diff --git a/docs/app-developer-guide.md b/docs/app-developer-guide.md
index eed3bcfe..11378008 100644
--- a/docs/app-developer-guide.md
+++ b/docs/app-developer-guide.md
@@ -341,6 +341,21 @@ cmp -s app-catalog/catalog.json neode-ui/public/catalog.json
 
 ## Testing Your App
 
+### Validate Your Manifest
+
+Before anything else, check your manifest against the schema and the app-submission
+rules:
+
+```bash
+./scripts/validate-app-manifest.sh apps/my-app/manifest.yml
+```
+
+It reports `STATUS: APPROVED` or `STATUS: REJECTED` with the specific failures —
+including the ones that block submission, such as an unpinned `:latest` image
+tag (new apps must pin a concrete version). It needs `python3` and PyYAML; it
+tells you if either is missing. The Rust parser in `core/container/src/manifest.rs`
+remains the canonical validator — this script is the fast local preflight.
+
 ### Local Testing
 
 ```bash