decomposer: generate deliverable files for Define the service contract and project architecture for the FastAPI endpoint monitoring service.; Implement the typed monitor CRUD API and concurrency-safe in-memory state according to the service design.; Implement secure on-demand endpoint checks with status updates, latency measurement, robust error handling, and redacted structured logs.; Add operational API endpoints and environment-driven runtime configuration to the monitoring service.; Create automated tests for the monitoring service.; Package the service with Docker and developer documentation.; Validate the complete project.

app/models.py

@@ -1,43 +1,60 @@
-from datetime import datetime, timezone
+from datetime import UTC, datetime
 from enum import StrEnum
-from uuid import UUID
+from uuid import UUID, uuid4
 
-from pydantic import BaseModel, ConfigDict, Field, HttpUrl
+from pydantic import BaseModel, ConfigDict, Field, HttpUrl, model_validator
 
 
-def utcnow() -> datetime:
-    return datetime.now(timezone.utc)
+def now_utc() -> datetime:
+    return datetime.now(UTC)
 
 
 class State(StrEnum):
-    UNKNOWN = "unknown"
+    NEVER_CHECKED = "never_checked"
     UP = "up"
     DOWN = "down"
     ERROR = "error"
+    BLOCKED = "blocked"
 
 
-class MonitorInput(BaseModel):
-    model_config = ConfigDict(str_strip_whitespace=True)
-
+class MonitorCreate(BaseModel):
     name: str = Field(min_length=1, max_length=100)
     url: HttpUrl
+    expected_status: int = Field(default=200, ge=100, le=599)
+
+
+class MonitorUpdate(BaseModel):
+    name: str | None = Field(default=None, min_length=1, max_length=100)
+    url: HttpUrl | None = None
+    expected_status: int | None = Field(default=None, ge=100, le=599)
+
+    @model_validator(mode="after")
+    def not_empty(self) -> "MonitorUpdate":
+        if not self.model_fields_set:
+            raise ValueError("at least one field is required")
+        return self
 
 
 class CurrentStatus(BaseModel):
-    state: State = State.UNKNOWN
+    model_config = ConfigDict(frozen=True)
+
+    state: State = State.NEVER_CHECKED
     checked_at: datetime | None = None
-    latency_ms: float | None = Field(default=None, ge=0)
-    status_code: int | None = Field(default=None, ge=100, le=599)
-    error_code: str | None = None
+    observed_status: int | None = None
+    latency_ms: float | None = None
+    error: str | None = None
 
 
 class Monitor(BaseModel):
-    id: UUID
+    model_config = ConfigDict(frozen=True)
+
+    id: UUID = Field(default_factory=uuid4)
     name: str
     url: HttpUrl
-    created_at: datetime
-    updated_at: datetime
-    current_status: CurrentStatus
+    expected_status: int
+    created_at: datetime = Field(default_factory=now_utc)
+    updated_at: datetime = Field(default_factory=now_utc)
+    current_status: CurrentStatus = Field(default_factory=CurrentStatus)
 
 
 class CheckResult(CurrentStatus):
@@ -49,5 +66,5 @@ class ErrorBody(BaseModel):
     message: str
 
 
-class ErrorEnvelope(BaseModel):
+class ErrorResponse(BaseModel):
     error: ErrorBody