + çıkışlar − girişler (+ bana borçlu, − ben borçluyum).
+ * "Yalnızca ben" işaretli cari ve hareketleri yalnızca sahibine görünür.
+ */
+const contactSchema = new Schema(
+  {
+    householdId: { type: Schema.Types.ObjectId, required: true },
+    name: { type: String, required: true, trim: true, maxlength: 80 },
+    relation: { type: String, enum: CONTACT_RELATIONS, default: "other" },
+    phone: { type: String, default: "", maxlength: 30 },
+    note: { type: String, default: "", maxlength: 500 },
+    /** Uygulamaya başlamadan önceki bakiye (+ bana borçlu, − ben borçluyum). */
+    openingBalanceMinor: { type: Number, default: 0 },
+    openingDate: { type: Date, required: true },
+    /** Kalan bakiyenin vadesi ("YYYY-MM-DD") ve kaç gün önce uyarılacağı. */
+    dueDate: { type: String, default: null },
+    reminderDays: { type: Number, default: 3, min: 0, max: 60 },
+    isPrivate: { type: Boolean, default: false },
+    ownerUserId: { type: Schema.Types.ObjectId, default: null },
+    archivedAt: { type: Date, default: null },
+    seedRef: { type: String, default: null },
+    createdBy: { type: Schema.Types.ObjectId, required: true },
+    updatedBy: { type: Schema.Types.ObjectId, required: true },
+  },
+  { timestamps: true, collection: "contacts" },
+);
+
+contactSchema.index({ householdId: 1, archivedAt: 1, name: 1 });
+contactSchema.index(
+  { householdId: 1, seedRef: 1 },
+  { unique: true, partialFilterExpression: { seedRef: { $type: "string" } } },
+);
+
+export type Contact = InferSchemaType<typeof contactSchema>;
+
+export const ContactModel: Model<Contact> =
+  (models.Contact as Model<Contact> | undefined) ?? model<Contact>("Contact", contactSchema);
diff --git a/src/models/transaction.ts b/src/models/transaction.ts
index f0382ef..ff08541 100644
--- a/src/models/transaction.ts
+++ b/src/models/transaction.ts
@@ -1,4 +1,5 @@
 import { model, models, Schema, type InferSchemaType, type Model } from "mongoose";
+import { CONTACT_ENTRY_KINDS } from "@/shared/contacts";
 import { TRANSACTION_STATUSES, TRANSACTION_TYPES } from "@/shared/transactions";
 
 /**
@@ -21,7 +22,8 @@ const transactionSchema = new Schema(
     status: { type: String, enum: TRANSACTION_STATUSES, default: "posted" },
     /** İstanbul gününün başlangıç anı (UTC). */
     date: { type: Date, required: true },
-    accountId: { type: Schema.Types.ObjectId, required: true },
+    /** Kaynak hesap. Cariden girişte (borç alma, tahsilat) null; hedef `toAccountId`. */
+    accountId: { type: Schema.Types.ObjectId, default: null },
     toAccountId: { type: Schema.Types.ObjectId, default: null },
     amountMinor: { type: Number, required: true, min: 1 },
     /** Bölünmemiş gelir/giderde kategori; bölünmüşte null ve kalemler `splits`te. */
@@ -53,7 +55,9 @@ const transactionSchema = new Schema(
       default: null,
     },
     statementId: { type: Schema.Types.ObjectId, default: null },
+    /** Cari transferi: karşı taraf kişi (hesabın biri boş). */
     contactId: { type: Schema.Types.ObjectId, default: null },
+    contactKind: { type: String, enum: [...CONTACT_ENTRY_KINDS, null], default: null },
     /**
      * Mutabakatı yapılmış hesaplar (Bölüm 6.1). Transfer iki hesaba dokunduğu için hesap bazında
      * tutulur. Tutar, tarih, tür veya hesap değişirse işaret kalkar.
@@ -76,6 +80,7 @@ transactionSchema.index({ householdId: 1, accountId: 1, date: -1 });
 transactionSchema.index({ householdId: 1, toAccountId: 1, date: -1 });
 transactionSchema.index({ householdId: 1, effectiveCategoryIds: 1, date: -1 });
 transactionSchema.index({ householdId: 1, tags: 1 });
+transactionSchema.index({ householdId: 1, contactId: 1, date: 1 }, { sparse: true });
 transactionSchema.index({ "installment.planId": 1 }, { sparse: true });
 transactionSchema.index(
   { recurringRuleId: 1, occurrenceIndex: 1 },
diff --git a/src/shared/contacts.test.ts b/src/shared/contacts.test.ts
new file mode 100644
index 0000000..3e45ce5
--- /dev/null
+++ b/src/shared/contacts.test.ts
@@ -0,0 +1,25 @@
+import { describe, expect, it } from "vitest";
+import { contactDelta, dueState, isOutgoing } from "./contacts";
+import { addDays } from "./recurrence";
+
+describe("cari", () => {
+  it("yön ve bakiye etkisi", () => {
+    expect(isOutgoing("lend")).toBe(true);
+    expect(isOutgoing("repay")).toBe(true);
+    expect(isOutgoing("borrow")).toBe(false);
+    expect(contactDelta("lend", 100)).toBe(100);
+    expect(contactDelta("repay", 100)).toBe(100);
+    expect(contactDelta("borrow", 100)).toBe(-100);
+    expect(contactDelta("collect", 100)).toBe(-100);
+  });
+
+  it("vade durumu", () => {
+    const today = "2026-11-05";
+    expect(dueState(100, null, 3, today, addDays)).toBe("none");
+    expect(dueState(0, "2026-11-01", 3, today, addDays)).toBe("none");
+    expect(dueState(-100, "2026-11-04", 3, today, addDays)).toBe("overdue");
+    expect(dueState(100, "2026-11-08", 3, today, addDays)).toBe("upcoming");
+    expect(dueState(100, "2026-11-09", 3, today, addDays)).toBe("none");
+    expect(dueState(100, "2026-11-05", 0, today, addDays)).toBe("upcoming");
+  });
+});
diff --git a/src/shared/contacts.ts b/src/shared/contacts.ts
new file mode 100644
index 0000000..0761e70
--- /dev/null
+++ b/src/shared/contacts.ts
@@ -0,0 +1,37 @@
+/** Cari hesaplar (Bölüm 6.4). */
+
+export const CONTACT_RELATIONS = ["family", "friend", "neighbor", "work", "other"] as const;
+export type ContactRelation = (typeof CONTACT_RELATIONS)[number];
+
+/**
+ * Cari hareket türleri. Hesaptan cariye (çıkış): borç verdim, borcumu ödedim.
+ * Cariden hesaba (giriş): borç aldım, tahsilat yaptım. Hepsi transferdir; gelir/gider değildir.
+ */
+export const CONTACT_ENTRY_KINDS = ["lend", "repay", "borrow", "collect"] as const;
+export type ContactEntryKind = (typeof CONTACT_ENTRY_KINDS)[number];
+
+/** Para hesaptan cariye mi gidiyor? */
+export const isOutgoing = (kind: ContactEntryKind) => kind === "lend" || kind === "repay";
+
+/**
+ * Cari bakiyesi (kuruş): + "Bana borçlu", − "Ben borçluyum".
+ * Çıkışlar (verdim/ödedim) bakiyeyi artırır, girişler (aldım/tahsil ettim) azaltır.
+ */
+export function contactDelta(kind: ContactEntryKind, amountMinor: number): number {
+  return isOutgoing(kind) ? amountMinor : -amountMinor;
+}
+
+export type DueState = "none" | "upcoming" | "overdue";
+
+/** Vade uyarısı: bakiye kapanmamışsa, vade geçtiyse "overdue", hatırlatma penceresindeyse "upcoming". */
+export function dueState(
+  balanceMinor: number,
+  dueDate: string | null,
+  reminderDays: number,
+  today: string,
+  addDays: (ymd: string, n: number) => string,
+): DueState {
+  if (!dueDate || balanceMinor === 0) return "none";
+  if (dueDate < today) return "overdue";
+  return addDays(today, reminderDays) >= dueDate ? "upcoming" : "none";
+}
diff --git a/src/shared/schemas/contact.ts b/src/shared/schemas/contact.ts
new file mode 100644
index 0000000..1628cd8
--- /dev/null
+++ b/src/shared/schemas/contact.ts
@@ -0,0 +1,58 @@
+import { z } from "zod";
+import { tr } from "../../i18n/tr";
+import { CONTACT_ENTRY_KINDS, CONTACT_RELATIONS } from "../contacts";
+import { parseMoney } from "../money";
+import { moneyInputSchema } from "./account";
+
+const v = tr.validation;
+const ymd = z.string().regex(/^\d{4}-\d{2}-\d{2}$/, v.date);
+const optionalYmd = z.preprocess((x) => (x === "" || x === undefined ? null : x), ymd.nullable());
+const reminderDays = z.coerce.number().int().min(0).max(60).default(3);
+
+/** Cari kişi formu (web + mobil). */
+export const contactFormSchema = z.object({
+  name: z.string().trim().min(1, tr.common.required).max(80, v.nameMax),
+  relation: z.enum(CONTACT_RELATIONS).default("other"),
+  phone: z
+    .string()
+    .trim()
+    .max(30)
+    .regex(/^[0-9+()\s-]*$/, v.phone)
+    .default(""),
+  note: z.string().trim().max(500).default(""),
+  /** + bana borçlu, − ben borçluyum. */
+  openingBalance: z.string().default("").pipe(moneyInputSchema),
+  openingDate: ymd,
+  isPrivate: z.boolean().default(false),
+  dueDate: optionalYmd,
+  reminderDays,
+});
+export type ContactFormInput = z.input<typeof contactFormSchema>;
+export type ContactForm = z.output<typeof contactFormSchema>;
+
+/** Cari hareketi: hesaptan cariye veya cariden hesaba transfer. */
+export const contactEntrySchema = z.object({
+  kind: z.enum(CONTACT_ENTRY_KINDS),
+  accountId: z.string().regex(/^[a-f0-9]{24}$/i, tr.transactions.validation.selectAccount),
+  amount: z
+    .string()
+    .trim()
+    .transform((s, ctx) => {
+      const minor = parseMoney(s);
+      if (minor === null || minor <= 0) {
+        ctx.addIssue({
+          code: "custom",
+          message: minor === null ? v.money : tr.transactions.validation.amountPositive,
+        });
+        return z.NEVER;
+      }
+      return minor;
+    }),
+  date: ymd,
+  description: z.string().trim().max(500).default(""),
+  /** Verilirse carinin vadesi güncellenir (boş string → vade kaldırılır). */
+  dueDate: optionalYmd.optional(),
+  reminderDays: reminderDays.optional(),
+});
+export type ContactEntryInput = z.input<typeof contactEntrySchema>;
+export type ContactEntry = z.output<typeof contactEntrySchema>;
diff --git a/src/shared/transactions.ts b/src/shared/transactions.ts
index a62e0ce..9cfacbb 100644
--- a/src/shared/transactions.ts
+++ b/src/shared/transactions.ts
@@ -13,7 +13,8 @@ export type EffectInput = {
   type: TransactionType;
   status: TransactionStatus;
   amountMinor: number;
-  accountId: string;
+  /** Cariden girişte (borç alma, tahsilat) boştur. */
+  accountId: string | null;
   toAccountId?: string | null;
   deleted?: boolean;
 };
@@ -27,16 +28,17 @@ export function transactionEffects(t: EffectInput): { accountId: string; deltaMi
   if (t.status !== "posted" || t.deleted) return [];
   switch (t.type) {
     case "income":
-      return [{ accountId: t.accountId, deltaMinor: t.amountMinor }];
+      return t.accountId ? [{ accountId: t.accountId, deltaMinor: t.amountMinor }] : [];
     case "expense":
-      return [{ accountId: t.accountId, deltaMinor: -t.amountMinor }];
-    case "transfer":
-      return t.toAccountId
-        ? [
-            { accountId: t.accountId, deltaMinor: -t.amountMinor },
-            { accountId: t.toAccountId, deltaMinor: t.amountMinor },
-          ]
-        : [];
+      return t.accountId ? [{ accountId: t.accountId, deltaMinor: -t.amountMinor }] : [];
+    case "transfer": {
+      // Hesap ↔ hesap; cari transferinde bir taraf boştur (cariye çıkış: toAccountId yok,
+      // cariden giriş: accountId yok).
+      const out: { accountId: string; deltaMinor: number }[] = [];
+      if (t.accountId) out.push({ accountId: t.accountId, deltaMinor: -t.amountMinor });
+      if (t.toAccountId) out.push({ accountId: t.toAccountId, deltaMinor: t.amountMinor });
+      return out;
+    }
   }
 }