docs: sync from frontend a433067 — Docker Yarn cache ENOSPC fix

11 - Testing/Smoke and Regression Procedure.md

@@ -106,6 +106,28 @@ npx eslint src/web3/config.ts src/web3/types.ts src/sections/payment/checkout/rn
 npm run build
 ```
 
+Frontend Docker install-layer smoke:
+
+```bash
+cd ~/CascadeProjects/escrow/frontend
+DOCKER_BUILDKIT=1 docker build --no-cache --target builder -t escrow-frontend-builder-smoke .
+docker image rm escrow-frontend-builder-smoke
+docker builder prune -f
+```
+
+Use this when CI fails before `npm run build` in the Docker dependency install
+layer. For a faster local isolation check, create a temporary Dockerfile from the
+production Dockerfile through the Yarn install `RUN` block, then append:
+
+```dockerfile
+RUN test -d node_modules/country-flag-icons && test ! -d /root/.yarn/v6
+```
+
+The expected install command uses a locked BuildKit Yarn cache, a Yarn mutex,
+`--frozen-lockfile`, and `--link-duplicates`; the layer must clear `/root/.yarn`
+before and after install so stale Yarn v6 cache contents do not exhaust builder
+disk while copying packages such as `country-flag-icons`.
+
 Scanner focus:
 
 ```bash