feat(backend): implement postgres job queue

backend/config/__init__.py

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+

backend/config/asgi.py

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+import os
+
+from django.core.asgi import get_asgi_application
+
+os.environ.setdefault("DJANGO_SETTINGS_MODULE", "config.settings")
+
+application = get_asgi_application()

backend/config/settings.py

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+import os
+from pathlib import Path
+
+from dotenv import load_dotenv
+
+load_dotenv()
+
+BASE_DIR = Path(__file__).resolve().parent.parent
+
+SECRET_KEY = os.getenv("DJANGO_SECRET_KEY", "django-insecure-job-queue-local-dev-key")
+DEBUG = os.getenv("DEBUG", "true").lower() in {"1", "true", "yes"}
+ALLOWED_HOSTS = [host.strip() for host in os.getenv("DJANGO_ALLOWED_HOSTS", "localhost,127.0.0.1,0.0.0.0").split(",")]
+
+INSTALLED_APPS = [
+    "django.contrib.admin",
+    "django.contrib.auth",
+    "django.contrib.contenttypes",
+    "django.contrib.sessions",
+    "django.contrib.messages",
+    "django.contrib.staticfiles",
+    "corsheaders",
+    "rest_framework",
+    "drf_spectacular",
+    "jobs",
+]
+
+MIDDLEWARE = [
+    "django.middleware.security.SecurityMiddleware",
+    "corsheaders.middleware.CorsMiddleware",
+    "django.contrib.sessions.middleware.SessionMiddleware",
+    "django.middleware.common.CommonMiddleware",
+    "django.middleware.csrf.CsrfViewMiddleware",
+    "django.contrib.auth.middleware.AuthenticationMiddleware",
+    "django.contrib.messages.middleware.MessageMiddleware",
+    "django.middleware.clickjacking.XFrameOptionsMiddleware",
+]
+
+ROOT_URLCONF = "config.urls"
+
+TEMPLATES = [
+    {
+        "BACKEND": "django.template.backends.django.DjangoTemplates",
+        "DIRS": [],
+        "APP_DIRS": True,
+        "OPTIONS": {
+            "context_processors": [
+                "django.template.context_processors.debug",
+                "django.template.context_processors.request",
+                "django.contrib.auth.context_processors.auth",
+                "django.contrib.messages.context_processors.messages",
+            ],
+        },
+    }
+]
+
+WSGI_APPLICATION = "config.wsgi.application"
+ASGI_APPLICATION = "config.asgi.application"
+
+if os.getenv("TEST_DATABASE_ENGINE") == "sqlite":
+    DATABASES = {
+        "default": {
+            "ENGINE": "django.db.backends.sqlite3",
+            "NAME": BASE_DIR / "test.sqlite3",
+        }
+    }
+else:
+    DATABASES = {
+        "default": {
+            "ENGINE": "django.db.backends.postgresql",
+            "NAME": os.getenv("POSTGRES_DB", "job_queue"),
+            "USER": os.getenv("POSTGRES_USER", "postgres"),
+            "PASSWORD": os.getenv("POSTGRES_PASSWORD", "postgres"),
+            "HOST": os.getenv("POSTGRES_HOST", "localhost"),
+            "PORT": os.getenv("POSTGRES_PORT", "5432"),
+            "CONN_MAX_AGE": int(os.getenv("POSTGRES_CONN_MAX_AGE", "0")),
+        }
+    }
+
+AUTH_PASSWORD_VALIDATORS = [
+    {"NAME": "django.contrib.auth.password_validation.UserAttributeSimilarityValidator"},
+    {"NAME": "django.contrib.auth.password_validation.MinimumLengthValidator"},
+    {"NAME": "django.contrib.auth.password_validation.CommonPasswordValidator"},
+    {"NAME": "django.contrib.auth.password_validation.NumericPasswordValidator"},
+]
+
+LANGUAGE_CODE = "en-us"
+TIME_ZONE = os.getenv("TIME_ZONE", "Asia/Tehran")
+USE_I18N = True
+USE_TZ = True
+
+STATIC_URL = "/static/"
+STATIC_ROOT = BASE_DIR / "staticfiles"
+
+DEFAULT_AUTO_FIELD = "django.db.models.BigAutoField"
+
+CORS_ALLOW_ALL_ORIGINS = DEBUG
+CORS_ALLOWED_ORIGINS = [
+    origin.strip()
+    for origin in os.getenv("DJANGO_CORS_ALLOWED_ORIGINS", "http://localhost:5173,http://127.0.0.1:5173").split(",")
+    if origin.strip()
+]
+
+REST_FRAMEWORK = {
+    "DEFAULT_AUTHENTICATION_CLASSES": [],
+    "DEFAULT_PERMISSION_CLASSES": ["rest_framework.permissions.AllowAny"],
+    "DEFAULT_SCHEMA_CLASS": "drf_spectacular.openapi.AutoSchema",
+}
+
+SPECTACULAR_SETTINGS = {
+    "TITLE": "Minimal Job Queue API",
+    "DESCRIPTION": "PostgreSQL-backed job queue with safe claiming and deterministic state transitions.",
+    "VERSION": "1.0.0",
+    "SERVE_INCLUDE_SCHEMA": False,
+}
+
+JOB_WORKER_THREADS = int(os.getenv("JOB_WORKER_THREADS", "4"))
+JOB_WORKER_POLL_INTERVAL_MS = int(os.getenv("JOB_WORKER_POLL_INTERVAL_MS", "500"))
+JOB_WORKER_LEASE_SECONDS = int(os.getenv("JOB_WORKER_LEASE_SECONDS", "30"))
+JOB_WORKER_CLEANUP_INTERVAL_SECONDS = int(os.getenv("JOB_WORKER_CLEANUP_INTERVAL_SECONDS", "5"))
+JOB_WORKER_CLEANUP_BATCH_SIZE = int(os.getenv("JOB_WORKER_CLEANUP_BATCH_SIZE", "100"))
+JOB_WORKER_BACKOFF_BASE_SECONDS = int(os.getenv("JOB_WORKER_BACKOFF_BASE_SECONDS", "5"))
+JOB_WORKER_BACKOFF_MAX_SECONDS = int(os.getenv("JOB_WORKER_BACKOFF_MAX_SECONDS", "300"))
+JOB_WORKER_MAX_ATTEMPTS_DEFAULT = int(os.getenv("JOB_WORKER_MAX_ATTEMPTS_DEFAULT", "3"))

backend/config/urls.py

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+from django.contrib import admin
+from django.urls import include, path
+from drf_spectacular.views import SpectacularAPIView, SpectacularSwaggerView
+from rest_framework.response import Response
+from rest_framework.views import APIView
+
+from jobs.views import HealthAPIView
+
+
+class ConfigAPIView(APIView):
+    def get(self, request):
+        return Response(
+            {
+                "default_priority": 50,
+                "job_types": [
+                    "demo.success",
+                    "demo.fail",
+                    "demo.slow",
+                    "demo.timeout",
+                    "demo.flaky",
+                ],
+            }
+        )
+
+
+urlpatterns = [
+    path("admin/", admin.site.urls),
+    path("api/schema/", SpectacularAPIView.as_view(), name="schema"),
+    path("api/docs/", SpectacularSwaggerView.as_view(url_name="schema"), name="swagger-ui"),
+    path("api/health/", HealthAPIView.as_view(), name="health"),
+    path("api/config/", ConfigAPIView.as_view(), name="config"),
+    path("api/", include("jobs.urls")),
+]

backend/config/wsgi.py

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+import os
+
+from django.core.wsgi import get_wsgi_application
+
+os.environ.setdefault("DJANGO_SETTINGS_MODULE", "config.settings")
+
+application = get_wsgi_application()