diff --git a/scripts/cluster/run-production-acceptance.sh b/scripts/cluster/run-production-acceptance.sh
index 065a52d..371a5e4 100755
--- a/scripts/cluster/run-production-acceptance.sh
+++ b/scripts/cluster/run-production-acceptance.sh
@@ -243,6 +243,9 @@ deploy_protocol_emulator() {
 create_and_activate_run() {
   local create_response=$temporary_root/create-run.json
   local activate_response=$temporary_root/activate-run.json
+  local traffic_response=$temporary_root/pre-activate-traffic.json
+  local previous_run_response=$temporary_root/previous-run.json
+  local abort_response=$temporary_root/abort-previous-run.json
   local body
   body=$(jq -cn \
     --arg releaseSha "$release_sha" \
@@ -274,8 +277,55 @@ create_and_activate_run() {
   report_root=${AI_GATEWAY_ACCEPTANCE_REPORT_DIR:-"$cluster_root/dist/acceptance/$run_id"}
   mkdir -p "$report_root"
   chmod 0700 "$report_root"
+
+  admin_request GET /api/admin/system/acceptance/traffic-mode '' "$traffic_response"
+  local traffic_mode previous_run_id previous_status
+  traffic_mode=$(jq -r '.mode // empty' "$traffic_response")
+  if [[ $traffic_mode == validation ]]; then
+    previous_run_id=$(jq -r '.runId // empty' "$traffic_response")
+    [[ $previous_run_id =~ ^[0-9a-f-]{36}$ && $previous_run_id != "$run_id" ]] || {
+      echo 'validation mode does not reference a different previous Run' >&2
+      return 1
+    }
+    [[ $(jq -r '.releaseSha // empty' "$traffic_response") == "$release_sha" &&
+       $(jq -r '.apiImageDigest // empty' "$traffic_response") == "$api_digest" &&
+       $(jq -r '.workerImageDigest // empty' "$traffic_response") == "$worker_digest" ]] || {
+      echo 'refusing to replace validation mode for a different production release' >&2
+      return 1
+    }
+    admin_request GET "/api/admin/system/acceptance/runs/$previous_run_id" '' \
+      "$previous_run_response"
+    previous_status=$(jq -r '.status // empty' "$previous_run_response")
+    [[ $previous_status == failed ]] || {
+      echo "refusing to replace previous acceptance Run in status $previous_status" >&2
+      return 1
+    }
+    body=$(jq -cn \
+      --argjson revision "$(jq -r '.revision' "$traffic_response")" \
+      --arg releaseSha "$release_sha" \
+      --arg apiDigest "$api_digest" \
+      --arg workerDigest "$worker_digest" \
+      '{
+        revision:$revision,
+        releaseSha:$releaseSha,
+        apiImageDigest:$apiDigest,
+        workerImageDigest:$workerDigest
+      }')
+    admin_request POST \
+      "/api/admin/system/acceptance/runs/$previous_run_id/abort" \
+      "$body" "$abort_response"
+    [[ $(jq -r '.mode // empty' "$abort_response") == live ]] || {
+      echo 'previous failed acceptance Run did not return traffic to live' >&2
+      return 1
+    }
+  elif [[ $traffic_mode != live ]]; then
+    echo "unsupported production traffic mode before acceptance: $traffic_mode" >&2
+    return 1
+  fi
+
   admin_request POST "/api/admin/system/acceptance/runs/$run_id/activate" '' "$activate_response"
-  [[ $(jq -r '.mode' "$activate_response") == validation ]]
+  [[ $(jq -r '.mode' "$activate_response") == validation &&
+     $(jq -r '.runId' "$activate_response") == "$run_id" ]]
 }
 
 mark_run_failed() {