Implement FastAPI Temporal MVP pipeline

app/infra/temporal/client.py

@@ -0,0 +1,35 @@
+"""Temporal client helpers."""
+
+import asyncio
+
+from temporalio.client import Client
+
+from app.config.settings import get_settings
+
+_client: Client | None = None
+_client_lock = asyncio.Lock()
+
+
+async def get_temporal_client() -> Client:
+    """Return a cached Temporal client."""
+
+    global _client
+    if _client is not None:
+        return _client
+
+    async with _client_lock:
+        if _client is None:
+            settings = get_settings()
+            _client = await Client.connect(
+                settings.temporal_address,
+                namespace=settings.temporal_namespace,
+            )
+    return _client
+
+
+def set_temporal_client(client: Client | None) -> None:
+    """Override the cached Temporal client, primarily for tests."""
+
+    global _client
+    _client = client
+