fix: second round review fixes for account merge

- Rename _compute_auth_methods to compute_auth_methods (public API)
- Add Literal type to _handle_subscription_merge param
- Add Literal type to keep_from in route handler
- Add Path(min_length=32, max_length=64) on merge_token params
- Import Path and Literal in account_linking routes

app/cabinet/routes/account_linking.py

@@ -5,10 +5,10 @@ Router 2 (`merge_router`): Public endpoints for merge preview and execution.
 """
 
 from datetime import UTC, datetime
-from typing import Any
+from typing import Any, Literal
 
 import structlog
-from fastapi import APIRouter, Depends, HTTPException, status
+from fastapi import APIRouter, Depends, HTTPException, Path, status
 from pydantic import BaseModel, Field
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -18,7 +18,7 @@ from app.database.crud.user import (
     set_user_oauth_provider_id,
 )
 from app.database.models import User
-from app.services.account_merge_service import _compute_auth_methods, execute_merge, get_merge_preview
+from app.services.account_merge_service import compute_auth_methods, execute_merge, get_merge_preview
 
 from ..auth.merge_service import (
     MERGE_TOKEN_TTL_SECONDS,
@@ -137,7 +137,7 @@ def _get_provider_identifier(user: User, provider: str) -> str | None:
 
 def _count_auth_methods(user: User) -> int:
     """Count how many auth methods the user has linked."""
-    return len(_compute_auth_methods(user))
+    return len(compute_auth_methods(user))
 
 
 # ---------------------------------------------------------------------------
@@ -364,7 +364,7 @@ merge_router = APIRouter(prefix='/auth/merge', tags=['Cabinet Account Merge'])
 
 @merge_router.get('/{merge_token}', response_model=MergePreviewResponse)
 async def get_merge_preview_endpoint(
-    merge_token: str,
+    merge_token: str = Path(..., min_length=32, max_length=64),
     db: AsyncSession = Depends(get_cabinet_db),
 ) -> MergePreviewResponse:
     """Preview the result of merging two accounts before confirming."""
@@ -407,8 +407,8 @@ async def get_merge_preview_endpoint(
 
 @merge_router.post('/{merge_token}', response_model=MergeResponse)
 async def execute_merge_endpoint(
-    merge_token: str,
     request: MergeRequest,
+    merge_token: str = Path(..., min_length=32, max_length=64),
     db: AsyncSession = Depends(get_cabinet_db),
 ) -> MergeResponse:
     """Execute account merge. Consumes the merge token (one-time use)."""
@@ -433,7 +433,7 @@ async def execute_merge_endpoint(
         )
 
     # Convert user_id to 'primary'/'secondary' string for execute_merge()
-    keep_from: str = 'primary' if request.keep_subscription_from == primary_user_id else 'secondary'
+    keep_from: Literal['primary', 'secondary'] = 'primary' if request.keep_subscription_from == primary_user_id else 'secondary'
 
     # 3. Execute merge
     try:

app/services/account_merge_service.py

@@ -60,7 +60,7 @@ _PARTNER_STATUS_PRIORITY: dict[str, int] = {
 }
 
 
-def _compute_auth_methods(user: User) -> list[str]:
+def compute_auth_methods(user: User) -> list[str]:
     """Вычисляет список методов авторизации пользователя."""
     methods: list[str] = []
     if user.telegram_id:
@@ -104,7 +104,7 @@ def _build_user_preview(user: User) -> dict[str, Any]:
         'username': user.username,
         'first_name': user.first_name,
         'email': user.email,
-        'auth_methods': _compute_auth_methods(user),
+        'auth_methods': compute_auth_methods(user),
         'balance_kopeks': user.balance_kopeks,
         'subscription': _build_subscription_preview(user.subscription),
         'created_at': user.created_at,
@@ -214,7 +214,7 @@ async def _handle_subscription_merge(
     db: AsyncSession,
     primary: User,
     secondary: User,
-    keep_subscription_from: str,
+    keep_subscription_from: Literal['primary', 'secondary'],
 ) -> None:
     """Обрабатывает мерж подписок между двумя аккаунтами.
 

tests/services/test_account_merge_service.py

@@ -10,7 +10,7 @@ from app.services import account_merge_service
 from app.services.account_merge_service import (
     _build_subscription_preview,
     _build_user_preview,
-    _compute_auth_methods,
+    compute_auth_methods,
     execute_merge,
     get_merge_preview,
 )
@@ -105,26 +105,26 @@ def _make_db() -> SimpleNamespace:
 
 
 # ---------------------------------------------------------------------------
-# _compute_auth_methods
+# compute_auth_methods
 # ---------------------------------------------------------------------------
 
 
 class TestComputeAuthMethods:
     def test_no_methods(self):
         user = _make_user()
-        assert _compute_auth_methods(user) == []
+        assert compute_auth_methods(user) == []
 
     def test_telegram_only(self):
         user = _make_user(telegram_id=12345)
-        assert _compute_auth_methods(user) == ['telegram']
+        assert compute_auth_methods(user) == ['telegram']
 
     def test_email_only(self):
         user = _make_user(email='test@example.com', password_hash='hash123')
-        assert _compute_auth_methods(user) == ['email']
+        assert compute_auth_methods(user) == ['email']
 
     def test_email_without_password_not_counted(self):
         user = _make_user(email='test@example.com')
-        assert _compute_auth_methods(user) == []
+        assert compute_auth_methods(user) == []
 
     def test_all_methods(self):
         user = _make_user(
@@ -136,11 +136,11 @@ class TestComputeAuthMethods:
             discord_id='d123',
             vk_id=99999,
         )
-        assert _compute_auth_methods(user) == ['telegram', 'email', 'google', 'yandex', 'discord', 'vk']
+        assert compute_auth_methods(user) == ['telegram', 'email', 'google', 'yandex', 'discord', 'vk']
 
     def test_oauth_only(self):
         user = _make_user(google_id='g123', discord_id='d123')
-        assert _compute_auth_methods(user) == ['google', 'discord']
+        assert compute_auth_methods(user) == ['google', 'discord']
 
 
 # ---------------------------------------------------------------------------