diff --git a/alembic/versions/0028_user_preferences.py b/alembic/versions/0028_user_preferences.py
new file mode 100644
index 0000000..bedcbe1
--- /dev/null
+++ b/alembic/versions/0028_user_preferences.py
@@ -0,0 +1,46 @@
+"""Create user_preferences table for per-user UI settings.
+
+Revision ID: 0028
+Revises: 0027_unify_company_to_contact
+Create Date: 2026-07-23
+
+Changes:
+- Create user_preferences table with tenant_id, user_id, key, value (JSONB)
+- Unique constraint on (tenant_id, user_id, key)
+- Indexes on tenant_id+user_id and user_id
+- tenant_id column (required by TenantMixin / RLS)
+- created_at, updated_at, deleted_at columns (TimestampMixin + SoftDeleteMixin)
+"""
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects.postgresql import JSONB, UUID as PGUUID
+
+
+revision = "0028_user_preferences"
+down_revision = "0027_unify_company_to_contact"
+
+
+def upgrade():
+    op.create_table(
+        "user_preferences",
+        sa.Column("id", PGUUID(as_uuid=True), primary_key=True, server_default=sa.text("gen_random_uuid()")),
+        sa.Column("tenant_id", PGUUID(as_uuid=True), sa.ForeignKey("tenants.id", ondelete="CASCADE"), nullable=False),
+        sa.Column("user_id", PGUUID(as_uuid=True), sa.ForeignKey("users.id", ondelete="CASCADE"), nullable=False),
+        sa.Column("key", sa.String(100), nullable=False),
+        sa.Column("value", JSONB, nullable=False, server_default=sa.text("'{}'::jsonb")),
+        sa.Column("created_at", sa.DateTime(timezone=True), nullable=False, server_default=sa.func.now()),
+        sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False, server_default=sa.func.now()),
+        sa.Column("deleted_at", sa.DateTime(timezone=True), nullable=True),
+        sa.UniqueConstraint("tenant_id", "user_id", "key", name="uq_user_prefs_tenant_user_key"),
+    )
+    op.create_index("ix_user_prefs_tenant_user", "user_preferences", ["tenant_id", "user_id"])
+    op.create_index("ix_user_prefs_user_id", "user_preferences", ["user_id"])
+    op.create_index("ix_user_prefs_tenant_id", "user_preferences", ["tenant_id"])
+
+
+def downgrade():
+    op.drop_index("ix_user_prefs_tenant_id", table_name="user_preferences")
+    op.drop_index("ix_user_prefs_user_id", table_name="user_preferences")
+    op.drop_index("ix_user_prefs_tenant_user", table_name="user_preferences")
+    op.drop_table("user_preferences")
diff --git a/app/core/permission_registry.py b/app/core/permission_registry.py
index 35f7246..cf05a7c 100644
--- a/app/core/permission_registry.py
+++ b/app/core/permission_registry.py
@@ -41,6 +41,8 @@ CORE_PERMISSIONS: list[dict[str, str]] = [
     {"key": "attachments:delete", "label": "Attachments: Delete", "category": "core", "module": "attachments"},
     {"key": "workflows:read", "label": "Workflows: Read", "category": "core", "module": "workflows"},
     {"key": "workflows:write", "label": "Workflows: Write", "category": "core", "module": "workflows"},
+    {"key": "user_preferences:read", "label": "User Preferences: Read", "category": "core", "module": "user_preferences"},
+    {"key": "user_preferences:write", "label": "User Preferences: Write", "category": "core", "module": "user_preferences"},
     {"key": "sequences:read", "label": "Sequences: Read", "category": "core", "module": "sequences"},
     {"key": "sequences:write", "label": "Sequences: Write", "category": "core", "module": "sequences"},
     {"key": "addresses:read", "label": "Addresses: Read", "category": "core", "module": "addresses"},
diff --git a/app/core/permissions.py b/app/core/permissions.py
index 2defb84..88ce6b1 100644
--- a/app/core/permissions.py
+++ b/app/core/permissions.py
@@ -162,12 +162,14 @@ async def resolve_permissions(
                         "sequences:read", "sequences:write", "addresses:read", "addresses:write",
                         "taxes:read", "taxes:write", "currencies:read", "currencies:write",
                         "notifications:read", "notifications:write", "import_export:read",
-                        "import_export:write"}
+                        "import_export:write",
+                        "user_preferences:read", "user_preferences:write"}
         elif legacy_role == "viewer":
             allowed |= {"contacts:read", "contacts:read", "users:read", "roles:read",
                         "audit:read", "attachments:read", "workflows:read", "sequences:read",
                         "addresses:read", "taxes:read", "currencies:read",
-                        "notifications:read", "import_export:read"}
+                        "notifications:read", "import_export:read",
+                        "user_preferences:read", "user_preferences:write"}
 
     # Load group permissions
     ug_q = select(UserGroup).where(
diff --git a/app/main.py b/app/main.py
index ac98232..5f6364a 100644
--- a/app/main.py
+++ b/app/main.py
@@ -40,6 +40,7 @@ from app.routes import (
     roles,
     tenants,
     users,
+    user_preferences,
     workflows,
     currencies,
     taxes,
@@ -239,6 +240,7 @@ def create_app() -> FastAPI:
     app.include_router(plugins.router)
     app.include_router(ai_copilot.router)
     app.include_router(workflows.router)
+    app.include_router(user_preferences.router)
     app.include_router(currencies.router)
     app.include_router(taxes.router)
     app.include_router(sequences.router)
diff --git a/app/models/user_preference.py b/app/models/user_preference.py
new file mode 100644
index 0000000..187bf66
--- /dev/null
+++ b/app/models/user_preference.py
@@ -0,0 +1,48 @@
+"""User Preference model — per-user UI settings stored as key/value JSONB, tenant-scoped."""
+
+from __future__ import annotations
+
+import uuid
+from typing import Any
+
+from sqlalchemy import ForeignKey, Index, String, UniqueConstraint
+from sqlalchemy.dialects.postgresql import JSONB
+from sqlalchemy.dialects.postgresql import UUID as PGUUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.db import Base, TenantMixin
+
+
+class UserPreference(Base, TenantMixin):
+    """Per-user preference entry — stores a single UI preference as JSONB value.
+
+    Keys are arbitrary strings (e.g. 'sidebar_collapsed', 'theme', 'active_tab').
+    Values are JSONB to support complex preference structures.
+    """
+
+    __tablename__ = "user_preferences"
+    __table_args__ = (
+        UniqueConstraint(
+            "tenant_id",
+            "user_id",
+            "key",
+            name="uq_user_prefs_tenant_user_key",
+        ),
+        Index(
+            "ix_user_prefs_tenant_user",
+            "tenant_id",
+            "user_id",
+        ),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    user_id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True),
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    key: Mapped[str] = mapped_column(String(100), nullable=False)
+    value: Mapped[Any] = mapped_column(JSONB, nullable=False, default=dict)
diff --git a/app/routes/__init__.py b/app/routes/__init__.py
index a2b7854..e04f6ca 100644
--- a/app/routes/__init__.py
+++ b/app/routes/__init__.py
@@ -20,5 +20,6 @@ from app.routes import (
     roles,  # noqa: F401
     tenants,  # noqa: F401
     users,  # noqa: F401
+    user_preferences,  # noqa: F401
     workflows,  # noqa: F401
 )
diff --git a/app/routes/user_preferences.py b/app/routes/user_preferences.py
new file mode 100644
index 0000000..6463c9b
--- /dev/null
+++ b/app/routes/user_preferences.py
@@ -0,0 +1,195 @@
+"""User Preferences routes — per-user UI settings via API, tenant-scoped with RBAC."""
+
+from __future__ import annotations
+
+import uuid
+from typing import Any
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from pydantic import BaseModel, Field
+from sqlalchemy import delete, select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.db import get_db
+from app.deps import require_permission
+from app.models.user_preference import UserPreference
+
+router = APIRouter(prefix="/api/v1/user/preferences", tags=["user-preferences"])
+
+
+# ─── Schemas ───
+
+
+class PreferenceValue(BaseModel):
+    """Arbitrary JSON value for a preference key."""
+
+    value: Any = Field(..., description="JSON value for the preference key")
+
+
+class PreferenceResponse(BaseModel):
+    """Single preference entry response."""
+
+    key: str
+    value: Any
+    updated_at: str | None = None
+
+
+class PreferenceListResponse(BaseModel):
+    """All preferences for the current user."""
+
+    preferences: list[PreferenceResponse]
+
+
+# ─── Helpers ───
+
+
+def _pref_to_response(p: UserPreference) -> PreferenceResponse:
+    """Convert UserPreference model to response schema."""
+    updated_at = None
+    try:
+        updated_at = p.updated_at.isoformat() if p.updated_at else None
+    except Exception:
+        pass
+    return PreferenceResponse(
+        key=p.key,
+        value=p.value,
+        updated_at=updated_at,
+    )
+
+
+# ─── Endpoints ───
+
+
+@router.get("")
+async def list_user_preferences(
+    db: AsyncSession = Depends(get_db),
+    current_user: dict[str, Any] = Depends(
+        require_permission("user_preferences:read")
+    ),
+) -> PreferenceListResponse:
+    """Get all preferences for the current user."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+
+    result = await db.execute(
+        select(UserPreference)
+        .where(
+            UserPreference.tenant_id == tenant_id,
+            UserPreference.user_id == user_id,
+            UserPreference.deleted_at.is_(None),
+        )
+        .order_by(UserPreference.key)
+    )
+    prefs = result.scalars().all()
+    return PreferenceListResponse(
+        preferences=[_pref_to_response(p) for p in prefs]
+    )
+
+
+@router.get("/{key}")
+async def get_user_preference(
+    key: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict[str, Any] = Depends(
+        require_permission("user_preferences:read")
+    ),
+) -> PreferenceResponse:
+    """Get a single preference by key."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+
+    result = await db.execute(
+        select(UserPreference).where(
+            UserPreference.tenant_id == tenant_id,
+            UserPreference.user_id == user_id,
+            UserPreference.key == key,
+            UserPreference.deleted_at.is_(None),
+        )
+    )
+    pref = result.scalar_one_or_none()
+    if pref is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "detail": f"Preference '{key}' not found",
+                "code": "not_found",
+            },
+        )
+    return _pref_to_response(pref)
+
+
+@router.put("/{key}")
+async def upsert_user_preference(
+    key: str,
+    body: PreferenceValue,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict[str, Any] = Depends(
+        require_permission("user_preferences:write")
+    ),
+) -> PreferenceResponse:
+    """Create or update a preference by key (upsert)."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+
+    result = await db.execute(
+        select(UserPreference).where(
+            UserPreference.tenant_id == tenant_id,
+            UserPreference.user_id == user_id,
+            UserPreference.key == key,
+            UserPreference.deleted_at.is_(None),
+        )
+    )
+    pref = result.scalar_one_or_none()
+
+    if pref is None:
+        pref = UserPreference(
+            tenant_id=tenant_id,
+            user_id=user_id,
+            key=key,
+            value=body.value,
+        )
+        db.add(pref)
+    else:
+        pref.value = body.value
+
+    await db.commit()
+    await db.refresh(pref)
+    return _pref_to_response(pref)
+
+
+@router.delete("/{key}", status_code=status.HTTP_204_NO_CONTENT)
+async def delete_user_preference(
+    key: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict[str, Any] = Depends(
+        require_permission("user_preferences:write")
+    ),
+):
+    """Delete a preference by key (soft-delete)."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+
+    result = await db.execute(
+        select(UserPreference).where(
+            UserPreference.tenant_id == tenant_id,
+            UserPreference.user_id == user_id,
+            UserPreference.key == key,
+            UserPreference.deleted_at.is_(None),
+        )
+    )
+    pref = result.scalar_one_or_none()
+    if pref is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "detail": f"Preference '{key}' not found",
+                "code": "not_found",
+            },
+        )
+
+    # Soft-delete via TenantMixin's deleted_at
+    from datetime import UTC, datetime
+
+    pref.deleted_at = datetime.now(UTC)
+    await db.commit()
+    return None
diff --git a/frontend/src/api/userPreferences.ts b/frontend/src/api/userPreferences.ts
new file mode 100644
index 0000000..396ee71
--- /dev/null
+++ b/frontend/src/api/userPreferences.ts
@@ -0,0 +1,74 @@
+/**
+ * User Preferences API — per-user UI settings stored server-side.
+ * Matches backend endpoints from /api/v1/user/preferences.
+ *
+ * Backend: app/routes/user_preferences.py, app/models/user_preference.py
+ */
+
+import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
+import { apiGet, apiPut, apiDelete } from './client';
+
+// ── Types ──
+
+export interface PreferenceEntry {
+  key: string;
+  value: unknown;
+  updated_at?: string | null;
+}
+
+export interface PreferenceListResponse {
+  preferences: PreferenceEntry[];
+}
+
+// ── Hooks ──
+
+export function useUserPreferences() {
+  return useQuery({
+    queryKey: ['userPreferences'],
+    queryFn: () =>
+      apiGet<PreferenceListResponse>('/user/preferences'),
+  });
+}
+
+export function useUserPreference(key: string) {
+  return useQuery({
+    queryKey: ['userPreferences', key],
+    queryFn: () =>
+      apiGet<PreferenceEntry>(`/user/preferences/${key}`),
+    enabled: !!key,
+  });
+}
+
+export function useUpsertUserPreference() {
+  const queryClient = useQueryClient();
+  return useMutation({
+    mutationFn: ({
+      key,
+      value,
+    }: {
+      key: string;
+      value: unknown;
+    }) =>
+      apiPut<PreferenceEntry>(`/user/preferences/${key}`, {
+        value,
+      }),
+    onSuccess: () => {
+      queryClient.invalidateQueries({
+        queryKey: ['userPreferences'],
+      });
+    },
+  });
+}
+
+export function useDeleteUserPreference() {
+  const queryClient = useQueryClient();
+  return useMutation({
+    mutationFn: (key: string) =>
+      apiDelete(`/user/preferences/${key}`),
+    onSuccess: () => {
+      queryClient.invalidateQueries({
+        queryKey: ['userPreferences'],
+      });
+    },
+  });
+}
diff --git a/frontend/src/hooks/useUserPreferences.ts b/frontend/src/hooks/useUserPreferences.ts
new file mode 100644
index 0000000..63187be
--- /dev/null
+++ b/frontend/src/hooks/useUserPreferences.ts
@@ -0,0 +1,125 @@
+/**
+ * useUserPreferences — loads user preferences from API and syncs with uiStore.
+ *
+ * On load: applies server-side preferences to the Zustand uiStore (theme, locale,
+ * sidebar state, AI sidebar tab, etc.).
+ * On change: persists uiStore state to the server via upsert mutation.
+ */
+
+import { useEffect, useCallback } from 'react';
+import { useUIStore, type Theme, type Locale, type AISidebarTab } from '@/store/uiStore';
+import {
+  useUserPreferences,
+  useUpsertUserPreference,
+  useDeleteUserPreference,
+} from '@/api/userPreferences';
+
+// Known preference keys that map to uiStore fields
+const PREF_KEYS = {
+  THEME: 'theme',
+  LOCALE: 'locale',
+  SIDEBAR_OPEN: 'sidebar_open',
+  AI_SIDEBAR_COLLAPSED: 'ai_sidebar_collapsed',
+  AI_SIDEBAR_TAB: 'ai_sidebar_tab',
+  MESSAGE_SIDEBAR_COLLAPSED: 'message_sidebar_collapsed',
+  SUGGESTION_SIDEBAR_OPEN: 'suggestion_sidebar_open',
+} as const;
+
+export function useUserPreferencesSync() {
+  const { data, isLoading } = useUserPreferences();
+  const upsertMutation = useUpsertUserPreference();
+  const deleteMutation = useDeleteUserPreference();
+
+  const {
+    theme,
+    locale,
+    sidebarOpen,
+    aiSidebarCollapsed,
+    aiSidebarTab,
+    messageSidebarCollapsed,
+    suggestionSidebarOpen: _suggestionSidebarOpen,
+    setTheme,
+    setLocale,
+    setSidebarOpen,
+    setAISidebarCollapsed,
+    setAISidebarTab,
+    setMessageSidebarCollapsed,
+  } = useUIStore();
+
+  // Apply server preferences to uiStore on initial load
+  useEffect(() => {
+    if (!data?.preferences) return;
+
+    const prefMap = new Map<string, unknown>();
+    for (const pref of data.preferences) {
+      prefMap.set(pref.key, pref.value);
+    }
+
+    // Only apply if the server has a value — don't override local defaults with null
+    if (prefMap.has(PREF_KEYS.THEME)) {
+      const serverTheme = prefMap.get(PREF_KEYS.THEME) as Theme;
+      if (serverTheme && serverTheme !== theme) {
+        setTheme(serverTheme);
+      }
+    }
+    if (prefMap.has(PREF_KEYS.LOCALE)) {
+      const serverLocale = prefMap.get(PREF_KEYS.LOCALE) as Locale;
+      if (serverLocale && serverLocale !== locale) {
+        setLocale(serverLocale);
+      }
+    }
+    if (prefMap.has(PREF_KEYS.SIDEBAR_OPEN)) {
+      const serverSidebar = prefMap.get(PREF_KEYS.SIDEBAR_OPEN) as boolean;
+      if (serverSidebar !== sidebarOpen) {
+        setSidebarOpen(serverSidebar);
+      }
+    }
+    if (prefMap.has(PREF_KEYS.AI_SIDEBAR_COLLAPSED)) {
+      const serverCollapsed = prefMap.get(
+        PREF_KEYS.AI_SIDEBAR_COLLAPSED
+      ) as boolean;
+      if (serverCollapsed !== aiSidebarCollapsed) {
+        setAISidebarCollapsed(serverCollapsed);
+      }
+    }
+    if (prefMap.has(PREF_KEYS.AI_SIDEBAR_TAB)) {
+      const serverTab = prefMap.get(PREF_KEYS.AI_SIDEBAR_TAB) as AISidebarTab;
+      if (serverTab && serverTab !== aiSidebarTab) {
+        setAISidebarTab(serverTab);
+      }
+    }
+    if (prefMap.has(PREF_KEYS.MESSAGE_SIDEBAR_COLLAPSED)) {
+      const serverCollapsed = prefMap.get(
+        PREF_KEYS.MESSAGE_SIDEBAR_COLLAPSED
+      ) as boolean;
+      if (serverCollapsed !== messageSidebarCollapsed) {
+        setMessageSidebarCollapsed(serverCollapsed);
+      }
+    }
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [data]);
+
+  // Persist a single preference to the server
+  const savePreference = useCallback(
+    (key: string, value: unknown) => {
+      upsertMutation.mutate({ key, value });
+    },
+    [upsertMutation]
+  );
+
+  // Delete a preference from the server
+  const removePreference = useCallback(
+    (key: string) => {
+      deleteMutation.mutate(key);
+    },
+    [deleteMutation]
+  );
+
+  return {
+    isLoading,
+    savePreference,
+    removePreference,
+    isSaving: upsertMutation.isPending,
+    isDeleting: deleteMutation.isPending,
+  };
+}
diff --git a/frontend/src/i18n/locales/de.json b/frontend/src/i18n/locales/de.json
index 0c0063f..0618489 100644
--- a/frontend/src/i18n/locales/de.json
+++ b/frontend/src/i18n/locales/de.json
@@ -893,6 +893,20 @@
     "changes": "Änderungen",
     "fieldsChanged": "Felder geändert"
   },
+  "userPreferences": {
+    "title": "Benutzereinstellungen",
+    "saved": "Einstellungen gespeichert",
+    "saveError": "Fehler beim Speichern der Einstellungen",
+    "deleted": "Einstellung gelöscht",
+    "deleteError": "Fehler beim Löschen der Einstellung",
+    "loading": "Einstellungen werden geladen",
+    "theme": "Design",
+    "language": "Sprache",
+    "sidebar": "Seitenleiste",
+    "activeTab": "Aktiver Tab",
+    "sortOrder": "Sortierreihenfolge",
+    "synced": "Einstellungen synchronisiert"
+  },
   "ai": {
     "uiControl": {
       "active": "KI steuert die UI",
diff --git a/frontend/src/i18n/locales/en.json b/frontend/src/i18n/locales/en.json
index fd5b8c1..22073f4 100644
--- a/frontend/src/i18n/locales/en.json
+++ b/frontend/src/i18n/locales/en.json
@@ -893,6 +893,20 @@
     "changes": "Changes",
     "fieldsChanged": "fields changed"
   },
+  "userPreferences": {
+    "title": "User Preferences",
+    "saved": "Preferences saved",
+    "saveError": "Failed to save preferences",
+    "deleted": "Preference deleted",
+    "deleteError": "Failed to delete preference",
+    "loading": "Loading preferences",
+    "theme": "Theme",
+    "language": "Language",
+    "sidebar": "Sidebar",
+    "activeTab": "Active Tab",
+    "sortOrder": "Sort Order",
+    "synced": "Preferences synced"
+  },
   "ai": {
     "uiControl": {
       "active": "AI is controlling the UI",
diff --git a/tests/conftest.py b/tests/conftest.py
index d2870e7..c88fc64 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -35,6 +35,7 @@ from app.models.plugin import Plugin, PluginMigration  # noqa: F401
 from app.models.role import Role
 from app.models.tenant import Tenant
 from app.models.user import User, UserTenant
+from app.models.user_preference import UserPreference  # noqa: F401
 from app.models.workflow import Workflow, WorkflowInstance, WorkflowStepHistory  # noqa: F401
 from app.plugins.builtins.calendar import CalendarPlugin  # noqa: F401
 from app.plugins.builtins.calendar.models import (  # noqa: F401
@@ -270,16 +271,18 @@ async def seed_tenant_and_users(db: AsyncSession) -> dict[str, Any]:
     # Create a company in tenant A
     company_a = Contact(
         tenant_id=tenant_a.id,
+        type="company",
         name="Company Alpha",
-        industry="IT",
+        displayname="Company Alpha",
         created_by=admin_a.id,
         updated_by=admin_a.id,
     )
     # Create a company in tenant B
     company_b = Contact(
         tenant_id=tenant_b.id,
+        type="company",
         name="Company Beta",
-        industry="Finance",
+        displayname="Company Beta",
         created_by=admin_b.id,
         updated_by=admin_b.id,
     )
diff --git a/tests/test_user_preferences.py b/tests/test_user_preferences.py
new file mode 100644
index 0000000..1992e08
--- /dev/null
+++ b/tests/test_user_preferences.py
@@ -0,0 +1,232 @@
+"""Tests for User Preferences API — CRUD, tenant isolation, RBAC enforcement."""
+
+from __future__ import annotations
+
+import pytest
+from httpx import AsyncClient
+
+from tests.conftest import ORIGIN_HEADER, login_client, seed_tenant_and_users
+
+
+async def _login_with_csrf(client: AsyncClient, email: str) -> str:
+    """Login and return the CSRF token for subsequent unsafe requests."""
+    resp = await client.post(
+        "/api/v1/auth/login",
+        json={"email": email, "password": "TestPass123!"},
+        headers=ORIGIN_HEADER,
+    )
+    assert resp.status_code == 200, f"Login failed: {resp.status_code} {resp.text}"
+    return resp.json()["csrf_token"]
+
+
+def _csrf_headers(csrf_token: str) -> dict:
+    """Return headers dict with Origin + X-CSRF-Token for unsafe methods."""
+    return {**ORIGIN_HEADER, "X-CSRF-Token": csrf_token}
+
+
+@pytest.mark.asyncio
+class TestUserPreferencesList:
+    """GET /api/v1/user/preferences — list all preferences for current user."""
+
+    async def test_list_empty_returns_200(self, client: AsyncClient, db_session):
+        """GET /user/preferences with no preferences → 200 + empty list."""
+        await seed_tenant_and_users(db_session)
+        csrf = await _login_with_csrf(client, "admin@tenanta.com")
+        resp = await client.get("/api/v1/user/preferences", headers=ORIGIN_HEADER)
+        assert resp.status_code == 200
+        data = resp.json()
+        assert "preferences" in data
+        assert data["preferences"] == []
+
+    async def test_list_returns_saved_preferences(self, client: AsyncClient, db_session):
+        """GET /user/preferences after PUT → 200 + saved entries."""
+        await seed_tenant_and_users(db_session)
+        csrf = await _login_with_csrf(client, "admin@tenanta.com")
+        # Save a preference first
+        resp = await client.put(
+            "/api/v1/user/preferences/theme",
+            json={"value": "dark"},
+            headers=_csrf_headers(csrf),
+        )
+        assert resp.status_code == 200
+        resp = await client.get("/api/v1/user/preferences", headers=ORIGIN_HEADER)
+        assert resp.status_code == 200
+        data = resp.json()
+        assert len(data["preferences"]) >= 1
+        keys = [p["key"] for p in data["preferences"]]
+        assert "theme" in keys
+
+    async def test_list_unauthenticated_returns_401(self, client: AsyncClient):
+        """GET /user/preferences without auth → 401."""
+        resp = await client.get("/api/v1/user/preferences")
+        assert resp.status_code == 401
+
+
+@pytest.mark.asyncio
+class TestUserPreferencesGet:
+    """GET /api/v1/user/preferences/{key} — get single preference."""
+
+    async def test_get_existing_preference_returns_200(self, client: AsyncClient, db_session):
+        """GET /user/preferences/{key} after PUT → 200 + value."""
+        await seed_tenant_and_users(db_session)
+        csrf = await _login_with_csrf(client, "admin@tenanta.com")
+        await client.put(
+            "/api/v1/user/preferences/sidebar_open",
+            json={"value": False},
+            headers=_csrf_headers(csrf),
+        )
+        resp = await client.get(
+            "/api/v1/user/preferences/sidebar_open", headers=ORIGIN_HEADER
+        )
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["key"] == "sidebar_open"
+        assert data["value"] is False
+
+    async def test_get_nonexistent_returns_404(self, client: AsyncClient, db_session):
+        """GET /user/preferences/{key} for missing key → 404."""
+        await seed_tenant_and_users(db_session)
+        await _login_with_csrf(client, "admin@tenanta.com")
+        resp = await client.get(
+            "/api/v1/user/preferences/nonexistent", headers=ORIGIN_HEADER
+        )
+        assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+class TestUserPreferencesUpsert:
+    """PUT /api/v1/user/preferences/{key} — create or update preference."""
+
+    async def test_create_new_preference_returns_200(self, client: AsyncClient, db_session):
+        """PUT /user/preferences/{key} with new key → 200 + created entry."""
+        await seed_tenant_and_users(db_session)
+        csrf = await _login_with_csrf(client, "admin@tenanta.com")
+        resp = await client.put(
+            "/api/v1/user/preferences/theme",
+            json={"value": "dark"},
+            headers=_csrf_headers(csrf),
+        )
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["key"] == "theme"
+        assert data["value"] == "dark"
+        assert "updated_at" in data
+
+    async def test_update_existing_preference_returns_200(self, client: AsyncClient, db_session):
+        """PUT /user/preferences/{key} with existing key → 200 + updated value."""
+        await seed_tenant_and_users(db_session)
+        csrf = await _login_with_csrf(client, "admin@tenanta.com")
+        # Create
+        await client.put(
+            "/api/v1/user/preferences/locale",
+            json={"value": "de"},
+            headers=_csrf_headers(csrf),
+        )
+        # Update
+        resp = await client.put(
+            "/api/v1/user/preferences/locale",
+            json={"value": "en"},
+            headers=_csrf_headers(csrf),
+        )
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["key"] == "locale"
+        assert data["value"] == "en"
+
+    async def test_upsert_complex_json_value(self, client: AsyncClient, db_session):
+        """PUT /user/preferences/{key} with complex JSON value → 200."""
+        await seed_tenant_and_users(db_session)
+        csrf = await _login_with_csrf(client, "admin@tenanta.com")
+        complex_value = {
+            "sort_by": "name",
+            "sort_order": "asc",
+            "filters": {"industry": "IT", "status": "active"},
+        }
+        resp = await client.put(
+            "/api/v1/user/preferences/contact_list_settings",
+            json={"value": complex_value},
+            headers=_csrf_headers(csrf),
+        )
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["value"]["sort_by"] == "name"
+        assert data["value"]["filters"]["industry"] == "IT"
+
+    async def test_upsert_unauthenticated_returns_401(self, client: AsyncClient):
+        """PUT /user/preferences/{key} without auth → 401 or 403 (CSRF block)."""
+        resp = await client.put(
+            "/api/v1/user/preferences/theme",
+            json={"value": "dark"},
+            headers=ORIGIN_HEADER,
+        )
+        # Without session, CSRF middleware blocks with 403 before auth check
+        assert resp.status_code in (401, 403)
+
+
+@pytest.mark.asyncio
+class TestUserPreferencesDelete:
+    """DELETE /api/v1/user/preferences/{key} — remove a preference."""
+
+    async def test_delete_existing_returns_204(self, client: AsyncClient, db_session):
+        """DELETE /user/preferences/{key} for existing key → 204."""
+        await seed_tenant_and_users(db_session)
+        csrf = await _login_with_csrf(client, "admin@tenanta.com")
+        # Create first
+        await client.put(
+            "/api/v1/user/preferences/theme",
+            json={"value": "dark"},
+            headers=_csrf_headers(csrf),
+        )
+        resp = await client.delete(
+            "/api/v1/user/preferences/theme", headers=_csrf_headers(csrf)
+        )
+        assert resp.status_code == 204
+
+    async def test_delete_nonexistent_returns_404(self, client: AsyncClient, db_session):
+        """DELETE /user/preferences/{key} for missing key → 404."""
+        await seed_tenant_and_users(db_session)
+        csrf = await _login_with_csrf(client, "admin@tenanta.com")
+        resp = await client.delete(
+            "/api/v1/user/preferences/nonexistent", headers=_csrf_headers(csrf)
+        )
+        assert resp.status_code == 404
+
+    async def test_delete_then_get_returns_404(self, client: AsyncClient, db_session):
+        """After DELETE, GET /user/preferences/{key} → 404."""
+        await seed_tenant_and_users(db_session)
+        csrf = await _login_with_csrf(client, "admin@tenanta.com")
+        await client.put(
+            "/api/v1/user/preferences/locale",
+            json={"value": "de"},
+            headers=_csrf_headers(csrf),
+        )
+        await client.delete(
+            "/api/v1/user/preferences/locale", headers=_csrf_headers(csrf)
+        )
+        resp = await client.get(
+            "/api/v1/user/preferences/locale", headers=ORIGIN_HEADER
+        )
+        assert resp.status_code == 404
+
+
+@pytest.mark.asyncio
+class TestUserPreferencesTenantIsolation:
+    """Preferences are tenant-scoped — users in different tenants can't see each other."""
+
+    async def test_preferences_isolated_per_user(self, client: AsyncClient, db_session):
+        """User A's preferences are not visible to User B in the same tenant."""
+        await seed_tenant_and_users(db_session)
+        # Admin saves a preference
+        csrf_admin = await _login_with_csrf(client, "admin@tenanta.com")
+        await client.put(
+            "/api/v1/user/preferences/theme",
+            json={"value": "dark"},
+            headers=_csrf_headers(csrf_admin),
+        )
+        # Viewer logs in — should not see admin's preferences
+        csrf_viewer = await _login_with_csrf(client, "viewer@tenanta.com")
+        resp = await client.get("/api/v1/user/preferences", headers=ORIGIN_HEADER)
+        assert resp.status_code == 200
+        data = resp.json()
+        keys = [p["key"] for p in data["preferences"]]
+        assert "theme" not in keys