feat: add push_dag and get_dag methods to SiloClient

- push_dag(part_number, revision_number, nodes, edges): PUT /api/items/{pn}/dag
- get_dag(part_number, revision_number=None): GET /api/items/{pn}/dag

Closes kindred/create#215

silo_client/__init__.py

@@ -844,16 +844,7 @@ class SiloClient:
     def delete_bom_entry(self, parent_pn: str, child_pn: str) -> None:
         ppn = urllib.parse.quote(parent_pn, safe="")
         cpn = urllib.parse.quote(child_pn, safe="")
-        url = f"{self.base_url}/items/{ppn}/bom/{cpn}"
-        headers = {"Content-Type": "application/json"}
-        headers.update(self._auth_headers())
-        req = urllib.request.Request(url, headers=headers, method="DELETE")
-        try:
-            urllib.request.urlopen(req, context=self._ssl_context())
-        except urllib.error.HTTPError as e:
-            raise RuntimeError(f"API error {e.code}: {e.read().decode()}")
-        except urllib.error.URLError as e:
-            raise RuntimeError(f"Connection error: {e.reason}")
+        self._request("DELETE", f"/items/{ppn}/bom/{cpn}", raw=True)
 
     # -- Schemas ------------------------------------------------------------
 
@@ -911,3 +902,42 @@ class SiloClient:
         self, ods_bytes: bytes, filename: str = "sheet.ods"
     ) -> Dict[str, Any]:
         return self._upload_ods("/sheets/diff", ods_bytes, filename)
+
+    # -- DAG (feature tree) -------------------------------------------------
+
+    def push_dag(
+        self,
+        part_number: str,
+        revision_number: int,
+        nodes: List[Dict[str, Any]],
+        edges: List[Dict[str, Any]],
+    ) -> Dict[str, Any]:
+        """Push a feature DAG to the server.
+
+        Calls ``PUT /api/items/{partNumber}/dag`` with the payload
+        described in ``MULTI_USER_CLIENT.md`` Section 2.
+        """
+        pn = urllib.parse.quote(part_number, safe="")
+        return self._request(
+            "PUT",
+            f"/items/{pn}/dag",
+            {
+                "revision_number": revision_number,
+                "nodes": nodes,
+                "edges": edges,
+            },
+        )
+
+    def get_dag(
+        self, part_number: str, revision_number: Optional[int] = None
+    ) -> Dict[str, Any]:
+        """Fetch the stored DAG for an item.
+
+        Calls ``GET /api/items/{partNumber}/dag``, optionally filtered
+        by *revision_number*.
+        """
+        pn = urllib.parse.quote(part_number, safe="")
+        path = f"/items/{pn}/dag"
+        if revision_number is not None:
+            path += f"?revision={revision_number}"
+        return self._request("GET", path)