diff --git a/.circleci/config.yml b/.circleci/config.yml
index 9f01bae3e5b..b3969fd8446 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -2006,6 +2006,70 @@ jobs:
       - store_test_results:
           path: test-results
 
+  proxy_e2e_claude_code_tests:
+    machine:
+      image: ubuntu-2204:2024.04.1
+    resource_class: large
+    working_directory: ~/project
+    steps:
+      - checkout
+      - setup_google_dns
+      - attach_workspace:
+          at: ~/project
+      - run:
+          name: Load Docker Database Image
+          command: |
+            zstd -d litellm-docker-database.tar.zst --stdout | docker load
+            docker images | grep litellm-docker-database
+      - run:
+          name: Load Claude Code client image
+          command: |
+            zstd -d claude-code-client.tar.zst --stdout | docker load
+            docker images | grep claude-code-client
+      - run:
+          name: Verify required container images stage
+          command: |
+            docker image inspect litellm-docker-database:ci >/dev/null
+            docker image inspect claude-code-client:ci >/dev/null
+            echo "LiteLLM and Claude Code images are ready"
+      - run:
+          name: Run Dockerized Claude Code E2E Tests
+          command: |
+            mkdir -p test-results
+            : "${LITELLM_MASTER_KEY:?Set LITELLM_MASTER_KEY in CircleCI project env vars.}"
+            : "${ANTHROPIC_API_KEY:?Set ANTHROPIC_API_KEY in CircleCI project env vars.}"
+            set +e
+            LITELLM_IMAGE=litellm-docker-database:ci \
+              CLAUDE_CODE_IMAGE=claude-code-client:ci \
+              LITELLM_SKIP_BUILD=true \
+              CLAUDE_CODE_SKIP_BUILD=true \
+              LITELLM_MASTER_KEY="${LITELLM_MASTER_KEY}" \
+              tests/proxy_e2e_anthropic_messages_tests/claude_code/run_claude_code_docker_test.sh
+            status=$?
+            if [ "$status" -eq 0 ]; then
+              printf '%s\n' \
+                '<?xml version="1.0" encoding="UTF-8"?>' \
+                '<testsuite name="proxy_e2e_anthropic_messages_tests" tests="1" failures="0">' \
+                '  <testcase classname="claude_code_docker" name="claude_code_through_litellm"/>' \
+                '</testsuite>' \
+                > test-results/junit.xml
+            else
+              printf '%s\n' \
+                '<?xml version="1.0" encoding="UTF-8"?>' \
+                '<testsuite name="proxy_e2e_anthropic_messages_tests" tests="1" failures="1">' \
+                '  <testcase classname="claude_code_docker" name="claude_code_through_litellm">' \
+                '    <failure message="Dockerized Claude Code E2E test failed">See CircleCI job output for Docker and LiteLLM logs.</failure>' \
+                '  </testcase>' \
+                '</testsuite>' \
+                > test-results/junit.xml
+            fi
+            exit "$status"
+          no_output_timeout: 15m
+
+      # Store test results
+      - store_test_results:
+          path: test-results
+
   upload-coverage:
     docker:
       - *python312_image
@@ -2247,6 +2311,29 @@ jobs:
           paths:
             - litellm-docker-database.tar.zst
 
+  build_claude_code_client_image:
+    machine:
+      image: ubuntu-2204:2024.04.1
+    resource_class: medium
+    working_directory: ~/project
+    steps:
+      - checkout
+      - run:
+          name: Build Claude Code client image
+          command: |
+            docker build \
+              -t claude-code-client:ci \
+              -f tests/proxy_e2e_anthropic_messages_tests/claude_code/Dockerfile.claude-code \
+              tests/proxy_e2e_anthropic_messages_tests/claude_code
+      - run:
+          name: Save Claude Code image to workspace root
+          command: |
+            docker save claude-code-client:ci | zstd -1 -T0 > claude-code-client.tar.zst
+      - persist_to_workspace:
+          root: .
+          paths:
+            - claude-code-client.tar.zst
+
 
   test_bad_database_url:
     machine:
@@ -2320,6 +2407,8 @@ workflows:
           filters: *main_branches
       - build_docker_database_image:
           filters: *main_branches
+      - build_claude_code_client_image:
+          filters: *main_branches
       - e2e_ui_testing:
           filters: *main_branches
       - build_and_test:
@@ -2356,6 +2445,11 @@ workflows:
           requires:
             - build_docker_database_image
           filters: *main_branches
+      - proxy_e2e_claude_code_tests:
+          requires:
+            - build_docker_database_image
+            - build_claude_code_client_image
+          filters: *main_branches
       - llm_translation_testing:
           filters: *main_branches
       - realtime_translation_testing:
@@ -2426,3 +2520,4 @@ workflows:
           requires:
             - build_docker_database_image
           filters: *main_branches
+
diff --git a/tests/proxy_e2e_anthropic_messages_tests/claude_code/Dockerfile.claude-code b/tests/proxy_e2e_anthropic_messages_tests/claude_code/Dockerfile.claude-code
new file mode 100644
index 00000000000..5ae9938a13c
--- /dev/null
+++ b/tests/proxy_e2e_anthropic_messages_tests/claude_code/Dockerfile.claude-code
@@ -0,0 +1,41 @@
+ARG CLAUDE_CODE_BASE_IMAGE=cgr.dev/chainguard/wolfi-base@sha256:f26d42a15d09d9a643b231df929fa3cf609bedc58a728eb445be89a9d8d1da9f
+FROM ${CLAUDE_CODE_BASE_IMAGE}
+
+ARG CLAUDE_CODE_VERSION=latest
+
+USER root
+
+COPY resolve_claude_code_version.js /tmp/resolve_claude_code_version.js
+
+RUN apk add --no-cache \
+    bash \
+    ca-certificates \
+    curl \
+    nodejs \
+    npm \
+    shadow && \
+    if [ "${CLAUDE_CODE_VERSION}" = "latest" ]; then \
+      CLAUDE_CODE_RESOLVED_VERSION="$(node /tmp/resolve_claude_code_version.js)"; \
+    else \
+      CLAUDE_CODE_RESOLVED_VERSION="${CLAUDE_CODE_VERSION}"; \
+    fi && \
+    echo "Installing @anthropic-ai/claude-code@${CLAUDE_CODE_RESOLVED_VERSION}" && \
+    npm install -g --ignore-scripts "@anthropic-ai/claude-code@${CLAUDE_CODE_RESOLVED_VERSION}" && \
+    CLAUDE_CODE_GLOBAL_ROOT="$(npm root -g)" && \
+    node "${CLAUDE_CODE_GLOBAL_ROOT}/@anthropic-ai/claude-code/install.cjs" && \
+    npm cache clean --force && \
+    groupadd --system claude && \
+    useradd --system --create-home --gid claude --shell /bin/bash claude && \
+    mkdir -p /workspace /home/claude/.claude && \
+    chown -R claude:claude /workspace /home/claude
+
+COPY --chown=claude:claude run_claude_code_check.sh /usr/local/bin/run_claude_code_check.sh
+RUN chmod 0755 /usr/local/bin/run_claude_code_check.sh
+
+USER claude
+WORKDIR /workspace
+
+ENV CI=true \
+    HOME=/home/claude
+
+ENTRYPOINT ["/usr/local/bin/run_claude_code_check.sh"]
diff --git a/tests/proxy_e2e_anthropic_messages_tests/claude_code/README.md b/tests/proxy_e2e_anthropic_messages_tests/claude_code/README.md
new file mode 100644
index 00000000000..5d549769421
--- /dev/null
+++ b/tests/proxy_e2e_anthropic_messages_tests/claude_code/README.md
@@ -0,0 +1,62 @@
+# Claude Code LiteLLM E2E Test
+
+This V0 test validates the customer-critical Claude Code -> LiteLLM -> Anthropic path in CircleCI.
+
+## What It Covers
+
+- Builds/runs the LiteLLM proxy container from the current checkout.
+- Starts an isolated Postgres container for proxy database state.
+- Builds a separate Claude Code client container.
+- Runs Claude Code as a non-root user with only the LiteLLM proxy key.
+- Points Claude Code at LiteLLM via `ANTHROPIC_BASE_URL`.
+- Verifies the configured Anthropic model is visible from `/v1/models`.
+- Sends back-to-back Claude Code prompts through LiteLLM and validates both responses.
+- Sends a direct Anthropic Messages API request through LiteLLM and checks proxy response headers:
+  - `x-litellm-call-id`
+  - `x-litellm-response-cost`
+
+The direct `/v1/messages` header check gives a clear proxy-side signal that LiteLLM handled and accounted for the request, instead of only proving the client printed text.
+
+## Claude Code Version Policy
+
+The Claude Code image resolves `@anthropic-ai/claude-code@latest` by querying npm publish times, selecting the newest version older than three days, then installing that exact version.
+
+This intentionally follows the newest Claude Code release that has aged at least three days, which catches customer-facing compatibility issues while avoiding just-published releases that are more likely to be pulled or patched.
+
+Set `CLAUDE_CODE_VERSION=<version>` to test a specific version locally or in a follow-up CI job.
+
+## Running Locally
+
+Set `ANTHROPIC_API_KEY` in the environment or in `tests/proxy_e2e_anthropic_messages_tests/claude_code/.env`, then run:
+
+```bash
+tests/proxy_e2e_anthropic_messages_tests/claude_code/run_claude_code_docker_test.sh
+```
+
+Useful overrides:
+
+```bash
+MODEL_NAME=claude-sonnet-4-6
+LITELLM_UPSTREAM_MODEL=anthropic/claude-sonnet-4-6
+CLAUDE_CODE_IMAGE=litellm-claude-code-client:local
+CLAUDE_CODE_VERSION=latest
+KEEP_CONTAINERS=1
+```
+
+In CircleCI, the job sets `LITELLM_IMAGE=litellm-docker-database:ci` and `LITELLM_SKIP_BUILD=true` so the test uses the LiteLLM image already built from the checked-out commit.
+The CircleCI job now has explicit component stages before test execution:
+
+- verify LiteLLM image exists (`litellm-docker-database:ci`)
+- use prebuilt Claude Code client image (`claude-code-client:ci`)
+- run end-to-end test with both image builds skipped (`LITELLM_SKIP_BUILD=true` and `CLAUDE_CODE_SKIP_BUILD=true`)
+
+## Intentionally Left Out Of V0
+
+- Bedrock and other providers. Those belong in V1 after the Anthropic path is stable.
+- Back-to-back session behavior. V0 proves the request path works; V1 can add repeated requests and long-running session checks.
+- Tool-use assertions. Claude Code can invoke tools in richer scenarios, but V0 keeps the signal focused on proxy compatibility and real Anthropic request success.
+- A Claude Code version matrix. The Dockerfile supports `CLAUDE_CODE_VERSION`, but the default CI path tests one recent version to keep cost and flake surface low.
+
+## Failure Output
+
+The runner prints each phase, dumps LiteLLM logs if the proxy fails readiness, and emits a JUnit result in CircleCI. Header-check failures print the response headers and body so regressions are visible without SSHing into the job.
diff --git a/tests/proxy_e2e_anthropic_messages_tests/claude_code/docker-compose.yaml b/tests/proxy_e2e_anthropic_messages_tests/claude_code/docker-compose.yaml
new file mode 100644
index 00000000000..e4239f40597
--- /dev/null
+++ b/tests/proxy_e2e_anthropic_messages_tests/claude_code/docker-compose.yaml
@@ -0,0 +1,57 @@
+services:
+  postgres:
+    image: postgres:14@sha256:6a70deda415ec296f977890e11aba04a0db9f632a362e3fce45e845e3db74f26
+    environment:
+      POSTGRES_DB: litellm
+      POSTGRES_USER: litellm
+      POSTGRES_PASSWORD: litellm
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -d litellm -U litellm"]
+      interval: 2s
+      timeout: 5s
+      retries: 30
+
+  litellm:
+    image: ${LITELLM_IMAGE:-litellm-claude-code-e2e:local}
+    build:
+      context: ../../..
+      dockerfile: Dockerfile
+      target: runtime
+    command: ["--config", "/app/config.yaml", "--port", "4000", "--detailed_debug"]
+    ports:
+      - "${PROXY_PORT:-4000}:4000"
+    environment:
+      DATABASE_URL: postgresql://litellm:litellm@postgres:5432/litellm
+      LITELLM_MASTER_KEY: ${LITELLM_MASTER_KEY:-sk-1234}
+      ANTHROPIC_API_KEY: ${ANTHROPIC_API_KEY:?ANTHROPIC_API_KEY is required}
+      LITELLM_LOCAL_ANTHROPIC_BETA_HEADERS: "True"
+    volumes:
+      - ${CLAUDE_CODE_LITELLM_CONFIG:?CLAUDE_CODE_LITELLM_CONFIG is required}:/app/config.yaml:ro
+    depends_on:
+      postgres:
+        condition: service_healthy
+    healthcheck:
+      test:
+        [
+          "CMD-SHELL",
+          "python3 -c \"import urllib.request; urllib.request.urlopen('http://127.0.0.1:4000/health/liveliness', timeout=5)\"",
+        ]
+      interval: 5s
+      timeout: 10s
+      retries: 60
+
+  claude-code:
+    image: ${CLAUDE_CODE_IMAGE:-litellm-claude-code-client:local}
+    build:
+      context: .
+      dockerfile: Dockerfile.claude-code
+      args:
+        CLAUDE_CODE_VERSION: ${CLAUDE_CODE_VERSION:-latest}
+    environment:
+      ANTHROPIC_BASE_URL: http://litellm:4000
+      ANTHROPIC_AUTH_TOKEN: ${LITELLM_MASTER_KEY:-sk-1234}
+      MODEL_NAME: ${MODEL_NAME:-claude-sonnet-4-6}
+      CLAUDE_CODE_PROMPT: "${CLAUDE_CODE_PROMPT:-Respond with exactly this text and nothing else: Hello from LiteLLM Claude Code.}"
+    depends_on:
+      litellm:
+        condition: service_healthy
diff --git a/tests/proxy_e2e_anthropic_messages_tests/claude_code/resolve_claude_code_version.js b/tests/proxy_e2e_anthropic_messages_tests/claude_code/resolve_claude_code_version.js
new file mode 100644
index 00000000000..aaf04e64a1f
--- /dev/null
+++ b/tests/proxy_e2e_anthropic_messages_tests/claude_code/resolve_claude_code_version.js
@@ -0,0 +1,22 @@
+const { execFileSync } = require("node:child_process");
+
+const packageName = "@anthropic-ai/claude-code";
+const minAgeMs = 3 * 24 * 60 * 60 * 1000;
+const cutoff = Date.now() - minAgeMs;
+const raw = execFileSync("npm", ["view", packageName, "time", "--json"], {
+  encoding: "utf8",
+});
+const time = JSON.parse(raw);
+const versions = Object.keys(time)
+  .filter((version) => /^\d/.test(version))
+  .filter((version) => new Date(time[version]).getTime() <= cutoff)
+  .sort((a, b) => a.localeCompare(b, undefined, { numeric: true }));
+
+if (versions.length === 0) {
+  console.error(
+    `No ${packageName} version is older than the 3-day exclusion window.`
+  );
+  process.exit(1);
+}
+
+console.log(versions[versions.length - 1]);
diff --git a/tests/proxy_e2e_anthropic_messages_tests/claude_code/run_claude_code_check.sh b/tests/proxy_e2e_anthropic_messages_tests/claude_code/run_claude_code_check.sh
new file mode 100755
index 00000000000..f4b2891c25a
--- /dev/null
+++ b/tests/proxy_e2e_anthropic_messages_tests/claude_code/run_claude_code_check.sh
@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+: "${ANTHROPIC_BASE_URL:?ANTHROPIC_BASE_URL is required}"
+: "${ANTHROPIC_AUTH_TOKEN:?ANTHROPIC_AUTH_TOKEN is required}"
+: "${MODEL_NAME:?MODEL_NAME is required}"
+
+OUTPUT_FILE="${CLAUDE_CODE_OUTPUT_FILE:-/tmp/claude-code-output.txt}"
+PROMPT="${CLAUDE_CODE_PROMPT:-Respond with exactly this text and nothing else: Hello from LiteLLM Claude Code.}"
+
+echo "Running Claude Code against ${ANTHROPIC_BASE_URL} with model ${MODEL_NAME}"
+
+claude -p "${PROMPT}" --model "${MODEL_NAME}" >"${OUTPUT_FILE}"
+
+if [[ ! -s "${OUTPUT_FILE}" ]]; then
+  echo "Claude Code produced no output."
+  exit 1
+fi
+
+echo "Claude Code output:"
+sed -n '1,20p' "${OUTPUT_FILE}"
diff --git a/tests/proxy_e2e_anthropic_messages_tests/claude_code/run_claude_code_docker_test.sh b/tests/proxy_e2e_anthropic_messages_tests/claude_code/run_claude_code_docker_test.sh
new file mode 100755
index 00000000000..350a128683a
--- /dev/null
+++ b/tests/proxy_e2e_anthropic_messages_tests/claude_code/run_claude_code_docker_test.sh
@@ -0,0 +1,244 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Dockerized Claude Code + LiteLLM integration test.
+#
+# Required:
+#   ANTHROPIC_API_KEY or tests/proxy_e2e_anthropic_messages_tests/claude_code/.env
+#
+# Optional:
+#   MODEL_NAME=claude-sonnet-4-6
+#   LITELLM_UPSTREAM_MODEL=anthropic/${MODEL_NAME}
+#   LITELLM_IMAGE=litellm-claude-code-e2e:local
+#   CLAUDE_CODE_IMAGE=litellm-claude-code-client:local
+#   LITELLM_SKIP_BUILD=true
+#   CLAUDE_CODE_SKIP_BUILD=true
+#   CLAUDE_CODE_VERSION=latest
+#   PROXY_PORT=4000
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+COMPOSE_FILE="${SCRIPT_DIR}/docker-compose.yaml"
+ENV_FILE="${SCRIPT_DIR}/.env"
+MODEL_NAME="${MODEL_NAME:-claude-sonnet-4-6}"
+LITELLM_UPSTREAM_MODEL="${LITELLM_UPSTREAM_MODEL:-anthropic/${MODEL_NAME}}"
+LITELLM_MASTER_KEY="${LITELLM_MASTER_KEY:-sk-1234}"
+PROXY_PORT="${PROXY_PORT:-4000}"
+PROXY_URL="http://127.0.0.1:${PROXY_PORT}"
+STARTUP_TIMEOUT_S="${STARTUP_TIMEOUT_S:-300}"
+COMPOSE_PROJECT_NAME="${COMPOSE_PROJECT_NAME:-litellm-claude-code-e2e}"
+TMP_DIR="$(mktemp -d)"
+CLAUDE_CODE_LITELLM_CONFIG="${TMP_DIR}/config.yaml"
+HEADERS_FILE="${TMP_DIR}/headers.txt"
+BODY_FILE="${TMP_DIR}/body.json"
+
+cleanup() {
+  if [[ "${KEEP_CONTAINERS:-}" == "1" ]]; then
+    echo "KEEP_CONTAINERS=1 set; leaving docker compose project ${COMPOSE_PROJECT_NAME} running."
+    echo "Generated config left at ${CLAUDE_CODE_LITELLM_CONFIG}"
+    return
+  fi
+  docker compose -p "${COMPOSE_PROJECT_NAME}" -f "${COMPOSE_FILE}" down -v >/dev/null 2>&1 || true
+  rm -rf "${TMP_DIR}"
+}
+trap cleanup EXIT
+
+if [[ -f "${ENV_FILE}" ]]; then
+  # shellcheck disable=SC1090
+  source "${ENV_FILE}"
+fi
+
+if [[ -z "${ANTHROPIC_API_KEY:-}" ]]; then
+  echo "ANTHROPIC_API_KEY is required in the environment or ${ENV_FILE}"
+  exit 1
+fi
+
+if ! command -v docker >/dev/null 2>&1; then
+  echo "docker is required"
+  exit 1
+fi
+
+if ! docker compose version >/dev/null 2>&1; then
+  echo "docker compose v2 is required"
+  exit 1
+fi
+
+if ! command -v python3 >/dev/null 2>&1; then
+  echo "python3 is required"
+  exit 1
+fi
+
+is_port_available() {
+  python3 - "$1" <<'PY'
+import socket
+import sys
+
+port = int(sys.argv[1])
+sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+try:
+    sock.bind(("127.0.0.1", port))
+    print("yes")
+except OSError:
+    print("no")
+finally:
+    sock.close()
+PY
+}
+
+if [[ "$(is_port_available "${PROXY_PORT}")" != "yes" ]]; then
+  echo "Port ${PROXY_PORT} is in use. Searching for a free port..."
+  FOUND_PORT=""
+  for candidate in $(seq 4001 4050); do
+    if [[ "$(is_port_available "${candidate}")" == "yes" ]]; then
+      FOUND_PORT="${candidate}"
+      break
+    fi
+  done
+  if [[ -z "${FOUND_PORT}" ]]; then
+    echo "No free local port found between 4001-4050."
+    exit 1
+  fi
+  PROXY_PORT="${FOUND_PORT}"
+  PROXY_URL="http://127.0.0.1:${PROXY_PORT}"
+  echo "Using fallback PROXY_PORT=${PROXY_PORT}"
+fi
+
+cat >"${CLAUDE_CODE_LITELLM_CONFIG}" <<EOF
+model_list:
+  - model_name: ${MODEL_NAME}
+    litellm_params:
+      model: ${LITELLM_UPSTREAM_MODEL}
+      api_key: os.environ/ANTHROPIC_API_KEY
+
+general_settings:
+  forward_client_headers_to_llm_api: true
+  master_key: "${LITELLM_MASTER_KEY}"
+
+litellm_settings:
+  drop_params: true
+  modify_params: true
+EOF
+
+export ANTHROPIC_API_KEY
+export CLAUDE_CODE_LITELLM_CONFIG
+export LITELLM_IMAGE="${LITELLM_IMAGE:-litellm-claude-code-e2e:local}"
+export CLAUDE_CODE_IMAGE="${CLAUDE_CODE_IMAGE:-litellm-claude-code-client:local}"
+export LITELLM_MASTER_KEY
+export MODEL_NAME
+export PROXY_PORT
+
+echo "[0/5] Preparing Docker images..."
+if [[ "${LITELLM_SKIP_BUILD:-}" == "true" && "${CLAUDE_CODE_SKIP_BUILD:-}" == "true" ]]; then
+  echo "Skipping image builds (LITELLM_SKIP_BUILD=true and CLAUDE_CODE_SKIP_BUILD=true)."
+elif [[ "${LITELLM_SKIP_BUILD:-}" == "true" ]]; then
+  docker compose -p "${COMPOSE_PROJECT_NAME}" -f "${COMPOSE_FILE}" build claude-code
+elif [[ "${CLAUDE_CODE_SKIP_BUILD:-}" == "true" ]]; then
+  docker compose -p "${COMPOSE_PROJECT_NAME}" -f "${COMPOSE_FILE}" build litellm
+else
+  docker compose -p "${COMPOSE_PROJECT_NAME}" -f "${COMPOSE_FILE}" build litellm claude-code
+fi
+
+echo "[1/5] Starting Postgres and LiteLLM proxy..."
+docker compose -p "${COMPOSE_PROJECT_NAME}" -f "${COMPOSE_FILE}" up -d postgres litellm
+
+echo "[2/5] Waiting for LiteLLM readiness at ${PROXY_URL}..."
+READY=0
+for _ in $(seq 1 "${STARTUP_TIMEOUT_S}"); do
+  if curl -fsS --connect-timeout 5 --max-time 15 \
+      -H "Authorization: Bearer ${LITELLM_MASTER_KEY}" "${PROXY_URL}/v1/models" >/dev/null 2>&1; then
+    READY=1
+    break
+  fi
+  sleep 1
+done
+
+if [[ "${READY}" != "1" ]]; then
+  echo "LiteLLM failed to become ready within ${STARTUP_TIMEOUT_S}s"
+  docker compose -p "${COMPOSE_PROJECT_NAME}" -f "${COMPOSE_FILE}" logs --tail=200 litellm || true
+  exit 1
+fi
+
+echo "[3/5] Checking configured model..."
+curl -fsS --connect-timeout 5 --max-time 20 \
+  -H "Authorization: Bearer ${LITELLM_MASTER_KEY}" "${PROXY_URL}/v1/models" | grep -q "\"${MODEL_NAME}\""
+
+echo "[4/5] Running back-to-back Claude Code requests in an isolated non-root container..."
+FIRST_RESPONSE="$(
+docker compose -p "${COMPOSE_PROJECT_NAME}" -f "${COMPOSE_FILE}" run --rm \
+  -e CLAUDE_CODE_PROMPT="Respond with exactly this text and nothing else: Hello from LiteLLM Claude Code request one." \
+  -e CLAUDE_CODE_OUTPUT_FILE="/tmp/claude-output-1.txt" \
+  claude-code
+)"
+
+SECOND_RESPONSE="$(
+docker compose -p "${COMPOSE_PROJECT_NAME}" -f "${COMPOSE_FILE}" run --rm \
+  -e CLAUDE_CODE_PROMPT="Respond with exactly this text and nothing else: Hello from LiteLLM Claude Code request two." \
+  -e CLAUDE_CODE_OUTPUT_FILE="/tmp/claude-output-2.txt" \
+  claude-code
+)"
+
+[[ -n "${FIRST_RESPONSE}" ]] || {
+  echo "First Claude Code request produced no response output."
+  exit 1
+}
+[[ -n "${SECOND_RESPONSE}" ]] || {
+  echo "Second Claude Code request produced no response output."
+  exit 1
+}
+
+printf '%s\n' "${FIRST_RESPONSE}" | grep -qi "request one" || {
+  echo "First Claude Code response did not contain expected content."
+  printf '%s\n' "${FIRST_RESPONSE}" | sed -n '1,40p'
+  exit 1
+}
+printf '%s\n' "${SECOND_RESPONSE}" | grep -qi "request two" || {
+  echo "Second Claude Code response did not contain expected content."
+  printf '%s\n' "${SECOND_RESPONSE}" | sed -n '1,40p'
+  exit 1
+}
+
+echo "[5/5] Verifying LiteLLM request headers on Anthropic messages endpoint..."
+REQUEST_BODY="$(python3 - "${MODEL_NAME}" <<'PY'
+import json
+import sys
+
+print(
+    json.dumps(
+        {
+            "model": sys.argv[1],
+            "max_tokens": 16,
+            "messages": [
+                {
+                    "role": "user",
+                    "content": "Respond with the word ok.",
+                }
+            ],
+        }
+    )
+)
+PY
+)"
+
+curl -fsS --connect-timeout 5 --max-time 30 -D "${HEADERS_FILE}" -o "${BODY_FILE}" \
+  -X POST "${PROXY_URL}/v1/messages" \
+  -H "Authorization: Bearer ${LITELLM_MASTER_KEY}" \
+  -H "Content-Type: application/json" \
+  -H "anthropic-version: 2023-06-01" \
+  --data "${REQUEST_BODY}"
+
+grep -qi "^x-litellm-call-id:" "${HEADERS_FILE}" || {
+  echo "Missing x-litellm-call-id header; proxy record signal not found."
+  sed -n '1,80p' "${HEADERS_FILE}"
+  sed -n '1,80p' "${BODY_FILE}"
+  exit 1
+}
+
+if ! grep -qi "^x-litellm-response-cost:" "${HEADERS_FILE}" && \
+   ! grep -qi "^x-litellm-response-cost-original:" "${HEADERS_FILE}"; then
+  echo "Missing LiteLLM response cost headers; proxy usage signal not found."
+  echo "Expected one of: x-litellm-response-cost or x-litellm-response-cost-original"
+  sed -n '1,80p' "${HEADERS_FILE}"
+  sed -n '1,80p' "${BODY_FILE}"
+  exit 1
+fi
+
+echo "Success: Claude Code ran in its own non-root container through LiteLLM, with Postgres-backed proxy headers present."