diff --git a/tests/integration/cost_calculation/cost_tracking_case.py b/tests/integration/cost_calculation/cost_tracking_case.py
index ea8bf230d05..ac3fcd33d2e 100644
--- a/tests/integration/cost_calculation/cost_tracking_case.py
+++ b/tests/integration/cost_calculation/cost_tracking_case.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import json
 from collections.abc import Mapping
 from pathlib import Path
 from types import MappingProxyType
@@ -8,6 +9,7 @@ from typing import Annotated, Final, Literal, TypeAlias
 from pydantic import BaseModel, ConfigDict, Field, JsonValue, field_validator, model_validator
 
 CASES_PATH: Final = Path(__file__).resolve().parent / "cost_tracking_cases.json"
+PRIOR_RESPONSE_ID_MARKER: Final = "$PRIOR_RESPONSE_ID"
 
 
 class SearchContextCostPerQuery(BaseModel):
@@ -312,6 +314,21 @@ class CostTrackingTestCase(BaseModel):
         usage: Final = self.response.body.get("usage")
         return isinstance(usage, dict) and isinstance(usage.get("cost"), (int, float))
 
+    @property
+    def chains_prior_response(self) -> bool:
+        return self.request.get("previous_response_id") == PRIOR_RESPONSE_ID_MARKER
+
+    @property
+    def can_chain_prior_response(self) -> bool:
+        return (
+            self.chains_prior_response
+            and self.endpoint == "/v1/responses"
+            and isinstance(self.response, JsonResponse)
+            and isinstance(self.response.body.get("id"), str)
+            and not isinstance(self.expected, FailureExpected)
+            and not (isinstance(self.expected, ExactExpected) and self.expected.rollups)
+        )
+
 
 class BatchOutputLine(BaseModel):
     model_config = ConfigDict(frozen=True, extra="forbid")
@@ -681,6 +698,11 @@ def data_errors() -> tuple[str, ...]:
             for marker in ('"id": "call_$REQUEST_ID"', '"id": "toolu_$REQUEST_ID"')
         )
     )
+    invalid_prior_response_chains: Final = sorted(
+        case.name
+        for case in CASES
+        if PRIOR_RESPONSE_ID_MARKER in json.dumps(case.request) and not case.can_chain_prior_response
+    )
     return tuple(
         message
         for message in (
@@ -700,6 +722,10 @@ def data_errors() -> tuple[str, ...]:
             f"pinned tool IDs contain $REQUEST_ID: {invalid_pinned_tool_ids}"
             if invalid_pinned_tool_ids
             else None,
+            f"{PRIOR_RESPONSE_ID_MARKER} needs a non-rollup, non-failure /v1/responses JSON response with a string id"
+            f" as previous_response_id: {invalid_prior_response_chains}"
+            if invalid_prior_response_chains
+            else None,
         )
         if message is not None
     )
diff --git a/tests/integration/cost_calculation/cost_tracking_cases.json b/tests/integration/cost_calculation/cost_tracking_cases.json
index 17ebc793fae..09dfa66012f 100644
--- a/tests/integration/cost_calculation/cost_tracking_cases.json
+++ b/tests/integration/cost_calculation/cost_tracking_cases.json
@@ -27733,7 +27733,7 @@
       "request": {
         "model": "$MODEL",
         "input": "continue this text",
-        "previous_response_id": "resp_scripted_prior"
+        "previous_response_id": "$PRIOR_RESPONSE_ID"
       },
       "response": {
         "content_type": "application/json",
diff --git a/tests/integration/cost_calculation/test_cost_tracking.py b/tests/integration/cost_calculation/test_cost_tracking.py
index efab17acba4..82878634677 100644
--- a/tests/integration/cost_calculation/test_cost_tracking.py
+++ b/tests/integration/cost_calculation/test_cost_tracking.py
@@ -9,13 +9,14 @@ import time
 import uuid
 import wave
 import zlib
+from collections.abc import Mapping
 from hashlib import sha256
 from itertools import islice
 from typing import Final, cast
 
 import httpx
 import pytest
-from integration._support.client import JSON_OBJECT, Gateway
+from integration._support.client import JSON_OBJECT, Gateway, string_value
 from integration._support.upstream import delete_scenario, register_scenario
 from integration.cost_calculation.assertions import assert_exact, assert_recount
 from integration.cost_calculation.conftest import (
@@ -112,6 +113,19 @@ def _replace_model(value: JsonValue, model_name: str) -> JsonValue:
     return value
 
 
+def _prime_prior_response(
+    gateway: Gateway, request_path: str, request_values: Mapping[str, JsonValue], key: str
+) -> str:
+    primed: Final = gateway.request(
+        "POST",
+        request_path,
+        {field: value for field, value in request_values.items() if field != "previous_response_id"},
+        key=key,
+    )
+    assert primed.is_success, f"priming response failed: {primed.status_code}: {primed.text[:400]}"
+    return string_value(JSON_OBJECT.validate_json(primed.content)["id"])
+
+
 @pytest.mark.parametrize("case", _CASES)
 def test_case_bills_expected_cost(gateway: Gateway, case: CostTrackingTestCase) -> None:
     marker: Final = sha256(case.name.encode()).hexdigest()[:12]
@@ -175,21 +189,6 @@ def test_case_bills_expected_cost(gateway: Gateway, case: CostTrackingTestCase)
             if isinstance(expected, ExactExpected) and expected.rollups
             else None
         )
-        request_body: Final = JSON_OBJECT.validate_python(
-            {
-                **base_request_values,
-                **(
-                    {"model": fallback_deployment.model_name, "fallbacks": [model_name]}
-                    if fallback_deployment is not None
-                    else {}
-                ),
-                **(
-                    {"user": end_user_id, "cache": {"no-cache": True}}
-                    if end_user_id is not None
-                    else {}
-                ),
-            }
-        )
         request_headers: Final = (
             {
                 "x-pass-x-scripted-scenario": scenario_id,
@@ -207,6 +206,27 @@ def test_case_bills_expected_cost(gateway: Gateway, case: CostTrackingTestCase)
             if passthrough_provider is not None
             else case.endpoint
         )
+        prior_response_id: Final = (
+            _prime_prior_response(gateway, request_path, base_request_values, key)
+            if case.chains_prior_response
+            else None
+        )
+        request_body: Final = JSON_OBJECT.validate_python(
+            {
+                **base_request_values,
+                **(
+                    {"model": fallback_deployment.model_name, "fallbacks": [model_name]}
+                    if fallback_deployment is not None
+                    else {}
+                ),
+                **(
+                    {"user": end_user_id, "cache": {"no-cache": True}}
+                    if end_user_id is not None
+                    else {}
+                ),
+                **({"previous_response_id": prior_response_id} if prior_response_id is not None else {}),
+            }
+        )
         if case.disconnect_after_frames is not None:
             with gateway.client.stream(
                 "POST",
@@ -250,7 +270,7 @@ def test_case_bills_expected_cost(gateway: Gateway, case: CostTrackingTestCase)
         assert response.is_success, f"{case.name}: proxy returned {response.status_code}: {response.text[:400]}"
         if case.response.content_type == "text/event-stream":
             _assert_stream_has_no_error(response.text)
-        rows: Final = poll_rows(key, len(responses))
+        rows: Final = poll_rows(key, len(responses) + (prior_response_id is not None))
         if isinstance(expected, RecountExpected):
             row: Final = rows[0]
             assert_recount(case.name, expected, row)
diff --git a/tests/integration/proxy_config.yaml b/tests/integration/proxy_config.yaml
index 34e48228dd7..a3b07f76d2f 100644
--- a/tests/integration/proxy_config.yaml
+++ b/tests/integration/proxy_config.yaml
@@ -5,7 +5,6 @@ general_settings:
   store_model_in_db: true
   disable_spend_logs: false
   proxy_batch_write_at: 1
-  allow_unmanaged_response_ids: true
 litellm_settings:
   enable_redis_auth_cache: true
   cache: true