Initial commit

backend/app/db/__init__.py

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+"""Database package exposing engine and session utilities."""

backend/app/db/base.py

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+"""Database engine and session utilities for persistence operations."""
+
+from collections.abc import Generator
+
+from sqlalchemy import create_engine, text
+from sqlalchemy.orm import Session, declarative_base, sessionmaker
+
+from app.core.config import get_settings
+
+
+Base = declarative_base()
+
+
+settings = get_settings()
+engine = create_engine(settings.database_url, pool_pre_ping=True)
+SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False, expire_on_commit=False)
+
+
+def get_session() -> Generator[Session, None, None]:
+    """Provides a transactional database session for FastAPI request handling."""
+
+    session = SessionLocal()
+    try:
+        yield session
+    finally:
+        session.close()
+
+
+def init_db() -> None:
+    """Initializes all ORM tables and search-related database extensions/indexes."""
+
+    from app import models  # noqa: F401
+
+    Base.metadata.create_all(bind=engine)
+    with engine.begin() as connection:
+        connection.execute(text("CREATE EXTENSION IF NOT EXISTS pg_trgm"))
+        connection.execute(
+            text(
+                """
+                CREATE INDEX IF NOT EXISTS idx_documents_text_search
+                ON documents
+                USING GIN (
+                    to_tsvector(
+                        'simple',
+                        coalesce(original_filename, '') || ' ' ||
+                        coalesce(logical_path, '') || ' ' ||
+                        coalesce(extracted_text, '')
+                    )
+                )
+                """
+            )
+        )
+        connection.execute(text("CREATE INDEX IF NOT EXISTS idx_documents_sha256 ON documents (sha256)"))