施工(HEL-226): 实现登录门户与本机免密切换账号

用设备 Cookie 和授权表记住本机已验证账号，登录页按确认样图做成门户，不再把密码写进浏览器。

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

backend/features/accounts/service.py

@@ -77,15 +77,22 @@ class AccountService:
         access = self.access_supplier() or self.database.user_access(self.current_user_id) or {}
         return self.membership_for_access(access)
 
-    def register(self, username: str, password: str) -> dict[str, Any]:
+    GRANT_SLIDE_DAYS = 30
+    GRANT_HARD_DAYS = 180
+    MAX_GRANTS_PER_DEVICE = 5
+    SWITCH_REAUTH_MESSAGE = "该账号需重新验证"
+
+    def register(self, username: str, password: str, device_hash: str = "") -> dict[str, Any]:
         username = username.strip()
         self.validate_input(username, password)
         with self.auth_lock:
             salt, password_digest = hash_password(password)
             user = self.database.create_user(username, salt, password_digest)
-        return self.create_session(user)
+        result = self.create_session(user)
+        self.remember_account(device_hash, int(user["id"]), fresh=True)
+        return result
 
-    def login(self, username: str, password: str) -> dict[str, Any]:
+    def login(self, username: str, password: str, device_hash: str = "") -> dict[str, Any]:
         username = username.strip()
         if not username or not password:
             raise ValueError("账号名和密码不能为空。")
@@ -96,7 +103,9 @@ class AccountService:
             str(user.get("password_hash") or ""),
         ):
             raise ValueError("账号名或密码不正确。")
-        return self.create_session(user)
+        result = self.create_session(user)
+        self.remember_account(device_hash, int(user["id"]), fresh=True)
+        return result
 
     def change_password(self, current_password: str, new_password: str) -> None:
         current_password = str(current_password or "")
@@ -112,6 +121,86 @@ class AccountService:
         salt, digest = hash_password(new_password)
         if not self.database.update_user_password(self.current_user_id, salt, digest):
             raise ValueError("账号不存在。")
+        self.database.delete_switch_grants_for_user(self.current_user_id)
+
+    @staticmethod
+    def _utc_now() -> datetime:
+        return datetime.now(timezone.utc)
+
+    @classmethod
+    def _iso(cls, value: datetime) -> str:
+        return value.isoformat(timespec="seconds")
+
+    def remember_account(self, device_hash: str, user_id: int, *, fresh: bool = False) -> None:
+        if not device_hash or user_id <= 0:
+            return
+        now = self._utc_now()
+        now_text = self._iso(now)
+        self.database.cleanup_expired_switch_grants(now_text)
+        existing = None if fresh else self.database.get_switch_grant(device_hash, user_id)
+        granted_at = parse_iso_datetime(existing["granted_at"]) if existing else now
+        if granted_at is None:
+            granted_at = now
+        expires = min(
+            now + timedelta(days=self.GRANT_SLIDE_DAYS),
+            granted_at + timedelta(days=self.GRANT_HARD_DAYS),
+        )
+        if not existing:
+            self.database.prune_switch_grants(device_hash, self.MAX_GRANTS_PER_DEVICE - 1)
+        self.database.upsert_switch_grant(
+            device_hash,
+            user_id,
+            self._iso(granted_at),
+            now_text,
+            self._iso(expires),
+        )
+
+    def list_device_accounts(
+        self, device_hash: str, current_user_id: int | None = None
+    ) -> dict[str, Any]:
+        if not device_hash:
+            return {"accounts": [], "current_user_id": current_user_id}
+        now_text = self._iso(self._utc_now())
+        self.database.cleanup_expired_switch_grants(now_text)
+        accounts = []
+        for row in self.database.list_switch_grants(device_hash, now_text):
+            accounts.append(
+                {
+                    "user_id": int(row["id"]),
+                    "username": str(row["username"]),
+                    "role": str(row.get("role") or "user"),
+                    "membership": self.membership_for_access(row),
+                    "last_used_at": str(row.get("last_used_at") or ""),
+                }
+            )
+        return {"accounts": accounts, "current_user_id": current_user_id}
+
+    def switch_account(self, device_hash: str, user_id: int) -> dict[str, Any]:
+        if not device_hash or user_id <= 0:
+            raise PermissionError(self.SWITCH_REAUTH_MESSAGE)
+        now = self._utc_now()
+        now_text = self._iso(now)
+        self.database.cleanup_expired_switch_grants(now_text)
+        grant = self.database.get_switch_grant(device_hash, user_id)
+        expires = parse_iso_datetime(grant.get("expires_at")) if grant else None
+        if not grant or not expires or expires <= now:
+            if grant:
+                self.database.delete_switch_grant(device_hash, user_id)
+            raise PermissionError(self.SWITCH_REAUTH_MESSAGE)
+        user = self.database.user_access(user_id)
+        if not user:
+            raise PermissionError(self.SWITCH_REAUTH_MESSAGE)
+        result = self.create_session(user)
+        self.remember_account(device_hash, user_id)
+        return result
+
+    def forget_account(self, device_hash: str, user_id: int) -> None:
+        if device_hash and user_id > 0:
+            self.database.delete_switch_grant(device_hash, user_id)
+
+    def revoke_current_device_grant(self, device_hash: str, user_id: int) -> None:
+        if device_hash and user_id > 0:
+            self.database.delete_switch_grant(device_hash, user_id)
 
     def create_session(self, user: dict[str, Any]) -> dict[str, Any]:
         session_token = secrets.token_urlsafe(32)