feat: bulk upsert API with idempotent writes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_api.py

@@ -0,0 +1,41 @@
+import pytest
+
+from openclaw.models import Session
+
+BULK_URL = "/api/sessions/bulk_upsert/"
+
+
+def _minimal_payload():
+    return {
+        "agent_name": "test",
+        "source_node": "macmini",
+        "sessions": [
+            {
+                "session_id": "test-session",
+                "model_provider": "test",
+                "model_id": "test-model",
+            }
+        ],
+        "messages": [],
+        "tool_calls": [],
+    }
+
+
+@pytest.mark.django_db
+class TestBulkUpsertAPI:
+    def test_bulk_upsert_ok(self, client):
+        resp = client.post(BULK_URL, _minimal_payload(), content_type="application/json")
+        assert resp.status_code == 200
+        data = resp.json()
+        assert data["status"] == "ok"
+        assert data["sessions_upserted"] == 1
+
+    def test_bulk_upsert_idempotent(self, client):
+        client.post(BULK_URL, _minimal_payload(), content_type="application/json")
+        resp = client.post(BULK_URL, _minimal_payload(), content_type="application/json")
+        data = resp.json()
+        assert data["sessions_upserted"] == 0
+
+    def test_bulk_upsert_missing_fields_returns_400(self, client):
+        resp = client.post(BULK_URL, {}, content_type="application/json")
+        assert resp.status_code == 400