feat: save next_steps on session completion and update

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

backend/tests/test_sessions.py

@@ -1010,3 +1010,51 @@ class TestSessions:
         data = response.json()
         assert isinstance(data, list)
         assert len(data) == 0
+
+    @pytest.mark.asyncio
+    async def test_complete_session_with_next_steps(
+        self, client: AsyncClient, auth_headers: dict, test_tree: dict
+    ):
+        """Test completing session saves next_steps."""
+        create_response = await client.post(
+            "/api/v1/sessions",
+            json={"tree_id": test_tree["id"]},
+            headers=auth_headers
+        )
+        session_id = create_response.json()["id"]
+
+        response = await client.post(
+            f"/api/v1/sessions/{session_id}/complete",
+            json={
+                "outcome": "resolved",
+                "outcome_notes": "Fixed the issue",
+                "next_steps": "Monitor for 48 hours"
+            },
+            headers=auth_headers
+        )
+
+        assert response.status_code == 200
+        data = response.json()
+        assert data["next_steps"] == "Monitor for 48 hours"
+        assert data["outcome_notes"] == "Fixed the issue"
+
+    @pytest.mark.asyncio
+    async def test_update_session_next_steps(
+        self, client: AsyncClient, auth_headers: dict, test_tree: dict
+    ):
+        """Test updating next_steps via session update."""
+        create_response = await client.post(
+            "/api/v1/sessions",
+            json={"tree_id": test_tree["id"]},
+            headers=auth_headers
+        )
+        session_id = create_response.json()["id"]
+
+        response = await client.put(
+            f"/api/v1/sessions/{session_id}",
+            json={"next_steps": "Schedule follow-up call"},
+            headers=auth_headers
+        )
+
+        assert response.status_code == 200
+        assert response.json()["next_steps"] == "Schedule follow-up call"