diff --git a/.github/actions/test-charts/action.yml b/.github/actions/test-charts/action.yml
index f11f015be..2965bb9d1 100644
--- a/.github/actions/test-charts/action.yml
+++ b/.github/actions/test-charts/action.yml
@@ -121,6 +121,16 @@ runs:
             --values "$VALUES_FILE" 2>&1) || { echo "$output"; exit 1; }
         done
 
+    # Mirrored-registry and StorageClass assertions on the rendered manifests (no cluster needed).
+    - name: Rendered values assertions
+      if: steps.list-changed.outputs.changed == 'true' && inputs.chart == 'charts/rhdh'
+      shell: bash
+      env:
+        INPUT_CHART: ${{ inputs.chart }}
+      run: |
+        helm dependency build "$INPUT_CHART"
+        ./hack/assert-rendered-values.sh "$INPUT_CHART"
+
     - name: Generate KinD Config
       if: steps.list-changed.outputs.changed == 'true'
       shell: bash
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 91eb4bd0a..86aa7b738 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -6,6 +6,7 @@ Before making a contribution to the charts in this repository, you will need to
 
 - Run `helm template` on the changes you're making to ensure they are correctly rendered into Kubernetes manifests.
 - Lint tests have been run for the Chart using the [Chart Testing](https://github.com/helm/chart-testing) tool and the `ct lint` command.
+- For the [rhdh](./charts/rhdh) chart, run `./hack/assert-rendered-values.sh` (after `helm dependency build charts/rhdh`) to check that every rendered image honours `global.imageRegistry` and that the dynamic plugins volume honours the StorageClass settings. CI runs it too.
 - For each Chart updated, version bumped in the corresponding `Chart.yaml` according to [Semantic Versioning](http://semver.org/).
 - For each Chart updated, ensure variables are documented in the corresponding `values.yaml` file and the [pre-commit](https://pre-commit.com/) hook has been run with `pre-commit run --all-files` to generate the corresponding `README.md` documentation. The [pre-commit Workflow](./.github/workflows/pre-commit.yaml) will enforce this and warn you if needed.
 - JSON Schema template updated and re-generated the raw schema via the `pre-commit` hook.
diff --git a/charts/rhdh/Chart.yaml b/charts/rhdh/Chart.yaml
index 18f646d7a..34ed9cb02 100644
--- a/charts/rhdh/Chart.yaml
+++ b/charts/rhdh/Chart.yaml
@@ -1,7 +1,7 @@
 apiVersion: v2
 name: redhat-developer-hub
 type: application
-version: 3.5.17
+version: 3.5.18
 appVersion: 2.2.0
 annotations:
   artifacthub.io/category: integration-delivery
diff --git a/charts/rhdh/README.md b/charts/rhdh/README.md
index c7f4a5f71..7765f2111 100644
--- a/charts/rhdh/README.md
+++ b/charts/rhdh/README.md
@@ -1,7 +1,7 @@
 
 # RHDH Helm Chart for OpenShift and Kubernetes
 
-![Version: 3.5.17](https://img.shields.io/badge/Version-3.5.17-informational?style=flat-square)
+![Version: 3.5.18](https://img.shields.io/badge/Version-3.5.18-informational?style=flat-square)
 ![Type: application](https://img.shields.io/badge/Type-application-informational?style=flat-square)
 
 A Helm chart for deploying Red Hat Developer Hub, which is a Red Hat supported version of Backstage.
@@ -36,7 +36,7 @@ For the **Generally Available** version of this chart, see:
 helm repo add bitnami https://charts.bitnami.com/bitnami
 helm repo add redhat-developer https://redhat-developer.github.io/rhdh-chart
 
-helm install my-rhdh redhat-developer/redhat-developer-hub --version 3.5.17
+helm install my-rhdh redhat-developer/redhat-developer-hub --version 3.5.18
 ```
 
 ## Introduction
diff --git a/charts/rhdh/ci/with-custom-storage-class-values.yaml b/charts/rhdh/ci/with-custom-storage-class-values.yaml
new file mode 100644
index 000000000..88bd4dac2
--- /dev/null
+++ b/charts/rhdh/ci/with-custom-storage-class-values.yaml
@@ -0,0 +1,17 @@
+# CI: provision the dynamic plugins ephemeral volume through an explicit StorageClass
+# instead of the cluster default. The test action creates `custom-sc` before `ct install`.
+dynamicPlugins:
+  includes: []
+  volume:
+    type: ephemeral
+    ephemeral:
+      storageClassName: custom-sc
+intelligentAssistant:
+  plugins: []
+  okp:
+    route:
+      enabled: false
+    ingress:
+      enabled: false
+orchestrator:
+  plugins: []
diff --git a/hack/assert-rendered-values.sh b/hack/assert-rendered-values.sh
new file mode 100755
index 000000000..9fd1d6456
--- /dev/null
+++ b/hack/assert-rendered-values.sh
@@ -0,0 +1,152 @@
+#!/usr/bin/env bash
+#
+# Renders the rhdh chart with `helm template` and asserts the values that a
+# constrained cluster (mirrored registry only, no default StorageClass) relies on:
+#   - global.imageRegistry is applied to every rendered image reference,
+#   - the helm test pod image follows test.image.*,
+#   - the dynamic plugins volume honours the StorageClass settings.
+#
+# Usage: hack/assert-rendered-values.sh [chart-dir]   (default: charts/rhdh)
+# Requires helm and yq (mikefarah v4); run `helm dependency build <chart-dir>` first.
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd -- "${SCRIPT_DIR}/.." && pwd)"
+CHART="${1:-${REPO_ROOT}/charts/rhdh}"
+MIRROR="mirror.local"
+
+failures=0
+checks=0
+
+pass() {
+  checks=$((checks + 1))
+  echo "  ok: $1"
+}
+
+fail() {
+  checks=$((checks + 1))
+  failures=$((failures + 1))
+  echo "  FAIL: $1" >&2
+}
+
+render() {
+  helm template test-release "${CHART}" "$@"
+}
+
+# Prints every image reference in the rendered manifests: `image` string fields
+# (containers, initContainers, test pod, CRs) and *_IMAGE / *_IMAGES env values.
+list_images() {
+  yq -N '
+    (.. | select(tag == "!!map" and has("image")) | .image | select(tag == "!!str")),
+    (.. | select(tag == "!!map" and has("name") and has("value"))
+        | select(.name | test("_IMAGES?$")) | .value | select(tag == "!!str")
+        | split(",") | .[] | sub("^[^=/]+=", ""))
+  ' | { grep -v '^$' || true; } | sort -u
+}
+
+assert_images_mirrored() {
+  local label=$1
+  shift
+  local images
+  images=$(render --set global.imageRegistry="${MIRROR}" "$@" | list_images)
+  if [[ -z "${images}" ]]; then
+    fail "${label}: no image references found in the rendered output"
+    return
+  fi
+  local bad
+  bad=$(grep -v "^${MIRROR//./\\.}/" <<<"${images}" || true)
+  if [[ -n "${bad}" ]]; then
+    fail "${label}: images not under ${MIRROR}/: $(tr '\n' ' ' <<<"${bad}")"
+  else
+    pass "${label}: $(wc -l <<<"${images}" | tr -d ' ') images under ${MIRROR}/"
+  fi
+}
+
+assert_equals() {
+  local label=$1 expected=$2 actual=$3
+  if [[ "${actual}" == "${expected}" ]]; then
+    pass "${label}"
+  else
+    fail "${label}: expected '${expected}', got '${actual}'"
+  fi
+}
+
+plugins_root_volume() {
+  yq -N 'select(.kind == "Deployment") | .spec.template.spec.volumes[] | select(.name == "dynamic-plugins-root")'
+}
+
+echo "==> global.imageRegistry=${MIRROR} applies to every rendered image"
+assert_images_mirrored "default values"
+for ci_values in "${CHART}"/ci/*-values.yaml; do
+  [[ -f "${ci_values}" ]] || continue
+  assert_images_mirrored "$(basename "${ci_values}")" --values "${ci_values}"
+done
+# Optional images that no CI scenario enables.
+assert_images_mirrored "optional images enabled" \
+  --set intelligentAssistant.okp.enabled=true \
+  --set orchestrator.enabled=true \
+  --set orchestrator.sonataflowPlatform.dataIndex.image.registry=quay.io \
+  --set orchestrator.sonataflowPlatform.dataIndex.image.repository=ci/data-index \
+  --set orchestrator.sonataflowPlatform.dataIndex.image.tag=1.0 \
+  --set orchestrator.sonataflowPlatform.jobService.image.registry=quay.io \
+  --set orchestrator.sonataflowPlatform.jobService.image.repository=ci/jobs-service \
+  --set orchestrator.sonataflowPlatform.jobService.image.tag=1.0 \
+  --set 'catalogIndex.extraImages[0].name=community' \
+  --set 'catalogIndex.extraImages[0].registry=ghcr.io' \
+  --set 'catalogIndex.extraImages[0].repository=ci/community-index' \
+  --set 'catalogIndex.extraImages[0].tag=1.0' \
+  --set 'catalogIndex.extraImages[1].registry=ghcr.io' \
+  --set 'catalogIndex.extraImages[1].repository=ci/other-index' \
+  --set 'catalogIndex.extraImages[1].tag=1.0'
+
+echo "==> helm test pod image follows test.image.*"
+test_image=$(render \
+  --set test.image.registry=registry.example.test \
+  --set test.image.repository=ci/curl \
+  --set test.image.tag=9.9.9 |
+  yq -N 'select(.metadata.annotations["helm.sh/hook"] == "test") | .spec.containers[].image')
+assert_equals "test pod image" "registry.example.test/ci/curl:9.9.9" "${test_image}"
+
+echo "==> dynamic plugins volume StorageClass"
+# Default is an ephemeral claim with no storageClassName, so the cluster default applies.
+spec_keys=$(render | plugins_root_volume | yq -N '.ephemeral.volumeClaimTemplate.spec // {} | keys | sort | join(",")')
+assert_equals "ephemeral, nothing set: no storageClassName (cluster default)" "accessModes,resources" "${spec_keys}"
+
+sc=$(render --set dynamicPlugins.volume.ephemeral.storageClassName=custom-sc |
+  plugins_root_volume | yq -N '.ephemeral.volumeClaimTemplate.spec.storageClassName')
+assert_equals "ephemeral.storageClassName" "custom-sc" "${sc}"
+
+sc=$(render --set global.defaultStorageClass=global-sc |
+  plugins_root_volume | yq -N '.ephemeral.volumeClaimTemplate.spec.storageClassName')
+assert_equals "global.defaultStorageClass" "global-sc" "${sc}"
+
+sc=$(render --set global.defaultStorageClass=global-sc \
+  --set dynamicPlugins.volume.ephemeral.storageClassName=custom-sc |
+  plugins_root_volume | yq -N '.ephemeral.volumeClaimTemplate.spec.storageClassName')
+assert_equals "ephemeral.storageClassName overrides global.defaultStorageClass" "custom-sc" "${sc}"
+
+sc=$(render \
+  --set workload.kind=StatefulSet \
+  --set dynamicPlugins.volume.type=statefulSetPVC \
+  --set dynamicPlugins.volume.statefulSetPVC.storageClassName=custom-sc |
+  yq -N 'select(.kind == "StatefulSet") | .spec.volumeClaimTemplates[]
+    | select(.metadata.name == "dynamic-plugins-root") | .spec.storageClassName')
+assert_equals "statefulSetPVC.storageClassName" "custom-sc" "${sc}"
+
+# emptyDir must not create any claim, even when a StorageClass is configured.
+out=$(render --set dynamicPlugins.volume.type=emptyDir \
+  --set dynamicPlugins.volume.ephemeral.storageClassName=custom-sc)
+vol=$(plugins_root_volume <<<"${out}" | yq -N -o=json -I=0 'keys | sort')
+assert_equals "type=emptyDir: plugins volume is an emptyDir" '["emptyDir","name"]' "${vol}"
+claims=$(yq ea -N '[select(.kind == "PersistentVolumeClaim"),
+  (.. | select(tag == "!!map" and has("volumeClaimTemplate")))]
+  | length' <<<"${out}")
+assert_equals "type=emptyDir: no PVC or ephemeral claim rendered" "0" "${claims}"
+
+echo
+if ((failures > 0)); then
+  echo "${failures} of ${checks} rendered-values assertions failed" >&2
+  exit 1
+fi
+echo "All ${checks} rendered-values assertions passed"