fix(proxy): seed a new member budget row from the team default cap

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm/proxy/management_endpoints/common_utils.py

@@ -570,8 +570,10 @@ async def _upsert_budget_and_membership(
         "updated_by": user_api_key_dict.user_id or "",
     }
 
-    if is_shared_default:
-        default_budget_row: Final = await tx.litellm_budgettable.find_unique(where={"budget_id": existing_budget_id})
+    if team_default_budget_id is not None:
+        default_budget_row: Final = await tx.litellm_budgettable.find_unique(
+            where={"budget_id": team_default_budget_id}
+        )
         if default_budget_row is not None:
             default_budget_dict: Final = default_budget_row.model_dump()
             for field in _TEAM_MEMBER_BUDGET_LIMIT_FIELDS:

tests/test_litellm/proxy/common_utils/test_upsert_budget_membership.py

@@ -243,6 +243,34 @@ async def test_create_from_temp_budget_pair_only(mock_tx, fake_user):
     mock_tx.litellm_teammembership.update.assert_not_called()
 
 
+# TEST: a member with no budget row who falls back to the team default at
+# enforcement time must keep that default cap on the new private row, or the
+# temporary increase has nothing to add to.
+@pytest.mark.asyncio
+async def test_create_from_temp_pair_keeps_team_default_cap(mock_tx, fake_user):
+    expiry = datetime(2100, 1, 1, tzinfo=timezone.utc)
+    mock_tx.litellm_budgettable.find_unique = AsyncMock(
+        return_value=budget_row(budget_id="team-default-budget-1", max_budget=0.4, allowed_models=[])
+    )
+    await _upsert_budget_and_membership(
+        mock_tx,
+        team_id="team-default",
+        user_id="user-unlinked",
+        existing_budget_id=None,
+        user_api_key_dict=fake_user,
+        budget_patch={"temp_budget_increase": 1.0, "temp_budget_expiry": expiry},
+        team_default_budget_id="team-default-budget-1",
+    )
+
+    mock_tx.litellm_budgettable.find_unique.assert_awaited_once_with(where={"budget_id": "team-default-budget-1"})
+    data = mock_tx.litellm_budgettable.create.await_args.kwargs["data"]
+    assert data["max_budget"] == 0.4
+    assert data["temp_budget_increase"] == 1.0
+    assert data["temp_budget_expiry"] == expiry
+    assert "allowed_models" not in data
+    mock_tx.litellm_teammembership.upsert.assert_awaited_once()
+
+
 # TEST: clone-on-write when the membership still points at the team's shared
 # default budget. Editing this member must fork a private budget instead of
 # mutating the shared row, and cloning a duration must seed a fresh reset time.