decomposer: generate deliverable files for Implement the task REST API service with FastAPI, including standard CRUD endpoints, HTTP status semantics, request and response models, and structured error handling.; Add a PostgreSQL persistence layer for the task service using SQLAlchemy models, session management, database initialization or migrations, and durable task storage integrated with the existing API contract.; Define and integrate Pydantic request and response schemas for task fields, status values, identifiers, timestamps, and validation errors across the existing FastAPI service and persistence contract.; Add automated pytest coverage for the task API, including CRUD behavior, request and response validation failures, HTTP status semantics, and persistence interactions using isolated test data.; Containerize the FastAPI task service and PostgreSQL persistence service with Docker Compose, including environment-based configuration, health checks, networking, startup dependencies, and persistent database storage.; Create project documentation and operational guidance covering local setup, Docker Compose configuration, environment variables, API endpoints, validation and error responses, testing commands, persistence behavior, and relevant best-practice notes.

app/schemas.py

@@ -0,0 +1,64 @@
+from datetime import datetime
+from uuid import UUID
+
+from pydantic import BaseModel, ConfigDict, Field, field_validator
+
+from .models import TaskStatus
+
+
+class TaskBase(BaseModel):
+    title: str = Field(min_length=1, max_length=200)
+    description: str | None = Field(default=None, max_length=5000)
+    status: TaskStatus = TaskStatus.pending
+    due_at: datetime | None = None
+
+    @field_validator("title")
+    @classmethod
+    def title_not_blank(cls, value: str) -> str:
+        value = value.strip()
+        if not value:
+            raise ValueError("title must not be blank")
+        return value
+
+
+class TaskCreate(TaskBase):
+    pass
+
+
+class TaskUpdate(BaseModel):
+    title: str | None = Field(default=None, min_length=1, max_length=200)
+    description: str | None = Field(default=None, max_length=5000)
+    status: TaskStatus | None = None
+    due_at: datetime | None = None
+
+    @field_validator("title")
+    @classmethod
+    def title_not_blank(cls, value: str | None) -> str | None:
+        if value is not None:
+            value = value.strip()
+            if not value:
+                raise ValueError("title must not be blank")
+        return value
+
+
+class TaskRead(TaskBase):
+    id: UUID
+    created_at: datetime
+    updated_at: datetime
+    model_config = ConfigDict(from_attributes=True)
+
+
+class ErrorDetail(BaseModel):
+    loc: list[str | int] = []
+    msg: str
+    type: str | None = None
+
+
+class ErrorBody(BaseModel):
+    code: str
+    message: str
+    details: list[ErrorDetail] = []
+
+
+class ErrorResponse(BaseModel):
+    error: ErrorBody