diff --git a/chart/templates/config.yaml b/chart/templates/config.yaml
index 432468c..cab56fb 100644
--- a/chart/templates/config.yaml
+++ b/chart/templates/config.yaml
@@ -20,4 +20,9 @@ data:
   PHP_INI_DATE_TIMEZONE: Europe/Paris
   DOLI_AUTH: dolibarr
   DOLI_CRON: !!str 0
+  {{- if ne .Values.env "prod" }}
+  # Non-prod (sandbox): dev mode — render real errors inline instead of the generic
+  # prod "technical error" banner. Prod keeps the image default (DOLI_PROD=1).
+  DOLI_PROD: !!str 0
+  {{- end }}
   # DOLI_INSTANCE_UNIQUE_ID: <random salt for encryption>
\ No newline at end of file
diff --git a/test/README.md b/test/README.md
index 185d1e7..b35d417 100644
--- a/test/README.md
+++ b/test/README.md
@@ -34,12 +34,14 @@ sandbox:
 ```sh
 kubectl -n erp-sandbox exec \
   "$(kubectl get pod -n erp-sandbox -l app.kubernetes.io/instance=erp-sandbox -o name)" -- \
-  /bin/sh -c 'touch /var/www/html/install.lock && chown www-data:www-data /var/www/html/install.lock'
+  /bin/sh -c 'touch /var/www/documents/install.lock && chown www-data:www-data /var/www/documents/install.lock'
 ```
 
-For prod, swap to `-n erp -l app.kubernetes.io/instance=erp`. Not needed when the
-instance was seeded from a prod dump instead of freshly installed — see
-`../ops/sandbox/`.
+The path is the Dolibarr **data root** (`/var/www/documents`, a PVC) — that's where
+Dolibarr checks, and being on the PVC the lock persists across pod restarts. For
+prod, swap to `-n erp -l app.kubernetes.io/instance=erp`. A sandbox **seeded** from
+prod still needs this: the seed (see `../ops/sandbox/`) copies the DB +
+`documents/mycompany`, not `install.lock`.
 
 ## Provision the sandbox