chore: switch to all-SQLite stack (drop Postgres service)

backend/app/db.py

@@ -1,6 +1,7 @@
 """Database engine, sessions, and FastAPI dependency."""
 
 from collections.abc import Iterator
+from pathlib import Path
 
 from sqlalchemy import Engine
 from sqlmodel import Session, SQLModel, create_engine
@@ -10,11 +11,23 @@ from .settings import settings
 _engine: Engine | None = None
 
 
+def _engine_kwargs(url: str) -> dict:
+    if url.startswith("sqlite"):
+        # FastAPI runs sync endpoints in a threadpool; connections are shared
+        # across threads, so defer the same-thread check. File-based SQLite
+        # needs an existing parent dir (SQLite won't create it).
+        return {"connect_args": {"check_same_thread": False}}
+    return {}
+
+
 def get_engine(url: str | None = None) -> Engine:
     """Process-wide engine singleton (override URL in tests via settings)."""
     global _engine
     if _engine is None:
-        _engine = create_engine(url or settings.database_url)
+        url = url or settings.database_url
+        if url.startswith("sqlite:///") and not url.startswith("sqlite:///:memory:"):
+            Path(url.removeprefix("sqlite:///")).parent.mkdir(parents=True, exist_ok=True)
+        _engine = create_engine(url, **_engine_kwargs(url))
     return _engine
 
 

backend/app/settings.py

@@ -13,10 +13,13 @@ class Settings(BaseSettings):
     version: str = "0.1.0"
     debug: bool = False
 
-    database_url: str = "postgresql+psycopg://kirche:kirche@localhost:5432/kirche_einfach"
-    test_database_url: str = (
-        "postgresql+psycopg://kirche:kirche@localhost:5432/kirche_einfach_test"
-    )
+    # App database (SQLite file). Override via DATABASE_URL for other engines.
+    database_url: str = str(REPO_ROOT / "backend" / "data" / "kirche.db")
+
+    # Canonical flow definitions (source of truth): one Langflow export per file.
+    flows_dir: str = str(REPO_ROOT / "backend" / "flows")
+    # Auto-reconcile backend/flows into the DB + LFX while the API is running.
+    flows_watch_enabled: bool = True
 
     langflow_url: str = "http://localhost:7860"
     langflow_api_key: str = ""