feat: add portfolio graph enrichment

app/infrastructure/neo4j_graph_driver.py

@@ -0,0 +1,27 @@
+"""Bounded Neo4j adapter used only behind RelationshipService."""
+
+import asyncio
+from collections.abc import Sequence
+from typing import Any
+
+from neo4j import AsyncGraphDatabase
+
+from app.core.config import Settings
+
+
+class Neo4jGraphDriver:
+    def __init__(self, settings: Settings, *, timeout_seconds: float = 2.0) -> None:
+        self.settings = settings
+        self.timeout_seconds = timeout_seconds
+        self._driver: Any = None
+
+    async def execute_query(self, query: str, **parameters: Any) -> Sequence[Any]:
+        if self._driver is None:
+            self._driver = AsyncGraphDatabase.driver(
+                self.settings.neo4j_uri,
+                auth=(self.settings.neo4j_username, self.settings.neo4j_password),
+            )
+        async with asyncio.timeout(self.timeout_seconds):
+            async with self._driver.session(database=self.settings.neo4j_database) as session:
+                result = await session.run(query, parameters)
+                return [record.data() async for record in result]