Task 001: dockerized monorepo foundation

apps/backend/Dockerfile

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+FROM python:3.12-slim
+
+ENV PYTHONDONTWRITEBYTECODE=1
+ENV PYTHONUNBUFFERED=1
+
+WORKDIR /app
+
+COPY apps/backend/requirements.txt ./requirements.txt
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY apps/backend/src ./src
+
+EXPOSE 8000
+
+CMD ["uvicorn", "src.presentation.main:app", "--host", "0.0.0.0", "--port", "8000"]

apps/backend/requirements.txt

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+fastapi==0.115.6
+uvicorn[standard]==0.34.0
+psycopg[binary]==3.2.3
+redis==5.2.1
+boto3==1.35.90

apps/backend/src/__init__.py

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+"""Backend service package."""

apps/backend/src/application/README.md

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+# Application
+
+Application use cases and workflow orchestration belong in this layer.

apps/backend/src/application/__init__.py

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+"""Application layer for use cases and orchestration."""

apps/backend/src/domain/README.md

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+# Domain
+
+Business entities, value objects, and domain rules belong in this layer.

apps/backend/src/domain/__init__.py

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+"""Domain layer for business concepts and invariants."""

apps/backend/src/infrastructure/README.md

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+# Infrastructure
+
+Database, cache, object storage, queue, and other external adapters belong in
+this layer.

apps/backend/src/infrastructure/__init__.py

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+"""Infrastructure adapters for external services."""

apps/backend/src/infrastructure/dependencies.py

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+from __future__ import annotations
+
+import os
+from collections.abc import Callable
+
+import boto3
+import psycopg
+from botocore.config import Config
+from redis import Redis
+
+
+DependencyStatus = dict[str, str]
+
+
+def check_dependencies() -> DependencyStatus:
+    checks: dict[str, Callable[[], None]] = {
+        "postgres": _check_postgres,
+        "redis": _check_redis,
+        "object_storage": _check_object_storage,
+    }
+
+    results: DependencyStatus = {}
+    for name, check in checks.items():
+        try:
+            check()
+        except Exception:
+            results[name] = "error"
+        else:
+            results[name] = "ok"
+
+    return results
+
+
+def _check_postgres() -> None:
+    dsn = _required_env("POSTGRES_DSN")
+    with psycopg.connect(dsn, connect_timeout=3) as connection:
+        with connection.cursor() as cursor:
+            cursor.execute("SELECT 1")
+            cursor.fetchone()
+
+
+def _check_redis() -> None:
+    redis_url = _required_env("REDIS_URL")
+    client = Redis.from_url(redis_url, socket_connect_timeout=3, socket_timeout=3)
+    try:
+        if client.ping() is not True:
+            raise RuntimeError("Redis ping failed")
+    finally:
+        client.close()
+
+
+def _check_object_storage() -> None:
+    endpoint = _required_env("OBJECT_STORAGE_ENDPOINT")
+    access_key_id = _required_env("OBJECT_STORAGE_ACCESS_KEY_ID")
+    secret_access_key = _required_env("OBJECT_STORAGE_SECRET_ACCESS_KEY")
+    bucket = _required_env("OBJECT_STORAGE_BUCKET")
+    region = os.environ.get("OBJECT_STORAGE_REGION", "us-east-1")
+
+    client = boto3.client(
+        "s3",
+        endpoint_url=endpoint,
+        aws_access_key_id=access_key_id,
+        aws_secret_access_key=secret_access_key,
+        region_name=region,
+        config=Config(signature_version="s3v4", connect_timeout=3, read_timeout=3),
+    )
+    client.head_bucket(Bucket=bucket)
+
+
+def _required_env(name: str) -> str:
+    value = os.environ.get(name)
+    if not value:
+        raise RuntimeError(f"Missing required environment variable: {name}")
+    return value

apps/backend/src/presentation/README.md

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+# Presentation
+
+HTTP routes, request/response DTOs, and API wiring belong in this layer.

apps/backend/src/presentation/__init__.py

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+"""Presentation layer for HTTP APIs."""

apps/backend/src/presentation/main.py

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+from fastapi import FastAPI
+from fastapi.responses import JSONResponse
+
+from src.infrastructure.dependencies import check_dependencies
+
+
+app = FastAPI(title="AI Content Pipeline Backend")
+
+
+@app.get("/health")
+def health() -> dict[str, str]:
+    return {"service": "backend", "status": "ok"}
+
+
+@app.get("/health/dependencies")
+def dependency_health() -> JSONResponse:
+    dependencies = check_dependencies()
+    is_ok = all(status == "ok" for status in dependencies.values())
+
+    return JSONResponse(
+        status_code=200 if is_ok else 503,
+        content={
+            "service": "backend",
+            "status": "ok" if is_ok else "error",
+            "dependencies": dependencies,
+        },
+    )

apps/backend/src/shared/README.md

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+# Shared
+
+Cross-layer backend primitives belong here. Keep this layer small and avoid
+placing domain rules in shared code.

apps/backend/src/shared/__init__.py

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+"""Shared backend primitives."""