Graph access via SPARQL

backend/app/sparql_engine.py

@@ -56,6 +56,7 @@ class AnzoGraphEngine:
         self.timeout_s = settings.sparql_timeout_s
         self.ready_retries = settings.sparql_ready_retries
         self.ready_delay_s = settings.sparql_ready_delay_s
+        self.ready_timeout_s = settings.sparql_ready_timeout_s
 
         self.user = settings.sparql_user
         self.password = settings.sparql_pass
@@ -135,15 +136,34 @@ class AnzoGraphEngine:
         resp.raise_for_status()
 
     async def _wait_ready(self) -> None:
+        if self._client is None:
+            raise RuntimeError("AnzoGraphEngine not started")
+
+        # Match the repo's Julia readiness gate: real SPARQL POST + valid JSON parse.
+        headers = {
+            "Content-Type": "application/x-www-form-urlencoded",
+            "Accept": "application/sparql-results+json",
+        }
+        if self._auth_header:
+            headers["Authorization"] = self._auth_header
+
         last_err: Exception | None = None
         for _ in range(self.ready_retries):
             try:
-                # Keep it cheap and JSON-parseable.
-                await self.query_json("ASK WHERE { ?s ?p ?o }")
+                resp = await self._client.post(
+                    self.endpoint,
+                    headers=headers,
+                    data={"query": "ASK WHERE { ?s ?p ?o }"},
+                    timeout=self.ready_timeout_s,
+                )
+                resp.raise_for_status()
+                # Ensure it's JSON, not HTML/text during boot.
+                resp.json()
                 return
             except Exception as e:
                 last_err = e
                 await asyncio.sleep(self.ready_delay_s)
+
         raise RuntimeError(f"AnzoGraph not ready at {self.endpoint}") from last_err