diff --git a/tests/e2e/CLAUDE.md b/tests/e2e/CLAUDE.md
index b6c3840f626..49cfc29aa17 100644
--- a/tests/e2e/CLAUDE.md
+++ b/tests/e2e/CLAUDE.md
@@ -21,7 +21,7 @@ Each subdirectory under `tests/e2e/` is one suite, scoped to an endpoint family
 - `load/` - performance-category tests, kept OUT of the main suite: throughput/load SLO tests are a different testing category from functional e2e (variance-driven, historically flaky) and live outside this suite until re-implemented as their own pipeline (LIT-5163); do not add a live load test that runs in the default collection. What lives here: the weekly session-anomaly test (`test_weekly_session_anomaly_e2e.py`, Claude Code-shaped multi-turn sessions against real providers with ceilings on error rate, cache read/write, turn time, and spend; marked `weekly` and deselected unless `E2E_WEEKLY_ANOMALY` is set, driven by `.github/workflows/weekly_load_anomaly.yml`), the Redis chaos test (`test_redis_chaos_e2e.py`, locust load against mock deployments split round robin over `/chat/completions` and `/v1/messages`, one endpoint per simulated user, with `CLIENT PAUSE ALL` on the proxy's Redis mid-run to simulate it being down outright, asserting zero failed requests on every endpoint, budgeting RSS and CPU-per-request as ratios against the same run's healthy phase, and holding p50/p90/p99 latency and log-bytes-per-request to flat ceilings (a ratio cannot bound those two: an open breaker skips Redis instead of waiting on it, so the chaos phase can measure cheaper than baseline while still being far slower than a user should see); needs a proxy booted from `gateway/redis_chaos_ci_config.yml` on the same host with `E2E_PROXY_PID` and `E2E_PROXY_LOG` set, marked `redis_chaos`, deselected unless `E2E_REDIS_CHAOS` is set and excluded from the per-PR selector like the rest of `load/`, driven by `.github/workflows/test-e2e-redis-chaos.yml` and by the Buildkite `e2e-redis-chaos` step in project-releaser, which runs the proxy, Postgres and Valkey co-located with pytest in one pod and sets the opt-in), and markerless harness unit tests for the locust, process-usage, and session-anomaly aggregation logic
 - `other/` - the holding-pen suite for the `other.*` registry cluster with no home of its own yet: the master-key auth gate, JWT auth (access tokens issued by a real Keycloak realm, `idp.py` plus `idp_realm.json`, whose JWKS the proxy's `JWT_PUBLIC_KEY_URL` points at; see CONTRIBUTING.md for the start command and config block), and the process-lifecycle health probes (liveness, public readiness, authenticated readiness diagnostics). Promote a cluster out once it is large/stable enough for its own suite
 - `gateway/` - proxy configuration only (`litellm-config.yml`); no tests
-- `cost_calculation/` - cost accounting against a dedicated proxy whose whole model cost map is the test-owned `tests/e2e/cost_map.json` (loaded via `LITELLM_MODEL_COST_MAP_URL`), with provider calls answered by the scripted-provider sidecar in `scripted_provider.py`; asserts literal rate arithmetic on scripted usage across every provider wire and pricing component, deselected unless `E2E_COST_MAP_STACK` is set
+- `cost_calculation/` - cost accounting against a dedicated proxy whose whole model cost map is the test-owned `tests/e2e/cost_map.json` (loaded via `LITELLM_MODEL_COST_MAP_URL`), with provider calls answered by the scripted-provider sidecar in `scripted_provider.py`; asserts literal rate arithmetic on scripted usage across every provider wire and pricing component, deselected unless `E2E_COST_MAP_STACK` is set, driven by the Buildkite `e2e-cost-calculation` step in project-releaser, which runs a proxy booted from `gateway/cost_calculation_ci_config.yml`, Postgres and the scripted provider co-located with pytest in one pod and sets the opt-in
 - `claude_code/` - the Claude Code compatibility matrix: drives the real `claude` CLI (and HTTP probes) against a proxy for each feature x provider cell, reporting tagged-union outcomes via the `compat_result` fixture; ships its own driver/builder/publisher plus `_*_unit_tests/` trees. The HTTP probes ride the shared transport (`ProxyClient.count_tokens` / `ProxyClient.messages`); the CLI-driving path stays bespoke
 - `ui/` - the Admin UI browser suite: Playwright in TypeScript, driving the dashboard served by a live proxy on port 4000 (seeded postgres + mock LLM upstream; see its `run_e2e.sh`). It is a self-contained npm package with its own lockfile and does not use the Python harness, pytest markers, or the shared transport; the Python rules in this file (typed models, `Result` unions, basedpyright zero-error gate) do not apply inside it. Its only Python file, `fixtures/mock_llm_server/server.py`, is excluded from the e2e basedpyright gate via the root `pyrightconfig.json`
 
diff --git a/tests/e2e/gateway/cost_calculation_ci_config.yml b/tests/e2e/gateway/cost_calculation_ci_config.yml
new file mode 100644
index 00000000000..ac0603fa7c1
--- /dev/null
+++ b/tests/e2e/gateway/cost_calculation_ci_config.yml
@@ -0,0 +1,7 @@
+general_settings:
+  master_key: os.environ/LITELLM_MASTER_KEY
+  database_url: os.environ/DATABASE_URL
+  store_model_in_db: true
+  proxy_batch_write_at: 5
+
+model_list: []