diff --git a/app/models.py b/app/models.py
index d3c8f4a..3d2910a 100644
--- a/app/models.py
+++ b/app/models.py
@@ -1,33 +1,34 @@
 from datetime import datetime
-from enum import StrEnum
+from typing import Literal
 from uuid import UUID
 
-from pydantic import AnyHttpUrl, BaseModel, ConfigDict, Field
+from pydantic import AnyHttpUrl, BaseModel, ConfigDict, Field, model_validator
+
+StatusState = Literal["unknown", "up", "down", "error"]
 
 
-class MonitorState(StrEnum):
-    UNKNOWN = "unknown"
-    UP = "up"
-    DOWN = "down"
-    ERROR = "error"
-    BLOCKED = "blocked"
+class CheckStatus(BaseModel):
+    state: StatusState = "unknown"
+    checked_at: datetime | None = None
+    status_code: int | None = None
+    latency_ms: float | None = Field(default=None, ge=0)
+    error: str | None = None
 
 
 class MonitorCreate(BaseModel):
-    name: str = Field(min_length=1, max_length=100)
+    name: str = Field(min_length=1, max_length=200)
     url: AnyHttpUrl
 
 
-class MonitorUpdate(MonitorCreate):
-    pass
+class MonitorUpdate(BaseModel):
+    name: str | None = Field(default=None, min_length=1, max_length=200)
+    url: AnyHttpUrl | None = None
 
-
-class StatusSnapshot(BaseModel):
-    state: MonitorState = MonitorState.UNKNOWN
-    checked_at: datetime | None = None
-    latency_ms: float | None = Field(default=None, ge=0)
-    http_status: int | None = Field(default=None, ge=100, le=599)
-    error: str | None = None
+    @model_validator(mode="after")
+    def not_empty(self) -> "MonitorUpdate":
+        if self.name is None and self.url is None:
+            raise ValueError("at least one field is required")
+        return self
 
 
 class Monitor(BaseModel):
@@ -38,8 +39,13 @@ class Monitor(BaseModel):
     url: AnyHttpUrl
     created_at: datetime
     updated_at: datetime
-    status: StatusSnapshot
+    status: CheckStatus
 
 
-class Health(BaseModel):
-    status: str
+class CheckResult(CheckStatus):
+    monitor_id: UUID
+    status_applied: bool = True
+
+
+class HealthResponse(BaseModel):
+    status: Literal["ok", "ready"]