fix: tolerate empty body on legacy delete_document

delete_document unconditionally called response.json(), so a successful
DELETE that returns 200 with an empty body (the documented examples don't
consume one, and REST APIs commonly return no content for deletes) would
raise JSONDecodeError even though the document was already deleted. Return
{} when the response has no content, else parse the JSON body as before.

tests/test_legacy_sdk_contract.py

@@ -1,3 +1,5 @@
+import json
+
 import pytest
 import requests
 
@@ -7,14 +9,18 @@ from pageindex.client import CloudClient
 
 
 class FakeResponse:
-    def __init__(self, status_code=200, payload=None, text="ok", lines=None):
+    def __init__(self, status_code=200, payload=None, text="ok", lines=None, content=b"{}"):
         self.status_code = status_code
         self._payload = payload or {}
         self.text = text
         self._lines = lines or []
         self.closed = False
+        # Raw body bytes; empty bytes model a no-content success (e.g. DELETE).
+        self.content = content
 
     def json(self):
+        if not self.content:
+            raise json.JSONDecodeError("Expecting value", "", 0)
         return self._payload
 
     def iter_lines(self):
@@ -259,6 +265,26 @@ def test_chat_completions_stream_errors_are_pageindex_api_error(monkeypatch):
         list(stream)
 
 
+def test_delete_document_tolerates_empty_success_body(monkeypatch):
+    # A successful DELETE may return 200 with no body; delete_document must not
+    # raise JSONDecodeError parsing an empty response (the doc is already gone).
+    def fake_request(method, url, **kwargs):
+        assert method == "DELETE"
+        return FakeResponse(status_code=200, content=b"")
+
+    monkeypatch.setattr("pageindex.cloud_api.requests.request", fake_request)
+    assert PageIndexClient("pi-test").delete_document("doc-1") == {}
+
+
+def test_delete_document_returns_json_body_when_present(monkeypatch):
+    # When the server does return a body, it's parsed and passed through.
+    def fake_request(method, url, **kwargs):
+        return FakeResponse(status_code=200, payload={"deleted": True}, content=b'{"deleted": true}')
+
+    monkeypatch.setattr("pageindex.cloud_api.requests.request", fake_request)
+    assert PageIndexClient("pi-test").delete_document("doc-1") == {"deleted": True}
+
+
 def test_api_errors_are_pageindex_api_error(monkeypatch):
     def fake_request(*args, **kwargs):
         return FakeResponse(status_code=500, text="server error")