diff --git a/backend/awg_api/contract.py b/backend/awg_api/contract.py
new file mode 100644
index 0000000..30ebe8f
--- /dev/null
+++ b/backend/awg_api/contract.py
@@ -0,0 +1,242 @@
+"""Загрузка OpenAPI-контракта и валидация ответов реализации против схем.
+
+Контракт (``docs/openapi.yaml``) — источник истины: тесты
+``backend/tests/test_contract_responses.py`` прогоняют каждый эндпоинт реализации
+и сверяют ответ против схемы спецификации. Любое расхождение — ``ContractViolationError``,
+то есть красный CI.
+"""
+
+from __future__ import annotations
+
+import copy
+import os
+from functools import lru_cache
+from pathlib import Path
+from typing import Any
+
+import yaml
+from jsonschema import Draft202012Validator, FormatChecker
+
+SPEC_RELATIVE_PATH = Path("docs") / "openapi.yaml"
+SPEC_ENV_VAR = "AWG_OPENAPI_SPEC"
+JSON_MEDIA_TYPE = "application/json"
+HTTP_METHODS: tuple[str, ...] = ("get", "put", "post", "delete", "patch", "head", "options")
+DOC_ROUTE_PATHS: frozenset[str] = frozenset(
+    {"/openapi.json", "/docs", "/redoc", "/docs/oauth2-redirect"}
+)
+SECRET_FIELD_NAMES: frozenset[str] = frozenset({"private_key", "preshared_key", "password"})
+
+
+class ContractViolationError(AssertionError):
+    """Ответ реализации не соответствует схеме контракта."""
+
+
+def spec_path() -> Path:
+    """Путь до спецификации (``AWG_OPENAPI_SPEC`` переопределяет поиск от корня репозитория)."""
+    override = os.environ.get(SPEC_ENV_VAR)
+    if override:
+        return Path(override)
+    for parent in Path(__file__).resolve().parents:
+        candidate = parent / SPEC_RELATIVE_PATH
+        if candidate.is_file():
+            return candidate
+    raise FileNotFoundError(f"спецификация {SPEC_RELATIVE_PATH} не найдена")
+
+
+@lru_cache(maxsize=1)
+def load_spec() -> dict[str, Any]:
+    """Разобранная спецификация OpenAPI (кэшируется на процесс)."""
+    raw = yaml.safe_load(spec_path().read_text(encoding="utf-8"))
+    if not isinstance(raw, dict):
+        raise ContractViolationError("спецификация должна быть YAML-объектом на верхнем уровне")
+    return raw
+
+
+def iter_operations(spec: dict[str, Any]) -> list[tuple[str, str, dict[str, Any]]]:
+    """Перечень описанных в контракте операций как (путь, метод, операция)."""
+    operations: list[tuple[str, str, dict[str, Any]]] = []
+    for path, item in spec.get("paths", {}).items():
+        if not isinstance(item, dict):
+            continue
+        for method in HTTP_METHODS:
+            operation = item.get(method)
+            if isinstance(operation, dict):
+                operations.append((path, method, operation))
+    return operations
+
+
+def _resolve_ref(spec: dict[str, Any], ref: str) -> Any:
+    node: Any = spec
+    for part in ref.lstrip("#/").split("/"):
+        node = node[part]
+    return node
+
+
+def _strip_write_only(node: Any) -> None:
+    """Удаляет ``writeOnly``-свойства (секреты) из схемы ответа.
+
+    ``writeOnly`` в JSON Schema 2020-12 означает «только в запросе», поэтому в ответе
+    такие поля запрещены: они вырезаются, включая упоминание в ``required``; при этом
+    ``additionalProperties: false`` делает их присутствие ошибкой валидации.
+    """
+    if isinstance(node, dict):
+        properties = node.get("properties")
+        if isinstance(properties, dict):
+            dropped = [
+                name
+                for name, sub in properties.items()
+                if isinstance(sub, dict) and sub.get("writeOnly") is True
+            ]
+            for name in dropped:
+                del properties[name]
+            required = node.get("required")
+            if dropped and isinstance(required, list):
+                node["required"] = [name for name in required if name not in dropped]
+        for value in node.values():
+            _strip_write_only(value)
+    elif isinstance(node, list):
+        for item in node:
+            _strip_write_only(item)
+
+
+def _document_for(schema: dict[str, Any], spec: dict[str, Any]) -> dict[str, Any]:
+    document = copy.deepcopy(schema)
+    document["components"] = copy.deepcopy(spec.get("components", {}))
+    _strip_write_only(document)
+    return document
+
+
+def validator_for(schema: dict[str, Any], spec: dict[str, Any]) -> Draft202012Validator:
+    """Валидатор фрагмента спецификации: внутренние ссылки ``#/components`` разрешаются."""
+    return Draft202012Validator(_document_for(schema, spec), format_checker=FormatChecker())
+
+
+def response_schema(
+    spec: dict[str, Any], path: str, method: str, status: int | str
+) -> dict[str, Any] | None:
+    """Схема тела ответа для (path, method, status) или ``None``, если ответ не описан."""
+    operation = spec.get("paths", {}).get(path, {}).get(method)
+    if not isinstance(operation, dict):
+        return None
+    response = operation.get("responses", {}).get(str(status))
+    if isinstance(response, dict) and "$ref" in response:
+        response = _resolve_ref(spec, str(response["$ref"]))
+    if not isinstance(response, dict):
+        return None
+    media = response.get("content", {}).get(JSON_MEDIA_TYPE)
+    if not isinstance(media, dict):
+        # Non-JSON ответы (например, /metrics → text/plain): берём единственный медиатип.
+        content = response.get("content", {})
+        media = next((item for item in content.values() if isinstance(item, dict)), None)
+    if not isinstance(media, dict):
+        return None
+    schema = media.get("schema")
+    return schema if isinstance(schema, dict) else None
+
+
+def validate_response(
+    spec: dict[str, Any],
+    path: str,
+    method: str,
+    status: int,
+    payload: Any,
+) -> None:
+    """Проверяет тело ответа против схемы контракта; поднимает ``ContractViolationError``."""
+    schema = response_schema(spec, path, method, status)
+    if schema is None:
+        raise ContractViolationError(
+            f"{method.upper()} {path} -> {status}: ответ не описан в спецификации"
+        )
+    errors = sorted(
+        validator_for(schema, spec).iter_errors(payload), key=lambda err: list(err.absolute_path)
+    )
+    if errors:
+        lines = [f"{method.upper()} {path} -> {status}: несоответствий схеме: {len(errors)}"]
+        for err in errors[:10]:
+            location = "/".join(str(part) for part in err.absolute_path) or "<root>"
+            lines.append(f"  - {location}: {err.message}")
+        raise ContractViolationError("\n".join(lines))
+
+
+def error_codes(spec: dict[str, Any]) -> set[str]:
+    """Множество допустимых кодов ошибок из схемы ``ErrorCode``."""
+    enum = spec.get("components", {}).get("schemas", {}).get("ErrorCode", {}).get("enum", [])
+    return {str(item) for item in enum}
+
+
+def write_only_fields(node: Any) -> set[str]:
+    """Имена всех свойств, помеченных ``writeOnly`` (в любом месте документа)."""
+    found: set[str] = set()
+    if isinstance(node, dict):
+        for name, sub in node.get("properties", {}).items():
+            if isinstance(sub, dict) and sub.get("writeOnly") is True:
+                found.add(str(name))
+            found |= write_only_fields(sub)
+        for key, value in node.items():
+            if key != "properties":
+                found |= write_only_fields(value)
+    elif isinstance(node, list):
+        for item in node:
+            found |= write_only_fields(item)
+    return found
+
+
+def iter_route_operations(app: Any) -> set[tuple[str, str]]:
+    """Множество ``(путь, МЕТОД)`` для всех HTTP/WebSocket-маршрутов приложения.
+
+    Обходит вложенные роутеры: FastAPI 0.159 не разворачивает ``include_router``
+    в ``app.routes``: хранит обёртки, содержащие ``original_router``.
+    """
+    found: set[tuple[str, str]] = set()
+
+    def walk(router: Any, seen: set[int]) -> None:
+        if id(router) in seen:
+            return
+        seen.add(id(router))
+        for route in getattr(router, "routes", []):
+            path = getattr(route, "path", None)
+            if isinstance(path, str):
+                if path in DOC_ROUTE_PATHS:
+                    continue
+                methods = getattr(route, "methods", None)
+                if methods is None:
+                    found.add((path, "GET"))  # WebSocketRoute
+                    continue
+                for method in methods:
+                    if method.upper() not in {"HEAD", "OPTIONS"}:
+                        found.add((path, method.upper()))
+                continue
+            inner = (
+                getattr(route, "original_router", None)
+                or getattr(route, "router", None)
+                or getattr(route, "app", None)
+            )
+            if inner is not None:
+                walk(inner, seen)
+
+    walk(app, set())
+    return found
+
+
+def assert_routes_match(spec: dict[str, Any], app: Any) -> None:
+    """Двусторонняя сверка маршрутов приложения и контракта.
+
+    * каждая операция контракта обязана существовать в приложении;
+    * каждый HTTP/WebSocket-маршрут приложения обязан быть описан в контракте.
+    """
+    declared: set[tuple[str, str]] = {
+        (path, method.upper()) for path, method, _ in iter_operations(spec)
+    }
+    implemented = iter_route_operations(app)
+
+    missing = sorted(declared - implemented)
+    undocumented = sorted(implemented - declared)
+    problems: list[str] = []
+    if missing:
+        problems.append("нет в реализации: " + ", ".join(f"{m} {p}" for p, m in missing))
+    if undocumented:
+        problems.append("нет в контракте: " + ", ".join(f"{m} {p}" for p, m in undocumented))
+    if problems:
+        raise ContractViolationError(
+            "маршруты приложения и docs/openapi.yaml расходятся:\n  " + "\n  ".join(problems)
+        )
diff --git a/backend/awg_api/state.py b/backend/awg_api/state.py
new file mode 100644
index 0000000..518ff36
--- /dev/null
+++ b/backend/awg_api/state.py
@@ -0,0 +1,471 @@
+"""In-memory состояние мок-сервера (замена агента и SQLite до Sprint 1).
+
+Секреты (private key, preshared key, пароль UI) хранятся отдельно от словарей-ответов
+и никогда в них не попадают — это проверяется тестом «в ответах нет приватных ключей».
+"""
+
+from __future__ import annotations
+
+import time
+import uuid
+from datetime import UTC, datetime, timedelta
+from typing import Any
+
+from awg_api.errors import ApiError
+from awg_api.schemas import (
+    ConfigUpdateRequest,
+    ImportRequest,
+    RoutingRuleCreate,
+    RoutingRuleUpdate,
+)
+
+VERSION = "0.1.0-mock"
+GEOIP_PREFIX_COUNT = 11412
+DEV_TOKEN = "awg-dash-dev-token"  # noqa: S105 — документированный dev-дефолт мок-сервера
+DEV_UI_PASSWORD = "awg-dash-dev-password"  # noqa: S105 — документированный dev-дефолт
+PRIVATE_KEY_SENTINEL = "PRIVATE-KEY-MUST-NOT-LEAK"
+PRESHARED_KEY_SENTINEL = "PRESHARED-KEY-MUST-NOT-LEAK"
+LOG_LEVELS = ("debug", "info", "warning", "error")
+
+
+def _now() -> str:
+    """RFC 3339 (UTC), суффикс Z — формат всех таймстемпов контракта."""
+    return datetime.now(UTC).isoformat(timespec="seconds").replace("+00:00", "Z")
+
+
+class MockState:
+    """Состояние мок-контрол-плейна: туннель, правила, устройства, журнал, сессия."""
+
+    def __init__(self, *, ready: bool = True) -> None:
+        self._started = time.monotonic()
+        self.ready = ready
+        self.token = DEV_TOKEN
+        self.ui_password = DEV_UI_PASSWORD
+        self.session_token: str | None = None
+        self.username: str | None = None
+        self.expires_at: str | None = None
+
+        self.mode: str = "geoip"
+        self.kill_switch = True
+        self.dns_leak_protection = True
+        self.mtu_clamping = True
+        self.ipv6: str = "direct"
+        self.geoip: dict[str, Any] = {
+            "source": "ripe-stat",
+            "prefix_count": GEOIP_PREFIX_COUNT,
+            "updated_at": _now(),
+        }
+        self.tunnel_state: str = "up"
+        self.handshake_age_s: int | None = 27
+        self.rx_bytes = 5_812_664
+        self.tx_bytes = 1_204_331
+        self.peer_endpoint = "vpn.example.net:51820"
+        self.secrets: dict[str, str] = {
+            "private_key": PRIVATE_KEY_SENTINEL,
+            "preshared_key": PRESHARED_KEY_SENTINEL,
+        }
+        self.tunnel_config: dict[str, Any] = {
+            "address": "10.8.0.2/32",
+            "listen_port": 51820,
+            "mtu": 1420,
+            "dns": ["10.8.0.1"],
+        }
+        self.peers: list[dict[str, Any]] = [
+            {
+                "public_key": "kZ9vT4publicKeyExampleOnly0000000000000000000=",
+                "endpoint": "vpn.example.net:51820",
+                "allowed_ips": ["0.0.0.0/0", "::/0"],
+                "persistent_keepalive": 25,
+            }
+        ]
+        self.dns: dict[str, Any] = {"mode": "internal", "servers": ["10.8.0.1", "1.1.1.1"]}
+        self.rules: dict[str, dict[str, Any]] = {}
+        self.devices: list[dict[str, Any]] = [
+            {
+                "name": "laptop-anna",
+                "ip": "10.8.0.11",
+                "mac": "3c:22:fb:11:22:33",
+                "vpn": True,
+                "ipsets": ["awg_geoip", "awg_domains"],
+                "last_seen_at": _now(),
+            },
+            {
+                "name": "phone-max",
+                "ip": "10.8.0.12",
+                "mac": None,
+                "vpn": False,
+                "ipsets": [],
+                "last_seen_at": _now(),
+            },
+        ]
+        self.logs: list[dict[str, Any]] = []
+        self.updated_at = _now()
+        self._seed_rules()
+        self._seed_logs()
+
+    # ------------------------------------------------------------------ служебное
+
+    def uptime_s(self) -> int:
+        return max(0, int(time.monotonic() - self._started))
+
+    def _seed_rules(self) -> None:
+        self.rules["0192a1b2-0000-7000-8000-000000000001"] = {
+            "id": "0192a1b2-0000-7000-8000-000000000001",
+            "name": "Маршрутизировать домены сервисов",
+            "kind": "domain",
+            "value": "*.example.net",
+            "action": "vpn",
+            "enabled": True,
+            "priority": 100,
+            "comment": None,
+            "created_at": _now(),
+            "updated_at": _now(),
+        }
+        self.rules["0192a1b2-0000-7000-8000-000000000002"] = {
+            "id": "0192a1b2-0000-7000-8000-000000000002",
+            "name": "Локальная подсеть напрямую",
+            "kind": "cidr",
+            "value": "192.168.1.0/24",
+            "action": "direct",
+            "enabled": True,
+            "priority": 10,
+            "comment": "LAN исключаем из туннеля",
+            "created_at": _now(),
+            "updated_at": _now(),
+        }
+
+    def _seed_logs(self) -> None:
+        seeds = [
+            (
+                "info",
+                "awg_agent.reconcile",
+                "Применён desired state: 2 правила, 1 пир",
+                {"mode": "geoip"},
+            ),
+            (
+                "info",
+                "awg_api.routing",
+                "Режим split-tunnel: geoip",
+                {"prefix_count": GEOIP_PREFIX_COUNT},
+            ),
+            ("warning", "awg_agent.geoip", "Снапшот GeoIP старше 24 часов", {"age_h": 26}),
+            ("error", "awg_agent.tunnel", "Краткий разрыв handshake", {"duration_s": 4}),
+            ("debug", "awg_api.auth", "Создана сессия UI", {"username": "admin"}),
+        ]
+        for level, logger, message, fields in seeds:
+            self.logs.append(
+                {
+                    "ts": _now(),
+                    "level": level,
+                    "logger": logger,
+                    "message": message,
+                    "fields": fields,
+                }
+            )
+
+    # ------------------------------------------------------------------ ops
+
+    def get_health(self) -> dict[str, Any]:
+        return {
+            "status": "ok" if self.ready else "degraded",
+            "version": VERSION,
+            "uptime_s": self.uptime_s(),
+            "checks": [
+                {"name": "api", "ok": True, "detail": None},
+                {
+                    "name": "agent_socket",
+                    "ok": self.ready,
+                    "detail": None if self.ready else "unix-socket не отвечает",
+                },
+            ],
+        }
+
+    def get_ready(self) -> dict[str, Any]:
+        return {
+            "ready": self.ready,
+            "checks": [
+                {"name": "tunnel", "ok": self.ready, "detail": None},
+                {"name": "geoip_cache", "ok": True, "detail": None},
+            ],
+        }
+
+    def prometheus_text(self) -> str:
+        tunnel_up = 1 if self.tunnel_state == "up" else 0
+        lines = [
+            "# HELP awg_dash_tunnel_up Tunnel state (1 = up)",
+            "# TYPE awg_dash_tunnel_up gauge",
+            f"awg_dash_tunnel_up {tunnel_up}",
+            "# HELP awg_dash_rx_bytes_total Received bytes on the tunnel",
+            "# TYPE awg_dash_rx_bytes_total counter",
+            f"awg_dash_rx_bytes_total {self.rx_bytes}",
+            "# HELP awg_dash_tx_bytes_total Transmitted bytes on the tunnel",
+            "# TYPE awg_dash_tx_bytes_total counter",
+            f"awg_dash_tx_bytes_total {self.tx_bytes}",
+            "# HELP awg_dash_geoip_prefixes GeoIP prefix count in the active snapshot",
+            "# TYPE awg_dash_geoip_prefixes gauge",
+            f"awg_dash_geoip_prefixes {self.geoip['prefix_count']}",
+        ]
+        return "\n".join(lines) + "\n"
+
+    # ------------------------------------------------------------------ status
+
+    def get_status(self) -> dict[str, Any]:
+        return {
+            "version": VERSION,
+            "uptime_s": self.uptime_s(),
+            "mode": self.mode,
+            "tunnel": {
+                "interface": "awg0",
+                "state": self.tunnel_state,
+                "handshake_age_s": self.handshake_age_s,
+                "rx_bytes": self.rx_bytes,
+                "tx_bytes": self.tx_bytes,
+                "endpoint": self.peer_endpoint,
+                "last_handshake_at": _now(),
+            },
+            "geoip": dict(self.geoip),
+            "kill_switch": self.kill_switch,
+            "dns_leak_protection": self.dns_leak_protection,
+        }
+
+    def metrics_sample(self) -> dict[str, Any]:
+        return {
+            "rx_bytes": self.rx_bytes,
+            "tx_bytes": self.tx_bytes,
+            "rx_rate_bps": 1_048_576,
+            "tx_rate_bps": 262_144,
+            "handshake_age_s": self.handshake_age_s,
+            "active_peers": len(self.peers),
+        }
+
+    def metrics_frame(self) -> dict[str, Any]:
+        return {"type": "metrics", "ts": _now(), "data": self.metrics_sample()}
+
+    # ------------------------------------------------------------------ config
+
+    def get_config(self) -> dict[str, Any]:
+        """Конфигурация без секретов: private_key/preshared_key не сериализуются."""
+        return {
+            "tunnel": dict(self.tunnel_config),
+            "peers": [dict(peer) for peer in self.peers],
+            "dns": dict(self.dns),
+            "routing": self._routing_config(),
+            "updated_at": self.updated_at,
+        }
+
+    def _routing_config(self) -> dict[str, Any]:
+        return {
+            "mode": self.mode,
+            "kill_switch": self.kill_switch,
+            "mtu_clamping": self.mtu_clamping,
+            "ipv6": self.ipv6,
+            "geoip": dict(self.geoip),
+        }
+
+    def apply_config(self, update: ConfigUpdateRequest) -> dict[str, Any]:
+        if update.tunnel is not None:
+            payload = update.tunnel.model_dump(exclude={"private_key"})
+            self.tunnel_config = {**self.tunnel_config, **payload}
+            self.secrets["private_key"] = update.tunnel.private_key
+        if update.peers is not None:
+            self.peers = [peer.model_dump(exclude={"preshared_key"}) for peer in update.peers]
+            sentinel = next(
+                (peer.preshared_key for peer in update.peers if peer.preshared_key is not None),
+                None,
+            )
+            if sentinel is not None:
+                self.secrets["preshared_key"] = sentinel
+        if update.dns is not None:
+            self.dns = update.dns.model_dump()
+        if update.routing is not None:
+            routing = update.routing.model_dump()
+            self.mode = routing["mode"]
+            self.kill_switch = routing["kill_switch"]
+            self.mtu_clamping = routing["mtu_clamping"]
+            self.ipv6 = routing["ipv6"]
+            self.geoip = routing["geoip"]
+        self.updated_at = _now()
+        return self.get_config()
+
+    def validate_config(self, update: ConfigUpdateRequest) -> dict[str, Any]:
+        errors: list[dict[str, Any]] = []
+        warnings: list[dict[str, Any]] = []
+        if update.tunnel is not None:
+            address = update.tunnel.address
+            if "/" not in address:
+                errors.append(
+                    {
+                        "path": "/tunnel/address",
+                        "code": "invalid_cidr",
+                        "message": "Адрес интерфейса должен быть в CIDR-нотации",
+                        "severity": "error",
+                    }
+                )
+            if update.tunnel.mtu > 1420:
+                warnings.append(
+                    {
+                        "path": "/tunnel/mtu",
+                        "code": "mtu_above_recommended",
+                        "message": "MTU выше 1420 может требовать MSS clamping",
+                        "severity": "warning",
+                    }
+                )
+        for index, peer in enumerate(update.peers or []):
+            if ":" not in peer.endpoint:
+                errors.append(
+                    {
+                        "path": f"/peers/{index}/endpoint",
+                        "code": "invalid_endpoint",
+                        "message": "Endpoint должен содержать host:port",
+                        "severity": "error",
+                    }
+                )
+        return {"valid": not errors, "errors": errors, "warnings": warnings}
+
+    # ------------------------------------------------------------------ routing
+
+    def list_rules(self, *, enabled: bool | None = None, kind: str | None = None) -> dict[str, Any]:
+        items = [
+            dict(rule)
+            for rule in sorted(
+                self.rules.values(), key=lambda rule: (rule["priority"], rule["created_at"])
+            )
+            if (enabled is None or rule["enabled"] is enabled)
+            and (kind is None or rule["kind"] == kind)
+        ]
+        return {"items": items, "total": len(items)}
+
+    def create_rule(self, payload: RoutingRuleCreate) -> dict[str, Any]:
+        if any(
+            rule["kind"] == payload.kind and rule["value"] == payload.value
+            for rule in self.rules.values()
+        ):
+            raise ApiError(409, "conflict", "Правило для такого kind/value уже существует")
+        timestamp = _now()
+        rule_id = str(uuid.uuid4())
+        rule = {
+            "id": rule_id,
+            "name": payload.name,
+            "kind": payload.kind,
+            "value": payload.value,
+            "action": payload.action,
+            "enabled": payload.enabled,
+            "priority": payload.priority,
+            "comment": payload.comment,
+            "created_at": timestamp,
+            "updated_at": timestamp,
+        }
+        self.rules[rule_id] = rule
+        return dict(rule)
+
+    def get_rule(self, rule_id: str) -> dict[str, Any]:
+        rule = self.rules.get(rule_id)
+        if rule is None:
+            raise ApiError(404, "not_found", f"Правило {rule_id} не найдено")
+        return dict(rule)
+
+    def update_rule(self, rule_id: str, payload: RoutingRuleUpdate) -> dict[str, Any]:
+        rule = self.get_rule(rule_id)
+        rule.update(payload.model_dump(exclude_unset=True))
+        rule["updated_at"] = _now()
+        self.rules[rule_id] = rule
+        return dict(rule)
+
+    def delete_rule(self, rule_id: str) -> None:
+        if rule_id not in self.rules:
+            raise ApiError(404, "not_found", f"Правило {rule_id} не найдено")
+        del self.rules[rule_id]
+
+    def set_mode(self, mode: str) -> dict[str, Any]:
+        self.mode = mode
+        self.updated_at = _now()
+        return {"mode": mode, "applied_at": _now(), "reconcile_id": str(uuid.uuid4())}
+
+    def update_geoip(self, *, force: bool = False) -> dict[str, Any]:
+        status = "updated" if force or self.geoip["source"] == "none" else "cached"
+        if status == "updated":
+            self.geoip = {
+                "source": "ripe-stat",
+                "prefix_count": GEOIP_PREFIX_COUNT,
+                "updated_at": _now(),
+            }
+        return {
+            "status": status,
+            "source": self.geoip["source"],
+            "prefix_count": self.geoip["prefix_count"],
+            "updated_at": self.geoip["updated_at"] or _now(),
+            "duration_ms": 1870 if status == "updated" else 3,
+        }
+
+    def import_config(self, payload: ImportRequest) -> dict[str, Any]:
+        warnings: list[str] = []
+        peers = 0
+        for line in payload.content.splitlines():
+            stripped = line.strip()
+            if stripped.startswith("[Peer]"):
+                peers += 1
+            elif stripped.startswith("PresharedKey") and payload.format != "json":
+                warnings.append("PresharedKey импортирован в секреты и не будет возвращён в API")
+        return {
+            "imported_peers": peers,
+            "imported_rules": 0,
+            "warnings": warnings,
+        }
+
+    # ------------------------------------------------------------------ devices / logs
+
+    def list_devices(self) -> dict[str, Any]:
+        return {"items": [dict(device) for device in self.devices], "total": len(self.devices)}
+
+    def list_logs(
+        self,
+        *,
+        limit: int = 100,
+        cursor: str | None = None,
+        level: str | None = None,
+        query: str | None = None,
+    ) -> dict[str, Any]:
+        offset = 0
+        if cursor:
+            try:
+                offset = int(cursor)
+            except ValueError as exc:
+                raise ApiError(422, "validation_failed", "Некорректный курсор пагинации") from exc
+        entries = [entry for entry in self.logs if level is None or entry["level"] == level]
+        if query:
+            entries = [entry for entry in entries if query.lower() in entry["message"].lower()]
+        page = entries[offset : offset + limit]
+        next_offset = offset + len(page)
+        return {
+            "items": [dict(entry) for entry in page],
+            "total": len(entries),
+            "next_cursor": str(next_offset) if next_offset < len(entries) else None,
+        }
+
+    # ------------------------------------------------------------------ auth
+
+    def login(self, username: str, password: str) -> dict[str, Any]:
+        if password != self.ui_password:
+            raise ApiError(401, "unauthorized", "Неверные учётные данные")
+        self.username = username
+        self.session_token = str(uuid.uuid4())
+        self.expires_at = (
+            (datetime.now(UTC) + timedelta(hours=12))
+            .isoformat(timespec="seconds")
+            .replace("+00:00", "Z")
+        )
+        return self.get_session()
+
+    def logout(self) -> dict[str, Any]:
+        self.session_token = None
+        self.username = None
+        self.expires_at = None
+        return self.get_session()
+
+    def get_session(self) -> dict[str, Any]:
+        return {
+            "authenticated": self.session_token is not None,
+            "username": self.username,
+            "expires_at": self.expires_at,
+            "csrf_token": self.session_token,
+        }